Acorn User 1984 Magazine

BBC micro, Electron and Atom magazine

January 1984 £1

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Microcomputer

DESIGNED WITH
PROGRESS IN MIND

An example of superior technology, total reliability and outstanding
performance, combined to produce the LVL Disk Drive Family.

Truly professional units designed to work with the BBC \ \ |

• Compatible with the BBC drive units.
Disks are interchangeable with those
formatted on the BBC Drives.

• Operates either from the BBC DOS the
LVL Double Density DOS Kit or from th
optional Z80 and CP/M.

• Supplied complete with all necessary
connecting leads, utility disk and full
operating manual.

• Available from all LVL Dealer^.

• Powered from your BBC model B

computer. No chance of data corruption

Scientific House, Bridge Street. Sandiacre, Nottingham
NG105BA Tel: 0602 394000

BBC

MICROCOMPUTER

Model B

Model B & Disc Interface
Model B & Econet
Model B & Econet & Disc Int
Disc Interface Kit

£399
£469
£446
£516

£97

* Speech Synthesizer (official BBC) £54

Teletext Receiver £225

1 2 Operating System (me! fitting) £11.50

Basic 11 £15

* New in stock Price md fitting.

MANNESMANN MT80

High quality 80 column senal dot matnx
printer Dual density dot addressable
graphics, quick tear facility as standard,
optional sound reduction kit to give an
impressive L55dBa acoustic noise rating
Ability to handle both tractor-fed fanfold
and single paper
Special price of £295

EPSON

You can use tins latest
Philips Green Monitor
to». personal
computers business
computers control
systems automatic
test equipment The
picture quality otthe.
TP20Q means not
only 80x24 lines of
information but also
usage tor high
resolution graphics
At the bargain price of

BBC Official 12"

£79

£95

NOW AVAILABLE
THE ACORN ELECTRON

ONLY £199 .00

Ideal tor BBC Micro and any other computes
with standard interface b'A" S>rmne onboard
single chip microcomputer reduces TTL count
by 70% extra tow power requirement, direct
dnve (no belts') guide ran means completely
qu-et operation unique eiect mechanism tast
6ms track to track access t me tully guaranteed
Cased with leads

Pnced a! ’ • STAR BARGAIN PRICE
£169

£40

£9.50

£13.50

Th»s TV Monitor is not a modified
television as many TV Monitors are. but a
14" TV Monitor which has been designed to
perform both functions 't has RGB and
Composite video and sound An RGB cable
tor a BBC is supplied as standard

FLOPPY DISKS —4

Floppy Disks in packs of 10
Single sided 40 Track
Double sided 80 Track

WORD PROCESSORS

View Word Processor

£59

Word Wise Word Processor

£45

Epson FX80 F/T

Epson RX80 F/T
Epson FX100T/T

DAISYWHEELS

With Remote Control

Colour monitor

Microvitec 14" 1431

£269

£247

Logitec-FT 5001

Friction and adjustable sprocket feeding
variety of printing models, (PICA & ELITE
pitch) user font registry command,
automatic paper insertion, 96 ASCC1 1 with
descenter. 8 international character sets.

48 semi graphics'

At the very low price of £330

r

JUKI 6100

20 CPS pnnt speed, supports all Wordstar
features, emulates diablo protocols

Juki 6100 Daisywheel with 2K Buffer . £395

TORCH DISK PACK

Torch Z80 Disk Pack
4MH3 Z80 Application Processor
Perfect Software

At New Low Price
£835.00 Inc. Installation

SLIM DISK DRIVES-

BBC Compatible

KUK STIK L

JOYSTICK >■*

- 1

- SELF CENTRING

> : .;3

Two Fire Buttons

Single -£17.95

Dual - £34

%

SANYO

SLIM

3A

The slim 3G Sanyo Cassette Recorder cHv

NIT £28.95

O oa BBC Cassette Re - Jer £29.95
'Cassette Recorder lead £2.50

80 column, friction
and adjustable tractor
feed, bidirectional logic seeking
HI RES graphics and block graphics,
sub and supersenpts, condensed and
emphasised print, and underlining vertical and
horizontal tabs, self test, italic print etc
Shmwa CP80 FA £289

Parallel Printer Lead £13

2000 Sheets Fanfold Paper £15

Screen Dump Rom

£17.25

Analyse Disk

£15

Compatible for
MX80. FX80 etc

BROTHER HR15

Buffer 3K byte, shadow printing super/sub
script, carnage skip movement, text reprinting
colour pnntmg (red and black), auto under-
scoring proportional spacing clear buffer —

Also available with keyboard.

Brother HR15 £431

Keyboard £176

Jf

TEAC 55A
S/S 40 TRACK

100K SD Smgle
200K DD Dual

TEAC 55E
S/S 80 TRACK

200K Single
400K Dua

TEAC 55F
D/S 80 TRACK

400KS/D Smgie
800K D/D Duai

MITSUBISHI

400K D/S DD Smgle
Dual

ODDS

Official Joysticks

£13-

£269

£539

£269

£539

Compatible Joysticks Damping Contro£15
Dust Covers - for vanous machines -
from £3.95

* SERVICE CONTRACTS TO
EDUCATION AUTHORITIES
AT DISCOUNT

* OFFICIAL ORDERS FROM DEALERS,
GOVERNMENT DEPARTMENTS,
COLLEGES AND SCHOOLS WELCOME

* ALL PRICES INCLUSIVE OF VAT

FORMATTING DISK & MANUAL £10

♦ALL DRIVES CASED WITH FREE CABLES

NEW BOOKS
AND SOFTWARE
IN STOCK

FITTING

SERVICES

AVAILABLE

BBC Model B plus Disc Interface fitted view. V.OU
| Green Monitor Juki Daisywheel Printer
I 200K Dual Disc Drives and manual and formating disc
ONLY £1.360 (incl all cables)

HOW TO . You may purchase any of the items listed by cheque. Barclaycard or

_ Dn Access. All you have to do is fill in the details in the coupon below and list
U rv U t K your requirements on a separate sheet of paper. Post to us and we will
despatch within 7 to 14 days All prices inclusive of 15% VAT.

Add £2 50 P&P for orders below £150. over, add £8 P&P

TELEPHONE ORDERS (01) 574 5271

Credit card holders may order by telephone. Give Card No.. Name. Address and item required.

Post to:

TWILLSTAR COMPUTERS LTD.

17 REGINA ROAD. SOUTHALL MIDDLESEX.

I have enclosed my list of requirements along with my cheque/P 0 for £—

Twillstar Computers Limited

17 REGINA ROAD SOUTHALL MIDDLESEX TEL: (01) 574 5271

I prefer to pay with my ACCESS/BARCLAYCARD (Delete whichever not applicable)

CARD NO

SIGNATURE

NAME

ADDRESS

TEL: (Day)_
TEL: (Eve)_

m

(OPEN SIX DAYS A WEEK 10 a m to 8 p.m.)

CREDIT CARDS VALID IF SIGNED BY CARD HOLDER. ADDRESS ABOVE MUST BE THE SAME AS
CARD HOLDER.

/,cU-2

CONTENTS

ACORN USER

7

The News

Queen gives BBC micros to India,
Liberals set up computer groups, 52k
Beeb, £20 caption competition,
Winchester network

13

Software Top 20

A new feature where we try to put the
market into perspective

15

WIN a BBC micro

... or an ink-jet printer in our three-
section competition

20

Techniques

Stan Froco continues his look at
graphs and how they can be used in
computing

29

Joe’s Jottings

Stacks and queues in real life, Basic
and languages: Joe Telford explains
what they are

37

Hints and Tips

Teletext is the flavour of the month
here, as Martin Phillips takes the lid
off mode 7

43

Processing speech

There’s a lot more to Acorn’s voice
chip than meets the ear. Ian Rowlings
plumbs its hidden depths

53

Games writing

Snapper author Jonathan Griffiths
sets down his ideas on structure, and
gives away some Acornsoft secrets

Front cover illustration by David John Rowe

61

Electron interfacing

Paul Beverley downloads data at high
speed

67

Beeb Forum

Operating system commands are a
bone of contention this month. Ian
Birnbaum directs

71

Life

Graphics routines written by Malcolm
Banthorpe

79

Defencecom listing

Simon Williams explains how he wrote
a BBC version of Missile Command

in Basic

91

The Train Game

If you’re fed up with invaders, Peter
Balch's game is a refreshing change

103

Machine code graphics

Speeding up screen manipulation is
the aim of Nick Wilkinson

116

Forum Extra

Ian Birnbaum explains where to put
machine code

119

Schools

Caesar’s assassination was the
inspiration for a project by Charles
Bake’s pupils on handling data

123

OU micro pack

Robin Ward casts her critical eye over
this course for teachers

125

Daisywheel printer

Juki gives small businesses and
home users the chance to produce
quality letters, says George Hill

133

Atom Forum

Barry Pickles answers questions and
provides a single key input routine

137

Atom Adventure

It’s Christmas but all is not well with
Santa in this amusing, and crafty,
diversion

141

Reviews

■ Three Atom products

■ Salamander utilities

■ Escape from Orion

■ BBCSoft Toolbox

■ Transistor’s revenge

■ Mr T’s Money Box

How to submit articles:

You are welcome to send articles to the Editor of Acorn User for publication.
Acorn User cannot undertake to return them unless a stamped addressed
envelope is enclosed. Articles should be typed or computer written with double
line spacing. Black and white photographs or transparencies are also
appreciated. If submitting programs a cassette or disc is vital Payment is £50
per page or pro rata. Please indicate if you have submitted your article
elsewhere. Send articles, reviews and information to: The Editor, Acorn User,
53 Bedford Square. London WC1B 3DZ. Tel: 01-631 1636

Annual subscription rates:

UK

£15

Europe

£18

Middle East

£20

The Americas and Africa

£22

Rest of the World

£24

These prices are inclusive of post and

packing (air mail overseas) for 12

issues.

2

ACORN USER JANUARY 1984

JANUARY 1984

18

147

Word processor

Beeline is a cassette- based program
which gives a good introduction to the
subject, says Chris Drage

151

School programs

Five Ways and Bourne packages are
looked at

153

Reviews

■ Gemini’s Caterpillar

■ Owzat? from Virgin

■ Missile Control

■ Chemical Analysis

■ BBC/NEC Beyond Basic

■ Firehawks by Postern

■ Electronic Monopoly

159

Chess trial

BBCSoft and Acornsoft programs are
put through their paces by John Vaux

163

Dealers list

166

Readers’ letters

Six pages of comment, opinion, facts
and advice on everything from XREF
to impossible problems

176

Reader services

178

User groups

179

Readers’ free ads

183

£1 0 small adverts

Coming soon in Acorn User:

Adventures:

Our second special issue puts
some of the biggest names in
BBC adventures at your
fingertips. How they write
them, plan them, squeeze
them in, and some handy
routines. Who are the authors?
Think of the biggest names
and find out if you’re right in
the next issue

Languages

Forth, Lisp, BCPL,

Pascal . . . what are they all
about? Why should you use
one rather than the other?
Which one to choose for a
specific task? These questions
and many more will be
answered in a new series

Electron

More uses for Paul Beverley’s
6522 interface, and general
tips on using the machine

Reviews

3in discs, Prestel adapters,
RAM extension cards, second
processors - they’re all under
way

Authors please note

We've been inundated with
articles for publication - many of
an extremely high standard. It
takes time to read them, try

listings out and edit them - which
is the only way to maintain
standards. Also remember that

magazines work at least two

months in advance.

So please bear with us if you
hear nothing for weeks (although
all submissions are acknow-
ledged).

Thanks for your patience and
apologies for any frustration

caused.

Actual screen shot of Swordmaster

£7.95 each

TWO games are now available from
Acorn User. They are Sword Master
(BBC B and Electron) and Trek (BBC B
and Electron). Both make extensive use
of the excellent graphics, speed and
sound of the machines. Turn to page 10
for details.

All rights reserved. No part of this publication
may be reproduced without prior written permis-
sion of the publisher The publisher cannot
accept any responsibility for claims or errors in
articles, programs or advertisements published.
The opinions expressed on the pages of this
magazine are those of the authors and do not
necessarily represent those of the publisher,
Acorn Computers Ltd, or Acornsoft Ltd. Acorn,
Acornsoft, and the Acorn symbol are the regis-
tered trademarks of Acorn Computers Ltd and
Acornsoft Ltd

Editor Tony Quinn Editorial Assistant Kitty Milne Art Editor Phil Kanssen. Production

Peter Ansell, Tina Teare. Promotion Manager Pat Bitton. Publisher Stanley Malcolm.
Typesetting & Artwork Camden Typesetters, Camden Road, NW1. Printed in Great

Britain by E. T. Heron & Co Ltd Advertising Agents Computer Marketplace Ltd, 20
Orange Street, London WC2H 7ED. Tel: 01-930 1612 Distributors to the News Trade
Magnum Distribution Ltd, 72-8 Fleet Street, London EC4Y 1HY. Tel: 01-583 0961. Telex:
893340 Magnum G. Subscriptions BKT Subscription Services, Douglas Road, Ton-
bridge, Kent TN9 2TS. Tel: (0732) 351216. Publishers Addison-Wesley Publishers Ltd, 53
Bedford Square, London WC1B 3DZ. Tel: 01-631 1636. Telex: 881 1948.

ISSN: 201-1 7002 7 © Addison-Wesley Publishers Ltd 1983

ACORN USER JANUARY 1984

3

The best thing next

The BBC Model B microcomputer is widely recognised as an
impressive first computer for the home or the school, but its capabilities
are restricted by its lack of data storage and the limitations of Basic for
serious programming. For the user who needs more from this computer
the Torch Z80 Disc Pack is a gateway to the world of advanced computing.

The Disc Pack includes a second processor-the proven and
reliable Z80 which powers Torch’s highly acclaimed C-series business
computer. The Z80 co-operates with the Model B’s own 6502 chip,
delegating screen and peripheral handling to provide faster access speeds
than any other comparable disc drive system.

ft

Model B’s fitted with disc interface can be upgraded to full business
machines by the Torch Z80 Disc Pack thereby offering the use of more
powerful and flexible languages such as Fortran, Pascal, BCPL and Cobol,
while twin 400K disc drives provide a massive storehouse for

information and rapid data transfer from
disc to processor.

In addition to accepting the BBC’s extensive range of software, the
Z80 Disc Pack supplies Torch’s own CP/M - compatible Network
operating system, based in Readonly Memory (ROM). 'This advanced
design means that almost all of the 64K of Random Access Memory
( RAM ) provided on the Z80 board is available for CP/M programming
use- an advantage that no other BBC micro upgrade can offer.

If your BBC micro has the Econet option, there is a further benefit
the Z80 Disc Pack can provide.Torchnet can link together up to 254
upgraded Model B’s on a local area network, so for enthusiasts’ clubs and
schools it is a simple and low-cost way to set up a local area network.

At only £730? including installation at your dealer, the Torch
Z80 Disc Pack offers real value for money. It is supplied with an
impressive package of software including the PERFECT" range of
business software comprising Perfect Writer ( word processing) Perfect
Filer ( database management) and Perfect Calc ( advanced, powerful
spreadsheet). Add to that COMANEX the interactive management game,
approved and used by leading Management Consultants -and you have a
software package valued at over £1,000.

The Torch Z80 Disc Pack is a proven and cost-effective way of
increasing the computing power of your BBC Model B micro, so if you are
ready to take a step into the world of serious computing, contact your
local dealer, listed on the facing page.

to a BBC micro.

i

Torch Z80 Disc Pack. Technical Specification.

4MHzZ80 Application processor • (>4K RAM • IfiK
R( )M • Torch MCP ( 8K CP/M compatible
operating system with Networking in firmware) •
Disc interface lead • 2MHz BUS lead for Tube
socket • Low voltage PSu output • Perfect
Software comprising: 1 . Perfect Writer-word
processing • 2. Perfect Filer- database
management • 3. Perfect Calc -financial
spreadsheet • 4. Perfect Speller- spelling checker
• Comanex - interactive management game
Torch CPN CP/M compatible O/S disc utilities
( Pokedisc, Mapdisc) music system (Muscmpx,
Music) • Miscellaneous utilities (Font, Rd Acorn,
Torchbugetc)

2 400K ( formatted) floppy disc drives
UCSD p-system available from I.S.V. Languages
available Cobol, Forth, Fortran, Lisp, Pascal, Pilot,
Basic, Prolog, BBC Basic (Z80), BCPL, C(Z80)

Torch Computers Limited, Abberley House
Great Shelford, Cambridge CB2 5LQ
Telephone: (0223) 841000 Telex 818841 TORCH G.

*RRP£730ex VAT.

CP M is a registered trademark of Digital Research Inc. Econet is a
registered trademark of Acorn Computers Ltd. Perfect Software is a
registered trademark of Perfect Software Inc.

Comanex is a registered trademark of Sapphire Systems
Text, graphics and keyboard ‘provided by BBC Model B

TORCH A

COMPUTERS

Lighting the way ahead.

Where to find your Torch dealer

AVON

ESSEX

MERIT COMPUTERS

PACEMAKER COMPUTING LTD

AVON COMPUTER RENTALS

AKHTER INSTRUMENTS LTD

Unit 4 Caroline Street Wigan

5th Floor. Scala House Small Brook

8 Eastbury Close Thornbury Bristol

Unit 19 Arimghide Estate. South Road

Tel 0942 495821

Birmingham

Tel 0454 415460

Templelie’ds Harlow

NORTHERN COMPUTERS

Tel 021643 0544

CCE EUROPE LH)

Tel 0279 412639

Churchfreld Road frodsham Wamnginn

PSB

10 Somerset Avenue Ybte. Bristol

CAPRICORN COMPUTER CENTRE

Tel 0928 35110

11 Bennetts Ruad Washwood Heath

Tel 0454 321088

32 North Hill Colchester

NSC COMPUTER SHOPS

Birmingham

JA0E COMPUTERS

Tel 0206 68471

2A Hanging Ditch Manchester

Tel 021328 7124

Coombond Radstock

CLACTON COMPUTER CENTRE

Tel 061832 2269

STARMER COMPUTERS LTD

Tei 076136397

29-31 Pier Avenue Clacton on Sea

LEICESTERSHIRE

Richmond House 69 School Sheet

BEDFORDSHIRE

tel 0255 422 644

PERCY LORD & SON

Wolverhampton

BR0A0WAY ELECTRONICS

EASTERN DA1A PROCESSING LTD

63BlabyRoad Wigstnn

Tel 0902 713173

1 The Broadway. Bedford

Whilelands. Hatfield Peverel Chelmsford

Tel 0535 785033

WAL1ERS COMPUTER SYSTEMS

Tel 0234 213639

Tel 0245 380009

RHMURC0T1 LTO

1? Hagley Road Stourbridge

0ATASINE

ESSEX COMPUTER CENTRE LTO

Great Central Rd L oughbotnugh

lel 03843 70811

59 North Sheet. Leighton Buuard

150 Moulsham Sheet Chelmsford

Tel 0509214444

NORFOLK

Tei 0525374200

Tel 0245358702

MNCOINSHIRE

JARROLD OFFICE EQUIPMENT

BERKSHIRE

HESELTINE BUSINESS SYSTEMS

COMPUTACROP

Barrack Street Norwich

GOLEM LTD

7 Cambridge House. Cambndge Road

SCornmarket Louth

lel 0603 660661

77 0uahtas Bracknell

Barkmq

Tel 05076042/1

SYNERGY LID

Tel 0344 507020

Tel 01 5916111

FELIX COMPUTERS

E Block. University Village Umveistlyol

MICR0STYIE

MICROCORE LTD

63 Wide Bargate, Boston

fast Anglia Norwich

Newbury Computer Centre

5 Broomfield Road Chelmsford

Tel 02055432)

Tel 0603 503015

47 Cheap Sheet, Newbury

Tel 0245 64230

OAKLEAf COMPUTERS LTD

NORTHAMPTONSHIRE

Tel 0635 41929

GLOUCESTERSHIRE

121 Oudley Road Grantham

COPUTERWORLO

P J MICROSYSTEMS

COMPUTER SHACK

Tel 0476 76994

19 Abmglon Square Northampton

l4Wtiodend Crowthorne

14 Pittville Street. Cheltenham

LONDON ANO GREATER L0N00N

Tel 0604 31661

Tel 0344 772351

lei 0242 564343

AUOIOTRONIC SYSTEMS LTD

DATABASE COMPUTERS

SLOUGH RA0I0 CONTROL

TELEMATICS WEST

78 Buckingham Gate. SWt

7 High Sheet Irlhlmgborough

The Bishops Centre Bath Road

31 Oyer Street Cirencester

Tel 01-222 2615

lel 0933 650133

Taplow

Tel 0205 68349

BAINBRIOGF COMPUTERS ITD

DAIAlEAf LTO

Tel 0628666828

HAMPSHIRE

78 Green Sheet E7

63 Bradshaw Way. Irchesler

WIN0S0R COMPUTER CENTRE

ADACS

Tel 01 4713350

Tel 09334 50362

1 Thames Road Windsor

41 London Road Andover

BRAINSTORM COMPUTER SOLUTIONS

NOTTINGHAMSHIRE

Tel 0753558077

Tel 0264 52187

103A Seven Sisters Road N7

G A COMPUTERS LTO

BUCKINGHAMSHIRE

AMEECO (HYQROSPACE) HD

lel 01 2726619/2636926

20 22 High Street. Ruddmgton

COMPUTER SYSTEMS ANALYSIS LTD

2 North Way Walworth Industrial Estate

CAVENDISH GRAPHICS

lel 0602 2134927211225

Europa House. Marsham Way

Andover

43 New Cavendish Sheet W1

HN&L FISHER (HUT HWAIIE) LTO

G err ard Cross

Tel 0264 56744751699

lel 01 462 2173

264 Huthwaite Road. Sutton in Ashheld

Tel 0753 885389

ELECT RONEQUIP

CHROMASONIC

Tel 0623 553437

CHILTERN ELECTRONICS

34/38 West Street. Fareham

48 Junction Road Archway N19

LEASAUNK VIEWDATA

High Street. Chaltont St Giles

Tel 0329230670

Tel 01-2639493

230 236 Derby Road Staplelord

Tel 02407 71234

FERRANTI AND CRAIG

COMPUIALINE

tel 0602 394000

TYPOS SYSTEMS LTD

5 New Market Sq . Basingstoke

14-16 Oxford Circus Avenue

OXFORDSHIRE

Office tl Spareregal Centre Coin Estate

Tel 025652203

231 Oxford Sheet Wl

ROCON LTD

733A Old Bath Road Coin Brook

JOHN LANE SYSTEMS LTO

lel 01-434 4017

Radley Road Industrial Estate

Tel 028123753

5A Charles Street Petersheld

COMPSHOPITO

Abingdon

CAMBRIDGESHIRE

Tel 073067221

14 Station Road New Barnet

Tel 023524206

ARDEN DATA PROCESSING LTD

NUDATA COMPUTER SYSTEMS

Tel 01 4412922

SHROPSHIRE

166 Park Road. Peterborough

Unit 1 Mitchell Close Fareham

HARRISON ASSOCIATES LTD

COMPUTER VILLAGE LTD

Tel 073347767

Tel 048958300

Unit 307 16 Brune Street El

Walker House Telford Town Centre

CAM8RIDGF COMPUTER CONSULTANTS

RMK ELECTRONICS LTD

Tel 01 3771630

Telford

124/126 Ross Sheet. Cambridge

Hinton House Station Road New Milton

ICT LTD

Tel 0952 506771

Tel 0223 210677

lei 042561600

76 Cannon Sheet. EC4

STAFFORDSHIRE

CAMBRIDGE COMPUTER STORE 1

HERTS

Tel 01 24BB895

CABEL ELECTRONIC LTD

Emmanuel Sheet Cambridge

COMPUTER PLUS

IN1ERAM COMPUTER SYS1EMS LTD

Mount Road Burntwood. Walsall

Tel 0223 358264/65334

47 Queens Road Wattord

46 Balham High Road. SW12

lel 05436 2121

CONTROL UNIVERSAL

Tel 092333927

Tel 01-675 5325

COMPUIERAMA

Unit 2, Andersons Court Newnham Road

HUMBERSIDE

LION HOUSE (RETAIL) LTD

59 Foregate Sheet. Stafford

Cambridge

THE COMPUTER CENTRE

227 Tottenham Court Road Wl

lel 0785 41899

Tel 0223358757

(HUMBERSIDE)

Tel 01 5B0 7383

PEN SPEED LIMITED

HI-TEK DISTRIBUTION U0

26AnlabyRoad Hull

0FFREC0R0S

Wharf House. Eradley Junction. Alrewas

Trafalgar Way Bar Hill Cambridge

Tel 0482 26297

Computer House. 59 Battersea Rise SW11

Burton on Trent

Tel 0954 81931

HOLOERNESS COMPUTER SERVICES

Tel 01 223 7730

Tel 0283 790338

HERALD COMPUTERS

17Westgate.Pahmgton Nr Hull

PERMEX LTD

SUFFOLK

93 East Road. Cambridge

Tel 0964 30225

l odge House l odge Road NW4

BRAINWAVE MICROS LTD

Tel 315622

VIXON COMPUTER SYSTEMS LTD

Tel 01-203 4243

24 Crown Sheet Ipswich

CHESHIRE

49 Grimsby Road Cleethorpes

REW VIDEO PRODUCTS LIMITED

Tel 04/3 50965

FAIRHURST INSTRUMENTS LTD

Tel 0472 58561

118 Garratt Lane SW18

SJEMERY&CO

Dean Court WoodlordRoad Wilmslow

ISLE OF MAN

Tel 01-8709911

10 Market Place Bunqay

Tel 0625525694

ICA SERVICES LTO

SATELLITE BUSINESS SYSTEMS LTD

Tel 0986 2141

MARPLE COMPUTER CENTRE

0 Mount Hoveiock Douglas

Satellite House 332 Goswell Road. EC1

MICROMANAGEMENI

30/32 Market Sheet, Marple Stockport

let 0624 26548

Tel 01- 278 3366

32 Princes Sheet. Ipswich

Tel 0614499933

TYPESIYLE LTD

SILICON VALLEY COMPUTER

Tel 0473 59181

MID-SHARES COMPUTER

1 Avondale Court Onchan

CENTRE (GROUP 18 LTD)

SURREY

(SERVICES) LTD

Tel 0624 24650

Suite 104/105 16 Baldwins Gardens EC1

COMPUTAID LTD

78 Nantwich Road. Crewe

ISLE OF WIGHT

Tel 01-242 2803

No 1 Warehouse HorleyRow Horley

Tel 0270 211086/211064

VECTIS COMPUTER SERVICES

STEIGER COMPUTERS LTD

Tel 02934 72206

NATIONAL MICRO CENTRES LTD

40 Cansbrooke Road. Newport

Steiger House North Circular Rd

CROYOON COMPUTER CENTRE

Norbury House. Norbury Crescent

Tel 0983 528345

Stonebndge Park NW10

29A Brrgstock Road. Thornton Heath

Hate! Grove Stockport

KENT

Tel Of 9616000

let 01 689 1280

Tel 061456 8500/9548

THE COMPUTER USERS CLUB

TECHNOMATlC LTD

3 D COMPUTERS

CLEVELAND

69HadlowRoad Welling

17 Burnley Road NW10

230 Tolwonh South Surbiton

AUTOCALL COMPUTERS LTD

Tel 01-3112555

lel 01 4521500/4506597

lel 01 337 4317

17 Middlesbrough Road Southbank

KENT MICROS LTO

IRIGON OFFICE SERVICES LTO

GUILOFORO COMPUTER CEN1RE

Middlesbrough

57 Union Sheet Maidstone

98 Victoria Road NW10

l The Quadrant Bridge Sheet Guildford

tel 0642 468618

Tel 0622 52784

lel 01 9611466

Tel 0483 578838

CUSTOMISED ELECTRONICS

KENT MICROSYSTEMS

THE VIDEO PALACE. (MEGAVIDEO) LTD

JSSIMNETT COMPUTERS LTD

155 Morton Road Middlesbrough

Conquest House 17 Palace Sheet

100 Oxford Street. Wl

91 Acre Road Kingston Upon Thames

Tel 0642247727

Canterbury

Tel 01 637 0366/7

Tel 01 5463793

CORNWALL

Tel 0227 50200750366

MERSEYSIDE

KINGSTON COMPUTER CENTRE

MICROTEST LTD

MEOWAY COMPUTERS LTO

DATA EXCHANGE

59 Surbiton Road

18 Normandy Way Bodmin

114 New Road, Chatham

Exchange House. 164 New Chester Rd

Kingston Upon Thames

Tel 02083171

Tel 0634 826080

Birkenhead

Tel 01 5499416

DERBYSHIRE

MICROSOURCE LTO

Tel 051647 9185

MISTER CALCULATOR (CCS) LTO

FBC SYSTEMS LTD

Lyons House 9 New Road

PLESSEY INFORMATION

First Floor. 19 Park Sheet Croydon

10 Main Centre. London Road Derby

Rochester

TECHNOLOGY CENTRE

lel 01 686 9616

Tel 0332 365280

Tel 0634 814931

Unit 9, Penpoll Works Hawthorne Rd

MODERN BUSINESS TECHNOLOGY

OEVON

MOOATA LTD

Bootle Liverpool

PO Box 87 Guildford

A & D COMPUTERS

30 St Johns Road

Tel 051933 3100

lel 04868 23956

Cumpuierland! 6 City Arcade

Tunbridge Wells

MIDDLESEX

PJ EQUIPMENT LTO

Fore Sheet. Exeter

Tel 0892 41555

OATASOLVE LTO

3 Bridge Street Guildford

Tel 0392 77117

PATHLINE LTO

99 Staines Road West

lel 0483 578848

COMPUTER SERVICES (SW) PIC

19 King Street West Mailing. Maidstone

Sunbury on Thames

STATACOM LTO

Mrllbay Road. Plymouth

Tel 0732 848477

Tel 09327 85566

234 High Sheet. Sutton

Tel 0752668814

PRESTEOGE ASSOCIATES LTD

MICROAGE

Tel 01 6112266

DEVON COMPUTERS LTD

188 Canterbury Road Margate

135 Hale Lane Edgware

VlTAlPQRT LTO

The White House 39 Totnes Road

tel 0843 32616

Tel 01 9598411

44 Radclitfe Road. Croydon

Paignton

LANCASHIRE

SYSGOUD

Tel 01 654 5751

Tel 0803 526303

THE BYTE SHOP (MANCHESTER) LTD

Hawkehouse Green Sheet

SUSSEX

DORSET

11/12 Gateway House Piccadilly Station

Sunbury on T hames Middlesex

CJE MICROCOMPUTERS

HUGH SYMONS

Approach. Manchester

Tel 09327 89571

25 Henry Avenue Rushngton

COMPUTER SERVICES LTD

Tel 061236 4737

TWICKENHAM COMPUTER CENTRE

Tel 09062 6647

lansdowne 5 Holdenhurst Road

DOUBLELINE LTD

72 Heath Road. Twickenham

SOUTHEAST C0MPU1ERSLT0

Bournemouth

Unit 2 Forrest Way Gateworth Industrial

Tel 01-8911612

Unit 2. Castleham Road Hastings

Tel 0202 20165

Estate. Great Sankey Warrington

MIOLANDS (WEST)

Tel 0424 426844

CO OURHAM

Tel 0925 573212

COMPUTACCOUNT

TYNE SWEAR

DARLINGTON COMPUTER SHOP

IMO (BUSINESS SYSTEMS) LID

21 Spnng Hill Ladywood Birmingham

HCCS

75 Bonolgate, Darlington

Tel 0325 487478

39-43 Standish Street. Burnley

Tel 0282 54299

Tel 0212363455

533 Durham Road. Low Fell Gateshead
Tel 0632 821924

QUALITY MICROPROOUCTS LTD

Victoria Buildings, 46 Grainger Street

Newcastle Upon Tyne

Tel 0637 614646

WARWICKSHIRE

CARVEltS Of RUGBY

9 Bank Street. Rugby
Tel 0/88 65775
lEAMINGION HOBBY CENTRE

171 Regents Street l eamington Spa

Tel 0976 79711

WILTSHIRE

BEESGREEN IT0

POBoil/4 Swindon

Tel 0/93 611455

WIllSHIRE MICRO CENTRE

4/ Victoua Road Swindon

Tel 0/93 617799

YORKSHIRE

BRA0E0RD OFFICE SUPPLIES CO

Colonial Buildings 139 Sunbndge Road

Bradford

Tel 07/4 776/83

COM TEC

6 Eastgale. Barnsley
lei 07764697?

DAI RON MICR0CFNTRE S
2 Abbeydale Road Sheffield
Tel 0/47 585490/585400
ELIEC COMPUTERS LID
731 Manninqham Lane Bradford
Tel 02/4 4913/2
GTM COMPUTERS LTD
864 York Road Leeds
Tel 0537 647474
SUPERIOR SYSTEMS
178 West Sheet Sheflield
lei 0742 755005
MICROPOWER

8/8A Regent Sreet Chapel Allerton
Leeds

Tel 0537683186

WALES

CIWY0

IECHNEGCLWYD TECHNICS LTD
The Coach House KelstertonRoad Flint
tel 0244 810518

DYFED

HIGHLANDS COMPUTER SYSTEMS
2 Cowell Street Llanelli
Tel 05542 70517

GLAMORGAN

BUC0N LT0

18 Mansel Sheet Swansea
Tel 0797 467980
CARDIFF MICROCOMPUTERS
46 Charles Street. Catdift
Tel 0222373072
GNOMON LTD

10 Mount Stuart Square Cardiff
lei 0222 489484

PENNY COMPUTER SYSTEMS

Oown Farm. Wrck Road LlantwitMaior

Tel 04465 4539

SIR COMPUTERS LID

91 Whitchurch Road Cardiff

Tel 0222 21341

6WENI

GWENT COMPUTERS

151 Chapstow Road Newport

Tel 0633 215008

PRIN1R0NIC LTD

Hill House Raglan

Tel 0291690214

SC0TLAN0

FIFE

COMPUTER SERVICES (SCOTLAND)

89/90 West law Place

Whitehill Industrial Estate

Glenrothes

Tel 0592 773710

GATE MICROSYSTEMS LTD

TheNethergateCenlie Dundee

Tel 0382 28194

LOT Hint

ANDREW WHYTES SON 110

Hupelown Works Hopeluwn Sheet

Edinburgh

Tel 031556 0191

SILICON CENTRE

7 Antigua Sheet. Edinburgh
Tel 031557 4546
STRATHCtVDE
C0MMSC0TT LT0

30 Gordon Sheet. Glasgow
Tel 041226 48/8

1 0RNE COMPUTER SERVICES LTD
12 High Sheet Oban Argyll
Tel 063165635

VICTOR MORRIS (AU) LIMITED
340 Aigyle Street, Glasgow
Tel 0412218958

WEST COAST PERSONAL COMPUTERS

70 Wellington Square Ayr

Tel 0292 285082

NORTHERN IREIAN0

CEM MICROCOMPUTER SERVICES

11/ University Sheet Belfast

Tel 0232 244111/243564

EVERYMAN COMPUTER SERVICES

80 Charlotte Sheet. Ballymoney

County Antrim

lei 02656 62658

NEWBURN ELECTRONICS

58 Manor Road. Ballycarry, County Antrim

Tel 09603 78330

SOUTHERN IREIAN0

IEN0AC0ATA SYSTEMS

8 Dawson Street, Dublin 2
Tel 710226/710/96

More than fun and games!

withthe,7HKl7lm

by Primer Educational Software

f heever-popularMr. Men help prepare
young children for reading with four
simple and absorbing games
designed to exercise essential skills as well
as entertain.

An easy-to-use, colour-coded key
guide is included with an illustrated
introductory book, featuring the Mr. Men.
For ages 4 to 8 years. Available now on
cassette for the BBC B and Electron (also
on the Spectrum 48K). £ 8.95

(lUIML

by Widgit Software

Two mind-stretching, space-age games to test
mental arithmetic and nimble fingers. In Sum
Vaders alien robots invade the earth. Only quick
thinking and fast reactions can prevent them.
Several levels of difficulty and a two-player game
with a handicap option make Sum Vaders equally
testing for all family members, from 8 years to adult
Robot Tables challenges the young player
to make a series of perfect robots.

Knowing your multiplication tables is the key
to controlling the robot-making machine. With a
learning mode and a testing mode, Robot Tables is
a fun way for early learners, and more advanced
children, to master an important and often
neglected skill.

Available now on cassette
for the BBC B and Electron
(also on the Spectrum 48K and
Commodore 64). £ 6.95

C/SSARTHECAT

by Andromeda Software

Meet Caesar, a cheeky young cat on duty in a well-
stocked larder. He's kept busy chasing a gang of
hungry mice eating the family’s food. Playing against
the clock, you guide Caesar along crowded shelves to
pounce on the mice.

A fast, colourful, all-action, arcade-style game
with catchy music and a best-score record.
Challenging for high-scoring arcade addicts as well as
great fun to play for the novice. Sorry, only available on
cassette for the Commodore 64! £8.95

Prices include VAT and post and packaging.

MIRRORSOFT programs are available from selected branches of
WH. Smith and Boots, and other leading software stockists.

Trade enquiries welcome: phone 01-822 3580.

SOFTWARE FOR ALL THE FAMILY

To MIRRORSOFT, PO Box 50, Bromley,
KentBR29TT

number required of each item in
the space provided):

Price

Spectrum
48K (01)

BBCB

(03)

Electron

(04)

CBM

64(05)

First Steps with the Mr Men (MM01)

£8.95

.

Quick Thinking (OTOI)

£695

Caesar the Cat (CC01)

I enclose a cheque/PO for £ made payable

to "Readers’ Account: Mirror Group Newspapers Ltd"

I understand that my
remittance will be
held on my behalf in
the bank account
named above until
the goods are
despatched.

Or please debit my ACCESS/BARCLAYCARD for the sum of £
card no rn r

urn

AU1 |

Signature

Name

Address...

Postcode

Offer applies to Great Britain and Fire only Please allow up to 28 days for delivery in the UK MIRRORSOFT ts a registered trade mart of Mirror Group Newspapers Ltd Co Reg No 168660 Reg Office Hofbom Circus. London EC1

6

ACORN USER JANUARY 1984

NEWS

Queen takes

Winchester

networks

PACE, who do the Amcom DFS,
have announced a Winchester-
based network aimed at schools. E
Net is the name and up to 250 BBC
micros can be linked.

At just under £2000 for a basic
system, it isn’t cheap, but then the
Winchester hard disc holds
10Mbyte of memory and can be
upgraded to 140Mbytes.

Each station on the network can
be given a priority level, and allocat-
ed a certain amount of memory.
The overseeing teacher has com-
plete control of all users and can
assign a password and station num-
ber to each user These must be
typed in before that station can be
used.

The teacher can view any screen
on the network at any time and send
messages to all or selected sta-
tions. This means advice or instruc-
tions can be passed to a pupil who
is having problems.

Printers can be shared by the
machines on the system, or at-
tached to each.

The micro which is reserved for
the role of ‘file server’ can be used
as printing takes place, because a
buffer in the Winchester takes care
of the data.

Pace are at 92 New Cross St,
Bradford BD5 8BS.

Cool memory

NO LESS than three memory ex-
tension boards are produced by
Ramamp Computers.

All three are designed to fit under
the BBC micro’s keyboard, rather
than over the RAM area, to reduce
the possibility of overheating.

They also avoid the need to bend
any of the power supply pins in the
RAM area, says Ramamp

The ROM extension board pro-
vides six extra chip slots; the RAM
board adds up to 16k, while the
ROM RAM extension gives four
ROM slots plus an extra 16k of
RAM.

Details are available from Ram-
amp at 25 Avon Drive, Whetstone,
Leicester. The company also pro-
duces a two-watt sound amplifier.

BUCKINGHAM Palace had Acorn
chiefs in a right royal flap shortly
before the Queen set off for the
Commonwealth Conference in In-
dia .. . when Her Majesty decided
the BBC micro would be her official
gift to the Indian people.

But it was without doubt the high-
est compliment the Beeb has ever
received and the company pulled
out all the stops - plus a number of
6502 second processors.

Half a dozen six-station Econet
systems were presented by the
Queen to the Indian President Mr
Zail Singh shortly before the confer-
ence began.

The machines are to be used in
education, where the Indian govern-
ment sees a great potential for
Beebs. In fact 200 more machines
have been ordered, and the
£700,000 deal could lead to Beebs
being assembled in India.

Acorn only knew about the gift
three weeks before they were hand-
ed over.

Six Econets are
official gift to
Indian President

Each of the systems arrived in
India complete with a 6502 second
processor - though this meant
whipping three of the rarities from
exhibition stock due to be shipped
to America for the Comdex show.

According to Tom Hohenberg,
the company’s marketing manager,
the idea to give BBC computers as
a present was the Queen’s own.

So is there a Beeb user group at
the Palace? Does Di play Snapper ?
Does William like Killer Gorilla ? A
discreet silence from Cambridge.

But the company makes no se-
cret of its pleasure at the decision.

‘We are absolutely delighted that
the Queen should consider that our
product will make a significant con-
tribution to Indian education,’ says
Tom Honehberg.

£20 on Digger and Roz

OUR two high-flyers this month are Roz Evitts and Sean de Bray of
the Visions software factory. And what we want you to do is to put a
humorous caption to their picture (£20-worth of software to the
winner, entries by Feb 5).

Visions has just added the zanily-named Pengi and Digger to its
Snooker and Dare Devil Dennis BBC games (there’s also an Electron
Snooker). All the games cost £7.95, apart from the Snookers which
are £1 more. Two new releases, Sound Studio and Paint Box are
planned for the New Year at £14.95 each.

Taking the drudge out of drugs

DISPENSARY is a software pack
for pharmacists which runs on the
Torch and BBC micros.

It comes on disc at £70 or in
EPROM at £75 and is capable of
stock control, age analysis and
labelling.

The main menu has nine options;
print labels; update drug file; view a
drug; update direction file; update

suffix file; update warning file; print
sales report; sort drug file; and
finish.

A minimum system with a 100k
disc drive can handle 1 000 drugs at
a time, although the addition of
further drives will increase this ca-
pacity considerably.

Each drug has its own file holding
the following information; name;

code; suffix code; warning code;
PIP code; quantity used to date;
supplier’s code.

Dispensary is designed to be
used with a dot matrix printer to
produce the drug labels and
reports.

A R Computers, who have re-
leased the package, are at Market
Lane, Ipswich IP1 1BN

Beebs

One obvious problem of course is
how the machines will be serviced
and maintained.

They were taken to India and set
up by Lawrence Hardwick, one of
Acorn’s customer service experts.

But what happens when . . . well,
any long-term Beeb user can think
of things that can go wrong and
need a bit of adjustment.

What will happen to the Indian
machines? Good question, says
Hohenberg, but unfortunately there
is not yet a clear answer.

However, the market potential of
the sub-continent is well recognised
by the company, which is busy
wooing several foreign govern-
ments to introduce BBC micros into
their education systems.

Arrangements for supplying the
gifts were personally supervised by
Acorn’s managing director, Chris
Curry.

So could this be described as an
Indian Curry? Only at your peril,
warns Hohenberg.

Project to help
disabled students

A NEW college course on assess-
ing the needs of physically disabled
students in further education has
been set up - equipped with Beebs.

The two-year project at Hereward
College, Coventry, will look at de-
velopments in information technol-
ogy. The college is buying equip-
ment for an assessment
programme which will be used with
external students from next year.

Each of the 15 students in 1984's
intake will be equipped with a BBC
model B, disc drive, monitor and
printer.

Hereward will work with a team
from Warwick University involving
both the psychology and the indus-
trial and business studies depart-
ments. Warwick research funds will
be used to help produce an integrat-
ed system providing word-process-
ing, calculation and graphics on
BBC micros.

The project is backed by the De-
partment of Trade and Industry and
requires analyst/programmers to
join the team. Anyone interested
should contact Geoff Stevens, In-
dustrial and Business Studies, War-
wick University, Coventry CV4 7AL.
(Tel; 0203 24011, ext 2456.)

40/80 disc choice

ACORNSOFT discs will in future
come in a format that is readable on
40 and 80 track drives. Sounds like
a good idea. Wonder which of the
major software houses is going to
be the first to offer cassette-disc
upgrades on programs?

ACORN USER JANUARY 1984

7

Fonts in ROM

FROM Watford Electronics
comes this press release adver-
tising the Beebfont monitor ROM.
The letter neglected to mention
the price, but no doubt Watford
can fill you in on that.

The picture on the right shows
the press release reduced to
slightly less than half size (it was
originally on A4 paper). It was
printed using a dot-matrix
machine.

Liberal micro alliance

Thi

s is

a sample printout from our

neu ”

monitor

ROM.

it

is a

very clever

rom. One can create any

character

including Chinese end info,

Can

l f

lease request

pon to mention

tits

in tl

je netns sect!

on of tie next

tMne

of 1

ico rn Bser.

Ham it up on a
micro with RTTY

TAPPING into transmissions from
the likes of Russia’s Tass and Lon-
don’s Reuters is possible on the
BBC micro.

Ham radio enthusiasts have for
years been tuning into such trans-
missions, called radioteletype
(RTTY) Now. through the Beeb,
news agency broadcasts can be
decoded and displayed in English
on a monitor.

A device to do just this, and
information about RTTY in general
is available from J Melvin, 2 Salters
Court, Gosforth. Newcastle NE3
5BH.

IT HAD to happen. Home micros
are going into local politics. And
already it is clear that a favourite
candidate for your constituency
computer is the Beeb . . probably
in alliance with the Electron.

Appropriately enough, the idea
for this Acorn alliance comes from
half of the other alliance, the Liber-
als. They are setting up a party
network based upon the privately-
owned micros of their members
throughout the country.

The network was launched last
September at the annual assembly
in Harrogate. It is called Micro Lib
(what else?) and is seen as an
important new way for the party to
organise wards and constituencies.

The first obvious problem in set-
ting up a network is, of course, the
difficulty of coping with the different
types of machines available.

Though Sinclairs of various sorts

Digital images
from video

VIDEO cameras and micros can get
together with an interface from Edu-
cational Electronics.

The device accepts signals from
sources such as video cameras,
VHS players and video discs.
These images are then digitised
and displayed with a maximum res-
olution of 220 x 312 pixels, in 64
shades of grey.

Once digitised, pictures can be
saved to disc or analysed by other
software.

A machine code program is sup-
plied with the interface (seen at the
front of the picture), and it comes
with a cable to the user port for
£200.

Digitising a picture takes about
four seconds, which can cause dis-
tortion of a moving image. Educa-
tional Electronics offers a software
writing service for specialist
applications.

Details from the company at 30
Lake St, Leighton Buzzard, Beds
LU7 8RX.

make up the biggest number of
home micros on the group’s list, the
Beeb is the single most popular
machine - and there are already
one or two Electron owners regis-
tered. This has led Micro Lib’s co-
ordinator, David Graham, to fore-
cast that an Acorn alliance could be
just the answer for local parties.

He sees the BBC being the stan-
dard machine for many constituen-
cies - but with ward and branches
equipped with Electrons.

According to the Liberals, the po-
tential for home computers in the
battle for the polls, though still un-
clear, is enormous. Among the most
obvious uses, of course, are boring
old files, membership, helper, and
supporter lists, plus branch and
constituency funds.

But the Liberals are very keen on
what they call community politics’.

This involves producing large

numbers of local newsletters, usual-
ly produced at home on small print-
ing machines, but typeset’ on ordi-
nary portable typewriters. The result
is less than professional in
appearance.

Now the advent of computerised
community politics' offers prospects
of wordprocessed papers using
View or Wordwise.

Further in the future, Micro Lib is
looking into the possibility of a nat-
ional network linked over the tele-
phone system by modems. But the
group admits it is still feeling its way
and the most immediate plans are a
one-day conference next February
in Wimbledon to prepare for next
spring’s local elections and the
Euro-elections next summer.

One can only assume - after
Micro Lib - it cannot be long before
we have Micro Soc Dems, possibly
Con Comps and Micro Labs.

Summer camps

CHRISTIANS, led by Acorn User
author Paul Beverley, are to run a
holiday for 13-16 year old boys. The
aim is to give them the opportunity
to learn more about computers and
electronics.

Micros will be used to control
model trains, cars, robot arms etc.
with sessions on simple electronics
and programming, and some as-
sembly language if there is a de-
mand. Interfacing electronic equip-
ment to BBC micros will be a prime
aim. The cost of the camp is £48 for
a week.

The camp comes under the aus-
pices of the Inter-Schools’ Christian
Fellowship and there will be a
chance in the evenings to learn
more about what it means to be a
Christian in today's world.

There are two one-week camps:
11-18 and 18-25 August. For de-
tails, contact Mrs Sue Beverley, 57
Cambridge Street, Norwich NR2
2BA.

Games weekend

WRITING games in Basic is the title
of a weekend course at Horncastle
Residential College in February,
and a second session on program-
ming will follow it.

Applicants should have a rea-
sonable knowledge' of Basic, and
are encouraged to take their BBC
micros along, to add to those al-
ready available.

The games weekend will be Feb-
ruary 17-19, and the programming
will be held mid-week on February
20-22. More facts from Horncastle
Residential College, Mareham Rd,
Horncasle, Lines LN9 6BW

Network theory

NETWORKS 84 covers the theory
and design of local and international
systems and takes place at the
Wembley Conference Centre in
London on July 3-5. Online are the
organisers at Pinner Green House,
Ash Hill Drive, Pinner, Middx HA5
2AE.

The interface from Educational Electronics (foreground of picture)
which can digitise a video image in about four seconds. Pictures can
be taken from a video camera, VHS player or disc. Interface plus
machine code program cost £200.

8

ACORN USER JANUARY 1984

’&% Christmas Cheer and Champagne

FREE bottle of Champagne with any marked item purchased
Champagne offer applies to marked items only
Offer closes 31st December 1983

BBC Model B

£399.00

Printers

BBC Model B + Disk

£469.00

MCP40 Colour Plotter

£129.95

BBC Model B + Econet

£446.00

% *Microline80(80cps)
*Star510(100cps)

£220.90

£287.50

Disk Drives

H * Epson RX80 FIT (lOOcps)

£339.25

BBC Single 100k

£265.00

f * Epson FX80 F/Y (1 60cps)

£440.73

^*Cumana Single 100k

£228.85

Epson MX100 (lOOcps)

£487.77

^‘Cumana Dual 200K

H * Broadway Switchable 400K

£419.75

£373.75

*Juki 6100 DaisyWheel

£458.85

<£* Broadway ” ” 800K

£688.85

Monitors

^*T orch Z80 Discpack

£839.50

‘Phoenix High Res Green 12"

£109.25

BBC Utilities Disk & Manual

£ 30.00

Phoenix ” ” Amber 12"

£113.85

BBC Games Paddles

£ 13.00

% ‘Microvitec 14" Colour

£247.25

BBCTeletext receiver

£225.00

Fidelity 14" Colour

£228.85

BBC Disc Interface

£ 97.00

■? ‘Oriel 48K

BBCGraphics Digitizer

£ 34.44

£139.00

BBC Light Pen £ 14.89

Sanyo Computer Cassette Rec £ 44.85

Dragon 32

£175.00

Acorn Electron

£199.00

All Prices include VAT.

We stock all the Acornsoft Software for the BBC also Program Power

and Computer Concepts.

Much more in stock please telephone for details.

11 DEVONSHIRE ROAD
LONDON W4
TEL:- 01-994-8588

1 THAMES AVE
WINDSOR BERKS
TEL- WINDSOR 58077

ACORN USER JANUARY 1984

9

ACORN USER SOFTWARE U NEWS

52k BBC micro

£7.95

for 32k BBC micro
or Electron

(joystick or keyboard)

Two-player game

£7.95

for Electron
or

32k BBC micro
(joystick or keyboard)

Uses voice synthesis

ARIES B20 is the board that adds a
potential 20k to the BBC micro -
which means you can run programs
in the highest graphics mode and
still have 28k left.

The board has virtually no effect
on processing speed, says Peter
Headland who heads Cambridge
Compu f er Consultants, makers of
the board. The only difference is
that operating system calls are
slowed down by something less
than 1 per cent.

Software which uses legal OS
structures works with the board -
including View, and Acornsoft’s ver-
sions of BCPL, Lisp and Forth Also,
the board will work with the second
processors.

Headland, who at one time
worked for Acorn, added that the
board makes use of an unused
*FXcall - 1 1 1 - which was sanc-
tioned by Acorn. (He had originally
wanted to use *FX80, but this is
reserved for something else!)

Games which make use of direct

screen access for speed, such as
Acornsoft’s, are coped with by the
board. It merely provides a com-
mand which switches back to nor-
mal BBC micro operation.

The Aries fits inside the BBC s
case and extends memory up to
&7FFF, whichever screen mode is
selected. In Basic, HIMEM is al-
ways &8000.

Major advantages of the board
will include a four-fold increase in
the size of files with View when in
mode 0.

Also, programmers will be able to
take advantage of the improved
screen layouts in 80-column modes
with Lisp and ether highly-struc-
tured languages.

The board can be fitted in five
minutes using just a screwdriver,
says Headland No soldering, no
cutting tracks or links.

It costs £99.95 from Cambridge
Computer Consultants, FREE-
POST, Cambridge CB1 1BR Tel:
(0223)210677.

Acorn User presents two high-quality games on cassette
for your micro which put you at opposite ends of time.
Developed, produced and tested by Micrograf.

Sword Master by Ken Worrall is based
on the fencing rules written in 1190 by
Herman von Salza for the Deutscritter
Order of Teutonic Knights. It features
full colour, machine code animation of
a sword duel between the players
shown on screen as knights.

Full instructions, music, sound ef-
fects, player rankings (from greenhorn
to Swordmaster) and a roll of honour
(which can be saved) and all included
The game also closely reflects the
rules, style and dress of the Deutscrit-
ter Order

Trek puts you in charge of a Starship
with the task of wiping out an alien
fleet. It’s an excellent adaptation of the
classic game with 7 screen displays, 3
on-board computers and 2 weapon
systems.

Versions have been written for BBC
micro and Electron to use both mach-
ines to their full. The BBC tape uses
voice synthesis (if the chips are fitted).

The game has been extensively de-
veloped from Tim Heaton’s Trek III. It
now barely fits into 32k - and the
graphics are in mode 7.

DCP Interbeeb with power supply

More tapes will soon be released.

i

. To: Acorn User Software, 53 Bedford Square, London WC1 B 3DZ.

Please send me:

1 copies of Sword Master at £7.95 each

for BBC (32k Series 1 OS) £

I for Electron £

. copies of Trek at £7.95 each

for BBC (32k Series 1 OS) £

j for Electron £

I I enclose a cheque for £ . made payable to Addison-Wesley

I Publishers Ltd.

I Name

, Address

1 Post code .

i i

Knight triumphs

WHITE KNIGHT, BBCSoft’s chess
program, fought its way to take a
joint first prize at the European
Chess Championship.

The Event was held at* the PCW
Show, and White Knight was
entered in the home program
section.

See John Vaux’s appraisal of the
game (page 159).

Medical exchange

THE Assocation for the Study of
Medical Education is setting up a
group for exchanging information
on computer-based material.

Commercial teaching aids will be
reviewed and the better ones
shown in regular news sheets.

Anyone interested should contact
Graham Clayden, Computer Teach-
ing Aid Clearing House, ASME, 2
Roseangle, Dundee DD1 4LR,
Scotland.

Interfacing
in a box

INTERBEEB provides a complete
electrical interfacing system in a
neat box, says DCP
Microdevelopments.

Each unit has four relay out-
puts, four switch inputs, an eight-
bit input port, output port, and an
eight-channel analogue to digital
converter. It costs £60.

Applications include control
projects, heating systems, bur-
glar alarms, model control, and
industrial monitoring.

Further details from DCP, 2
Station Close, Lingwood, Nor-
wich NR134AX.

4 .

C

10

ACORN USER JANUARY 1984

Christmas
gifts from
Cambridge!

The Advanced User Guide for the BBC Micro:

Over 500 pages of detailed informa- BBC computer. We sold over 1 0,000
tion on commands, programming, copies in 6 weeks; buy it and you’ll
interfaces and hardware, including see why! Excellent value at £12.95
the complete circuit diagram of the

Word-processing:

a complete
package for £899—
including VAT

Package comprises: BBC Model
B Microcomputer • TEAC disk
drive 100K • SHINWA CP80

printer, complete with cables,
ready to use.

TYPE ’N’ TALK

SPEECH COMPUTER

Developed and manufactured in
Cambridge, the Type ’n’ Talk is a
very powerful software package,
optimised to convert any text into
speech faster than it can be spoken.
Connected to any computer via an
RS232 or RS423 serial link, it allows
you to type in words or numbers
which are then spoken out loud over
a powerful speaker. All in all, an
amazing new concept in man/
machine communication. £171.35

PRINTERS

EPSON FX-80 £395.00

EPSON RX-80FT £315.00

EPSON RX-80T £275.00

SEIKOSHA GP 1 00A £220.00

SHINWA CP-80 £275.00

JUKI 6100 £395.00

BROTHER p.o.a.

Delivery charge: £6.00 per item

DISK DRIVES

100K TEAC Slimline, complete
with cables, etc. £165.00

200K TEAC 40/80 switchable,
complete with cables, etc. £190.00

400K TEAC/MITSUBISHI 40/80
switchable, complete with
cables, etc £250.00

Delivery charge: £ 6.00 per item

MONITORS

SANYO 14" green £86.31

KAGA 14" yellow £123.45

KAGA 14" green £108.00

KAGA 12" colour £300.00

Delivery charge: £10.00 per item

MISC. ITEMS

Printer cable for BBC £1 6.50
Disk drive signal cable BBC £9.75
Disk drive power cable BBC £4.50
Diskettes:

3M SS/DD
DS/DD
SS-96 TPI
DS-96 TPI

set of 10 £20.68
set of 10 £28.00
set of 10 £32.00
set of 10 £44.00

Delivery charge: £1.00 per item

BOOKS

Dragon 32 £5.95

Over the Spectrum £6.95

Understanding your Spectrum

£7.95

Practical Programming for
the BBC £6.95

Creating Advanced Programming
for the BBC £6.95

. . .and many other books.

ALL PRICES
INCLUDE VAT

Credit terms available
for orders of C500 or over.
Access, Barclaycard and
American Express welcome.

Cambridge

Alicrocomputer

Centre

Distributors of Computers & Computer Peripherals • Publishers
153-4 East Road, Cambridge CB1 1DD
Telephone (0223) 355404 Telex 817445

Limited

Cambridge Microcomputer Centre is a wholly owned subsidiary ol Narnal

ACORN USER JANUARY 1984

11

ummmrnm

12

ACORN USSR JANUARY 1984

SOFTWARE CHART

Publisher

Disc

Game

1 30 Bomb Alley

2 747 Flight Simulator

3 KMer Gorilla*

4 30 Deep Space

5 Planetoids

6 Dr Who

SoOwnre 'nwsion

Doctor Soft

Program Power

Postern

Acornsoft

7 Per ®GCSo ft

Escape from Moonbase A(pha*p r

8 Oblivion 9ram Powe r

£ 11. 95
£ 11.95

8 Oblivion

9 Wor '<1 Travel

'° Native Graphics

1 1 Copper

12 The Sentinel

13 G unsmoke

14 Hunchback

15 Monsters*

76 The Hobbit

17 0*Bert

18 Sea Lord

19 BeebArt
38 Chess*

Dug Byte

S,m °n H «ssel £fi g
Acornsoft

£9.9*

Acornsoft

£9.95

PSS

SoSware Invasion

Superior Software p*

Acornsoft _

£9.95

Welbouroe House C14. 95
Superior Software
Dug Byte
Quicksilva

£11.95

£ 11.95

I'll I C7 ' 95 < e 5-95)

Bubbling under: Spa,*, A<] ~ _______

-■■'■sasa:.'

ACORN USER JANUARY 1984

13

The best name in memory

b>^"-

In the rapidly expanding world of computer
peripherals there is one company which
continually leads the field — Cumana.
Whether it is the best Japanese components
used in our top quality designs, the rigorous
training which all staff receive, or the superb
technical service we offer, everything must be
of the highest standard.

Cumana disk drives have an independent
power supply, 12 months warranty, and are
fully assembled and tested before packaging;
and they are now available for the BBC and
Dragon Micros — at unbeatable value for
money prices — from selected branches of
W. H. Smith and Spectrum UK in addition to
Cumana’s nationwide dealer network.

For further information on these and other
Cumana products — including dual slimline
disk drives for the BBC Microcomputer —
contact:

Cumana Limited, Pines Trading Estate,

Broad Street, Guildford, Surrey, GU3 3BH.
Tel: (0483) 503121 Telex: 859380

Dragon is the registered trademark of Dragon Data Ltd.

For further

1 am interested

Interests:

information

in Cumana disk

Home Use 1 I

about Cumana

drives for the

Education □

disk drives,

BBC/Dragon *

Dealer IJ

please

Microcomputer

Business U

complete and

‘delete as

return this coupon

necessary

Name

Address

Tel. No

Note If dealer, please attach this form to your letterheading

COMPETITION

WIN A BBC MICRO

OR AN INK JET PRINTER

Simon Dally offers a BBC model B and two Olivetti printers
(worth £350 each) as prizes

SEPTEMBER

COMPETITION

RESULTS

SEPTEMBER’S competition for the
first level of the dungeon beneath
the Acorn User offices generated
an enormous response: over 600
entries were received from people
eager to win the printer.

A particular source of amusement
was the picture postcard brigade,
including readers in Australia. Hon-
ourable mentions in this category
go to P Lewis and Alan Cox of
Brighton, who managed to send in
between them a dozen postcards
featuring the more attractive parts
of that pleasant town’s nudist
beach! Well, it was more interesting
than the party political conference
going on there when I was reading
the entries!

Others interesting postcard-send-
ers were Marcus Goodey of Col-
chester, who sent us a patriotic
Union Jack, Peter Lumb of Berk-
hamsted, who opted for some ag-
gressive-looking lions and Adrian
Welch of Aberdeen, whose offering
featured a disgusting-looking half-
eaten salmon on a bed of dried-out
old lettuce!

Others of you preferred ribald
commentary. Why not make them
tax inspectors and insurance sales-
men instead of dwarfs and trolls?’
asked Andrew Newton of Derby.

A full list of the solutions will be
published, along with an explana-
tion of the dungeon characters in
two or three months time, when
entries for the other two competi-
tions have been received. The cor-
rect combination was 10836728,
which half of the entrants got right.
Owing to a couple of ambiguities in
the wording, not least the remark
that you always worked in positive
integers, a few other solutions were
admitted as well.

A word of warning: the first cor-
rect entry out of the bag came from
Liverpool but had no name or ad-
dress on it. Quite a lot of you in your
fervour do this: the only beneficiary
is the Post Office.

So, the winner of the Seikosha
printer was Jonathan Farmer of
Selby, Yorks.

Custo-

mers

A

R

C

D

E

F

COINS

G H 1

J

K

L

M

N

O

Retail

value

Adam

10

3

2

3

18

15

13

7

15

11

15

7

9

9

23

4688

Ben

14

24

20

25

23

24

7

1

10

15

9

4

11

13

11

4828

Carl

9

<0

25

3

7

14

5

17

1

1

7

15

4

18

20

4861

David

22

23

12

3

25

19

13

24

14

10

13

20

24

16

10

7097

Eddy

24

8

18

17

22

24

18

25

5

11

18

25

22

21

10

7649

Fred

15

14

5

20

1

11

7

10

22

24

15

7

8

2

11

4191

George

25

1

22

17

23

23

18

4

17

21

20

2

6

17

22

5970

Harry

20

17

1©

22

16

12

4

11

10

6

8

3

17

13

22

5275

Iris

4

14

12

23

8

18

20

17

1

15

14

15

2

22

15

5322

Jane

14

23

6

6

16

19

8

20

23

20

2

18

12

14

25

6172

Kate

24

2

15

1

13

9

10

17

5

0

14

24

16

18

3

5278

Len

25

15

15

15

23

14

18

7

15

13

2

1

0

1

18

3395

Mike

7

18

10

24

24

15

11

24

5

19

0

22

18

23

8

6133

Nigel

18

2

17

0

19

13

13

23

3

16

14

15

21

20

24

7147

What each customer got in his bag

PART ONE

The first problem is designed for the
younger members of the family to
attempt before they get any help.

American currency includes a
nickel (five cents) and a quarter (25
cents). There are 100 cents to the
dollar.

A currency reform enthusiast
once proposed the introduction of a
new coin called the grobble. He
declared that using grobbles and
quarters only (and at least one of
each) he could form the sum of
$100 in 14 different ways.

If a grobble consists of an exact
number of nickles what is the high-
est amount of cents it could be
worth?

WHEN you’ve completed all
three parts, send you entry to
January Competition, Acorn
User, 53 Bedford Square, Lon-
don WC1B 3DZ to arrive not
later than February 3, 1984.

PART TWO

THIS problem is for everyone. A
coin dealer decided one day to get
rid of some excess stock he had of
15 varieties of coin. He hit on the
idea of a lucky dip’, that is he made
the coins up into 14 bags containing
a random number of coins. These
he sold at £4000 a bag.

As this was quite a good deal he
had no trouble in selling his bags.
The figure shows what the custom-
ers found inside.

If a bag containing one example
each of all the 15 coins would be
worth £411 at normal retail prices,
what was each coin worth?

PART THREE

Clues down

1 ET once constructed a means of
linking BBC micros (6)

2 no kidding, but it has a negative
value (4)

3 Sounds like profane programmer's
editing aid (6)

4 Latest issue of Acorn's DOS? - let it
go! (7)

5 Graphics command on the allot-
ment? (4)

8 Discs and cassettes, etc might give
you star ego (7)

9 One who allows a non-numeric sym-
bol (6)

13 Frenchman, following fashion, gets
an add-on unit (5)

15 Program failure - hand round the
fags! (5)

1 7 Error message causes no anger (2.4)

18 Unaccommodating error message
(2.4)

20 Colour to see mother embracing a
spy (7)

23 Animated screen effect upsets priest
( 6 )

25 What a dollar gets you, basically? (6)

27 Somewhat medieval way of getting
the computer to do a calculation (4)

29 A pseudo-variable the old lag's seen
a lot of (4)

Clues across

6 The squirrel's monthly? (5,4)

7 A screen effect used off and on (5)

10 Ernest madly presses the return key
(6)

1 1 The micro to make Ronald an MP (8)

12 A cat - Acorn’s first? (4)

14 It’s soft just pressing break! (5)

15 Nancy loses her head and goes
peculiar colour! (4)

16 In gold a jumbled message for the
cassette user (7)

19 Shopping avenues setting the stan-
dard for computer games? (7)

21 A common seaside feature, it can't
be erased (4)

22 Studies at university as the computer
accepts data (5)

24 Symbol that's a real mess? (4)

26 Comprehensive sound command - it
may need addressing (8)

28 Confused tuner after right key (6)

30 Hold up part of Model A, you’ (5)

31 Something to be said for a program-
ming instruction (9)

• Crossword set on a BBC micro,
and printed on an Epson by Eddie
James

ACORN USER JANUARY 1984

15

o

WATFORD ELECTRONICS

Dept. ACORN, CARDIFF ROAD, WATFORD, HERTS, ENGLAND.
Tel: Watford (0923) 40588/37774 Telex: 8956095 WAELEC

BBC MICROCOMPUTER

Model A — £260; Model B-E346

Upgrade your Model A with our
Upgrade Kits and save yourself £ s s s

•

BBC1 16K Memory

(8 x 4816AP 3 lOOnS

£20.00

•

BBC2 Printer User I/O Port

£7.10

•

BBC3 Disc Interface Kit

£85.00

•

BBC4 Analogue I/O Kit

£7.25

•

BBC5 Serial I/O Kit

£7.50

•

BBC6 Expansion Bus Kit

£6.75

•

Complete Mod. A to B Upgrade Kit

£48.00

Dust Cover for BBC Micro

£3.95

Protects your expensive Micro
from foreign bodies

DISC DRIVES (CUMANA)
BBC COMPATIBLE

• New TEAC Slimline Uncased Drive S/S 40

track, 5K. 100K £135

• New TEAC Slimline Cased without PSU, S/S,

40 track, 5*", 100K £145

• CS100-TEAC Cased with own Power Supply,

S/S 40 track, 5}", 100K £180

• CD200 — TEAC Twin Cased with own PSU, S/S,

40 track, 5J", 200K £350

• CS200-TEAC Single Cased with own PSU,

S/S, 80 track, 5 y, 200K £250

• CD400-TEAC Twin Cased with own PSU, S/S,

80 track, 5*", 400K £475

• CS400-TEAC Single Cased with own PSU,

D/S, 80 track, 5**, 400K £310

• CD800-TEAC Twin Cased with own PSU, D/S,

80 track, 5J" 800 K £599

• MITSUBISHI Slimline - Uncased, double

density. Double track, 5$", 1 Megabytes, track
density 96TPI, track to track access time 3mSec.
Plugs directly to BBC Micro. ONLY £220

• SINGLE MITSUBISHI Slimline -Cased with
own PSU, DS/DD, 1 Megabytes. (400k with BBC)

£275

• TWIN MITSUBISHI Slimline Cased with own
PSU, DS/DD, 2 Megabytes. (800K with BBC) £535

• Single Drive Cable for BBC Micro £7

• Twin Drive Cable for BBC Micro £10

• Dual SWITCHABLE DRIVES, 40/80, 400K.

Cased with own PSU, Slimline £495

5£" DISKETTES

5 year warranty

10 Verbatim or 3M Diskettes, 5J", S/S £20

10 Verbatim or 3M Diskettes, 5J", D/S £30

2 year warranty

10 WABASH Diskettes, 5J", S/S £15

10 WABASH Diskettes, 5J", D/S £25

Carriage on Drives £7

DISC ALBUMS. Attractively finished in beige
leatherlook vinyl. Stores, protects and displays 20
Discs in double-sided clear view pockets.

Only: £4.95

PLASTIC LIBRARY CASES
for Disc Storage 5j" (holds io> £2

BBC

PRINTER

GP100A

10" Tractor Feed,
80 columns, 30CPS
Normal & Double width Char,
Dot res graphics. Parallel Interface standard.

ONLY £165 (£7 carr.)

INTERFACE CABLE

BBC to Seikosha Cable

£10.00

DUST COVER for gpioo

£3.95

FRICTION FEED

Attachment for GP100A or 250 X Printers

£22

• Spare RIBBON for GP80

• Spare RIBBON for GP100

• Spare RIBBON for GP250

£4.50

£4.95

£5.95

100 CPS, 9x9 matrix, dot addressable graphics
condensed and double width printing. Normal, Italic
and Elite Characters. Tractor feed, 10" max width,
bi-directional, logic seeking. Centronics Interface
standard.

ONLY £239 (£7 carr.)

RX80 F/T PRINTER: As above but has

both

Friction and T ractor feed £269

Epson FX80 Printer

160 CPS, 11x9 matrix, proportional spacing
superscripts, subscripts, dot addressable graphics.
Normal, Italic and Elite characters. Up to 256 user
definable characters. Down loadable character set.
Condensed and double width printing. Full
proportional spacing. Four user defined margin
positions. Tractor and Friction feed. 10" maximum
width Bi-directional, logic seeking Centronics
interface standard.

ONLY £369 (£7 carr.)

Ribbons

Dust Co

MX80FT

£4.75

£4.50

MX100

£10.00

£5.25

FX80

£4.75

£4.95

RX80

£4.75

£4.50

PRINTER INTERFACE BUFFER

When your system tries to serve you well but its
efforts are frustrated by slow printers delaying from
returning to more productive tasks then this is where
our Printer Buffer Interface comes to your resuce.
Available in 16K or 48K memory sizes. Simply
connect the integral cables to your Micro and the
Printer and switch on. The free standing compact
unit (130 x 135 x 40mm) is supplied complete with
interface cables, a power supply and a
comprehensive manual.

Price: 16K £115

48 K £149

BROTHER HR-15

DAISY-WHEEL PRINTER

An exceptionally high quality Daisy Wheel printer at
the price of a Dot matrix printer. 18CPS; Bi-
directional, 3K of Buffer; has clear buffer facility,
Carriage skip movement. Proportional spacing;
underlining; Bold print and Shadow print. Prints in
two colours; Super and Supscript facility. Impact
control facility to vary pressure on papar for making
carbon copies. Has Centronics parallel or RS-232
interface. Connects directly to BBC Micro. A ribbon
cassette plus a separate red ribbon. Optional extras:
Single Sheet Feeder takes up to 1 50 A4 sheets; A
Keyboard that transforms HR15 into a sophisticated
electronics typewriter. Attractively finished in Beige.

Special Introductory Offer: ONLY £375

Single Sheet Feeder £199

QPFPIAI

* XMAS OFFER *

Cumana CS100 Drive f/liKJ" £165

Cumana CS400 Drive £34lT £275

Cumana CD800 Drive £599" £530

Seikosha GP100A PRINTER ..£J7<f £155
Seikosha GP250X PRINTER .. £225" £199
Epson FX80 PRINTER £369" £349

LISTING PAPER

85" or 9 J" Fanfold paper plain or ruled
(1000 sheets) £7 (£1 .50p carr.)

15" Fanfold paper (1000 sheets) £9 (£1.50p carr.)
Teleprint Roll (econo paper) £4 (£1 ,50p carr.)

PRINTER LEAD 36"

Ready made printer lead to interface BBC Micro to
EPSON, SEIKOSHA, NEC, etc.. Printers.

ONLY £10

Special Extra Long (60") Cable £14

BBC Micro

WORD-PROCESSING

PACKAGE

A complete word processing package consisting of:
BBC Model B, Zenith 12" Green Monitor, Twin
200K highly reliable (1 year warranty) Twin Cased
Disc Drives with own power supply, the popular
WORDWISE word processor, Watford's own highly
sophisticated 62 File DFS interface fitted, the world
renowned Brother HR15 Daisy Wheel Printer,
Gemini's Beebplot Et Beebcalc Spreadsheet Analysis
Software disks, 1 0 blank diskettes, 500 sheets of
Fan-Fold paper, Manuals and all the leads. All you
require is a mains power point to have it up and
running (we even supply the 4 way mains trailing
socket).

ONLY £1,350 (carr. £15)
(P.S. We will alter the package to suit your
particular requirement. Call in for a demonstration).

MONITORS

MICROVITEC 1431.

14" Colour Monitor, RGB
Input, (as used in BBC
programmes). FREE Interface
Lead. £215 (carr. C7).

• KAGA RGB 12" Medium
Resolution Colour £219
(Carr. £7)

• MICROVITEC 1451 Hi res 14" Monitor incl. Lead £319

• KAGA RGB 12" High Resolution Colour £259 (carr. £7)

• BNC Connecting Lead £3

• RGB Connecting Lead £5

• ZENITH 12" Greent Monitor. Hi-resolution £75 (£7 carr.)
NEW

• MICROVITEC 14" colour MONITOR/COMPOSITE

VIDEO £249

DATA RECORDER &
ACCESSORIES

Top quality Slimline, portable Data Recorder for
Computer use. Mains/ Battery operated with
counter.

£24.00 (Carr. £1.50)

DATA RECORDER CABLE

For our DATA Recorder to BBC Micro £2.50

DATA CASSETTES

Top grade Cl 2 Data Cassettes in library cases. 40p

STACK PACK

The unique Cassettes drawer rack system including
10 off C12 Data Cassettes. £6

BEEBPLOTTER

The Unique Graphic Tablet

Watford Electronic's BEEBPLOTTER will work with
32K BBC Micro. Connects to Analogue port. The
unique design makes it accurate and simple to use.
Attractively finished. The comprehensive booklet
supplied describes its use in detail and shows some
of the possible applications.

The special features include: —

• Works in all graphics mode and any colour
selectable.

• Commands printed on Tablet and On-screen
instructions.

• Special routines enable pictures to be quickly
loaded from tape.

• Works with all operating systems and ECONET.
Tape and Disc versions available.

• Large drawing area (32cms x23cms).

• Maps, Pictures and Diagrams produced quickly
and easily.

• Transparent tablet enables maps and diagrams to
be copied directly from books.

• Commands include line, circles and rectangle
drawings, infilling, full editing and an easy to use
copy and move feature.

• Screen dump routines included for Seikosha and
EPSON printers.

• Routines are included to allow user to incorporate
pictures in their own programs.

• Designed by a professional teacher with eductional
uses in mind.

ONLY £80 (£3 carr.)

READY-MADE LEADS
for BBC

CASSETTE LEADS 7 pin DIN Plug

to 5 pin DIN Plug + 1 Jack Plug

£2.00

to 3 pin DIN Plug + 1 Jack Plug

£2.00

to 7 pin DIN Plug

£2.50

to 3 Jack Plugs

£2.00

6 pin DIN to 6 pin DIN Plug (RGB)

£2.50

Monitor Lead, BNC to PHONO

Disc Drive to BBC Micro Power Lead
Single: £3.00 Dual £3.75

£3.00

MISCELLANEOUS CONNECTORS

Plugs

Sockets

RGB (6 pin DIN)

30p

45p

RS423 (5 pin Domino)

30p

40p

Cassette (7 pin DIN)

25p

65p

ECONET (5 pin DIN)

15p

25p

Paddles (15 pin 'D')

£1.10

£2.15

Disc to BBC Power Plug 6 pin

70p

—

Disc Drive Power Plug 4 pin

60 p

—

* SPECIAL XMAS OFFER *

Microvitec 1431 Med res. 14"

MONITOR £225" £209

Microvitec 1451 Hi-res 14"

MONITOR pmT £319

KAGA 1 MONITOR

RGB £249" £205

NEW LAUNCH

Z80A WITH CP/M 2nd PROCESSOR BOARD

plus Double Density Interface for BBC MICRO

Yes it's here, our Z80A 4 MHz 2nd processor Board
with 64K memory, 4K Monitor EPROM, Parallel
printer interface, CP/M based, Double Density
board will handle, 3}", 5i" & 8" Floppy Disk Drives
and many more facilities. All neatly housed in a twin
slimline disc drive case.

Only: £399

(Cau in at our stano at The BBC Micro User show for a
demonstration)

13 ROM

SOCKET BOARD

Simply plugs into one of the four ROM sockets
currently available in BBC Micro. There are only 4
solder connections to be made.

Full instructions are supplied.

Our 13 ROM SOCKETS BOARD enables the User to
increase the Sideways ROM capacity the basic four
sockets on the main board up to the full SIXTEEN
capable of being supported by current operating
systems. In addition the board is designed with the
facility to hold up to 16K RAM, which when
switched into operation is automatically selected by
any WRITE signal to the Sideways ROM area. This
gives the User the ability to write a utility or
language and upon pressing break have the utility or
language up and running (new ROM software can
be developed and tested in situ.)

The Board gives the User, plenty of freedom to
explore the possiblities of the new paged ROMs due
in the coming months and offers them the chance to
develop their own.

All essential lines are buffered and the Board meets
or exceeds all timings for operation in the BBC
Microcomputer. When fully populated, the ROM
Board consumes less than half the recommended
maximum current limit.

Supplied ready built and tested complete with fitting
instructions.

ONLY £29.95 (carr. £1)

EPROM for the BBC MICRO &
13 ROM SOCKET BOARD

2764-250nS £4.20 £3.75

27128-250nS £18 £13

8271 £36

CMOS RAM for the
13 ROM SOCKET Board

61 16-150nS (2K) £3.40

6264-1 50nS (8K) 26.00

EPROM PROGRAMMER for
BBC MICRO

At last! — the EPROM Programmer for BBC Micro
Computer from WATFORD ELECTRONICS that will
suit both your pocket and all your requirements.
Programs all popular types of EPROMS from 2K
bytes upto 16K bytes -271 6 - 251 6 - 2532 - 2564-
2764 - 27128.

This extremely powerful system is designed for your
needs of TODAY & TOMORROW! - BBC Basic
programs can be copied into EPROM and
subsequently re loaded faster than from a disc!
Suitable for both hobbyist and professional users!

Just look at these features:

• COMPLETELY SELF CONTAINED- Housed in
its own sturdy case - Uses its own Power Supply -
Connects directly to the 1 MHz Bus— Simple and
Safe!

• FULL SOFTWARE SUPPORT-Comes

complete with simple to use fully machine code
ROM based software and easy to understand
manual. Facilities include Varification, Reading,
Virgin Testing, Writing, Editing, Saving, Loading
and more! NOTE!!! — This software does NOT simply
comprise hastily prepared routines to get you going,
but is a professional, purpose designed applications
package.

• ACORN BUS COMPATIBLE — Use of the 1 MHz

connection complies with all Acorn addressing
recommendations -That means your can still add-on
such things as the TELETEXT. IEEE 488 TUBE and
PRESTEL Adaptors without having to disconnect
everything.

• Allows more than one program to reside in an
EPROM using the ROM Filing System.

You don't need just any Eprom Programmer -you
need WATFORD ELECTRONICS EPROM
PROGRAMMER System.

ONLY £89 incl. Manual. (£3 carr.)

BEEBMON

A ROM based machine code Monitor for BBC
Micro. It enables machine code programs to be
debugged and altered easily and quickly. Being a
ROM, its commands are always readily available and
occupy no user memory. Appears to take no base
page and only one page of relocatable workspace
(256 bytes) and no more anywhere in RAM.
Beebmon can do more than any other machine code
monitors currently on the market. The special
features include facilites like: TABULATE, MODIFY,
FILL, COPY. COMPARE, SEARCH (HEX Et ASCII)
CHEKSUM, DISASSEMBLE, RE-LOCATE and by
Emulating the 6502 processor, SINGLE STEP,
BREAK POINTS ON READ/WRITE/EXECUTE OF
LOCATION also BREAK POINTS ON A, X Et Y
REGISTERS are provided.

HAS WINDOWS INTO MEMORY & TEST
WINDOWS. All this and more for only: £25

BBC LIGHT PEN KIT

All parts available as per Acorn User's 'SHINE A
LIGHT' Light Pen article.

Kit Price: £8.95

BBC LIGHT PEN

A ready-made Light Pen for BBC Micro. Enables you
to produce drawings on your own TV/MONITOR
screen. Supplied complete with Software Cassette
and instructions. _

ONLY £17

WATFORD

ELECTRONICS

Continued

★ THE ULTIMATE ★
BBC MICRO DFS

by Watford Electronics

Highly acclaimed at the Acorn User Show.

What do the independent press say?

Good Value for Money — Beebug Aug. '83
A very worthwhile package - The Micro User
You'll be buying a very powerful package. - Personal
Computer News.

Superior DFS; Excellent Disk sector editor.—
Computer Answers.

Without a doubt, the most sophisticated DFS
Software yet written for BBC Micro Computer.

This powerful new DFS is fully compatible with
ACORN DFS yet has much increased power due to
additions, carefully designed to make life easier in
normal use. It consists of over 14K of effeciently
written machine code. It is entirely self contained
and so does not require a utilities disc to function.

• The system can either use the ACORN standard
31 files per disc side or DOUBLE THE CAPACITY to
62 files. The size is selected at formatting time.
Copying between discs with different catalogue sizes
works perfectly normally.

• A FORMATTING PROGRAM is built in, permitting
formatting to 35, 40, 80 track formats with either 31
or 62 files. Since the formatter is built in to the DFS
it can be used without affecting whatever program
you are using.

• A DISC VERIFIER is also built in. This checks the
internal checksums on each sector to identify any
corrupted data. This is extremely useful when saving
valuable data as it shows faulty discs quickly and
easily. Again it does not affect the program you are
using.

• A built in DISC SECTOR EDITOR gives a screen
window onto the disc enabling detailed editing of
any byte on the disc. This is very useful for
recovering accidently deleted files and can save
weeks of work

• A double step mode allows the user of 80 TRACK
DRIVES TO READ 40 TRACK DISCS. This mode is
software selected for each drive individually, thus
allowing a 40 track disc to be copied onto an 80
track one very easily. THIS ELIMINATES THE NEED
FOR EXPENSIVE SWITCHABLE DRIVES.

• A WORKFILE function sets the name to be used
when the null filename is issued. This allows a
program to be edited and repeatedly saved having
only typed its name once.

• When using LOAD, CHAIN, etc, it is possible to
specify an ambiguous filename. This will result in the
first file whose name matches the specification being
used. This saves typing the end of a filename that
you know is uniquely identified by its first few
characters.

• Two commands exist to simplify the transfer of
programs from TAPE TO DISC. These load and file
to Etl 100, switch off the disc system and then move
the file to its correct load address; thus saving a lot
of complicated programming. This command can be
used to load files up to 27K75 long.

• An advanced COPY command is included which
will prompt the user, requesting whether to copy
each file.

• RENAME has been extended to allow the use of
ambiguous filenames. This allows you to change
BERT1 , BERT2, BERT3 to FRED1 , FRED2, FRED3
with only one command.

• OPENOUT has been improved to give you fewer
annoying Can't extend’ errors, as it automatically
picks the biggest space on the disc in which to put a
file. A SPACE command lets you know how much
space 'COMPACT could create before you waste
time doing it.

• 2K of RAM can be reclaimed from the DFS by
setting "PAGE” to &1 100.

• Comprehensive and clearly written Manual
(available separately) gives the user a complete
package deal.

• The powerful library system has been extended so
that libraries now work on all accesses not only
•RUN. This allows you to have a utility directory
with all your commonly used programs without
muddling in your current workfiles. Very useful for
BCPL User.

• Programs can now reside lower in memory by
reclaiming some of the DFS' workspaces, indeed
PAGE can be taken as low as £1 100 under most
circumstances.

• To make DFS easy to use, wild cards ("*") have
been made vastly powerful, e.g. ‘INFO # A* gives
information on all files in the current directory which
have an *A* anywhere at all in their filenames.

• Fully compatible with BBC TELETEX and TORCH
Systems.

DFS ROM only £39

cont.

Complete Disc Interface including our highly
sophisticated DFS ROM and fitting instructions £85
Comprehensive and clearly written DFS MANUAL.
(P.S. This manual will only be sold to those who
purchase our DFS.) 7.50 (no VAT)

P.S.

We will exchange your existing ACORN DFS or
AMCOM (PACE) DFS for the highly superior
Watford's DFS ROM for £35

Computer Concept's Firmware

DISC DOCTOR £26

A sophisticated Disc Utility ROM with many useful
commands. (For detail description please refer to
Computer Concept's advert in this magazine.)

Wordwise

Without doubt a very sophisticated piece of
software for the BBC Micro. It has all the features of
a professional word processor yet is easy to use.

SPECIAL XMAS OFFER: only £33

A new concept in BBC Software from Watford. This
is a character FONT ROM that gives you 5 16x16
predefined FONT. The ROM is ideal for high quality
demonstration on screen and when used in
conjunction with EPSON printer, allows printing of
letters etc., in mixed type faces, now with
BEEBFONT in your BBC you can write letters to
your European friends with the correct alphabet. The
package is complete, including an Editor to design
your own Fonts and several spare Fonts which could
not be fitted in the ROM. Can still be run from
RAM. Supplied complete with ROM, software on
DISC/tape and Manual.

Price: £45

DISASSEMBLER

Will generate fully labelled assembly listing of any
machine code program. Data is automatically
differentiated from code and displayed together with
its ASCII equivalent. Assembly listing can be saved
in 'EXEC format and subsequently incorporated into
user programs.

Cassette: £6.95
Disk: £8.95

EMULATOR

An extremely powerful and flexible machine code
interpreter. Allows you to write and debug machine
code as easily as BASIC. Features single step,
breakpoint register display, edit modes, etc.

Cassette: £7.25
Disk: £9.25

VIEW Acorn soft's Wordprocessor ROM. £52

ACCESS ORDERS BY TELEPHONE
Simply phone your order
through. We do the rest

(0923) 50234

FORTH ROM for BBC

This superb (FIG FORTH) compiling language now
avilable in ROM. Simply plugs into one of the ROM
Sockets. Manual included.

£36

GEMINI'S BUSINESS SOFTWARE

Written by Professionals.

Cashbook Accounts £52

Final Accounts £52

Invoices St Statements £17.25

Commercial Accounts £17.25

Mailing List £17.25

Database £17.25

Stock Control £17.25

Home Accounts £17.25

Beebcalc Spreadsheet Analysis £17.25

Beebplot £17.25

N.B. All the above Gemini software is on tape.

For Disc Based (40/80 track) please add £3.

BOOKS (No VAT on Books)

30 Programs- BBC Micro £4.95

30 Hour BASIC (BBC Micro) £6.00

36 Challenging Games for BBC Mic £5.95

100 Programs for BBC Micro £6.95

Cassette version of above £10

6502 Application Book £10.25

6502 Assembly Lang. Programming £12.50

6502 Assembly Lang. Subroutines £11.80

6502 Software Design £10.50

A young persons guide to BBC Basic £4.50

ACORN ATOM Magic Book £5.50

Advance User Guide for BBC £13.50

Advanced 6502 Interfacing £10.95

Advanced 6502 Programming £10.50

Assembly Lang. Programming for BBC £8.95

Advanced Programming Techniques for the

BBC Micro £7.95

BBC Basic £7.95

Assembly Lang. Prog, on BBC Micro £7.40

Basic Programming on BBC Micro £5.95

Basic Programming for BBC Micro £5.95

BBC Forth £7.50

BBC Lisp £7.50

BBC Micro An Expert Guide £6.95

BBC Micro Assembly Lang. Prog £7.95

BBC Micro Disc Companion £7.95

BBC Micro in Education £6.50

BBC Micro Grapics and Sound £6.95

BBC Micro ROM PAGING System Explained. £2.95

BBC Micro Revealed £7.95

BBC Micro Instant Machine Code

including Software Cassette £34.00

Creating Adventure Programs on BBC £6.95

36 Challenging Games for the BBC Micro £5.95

Creative Graphics Cassette (Acornsoft).

Has 36 graphics programs £8.95

Creative Graphics on BBC Micro £7.50

Complete Programmer for BBC £5.95

Discover BBC Machine Code £6.95

Discover FORTH - Osborne £1 1 .25

Easy Prog, for BBC Micro £5.95

35 Educational Programs for BBC Micro £6.95

Further Prog, for BBC Micro £6.90

FORTH Programming (Sams) £12.50

Functional forth for the BBC Micro £5.95

Games on your BBC Micro £2.95

Games BBC Computer can Play £6.95

Getting Acquainted/Acorn ATOM £7.95

Graphic Art for BBC Computer £5.95

Graphs and Charts (Cassette) £8.95

Graphics on BBC Micro £6.95

Graphs Ef Charts on BBC Micro £7.50

Intro to Micro Beginners Book (3 Ed.) £9.90

Introducing the BBC Micro £5.95

Let your BBC teach you to program £6.75

LISP £9.25

Logo Programming £8.95

Micros in the Classroom £4.90

Practical Prog for BBC St ATOM £5.95

Programming the 6502 £10.75

Programming the BBC Micro £6.95

PASCAL £9.25

Mastering VISICALC (Sybex) £1 1 .95

Programming for Education on BBC £5.95

Structured Prog, with BBC BASIC £9.50

The BBC Micro Book, BASIC, SOUND St

GRAPHICS £7.40

Using Floppy Disks with BBC Micro £5.95

N£W

DISC-FIX ROM

The ROM is an integrated, menu-driven DISC
MAINTENANCE PACKAGE. Using simple menu
selections, with intelligible prompts for any input
required, the user can recover data from damaged
discs. Facilities include: —

• Full screen editing of sectors on the disc.

• Sectors can be found by file name or sector
number.

• Files and sectors can quickly and easily be
dumped to a printer for examination and possible
subsequent modification.

• COPY; blocks of data can be copied from any
point on the disc to any other point. Blocks can be
as small as one byte and can be transferred
anywhere in a sector.

• SEARCH: The disc can be searched for any
string, starting and finishing at any designated
sector.

• VERIFY: Any block of sectors can be checked for
their validity.

• FORMAT: Any track or group of tracks can be
individually formatted to Acorn or Watford DFS
standard.

• INSERT: Allows the manual creation of new
directory entries to allow “undeletion” of files.

• BACKUP: This is similar to normal DFS backup
but allows recovery after a disc error. Completely
compatible with both Acorn and Watford Disc Filing
Systems. Instruction manual supplied.

Price £19.00

TINY PASCAL (in 16K ROM)

PASCAL T is capable of compiling source PASCAL
into a compact very fast threaded-interpreters-code.
Full editor and disc support are included.
Comprehensive documentation supplied £59

EDUCATION Software

JUNIOR MATHS PACK (32K) £6.95

Makes learning fun for 5-1 1 year olds. This package
consists of 3 programs (menu driven) that increase
in difficulty as your child becomes competent. A
very good supplement to standard educational
methods.

MATHS TRANSLATIONS £5.50

This package explains how to translate Triangles and
Quadrilaterals, moving these geometrical shapes on
a grid. It goes step by step through the concepts
and the matrix calculations involved. Excellent
software.

WORLD GEOGRAPHY (32K) £7.00

Beautifully drawn Hi-Res colour map of the world
illustrates and aids this graded series of tests on
capital cities and populations of the world

WORDHANG £7.80

(Age 7-13). A word guessing program based on the
well known Hangman game. Uses full colour
graphics. Complete with 260 words and the facility
save your own list of words.

WORLDWISE £7.80

(Age 7-15). Two constructive geography programs
allowing children to build detailed data bases
covering both the UK and the world. Encourages
children to refer to atlas and reference books. Save
the database anytime.

ANIMAL/VEGETABLE/MINERAL £4.95

(Age 7-13). Provides an opportunity for children to
teach the computer to differentiate between objects.
The program tries to guess the object the child has
thought of, using personalised responses like
Mmm ... I am thinking.

BRITISH GEOGRAPHY £6.95

Teaches a child the locations of Cities and Ports
using directional keys.

CAROUSEL £5.50

Aimed at junior school age. Sequences of colours
and sounds teaches a child to concentrate.

HAPPY NUMBERS £7.80

(Age 4-6). No reading skills are required to use this
colour graphics number recognition and counting
program. Children build patterns of flowers
corresponding to figures, quickly learning their
significance.

INTRO TO ARITHMETIC £10.45

4 programs - Additions, subtractions, multiplications
and divisions. Help stage, moving graphics and
colours. Worksheet produced at the end of program.
(5-7 years old).

BBC JOYSTICKS

Two versions available:

SINGLE: Player type
TWO: Player type

£7.00 each
£11.50 per pair

VOLTMACE'S DELTA 14
Hand-set

Highly acclaimed at the Acorn User show. This
handset set is very reliable and versatile. For further
details please see VOLTMACE's advert in this
magazine.

Price: 'Delta 14' Hand set
ADAPTOR MODULE
TRANSFER PROGRAM

£11.25

£11.95

Tape £5.15
Disc £7.75

SURGE PROTECTOR Plug

Safely eliminates dangerous voltage surges. During
a thunderstorm, a nearby lightning strike can induce
high voltage spikes in the voltage supply or
fluctuating loads can also result in transient
overvoltages which if unchecked, lead to expensive
data corruption/loss. Our surge protection plug will
provide the necessary surge protection. Simply
replace your standard 13 Amp mains plug with the
surge protection plug (which is almost the same
size). Ideal for computers, Hi-Fi systems, Precision
instruments, Fridge Freezers, etc. Max. surge
current 2KAmp; Max. Voltage 250Volts.

Price: £9

BEEB SPEECH SYNTHESISER

Simply the best!

Watford's very own speech System, Specially
designed so that even a novice can make his BBC
talk.

PHONEMES for word synthesis allows unlimited
vocabulary. Software in ROM supplied with the unit.
The system is built in a small plastic box. Very
compact. Connects directly to the user port.

Price including Manual: £39

DISC EXECUTOR

Disc Executor is a sophisticated disc utility, designed
for the BBC Micro, which allows you to transfer
almost all of your tape software to disc. It will
handle 'Locked' programs and allows you to load full
length adventure type programs (i.e. up to &6E
blocks) from disc in seconds rather than minutes.

Price £12

PLINTH FOR BBC MICRO

Protect your micro from the weight of the heavy
TV/ Monitor. This sturdy plinth is attractively
finished in BBC colour. It can be used to support a
monitor or a printer. The micro slides underneath
comfortably. A must for every BBC Micro owner,
specially for those who have to move/open their
computer frequently.

Price: £10 (carr. £1.50)

PLINTH FOR PRINTERS

Keeps your desk tidy. Place the printer on the plinth
and the paper underneath. Finished in BBC colour.

£10 (carr. £1.50)

Yes it's here . . .

BEEB PRINTER ROM

the ROM you have been waiting for!!!

Are you fed up with not being able to unravel your
printer manual and use all those features you paid
for? Need sensible paging for use in the creation of
booklets? Then you certainly need our Beeb Printer
ROM.

A machine code printer utility in ROM.

❖ 'Single' key operations replace control code
sequences for underline, front and size selection,
paper movement, etc. Up to 30 come pre defined,
without effecting normal fn key usage.

❖ Automatic fanfold page margins. Puts gaps in
listings. PRINTed text etc to skip the folds. The gap
size alternates to minimise paper wastage when
using binders.

❖ Form feed and related commands, made available
on ALL printers. Can also provide a left margin.

❖ User defined characters embedded within text are
printed as on VDU.

❖ ❖ Commands select option for GP100, STAR,
NEC, MX/FX, LP VII/DMP100, DMP200. Operates
with parallel interface printers and is turned on by
*FX5,3.

Supplied complete with Manual.

Price: £24

(When ordering, please specify the make of printer
you have.)

ATTACHE CARRYING
CASE for BBC Micro

These Attache Carrying cases are attractively
finished in mottled antique brown leatherette. An
ideal and very safe way to carry your BBC
Microcomputer. £12 (£2 carr.)

GAMES SOFTWARE

(PROGRAM POWER)

ALIEN DESTROYER

£6.95

ANDEROID ATTACK (C. Concept)

£6.95

CHESS

£6.95

COWBOY SHOOTOUT

£5.95

CROAKER

£6.95

Escape from Moobase ALPHA

£6.95

GALACTIC INTRUDER

£6.95

GALACTIC COMMANDER

£6.95

KILLER GORILLA

£6.95

LASER COMMAND

£6.95

MUNCHYMAN

£5.95

MASTERMIND

£4.95

MOONRAIDER

£6.95

MICRO BUDGET

£7.95

PENGO (Watford)

£7.75

SWOOP

£6.95

SEEK

£5.95

747 FLIGHT SIMULATION

£7.75

LEVEL 9 ADVENTURE GAMES

COLOSSAL ADVENTURE. The classical
mainframe game “Adventure” with all the
original puzzles plus 70 extra rooms.

£8.65

ADVENTURE QUEST. Through forest,
mountains, desert, caves, water, fire, moorland
and swamp on an epic quest vs tyranny.

£8.50

DUNGEON ADVENTURE. Over 100 puzzles in the
Demon Lord's dungeons.

£8.50

SNOWBALL. Save a 7000 location colony starship
in 2303 AD.

£8.50

Prices correct at the time of going to press.

MAIL ORDER AND RETAIL SHOP. TRADE AND EXPORT INQUIRIES WELCOME.
GOVERNMENT AND EDUCATIONAL ESTABLISHMENTS OFFICIAL ORDERS ACCEP
TED. CARRIAGE: Unless stated otherwise, please add 60p to all cash orders.

VAT: UK customers please add 15% VAT to the total cost incl. Carraige.

SHOP HOURS. 9.00am to 6.00pm. Monday to Saturday. (Ample Free Car Parking
Spaces)

ACCESS ORDERS: Simply phone: Watford (0923) 50234. (24 Hours)

WATFORD ELECTRONICS

Dept. Acorn, Cardiff Road, Watford, Herts, England.
Telephone: 0923 40588/37774. Telex: 8956095

TECHNIQUES

USING GRAPHS

Stan Froco considers applications for undirected graphs

AT THE end of last month’s article I left you
the problem of how to find your shortest
route once you had calculated its length
using Dijkstra’s method. The solution is
simple. An array p% is declared with one
member for each point in the graph being
considered. Each element of this is used to
hold the previous point, used on any shor-
test route to the element being considered.
Thus p%(3) would hold the previous point
on any shortest route to point 3.

This is updated after line 850 of the
listing I gave last'month. If d%(nearest%)
4- c%(nearest%,j%) is less that d%(j%),
then we can set p%(j%) to be nearest%. At
the end of run p% will be complete. To find
the route to, say, point 5 from point 1 we
start at the end and work backwards. We
look at p%(5) to find the point leading to it.
We can then look for the point leading to
this, and so on until we get to point 1 . A
small recursive procedure does this easily.

I will now consider another use of
graphs, which has an important appli-
cation within the computer industry. We
saw last month that a graph consists of a
number of vertices connected by a number
of edges. A graph can be either undirect-
ed, in which case the distance from vertex
a to vertex b is the same as the distance
from vertex b to vertex a, or directed, in
which case the distance between vertex a
and vertex b can be different from the
distance between vertex b and vertex a.

It can be seen that an undirected graph
is a special case of a directed graph, in
which any connected vertices can be
thought of as being joined by two edges,
one in each direction, both of the same
length. It is sometimes also convenient to
think of unconnected vertices as being
connected by edges of infinite length.

Of the graphs 1, 2 and 3, figure 3 is
special in that there is only one route
between any two points. Such a graph is
called a tree, and this is the type of graph

Figure 1

that I’ll be considering here.

When designing electronic circuitry, it is
often necessary to wire together a number
of points on a circuit board. If the circuit is
to handle high frequency signals it is often
important that the points be connected
only by one route to each other point.
Cycles in the wiring could lead to problems
such as signal corruption or oscillation. In
the past this could be solved by hand, but
the development of computers has led to a
manifestation of the problem that needs
mechanical assistance.

The back-plane of a large mainframe
computer consists of a large array of
hundreds or thousands of points which
must be connected in complex circuits by
thousands of wires. For obvious reasons
the signals must not be corrupted, and so it
is important that the wiring be designed
with only one route to each point. It is also
important that the wiring pattern should
use as little wire as possible to reduce the
cost and, more importantly, to cut down the
room taken up by the wire.

Such a network of points connected
each by only one route is, of course, a tree.
A tree whose edges total the least possible
length is called a minimum spanning sub-
tree (MST). The graph in figure 4 is not a
tree, but we can select some of the edges
to build three trees, visiting all the vertices.

Of the three possible trees the second
has a smaller total edge-length and so is
the MST.

We can make a number of observations
about trees. When we add an edge to a
tree it ceases to be a tree and becomes
cyclic.

We may remove any edge in the cycle to
obtain a tree again (possibly a different
one).

One way of constructing an MST is to
find all the cycles and remove the compo-
nent in each cycle which has the greatest
length. We are then left with the MST.

Figure 2

Another way is to start with a smaller MST
that only uses some of the vertices in the
graph. We can than make this bigger by
adding edges to the other vertices, one at
a time.

We must make sure that any edge we
add has one end in the existing MST and
one end not. The MST will then remain a
tree. If we always add the shortest edge
then the tree we obtain will also be an MST.
This is called Prim's Method and is shown
in listing 1 . The simple MST we start with is
just one vertex (I have used vertex 1). The
graph I am using is shown in figure 5
(distances in brackets).

The graph is represented by an adjacen-
cy matrix c% set up from DATA at data%
(lines 540-600). Since this is an undirected
graph, distances in both directions are the
same and are set up as such in lines 570
and 580. Unconnected points on the graph
are set to infinity% apart, a distance much
larger than any used elsewhere in the
program and thus suitable as an approxi-
mation to infinity.

The calculation is handled by PROC-
prim, which is generalised to handle
graphs with any number of vertices
(passed in nvert%). The array u% has one
element for each point in the graph. The
element is set to TRUE if the item is in the
MST constructed so far. Each time round
the main loop (lines 670-850) one more
edge is added to the MST. The method to
find the shortest edge to add is in lines
720-800 and involves two loops to look at
all possible edges.

This is far from efficient; it is possible to
make the program far faster by a subtler
method of finding the shortest edge. For a
start we could .keep the edges in a list
(Acorn User August) in order of length, and
just scan down until we found the first one
with one end in and one end out of the tree.
I have chosen the method in the program
instead because it is clearer and keeps the

Figure 3

20

ACORN USER JANUARY 1984

® CD © ® © ® © © ® ® ® CD © ® © ® © ® © ® ®

MICRO POWER

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COMPUTERS

MONITORS

PRINTERS

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. . . AND WE'VE WORKED HARD TO BE THE BEST! Micro Power are
an official service and information centre, and we are major
suppliers to Government and educational establishments, and
stock the complete range of Acornsoft and Program Power
software as well as a wide range of B.B.C. Micro and general
computing books. Our expert staff are always on hand to provide
advice and assistance in the relaxed
atmosphere of our showroom.

Electron (Carriage £5) 199.00

('Phone for availability)

BBC Model B 399.00

BBC Model B with Disk Interface 469.00

Microvitec 14" colour
Microvitec 20" colour
Kaga12"b&w

247.25
. 343.85
. 123.05

0

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MAIL ORDER ADDRESS

DEPT AU11

8/8 a REGENT STREET

CHAPEL ALLERTON

LEEDS LS7 4PE

Tel: (0532) 683186 or 696343

SHOWROOM ADDRESS:
NORTHWOOD HOUSE
NORTH STREET
LEEDS LS7 2AA
Tel: (0532) 458800

MICRO POWER - PUT TO THE
TEST WE'LL PASS WITH HONOURS!

79.35

20.70

13.00

3.95
.4.50

85.00

4.95
1.25

. 2.45
97 00

70.00
2.13

. 2.24
2.53
2.88
4.03
45.43
59.80

55.00

45.94

19.95
29.90

Epson FX80 458.85

Epson RX80 342.70

Epson MX80 IIIF/T 399.00

Olivetti Spark Jet 399.00*

Seikosha GP100A 229.00

NEC PC8023 373.75

Parallel Printer Cable 15.50'

Standard 10" tractor feed fanfold paper

(per 1000) 9.20>

Epson refill ribbons 3.39 f

Epson MX80 Dust Cover 4.50

Epson FX80 Dust Cover 4.50

DISK DRIVES

JP-

/

TEAC 40 track ( 100k) 228.85

TEAC 40 track (200k) 424.35

TEAC 80 track (200k) 327 75

TEAC 80 track (400k) 569.25

TEAC 80 track double sided (400k) 396.75

TEAC 80 track double sided double drive (800k) 71 1 .85

TEAC CS55ES 40/80 track 100/200k (switchable) . 374 90
TEAC CD55ES 40/80 track 200/400k (switchable) 626.75

TEAC connecting cable 17.25

Acorn 40 track ( 100k) 264.50

Acorn 80 track double sided double drive (800k) 803.85

Torch 80 track double sided double drive, 64k, Z80 & CPN

operating system plus software P.O.A.

Shugart 40 track (100k) 263.35

additional drive for above (100k) 163.30

Send an SAE for our complete listing
of hardware, software and books.
ACCESS and BARCLAYCARD welcome

Concept Keyboard

Cable for above

Acorn Joysticks (pair)

Canvas cover for BBC

Vinyl cover for BBC

Complete upgrade

VIA chip

Buffer chip LS244

26-way connector

Disk interface (including fitting)

Econet Interface

3 C12 Cassettes

3 C 15 Cassettes

3 C20 Cassettes

SS/SD Diskettes

DS/DD Diskettes

Wordwise

View

Speech Synthesiser

Beebpen

Kisho cassette recorder

Acorn BBC Recorder

ARE YOU SERIOUS?

STOP PRESS- REPLICA II NOW AVAILABLE
(NOW COMPATIBLE WITH ACORN, PACE &
WATFORD DFS)

In addition to the features below it also works with
Acornsoft "locked" programs plus very long programs
(HEX & EOO too 7BOO)

REPLICA II and THE KEY give you, the user, what you want.
You have bought your disc drives and now want to take
advantage of them, but most of your favourite software will
not run with the disc interface and even if you are prepared
to pay out for disc versions of everything you can't get them
and if you have 80 track drives you might as well give up. If
you know everything about the DFS. memory locations,
saving procedures etc, you can probably save some of them
onto disc. What's a half hour per program, and it only takes a
few minutes to find, load and relocate it each time (if you
can remember the sequence).

On the other hand you could buy REPLICA, enter a few
details i.e. 1) program name, 2) number of sections, 3)

CHAIN, *RUN or *LOAD 4) press play and then make a cup
of tea whilst the program loads from cassette for the last
time. When you return the program will be on the disc and
shown in a menu under the name you gave it. There are now
only two alternative storage methods required and one of them
will work with most programs. There are some exceptions to
REPLICA II but the number is insignificant. Many users have
purchased 4 or 5 copies of REPLICA and it is now the
recognised format that dealers use to display their software.
REPLICA II will now hold up to 16 programs on each disc, they
can be erased if required and a new batch saved, but why not
just buy another REPLICA and keep your programs on disc
permanently (it only costs approx. £1.00 per program).

REPLICA II £12.00 (state 40 or 80 track)

THE KEY

THE KEY provides you with the facilities that should have
been included in the Disc Filing System and also helps you
reach the parts other discs can't reach. This new version of
THE KEY has been made compatible with ECONET at the
request of many schools, colleges and universities. The whole
program has been turbocharged and the facilities are:

1) FORM40 - now much faster.

2) FORM80 - now much faster.

3) BACKUP - has that effect on some people because it
allows even most of the protected discs to be backed up -
faster too.

4) EDITOR - display, read and alter sectors, even if you can't
list the program. Highlight any byte whilst searching, make
additional searches, edit bytes - now allows entry in HEX or
ASCII and in string format. Dump a sector to printer, file
pointers etc etc. You can now see how data is stored on a
disc and alter it if you wish. Of course, it's also faster.

5) RETRIEVE - don’t despair when you have a corrupted disc
or if a program is accidentally deleted, using RETRIEVE your
worries are over.

With so much from one utility it is no wonder that THE KEY
is outselling programs that cost the same but provide far less.

THE KEY £12.95 (state 40 or 80 track)

GRAF KEY/GRAF DISK

SHADOW

The first and best CAD program for the BBC Micro. Used in
education, business, art, video etc. Recommended by
LASERBUG, BBC MICRO USER, PCW, SOFT and thousands
of satisfied users (see earlier issues of BBC Micro User for
screen pictures). In a comparative review of the major CAD
programs PCW said: ''Considering the options it is by far the
best value". Need we say more, if you need a graphics utility
then this is it.

GRAFKEY (joystick & keyboard) £9.00
GRAFDISK (state 40 or 80 track) £12.95

A tape cloning program that will enable you to make security back
ups of your valuable cassette based software.

SHADOW works with 99% of all known programs including those
with locked'' sections or those containing 300 BAUD sections.
Handles programs of any length and works with any operating
systems.

SHADOW is the definitive tape backup system. Also on the same
tape is a very useful program called "INSPECTOR'’ which allows the
user to page through memory, search for a string, etc.

BOTH PROGRAMS £8 incl.

(This program for personal use only).

EDUCATIONAL CORNER

JOYSTICK UTILITY

JOYSTICKS

(for the 5-1 1 age group)

Converts non-joystick programs to
work with joysticks. Works with any
program using INKEY(-), which
applies to most programs. Easy to
use, just press the keys you want to
transfer. Supplied on cassette but can
be transferred to disc.
CASSETTE £6.00

SINGLE KEY ENTRY

Requires 1 .2 O.S.

A very useful utility that provides
single key input of 66 key words.
Just like having 66 function keys.
Compatible with issue 1 & 2 basic
and discs.

CASSETTE £5 inclusive

Pair of fully proportional
joysticks of compact and
handy size

£17.95

CLARES

THE GARDEN - 3 programs with
superb graphics. Covers: colours,
spelling and understanding. Cassette
£ 8.00

COUNTING - robots, rockets,
flowers, etc. Excellent graphics, good
range. Cassette £6.00
MATCHING — 4 programs covering
numbers, words, shapes and patterns.
Cassette £7.00

HUE-MEN - A superb teaching-aid,
using animation techniques in Mode 7.
A hit with adults and children alike.
Cassette £6.00

And now SHAPE MEN using
the same techniques. This is the second
in an integrated approach to teaching.
£6.00

INTRO — A simple programming
language which uses the immediate
visual response of Turtle” graphics to
introduce a number of programming
concepts and techniques. Cassette
(and 9 page manual) £10.00

MICRO SUPPLIES

PROGRAMMERS

We are constantly seeking new and interesting programs. Why not send
yours for appraisal? You have got nothing to lose but much to gain - So
why not send your program today? 40 track disc if possible or two copies
on cassette. In some cases we will even provide disc drives against future
royalties.

AU1

DEPT. AU 12

98 MIDDLEWICH ROAD, NORTHWICH,
CHESHIRE CW9 7DS.

TEL: (0606) 48511

All prices inclusive of
VAT + Carriage - No Extras.

a

22

ACORN USER JANUARY 1984

program short. I leave it as an exercise for
the reader to improve it. Having found the
shortest edge, it is added to the MST.

This is not the only way of solving the
problem. Kruskall’s method works by
building several small MSTs and linking
them together. Like Prim’s technique it is
well described in Aho, Hopcroft and Ull-
man’s book Data Structures and Algo-
rithms, published by Addison-Wesley. This
is sometimes to be preferred for large

The graph

A

1

s/

U -A

3

The trees

3

3

BA -A

• i

5 /

w

t w ^ '

4

> • <>

Figure 4

problems of this nature, such as those
sometimes encountered in integrated cir-
cuit design.

In these two articles I have looked at only
two of a very large number of programming
techniques that use graphs. I’ll come back
to them in the future, but next month I’ll look
at how to measure the effectiveness of a
particular method of solving a problem,
and give examples of real-life problems
that can be solved using some of the
techniques I have described so far •

Listing 1. Prim s Method demonstrated

20

30REM A program to demonstrate Prim’s algorithm for finding MST's
40

50REM

60

70now% = TIME
80

90PROCprim (5, 200)

100

110PRINT "The following edges comprise the MST:” ’

120F0R i% = 2 TO 5

130 PRINT "(" ; t%(i%, 1) ; ", " ; t%(i%, 2) •

140 NEXT i%

150

160

170PR1NT ' "Time taken: " ; TIME - now% ; "cs.”

180END

190

200DATA 1. 2, 6
210DATA 1. 3, 5
220DATA 1. 4. 4
230DATA 2. 3, 1
240DATA 2, 5, 8
250DATA 3, 4, 2
260DATA 3, 5, 7
270DATA 4, 5, 3
280DATA 0, 0. 0
290

►

ACORN USER JANUARY 1984

23

—

300REM**********************************************************************

310

320REM PROCprim finds the MST, from a graph with nvert% vertices, and

330REM adjacency matrix read from DATA at data%. This particular version

340REM is slower than it could be because of the simple way it finds the

350REM shortest edge (the two inner loops). This could be replaced by a

360REM single loop, and a different way of holding the information in the

370REM adjacency matrix.

380

390REM**********************************************************************

400

410DEF PROCprim (nvert%, data%)

420

DIM u%(nvert%)

430

DIM t%(nvert%, 2) :REM One for each end of an edge

440

DIM c%(nvert%, nvert%) :REM The adjacency matrix

450

460

infinity% = 10000 : REM much larger than any distance we shall use

470

480

FOR i% = 1 TO nvert%

490

FOR j% = 1 TO nvert%

500

c%(i%, j%) = infinity% : REM reset the matrix

510

NEXT j%

520

NEXT i%

530

540

RESTORE data% : REM get the data

550

READ i %, j%, temp%

560

REPEAT

570

c%(i%, j %) = temp%

580

c%(j% , i %) = temp%

590

READ i%, j%, temp%

600

UNTIL i% = 0

610

620

FOR i% = 2 TO nvert% :REM Clear the table of edges in the MST

630

u%(i%) = FALSE

640

NEXT i%

650

u%(l) = TRUE :REM Just one in the tree

660

670

FOR i% = 2 TO nvert% :REM put the rest in the tree

680

lu% = -1 :REM end of shortest edge in the MST

690

lnotu% = -1 :REM end of shortest edge not in the MST

700

least% = infinity% : REM length of the shortest edge

710

720

FOR j% = 2 TO nvert% : REM possible edges not in MST

730

FOR k% = 1 TO nvert% :REM possible edges in MST

740

IF NOT (u%(k%) AND (NOT u%(j%))) THEN GOTO 790

750

760

REM the edge has one end in and one out of the MST

770

780

IF c%(j%, k%) < least% THEN

lu% = k % : lnotu% = j% : least% = c%(j%, k %)

790

NEXT k%

800

NEXT j%

810

820

t%(i%, l) = lu% :REM put in the tree

830

t%(i%, 2) = lnotu%

840

u%(lnotu%) = TRUE

850

NEXT i%

860

ENDPROC

24

ACORN USER JANUARY 1984

Name

| Send me the
, BBC Buggy at

£189.oo

tnc VAT, packing and postage Economatics (Educati

Address

I enclose cheque/PO or debit my Accessaccount [delete as necessary)

Card No.

Signature

Goods despatched within
7 days of rec eipt of order

Economatics (Education) Ltd., 4 Orgreave Crescent, Dore House Ind. Estate, Handswortti, Sheffield S13 9NQ. Tel: (0742) 690801

WITH A BBC BUGGY

Trying to determine the limitations of the BBC Buggy is a
task which will drive you to distraction. So sit back and
accept the fact that your BBC Micro computer (Model B)
controlled Robot will provide you with hours and hours
of stimulating entertainment.

This rugged little vehicle which has boon designed in
conjunction with the BBC Computer Literary Programme
and featured in the television series 'Making the most of
the Micro' is built from an easy to assemble flnchertochnfc
construction kit, complete with all necessary cables,
software and instructions.

M A

EC#NOMATICS

Vi r v

The Buggy's software which is based on the 'building
block' principle consists of 12 robust application
programs and one familiarisation program all of which
feature full graphics.

Take a trip into the future without ever leaving your
key-board - drive a BBC Buggy.

PROGRAMS

Test and familiarisation.

Switch - direct computet control.

Memory Switch - demotv.tr citing computer memory.
Routoplanner - advanced version of Snail.

Recorder- route* display.

Snail - t.t teen route planning.

Explore for wall - mapping of boundariov

Explore for object - seeks objects, define*, %hcipo*., return*, home.

Bar Code Roufeplanner non-keyboard information input.

Tin Pan Alley < (imposing music by bar code*.

Man vs Buggy ‘Flying blind'.

Sunsookor seeking a light and negotiating obstru< honv
Line Follower black or white line following.

The BBC Buggy is available from Acorn /BBC dealers
and other major outlets. \ fi

DRIVE YOURSELF
TO DISTRACTION

ACORN USER JANUARY 1984

25

TFrHMOM ATir KBC Computer & Econet Referral Centre

1 LCnl>UlVlAl It 01-4521500 01-4509764 01-4506597 Telex 922800

PRINTERS:

We have selected a range of
printers that will meet most
requirements.

SEIKOSHA-ranging from a
low-cost utility printer, right
up to an advanced four-
colour printer.

EPSON-the high quality
dot-matrix printers that set
the standard in the industry-
versatile printers that provide
the optimum in performance
& reliability. The RX80/FT provides all standard printing &
graphic functions, (single sheets & perforated paper), with
the de-luxe FX80 giving in addition proportional printing,
italics, programmable characters etc. The FX1 00 also allows
the use of 15” wide paper. The JUKI daisywheel provides a
quality normally found in printers costing far more.

Printer cables, interfaces, ribbons, paper etc. are all
normally available from stock.

DISC DRIVES:

Our disc drives are supplied ready to connect to your BBC, &
come complete with all necessary cables, formatting disc,
manual etc. Our switchable disc drives give the user
flexibility, by allowing access to both 40 & 80 Track discs. Our
40/80 Track switching module can be simply attached to
your standard 80 track drives, thereby vastly increasing their
versatility. We also have a full range of discettes, variety of
disc storage cases, disc-drive cables. The Roppiclene head
cleaning kit is the ideal way to ensure optimum
performance of your drives. The use of disposable cleaning
discs eliminate the risk of recontamination and abrasion,
and ensure continuous data capture and transmission.

TORCH Z-80 Pack:

Your BBC computer can be converted into a business
machine at a cost slightly higher than a 800K disc drive. The
Torch pack with twin disc drive and a Z80A processor card
greatly enhances the data storing and processing capability
of the computer (NOTE: In BBC mode the disc pack
functions as a normal BBC drive). Z80A card comes with
64K of RAM and a CP/M compatible operating system in
ROM. The system is supplied complete with a BBC owner’s
user guide, a System/ Demo disc, a PERFECT software
package and COMANEX, a business management game.
The PERFECT software package comprises of a DATABASE,
CALC, WORD PROCESSOR and SPELLER commercially
valued at over £1000. We are now supplying a Utility that
enables software on 40 Track discs to be transferred to 80
Track discs

AVAILABLE FOR THE FIRST TIME-The TORCH Z80
SECOND PROCESSOR CARD for those who already have
suitable disc drives. The card is supplied with all the free
software as detailed above, presenting a very attractive
package. TABS Software-specifically configured for the
Torch pack are ideal for the small business user.

SANYO DRIOl

Data Recorder. An advanced data recorder that consistently
achieves superior performance.

ACORN COMPUTER SYSTEMS

PRINTERS & PLOTTERS

BBC Model B

£348 00a

EPSON FX-80

£350.003

BBC Model B+ Econet

£389 00a

EPSON RX-80 FT

£270003

BBC Model B + DFS

£409.00a

EPSON FX-100

£555.003

BBC Model B+DFS + Econet

£450.00a

NEC PC80 23BE-N

£310003

Acorn Electron

£ 173.00a

SEIK0SHA GP100A

£170.003

BBC Teletext Receiver

£195 00a

SEIK0SHA GP250X

£199 003

BBC Dust Cover

£4.00d

SEIK0SHAGP700A Colour

£375 003

Pair ot Joysticks

£1 1.70c

JUKI 6100 Daisy wheel

£365003

MCP40 Col. Printer/Ptotter

£129 003

TORCH Z80 SYSTEM

GRAPHICS Plotter

£270003

TORCH 280 Disk Pack

£730.00a

Accessories:

TORCH 280 2nd Processor Card

£375.003

Parallel Printer Lead

£10 OOd

Serial Printer Lead

£8 OOd

UPGRADE KITS

Epson Serial Interface 2K

£60 OOd

A to B Upgrade Kit

£65. OOd

Epson Serial Interlace

£50.00d

Installation

£15.00

NEC Serial Interface

£42 00c

DFSKit

£84.00d

Epson Paper Roll Holder

£17 00c

Installation

£15.00

FX-80 Tractor Attachment

£37.00c

Econet Kit

£45.00d

PAPER Fanfold 2000 sheets

£13.501)

Installation

Speech Kit

Installation

£70.00

£47.00d

£10.00

COLOUR/GREEN MONITORS (leads incld)

Microvitec 1431 14” RGB Std Res

£215003

Microvitec 1451 14" RGB Med Res

£345003

ECONET ACCESSORIES

Printer Server Rom

File Server Level 1

File Server Level 2

Clock + 2 Terminators

Econet User Guide

£4 1.00c
£86 00c
£2 16.00c
£85 00b
£10 OOd
NoV.

Microvitec 1441 14” RGB Hi Res

Microvitec 2031 20” RGB Std Res

KAGA Vision 112” RGB Std Res

KAGA Vision III 12” RGB Hi Res

KAGA 12” Green Hi Res

SANYO DM8112CX 12 n Green Hi Res

KAGA RGB Lead

£440 003
£287 003
£230003
£385.003
£106.003
£99.003
£6 50d

BNC Green Screen Monitor Lead

£3.50d

BBC FIRMWARE

BBC COMPATIBLE 5.25" DISC DRIVES:

1.2 Operating System

£7.50

(All include cables, manual + format disc)

Basic II Rom

£32.00c

100K (40 Track)

£150003

View Word Processor Rom

.... £52 00c

100K (40 Track) with psu

£185003

WordwiseW/PRom

£32.00c

200K (40/80 Track)

£215003

Beebpen W/P Rom

£29.00c

200K (80 Track) with psu

£260.003

BCPL ROM + Disc

£87.00c

400K (80 Track DS)

£240.003

Pascal-T ROM

. . £44 00c

2x100K (40 Track) with psu

£335003

Disc Doctor Utility Rom

£30.00c

2x200K (40/80 Track) with psu

£440003

Termi Emulator Rom

£29.00c

2x400K (80 Track DS) with psu

£490003

Beebcalc Spreadsheet Rom

£32.00c

Accessories:

40/80 Track Switching Module

£30.00c

BBC ANCILLARY HARDWARE

Single Disc Cable

£6.001

EPROM Programmer

£79 501)

Double Disc Cable

£8 50(1

Smartmouth Speech Synthesiser

£37 00b

DISCS 40T SS/SD Pkt of 10

£ 15.00c

RH Light Pen

£39 50b

DISCS 80TSS/DDPktof 10

£2400c

Time- Warp" Real-Time

DISCS 40T DS/DD Pkt of 10

£ 18 00c

Clock/Calendar

£29 00b

DISCS 80TDS/DD Pkt of 10

£26 00c

ALL PRICES EXCLUDE VAT. Please add carriage 50p

COLOUR GRAPHICS PLOTTER:

This robustly built 3-colour graphics plotter provides both 1
versatility & precision. The carriage can be moved with an
accuracy of 0.025cm. over an area the size of A4 paper. The J
plotter bed can accept paper & far thicker materials, at sizes of .
up to A3. The basic plotter carries three pens each of which is '
software selectable. Optional accessories that can be fitted
include: Scriber, miniature drill, router, and optical sensor for
scanning. This versatile plotter can provide an endless source ;
of creative ideas.

Technomatic

Our in depth stocks alio* us to offer immediate deliveries on most items and our aim is to provide the
best available products at competitive prices. In addition to the items listed above we carry extensive
stocks of: connectors, connector assemblies, components including TTLs, CMOS, R AMs, EPROMs
and CPUs. Spares for the BBC” computers are normally available from stock. Orders from government
departments, public bodies, hospitals, schools, colleges, universities and recognised PLCs welcome.
We specialise in world wide exports. No VAT on exports and freight. Our specially negotiated freight
charges to many countries ensure the customer considerable sav ings on charges.

26

ACORN USER JANUARY 1984

Everything you need for your BBC Computer

Plus friendly service and professional advice

FLOPPICLENE Drive Head Cleaning
Kit

Disc Library Case
Disc File Case 30/40
Disc Lockable Case 30/40
Disc Lockable Case 60/70

EPROMS:

2764-250nS

27128-300nS

27128-250nS

£14.50c
£2.50d
£8.00c
£16.00c
£30 00b

£5.00

£1800

£2200

SOFTWARE'

GEMINI BUSINESS including Database Mail-List.
Beebcalc Beebptot. Stock-Control. Home Accounts,

Above on Cassette £17 25

Above on Disc £20.25

CasbBook on Disc £52.00

Final Accounts on Oise £52.00

Cashbook/Final Accounts both £82.00

GEMINI Leisure - Full Range

TABS BUSINESS SOFTWARE FOR TORCH

Sales Ledger (CP/N ) £99.00

Purchase Ledger (CP/N). £99.00

Mailing List (CP/N) £99 00

ACORNSOFT - Full Range

ACORN LANGUAGES including BCPL, LISP

FORTH with Manuals

BBCSOFT- Full Range

PROGRAM POWER -Full Range

ACORNSOFT (Electron) - Full Range

CASSETTE RECORDERS:
SANYO OR 101 Data Recorder
BBC Tape Recorder
Cassette Lead
HOBBIT Floppy Tape
HOBBIT Zero Memory Option
Computer Grade C-12 cassette
Computer Grade Cassette 10 off
Phillips Mini-data cassette

£34.00b
£28 50b
£300d
£135 00b
£25.00d
£0 50d
£4.50c
£3 OOd

BBC BOOKS (NO MOT) p&p £1 50/book
Advanced User Guide (p&p £2) £1 2.95

Advanced 6502 £10.25

CP/M Handbook
Micros Interfacing Techniques
Programming the 6502
6502 Applications

£10.75

£13.05

£9.75

£9.75

BBC Computer Books

Assembly Lang Prog for BBC £8.95

Assembly Lang Programming on BBC Micro
by Ferguson and Shaw £7.95

Basic Prog for BBC £5.95

BBC an Expert Guide £6.95

Micro Revealed £7.95

Easy Programming on BBC £5.95

Further Programming on BBC £5 95

Games BBC Computer Play £6.95

Introducing BBC Micro £5.95

Let Ybur BBC Teach Thu £6.45

Programming The BBC £6.50

30 Hour Basic £5 95

35 Educational Programs £6.95

BBC Sound & Graphics £7.95

Creating Adventure Programs £6.95

Discovering Machine Code £6.95

Structured Programming £6.50

Assembly Language Shiva £7.95

6502 ALP £12.50

6502 Using the 6502 Ass Lang £14.50

6502 Machme Code for Beginners £5.95

6502 Software Design £10.25

BBC Basic (Melbourne) £7.95

ALP on BBC Addison £7.95

BBC Graphics and Sound £695

Advanced Prog Techniques £7.95

Advanced User Guide (p&p £2) £12.95

Programming the Z80 £12.10

Forth Acorn £7.50

Using Floppy Disk with the BBC Micro
Computer Cumana £10.00

BCPL User Guide Acorn (p&p £2) £15.00

LISP Acorn £7.50

Creative Graphics Acorn £7.50

Graphs and Charts Acorn £7.50

The Friendly Computer Book BBC £4.50

Beyond Basic BBC £7.25

Into View BBC tor Word Processor

Acom £2.50

6502 Boohs

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and their influence on the BBC micro

Joe Telford outlines stacks

A ‘STACK’ is a data structure to which
items can be added and deleted only from
one end. Figure 1 shows a common stack
- plates piled on top of one another. In this
case the last plate on the stack must be the
first one off, and the stack can only be
accessed from the top. Because the num-
ber of plates is variable, the position of the
top of stack varies too. If we add too many
plates the stack will become unmanage-
able, so we must be careful to let the size
of our stack of plates vary within the
bounds of our stacking system.

Stacks are implemented on the BBC
micro, but normally they are controlled by
the operating system, and look after the
sequence of returns from subroutines and
procedures. To implement a stack in Ba-
sic, we turn to another data structure, a
'list'. Figure 2 shows a list of 1 0 items which
we will call our stack.

The bottom of the stack is item 0 and the
maximum size of the stack is 10 items, ie
when item number nine is entered, no
futher entries will fit onto the stack. This
condition is called an ‘overflow’. If we take
items away from the stack we will eventual-
ly be left with nothing on the stack. If we still
try to reduce the level of the stack, we will
cause an ‘underflow’. Because the top of
the stack varies up and down between 0
and 9, we need to know where the top is at
any time. To do this we use a ‘pointer’
which contains the item number of the last
addition to the stack.

Applications of stacks include stack-
based computer languages such as Forth
(available for the BBC micro) as well as
mathematical applications using Reverse
Polish Notation. RPN is particularly inter-
esting as it forms the basis of number
manipulation techniques used in Forth.
Because it can be easily applied to stacks,
RPN calculations are very fast.

Our normal technique of handling arith-
metic is to scan from left to right across an
expression and handle operators in order
of importance, for example multiplication

has precedence over addition so that in
the example:

2 + 3 * 7 — 3

We perform 3*7 = 21 before the other
items, giving us 2 + 21 - 3 which we add
from left to right to give a final answer of 20.
In RPN we start with a stack content of 0,
so the same expression would look like:

0)2 + 3*7-3

Where the 0 is already on stack.

The sequence of operations is strictly
from left to right and each operation refers
to the two items at the current top of stack.

1. 2 is placed on the stack.

2. 4- causes 2 4-0 = 2 (left on stack).

3. 3 is put on the stack.

4. * causes 2*3 = 6 (left on stack).

5. 7 is put on the stack.

6. - causes 6 - 7 = - 1 (left on stack).

7. 3 is put on the stack.

99

3

122

23

120

Physical top of stack
9 (stack (9))

8

7

6

5

4 <

3

Pointer
to current
top of stack

4

2

1

Bottom of stack
0 (stack (0))

Figure 2. A list as a stack

Nothing happens now because there is no
operator after the 3. RPN will go no futher
with the calculation. Figure 3 demonstrates
the condition of the stack at each stage.

It is valuable to be able to demonstrate
the use of stacks with examples, because
this prepares us for learning Forth-type
languages. Because of the structures of
BBC Basic, we can implement a simple
stack. As our implementation is graphic in
nature, we will call it a stack simulation.
Program 1 contains the complete stack
simulator.

Type the program in and run it. A Plate
Well appears in which the number 0 is item
0 on the stack. The word INPUT » invites
us to type either a number, or an operator
selected from ‘4- -7’. Numbers will be
added on to the stack while operators will
combine the top two numbers and leave
only their result on the stack. Errors are
trapped within the program and reported
to the user. The program also demon-
strates the accuracy of the micro, particu-
larly with small numbers. The escape key
will conclude the program.

The body of the program is made up of
the two lines 10 and 20. They call the
‘setup’ procedure, then repeatedly call the
‘input’ procedure.

PROCsetup clears the screen, prints the
title, dimensions space for the stack (list)
then draws the plate well. It sets the pointer
to location 0 of the stack, and initialises this
stack item to contain 0. It calls the ’print-
stack’ procedure.

PROCprintstack erases the stack on the
screen and prints out the values of the
stack contents, provided they exist (ie they
are not “ ”). It also prints the stack pointer
to the right of the plate well.

PROCinput prints the input prompt, and
waits for any input other than just the return
key. It clears the error line, then checks to
see if an operator has been input. If one
has, it calls the ‘operator’ procedure. If not,
it checks for a number. If a number has
been input it calls the ‘onstack’ procedure.

0

) 2

3

7

r -I

3

ITEM

5

4

3

2

1

0

Figure 3. Stack alterations during calculation

ACORN USER JANUARY 1984

29

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ACORN USER JANUARY 1984

Running the program now results in our
losing the top item from the stack when-
ever we type ‘P’

There are several problems for you to
attempt:

• increase the size of stack up to 20
items;

• alter the 'printstack' routine to account
for this;

• alter the 'setup' routine to draw the new
plate well to match the first two
problems;

• a stack-based language has the word
SWAP as part of its vocabulary. SWAP
causes the top two items on the stack to
be swapped. Alter the simulator to han-
dle ‘S' in this context;

• this same language has the word DUP
which causes the top item of the stack
to be duplicated as the new top of
stack, and the pointer incremented to
match. Add this facility to the simulator;

• the language has another word ROT
which moves the top stack item down
one place, the second top item is also
moved down one place and the third
top item is brought to the top. Add a
ROT facility to your stack.

Now let’s move on to queues. Most of you
will have queued at some time. It involves
joining the end of a line of people and
moving forward until we reach the front of
the queue, at which time we are served.
Program 2 sends a list of notes to the
sound generator of the BBC micro. These
notes are sounded in sequence as each
reaches the front of the queue. Because

Notes

Time(secs)

entered to finish program

1

0.01

3

0.02

6

0.03

7

1.01

8

2.01

9

3.01

Figure 4.

Results for sound queuing

the BBC micro can handle a short queue in
its sound buffer, control is returned to the
user before the notes finish sounding. The
purpose of the TIME=0 and the PRINT
TIME lines is to show how long it takes the
different numbers of notes to enter the
sound queue.

Try running the program several times
entering numbers from 1 to 10. Figure 4 is
the sort of table which can be produced.
The table indicates that the BBC micro can
play one note, and queue a further five
notes per voice without slowing down a
Basic program. When the program tries to
add a seventh note, this must wait until the
first one is finished so it can join the queue.
In our program, this takes a whole second.

Look at figures 5a and b which show a
queue in action. In computer terms, a
queue consists of a list to which informa-
tion is added at one end (called the tail)
and another end from which information
can be released, called the head.

Now, the BBC micro contains a number
of buffers, which can be regarded as

If an illegal character has been entered, it
calls the 'err’ procedure.

PROConstack checks for an overflow,
which would occur if the pointer is at item
nine. If an overflow occurs, it calls the 'err'
procedure. If not, the pointer is increment-
ed and the number entered is stored at the
new top of stack.

PROCoperator checks for an underflow
which would occur if the pointer is at item
0. If this occurs the ‘err’ procedure is
called. If not, the top two items are com-
bined according to the operator entered.
The top stack item is then deleted, the
pointer decremented, and the result is
placed in the new top of stack.

PROCerr is used to print error messages
at the bottom of the screen. It emits a
‘beep’ to alert the user to errors.

Although the 'input' procedure governs
much of what goes on in the simulator, it is
the 'operator' procedure which controls the
stack. If we make new commands legal by
adding them to the INSTR of line 301 0, they
will be passed through to the 'operator'
procedure. A particularly useful extra co-
mand might be ‘POP’ as in 'pop the top
item off the stack’. To achieve this com-
mand, we rewrite line 3010 to say:

3010INPUT TAB(8,15);“ "in$:

UNTILin$>" ”:A = INSTR(" + -7P”.in$)

Then we must alter the ‘operator’ proce-
dure to match.

5020IFop$o"P”stack$(pointer- 1 )
=STR$(

EVAL(stack$(pointer- 1 )+ op$ + stack$
(pointer)))

10 M0DE4: PROCsetup
20 REPEAT PROCinput: UNTIL FALSE
30

1000 DEFPROCsetup : CLS: PRINTTAB (10,2) "St
ack Demonstration" : DIMstack* (9)

1010 MOVE0 , 480: DRAW448 , 480: DRAW448 , 150:
DRAW960, 150 : DRAW960,480: DRAW1280,
480

1020 poi nter=0: stack! (0) ="0" : PROCpr i nts
tack:ENDFROC

1030

2000 DEFPROCpr i ntstack : FORI7.=0 TD9:PRIN
TTAB(15, 26-17.) ;

2010 PR I NTSTR I NG* (15," " ) : IFstack* ( I'/.) <
> " " PR I NTT AB ( 1 5 , 26- 1 7. ) VAL (stack* ( I
7.) )

2020 PRINTTAB (31, 26-17.) " " : NEXT : PRINTTA
B (31 ,26-pointer) : ENDPRDC

2030

3000 DEFPROCinput: REPEAT: PRINTTAB ( 0 , 15)
INPUT »” ; STRING* (31 , " ")

3010 INPUT TAB (8 , 15) " " in*: UNTIL in*>""
: A= INSTR ( "+—*/" , i n*)

3020 PRINTTAB (0,30) ; STRING* (39, " ")

3030 IFA>0 PROCoperator (in*) : ENDPROC* EL
SE no=VAL(in*)

3040 IFno=0 AND INSTR ( i n* , "0" ) =0PROCerr
("Entry not numeric or {+*/-}") :EN
DPROC

3050 PROConstack (no) : ENDPROC

3060

Program 1. Stack simulation

10 INPUT “number of notes? “no
20 T I ME=0

30 FOR note= 1 TO no
40 SOUND 1 , - 15 , note* 1 0 , 20

50 NEXT
60 PRINTTIME

►

Program 2. Sound queuing

4000 DEFPROConstack (no) : IF pointer=9 PR
OCerr ("stack overflow") : ENDPROC

4010 poi nter=poi nter+ 1 : stack* (pointer>=
STR* (no) : PROCpr i ntstack : ENDPROC

4020

5000 DEFF’ROCoper ator (op*) : IF pointer=0
PROCerr ("stack underflow") : ENDPROC

5010 IFop*=" / " AND VAL (stack* (poi nter ) )
=0 PROCerr ( "Di vi si on by 0 " ) : ENDPR
OC

5020 stack* (poi nter-1 ) =STR* (EVAL (stack*
(poi nter- 1) +op*+st ack* (poi nter ) ) )

50 _.0 stack* (poi nter )=*'": poi nter =poi nter
-1 : PROCpr intstack : ENDPROC

5040

6000 DEFPROCerr (X*) : PRINTTAB (0 , 28) ; "Cur
rent Error:-"

6020 PRINTTAB (0,30) ; STRING* (39, " " ) ; TAB
(0,30) ; X*: VDU7 : ENDPROC

ACORN USER JANUARY 1984

31

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ACORN USER JANUARY 1964

I

t

4

queuing structures, the one used most
often is the keyboard buffer. Here the first
character generated by the keyboard en-
ters the queue first and leaves it first. For
this reason a queue is called a FIFO (first in
first out) structure. Other examples of
queues are the RS423 input/output buffers
and the printer buffer.

The BBC micro has been designed
around interrupts to protect the buffers
from overflow and hence losing charac-
ters. The major problem is not so much the
loss of information, but the garbage which
can enter a buffer. It may become impera-
tive to clear a buffer, so the head of the
queue in that particular buffer is placed at
the beginning of the buffer, and the next
important piece of information can be swift-
ly used. To do this there are a number of
buffer clearing commands (figure 6).

With the discussion above related to the
use of queues as data structures, this is a
pertinent place to discuss queuing in the
outside world. Many services, for example
banks, supermarkets and post offices use
queues to order people, rather than data.
Although the inevitable queues are tedious
for people, the business must carefully
monitor them so customers are not lost,
and there will be a trade-off between
speed of service and cost of staffing. The
BBC micro can prove a useful aid in
predicting queue sizes, and lost custom,
simply by simulating, in seconds, the
queues which a business may expect over
a day or a week.

What follows cannot be an in-depth trea-
tise on queues, but our simulation exam-
ines a building society which maintains a
single queue up to a series of cashiers.
The head of the queue can be served at
any vacant position. Program 3 is the
queue simulation program.

The queue itself has three main attri-
butes: people enter it at a particular rate,
eg 20 per hour; people leave it at a
particular rate depending on the serving
rate of the cashiers, eg six per hour per
cashier; when the queue is full, customers
will not wait outside, and so custom is lost.

The simulation will produce a detailed
report every so often showing the state of
the queue, and the customers served or
lost (figure 7).

The program is based on random num-
bers. Because a number of people enter
the bank in an hour, we can say (in this
simple simulation) that the probability of a
person entering the bank in any one minute
is roughly the hourly rate divided by 60
(custom/60 in line 220). Similarly, the exit
rate per cashier is given as a number of
customers per hour. Again we can say that
the probability of a person being seved in
any one minute is roughly the hourly rate
divided by 60 (serve/60 in line 230). Once
we have this probability we can apply it to
the result of a random number, if the first
random number is less than the entry
probability then we add a person to the
queue. If any cashier’s random number is
less than the exit probability then we re-

Pointer to
head of Queue

Pointer to
tail of queue

Pointer to
head of queue

Pointer to
head of queue

Figure 5. Queuing diagrams (a) initial queue (b) after several additions and exits

*FX21 ,0

Keyboard

*FX21 ,5

Sound channel 1

*FX21 ,1

RS423 input

*FX21,6

Sound channel 2

*FX21 ,2

RS423 output

*FX21 ,7

Sound channel 3

*FX21 ,3

Printer

*FX21 ,8

Speech synthesis

*FX21 ,4

Sound channel 0

*FX15,0

All buffers

*FX15,1

Current buffer

Figure 6. Commands which flush buffers

Max queue length? 8

S t a r t q u eue 1 eng t h ? @

How many hours open? 3

C u s tome r s e n t e r i n g p e r h o u r ? 3 6

H o w m a n y c a s h i e r s ? 3

H o w m a n y e u s t o rn e r s c a n

1 c a shie r s e r v e pe r h o u r ? 1 2

H o w 1 o n g be twee n r e p o r t s ? < m ins) 1 5

* * # 5 TART** *

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ng

7

1

OS-

t

3

S e r v e d

56

Q

i

ng

7

1

DS

t

3

S e r v e d

63

Q

i

ng

7

1

0 s

t

3

2 H r ,

s

S e r v e d

71

Q

i

ng

0

1

o s

t

3

S e r v e d

78

Q

i

ng

3

1

OS

t

3

S e r v e d

87

Q

i

ng

4

1

os-

t

3

Served

97

Q

i

ng

0

1

os

t

7

o

3 H r , s

Figure 7. Possible printout from queue simulation

ACORN USER JANUARY 1984

33

SOFTWARE FOR THE BBC MICRO

WORDWISE

WORDUISE

The renowned word processing package. Still clearly the market
leader with sales now over 20,000. This has become “the standard”
word processor for the BBC Micro and is still receiving very
favourable reviews. Wordwise will work with tape, disc or Econet
and includes automatic word counting and full control over text
entered into the system. Supplied with a detailed spiral bound
manual and an excellent free typing tutor program. After 8 months
on the market there is still no other product as simple to use and as
powerful as Wordwise.

GREMLIN

The GREMUN system is a powerful de-bugging tool for 6502
machine-code programs. It includes all the usual features found in
good machine-code monitors, such as memory search, intelligent
memory move routines, memory editors etc. These work at byte,
word or string level. A built in help menu can also be displayed at
any time.

This ROM contains many more unique features such as an
assembler as well as a disassembler. An extremely powerful
expression evaluator is included allowing complex expressions to
be entered in a format that is only normally available in high level
languages. Variables are also allowed (any length) and may be
included into expressions.

GREMUN allows single stepping through machine-code programs. It
is also possible (on to a printer or disc) to single step through
graphic routines without disturbing the screen.

Supplied with full manual, this 8k ROM has more features than any
other de-bugging package for the BBC machine.

DISC DOCTOR

DISC DOCTOR 1 09

018 <<•««>> <<*nd>> <<of«>>

OISCTAPE <«fsp> <<«fsp>>

OOWNCOAO <f*p> <<«dr>>

OSEARCH <■ t r > <trk> << « rk><sc«Xdrv>>
OZAP (< t rk>> «trk><*ct><drv»

E01T <<k*u no >>

FINO <*tr>

FORM <<Jrv> <no t rku> <<■*<>> <<S>>
JOIN <«sp> <«fsp> <<«fsp>>

MENU (<drv>>

MOVE «d*tt p«a«>> (<src p«g«>>
MSEARCH <s t r > <<«dr>>

MZAP ««dr»

PARTLOAO <f«p> <ol*> <•*<> <«dr>
RECOVER < t rk> <«ct> <*ct> <odr> <drv>
RESTORE < t rk> <*cO <*cO <«dr> <drv>
SHIFT <>rc> <d»*t> <«xt>

SWAP «drv»

TAPEOISC <<fsp>>

VERIFY «drv» <<no trk»>> <<•»«>>

This utility package has many special features for use with discs but
also contains many other utilities that everyone will find useful:
Function key editing, powerful disassembler, recovery of any data
from the disc, merging of files, complete disc editor. Com potable
memory editor, String search in memory or on disc, automatic tape
to disc and disc to tape routines, built in help menus, formating of
35, 40 and 80 track discs, and also a special format that allows 60
files per disc.

TERMI

I?r«8tS8 T BU e »?ttKS i»3

Function k»v definition.

k«w — 88¥rT ith FM T rAi th

This program enables the BBC machine to act as an advanced
terminal when connected to another computer or to a modem via
the RS423 (RS-232) interface. This provides facilities to transmit
data from disc and the spooling of data from the line’ to the disc or
printer.

Term! has 3 modes of operation — dumb terminal, BBC graphics
terminal and customised intelligent terminals including DEC VT52.

DEPT AC14

16 Wayside, Chipperfield, Hertfordshire. WD4 9JJ Telephone: Kings Langley (09277) 69727

34

ACORN USER JANUARY 1984

1

1

move a customer from that cashier.

A problem can occur when either rate is
equal to or greater than 60 customers per
hour. This means that in our simple simula-
tion we would have a certainty every min-
ute, and the value of the random numbers
would be lost. In this instance it is best to
work on the probability of a person enter-
ing or leaving each second, and to adjust
queue lengths every second, rather than
every minute. This would mean adjusting
lines 220 and 230 to divide by 3600 rather
then by 60.

The main body of the program runs from
line 10 to line 90. First it calls the ‘setup’
procedure, then it produces an acceler-
ated day by which each loop round lines
40, 50 and 60 represents a minute in the
business. Every ‘minute’, the ‘transact’ pro-
cedure is called. At the end of every report
cycle, the results are printed by the proce-
dure called at line 70. This format of
transactions and results continues until the
end of the set time, tested in line 80

The ‘setup’ procedure creates the initial
variables which the program uses and
creates a list of cashiers, identified by
number. A 0 shows a particular cashier is
free, a 1 that the cashier is serving. Initially
the cashiers are all free.

The ‘transact’ procedure deals with the
cashiers first, by bringing a person from
the queue to any free cashier (line 330)
then by checking to see if a cashier has
finished serving and freeing that cashier
for the next person in the queue (line 340).
Because there may be a large number of
cashiers we loop around them between
lines 320 and 350.

The next task of the ‘transact’ routine is
to check for a customer joining the queue
(line 360). If the queue is full the customer
goes away (line 370), which also totals the
‘lost customers’. The use of the ‘flag’ vari-
able keeps track of the need to add a
person to the total served.

The ‘results’ procedure simply prints the
customers served, those queuing, and the
total lost customers to date. Every hour that
passes is indicated by line 430.

Further problems

1. Alter the queue simulation to handle
rates of customers greater than 60 per
hour.

2. Consider a queue at traffic lights. Write
a short simulator to account for traffic
entering a queue and leaving it. The
traffic should enter the queue constant-
ly, but may only leave it when the light is
green, so the period of the lights needs
to be taken into account.

3. Another queue at a road junction has
one queue of cars turning left on to the
major road, and another queue turning
right. Cars may enter either queue at a
particular rate, but the exit rate of each
queue depends of the frequency of
gaps in one or both lanes of traffic on
the major road. Write a program to
simulate these queues.

10 M0DE3
20 PROCsetup
30 REPEAT

40 FOR mins = 1 TO cycle
50 PROCtransact
60 NEXT
70 PROCresults
80 UNTIL time>=day
90 END

100 DEFPROCsetup

110 INPUT' '"Max queue length? "max
120 INPUT"Start queue length? "queue
130 INPUT"How many hours op.en? "hours
140 I NPUT " Oust omer s entering per hour?
"custom

150 I NPUT "How many cashiers? "cashiers
160 PRINT"How many customers can"

170 INPUT" 1 cashier serve per hour? "s
erve

180 INF*UT"How long between reports? (m
ins) "cycle
190 day=hours*60
200 1 ost=0: total =queue
210 time=0:@7=4
220 custom=custom/60
230 ser ve=serve/60
240 DIMcashier (cashiers)

250 LOCAL 1 7.

260 F0RI7=1 TO cashiers
270 cashi er (17.) =0
280 NEXT

290 PR I NT " ***ST ART *** "

300 ENDPROC
310 DEFPROCtr ansact
315 L0CALI7,-f lag
320 FOR 1 7.= 1 TO cashiers
330 IFcashi er (IX) =0 AND queue>0 cashi
er ( 17) =1 : queue=queue— 1
340 IF RND ( 1 ) < serve ANDcashi er ( 1 7) =1
cashier ( 17) =0
350 NEXT

360 IF RND ( 1 ) < custom queue=queue+ 1 : f 1 a
g = l

370 IF queue >max queue=queue-l : 1 ost=l o
st+ 1 : -f 1 ag=0

380 IF flag=l total =total + 1
390 ti me=ti me+1
400 ENDPROC
410 DEFPROr resul ts

420 PR I NT "Ser ved : "total -queue" Cling:"
queue" lost "lost

430 IFtime MOD60=0 PRINTtime DIV 60;

"Hr /s" ; STRING* (21 , )

440 ENDPROC

Program 3. Queue simulation

ACORN USER JANUARY 1984

35

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

LORDS OF TIME

Joins our range of acclaimed pure-text puzzle adventures, at £9.90, for:

BBC 32K COMMODORE 64 SPECTRUM 48K LYNX 48K NASCOM k ORIC 48K ATARI 32K

ADVENTURE
REVIEWS

“Adventures which have a
fast response time, are
spectacular in the amount
of detail and number of
locations, and are available
to cassette owners ..lam
extremely impressed The
Level 9 Adventures are
superbly designed and
programmed, the contents
first rate. The implementa-
tion of Colossal Cave
(Adventure) is nothing short
of brilliant: rush out and buy
it. While you’re at it, buy
their others too. Simply
smashing!’’

-SOFT, Sept 83
“I found Dungeon
exceedingly well planned
and written, with a fast
response. There are well
over 200 locations and the
descriptions are both
lengthy and interesting The
objects number about 100.

It could therefore take
some months to explore
the whole network, giving
many hours of enjoyment in
the process.”

-C&VG, Sept 83

“The descriptions are so
good that few players could
fail to be ensnared by the
realism of the mythical
worlds where they are the
hero or heroine . great fun
to play.”

-Which Micro?, Aug 83

"My appetite has been
whetted and I intend to get
my own copy (of Snowball)
to play.”

- What Micro?, Dec 83

MIDDLE EARTH ADVENTURES
1: COLOSSAL ADVENTURE

A complete, full size version of the classic mainframe game
"Adventure" with 70 bonus locations added

2: ADVENTURE QUEST

Centuries have passed since the time of Colossal Adventure
and evil armies have invaded The Land The way is long and
dangerous; but with cunning you can overcome all obstacles
on the way to the Black Tower, source of their demonic
power, and destroy it
3: DUNGEON ADVENTURE

The trilogy is completed by this superb adventure, set in the
Dungeons beneath the shattered Black Tower A sense of
humour is essential!

THE FIRST SILICON DREAM ADVENTURE
1: SNOWBALL

The first of Pete Austin’s second trilogy The giant colony
starship, Snowball 9, has been sabotaged and is heading for
the sun in this massive game with 7000 locations

ADVENTURE
REVIEWS

“This has to be the bargain
of the year. If adventures
are your game then this
(Colossal Adventure) is
your adventure.”

- HCW, 5 Sept 83

“Colossal Adventure is
simply superb. Anyone who
wishes to use adventures in
an educational setting
really must use and see this
program as it emulates
Crowther and Wood’s
masterpiece so well. For
those who wish to move
onto another adventure of
similar high quality,

Dungeon Adventure is to be
recommended. With more
than 200 locations, 700
messages and 100 objects
it will tease and delight!’’

- Educational Computing, Nov 83

Colossal Adventure is
included in Practical
Computing’s Top 10 games
choice “Poetic, moving and
tough as hell.”

- PC, Dec 83
“To sum up, Adventure
Quest is a wonderful
program, fast, exciting and
challenging If you like
adventures then this one is
for you”

-NILUG4F1.3
"Colossal Adventure . For
once here’s a program that
lives up to its name . a
masterful feat Thoroughly
recommended’’

- Computer Choice, Dec 83

“wholly admirable”

- Your Computer, Sept 83

THE LORDS OF TIME SAGA
7: LORDS OF TIME

Our congratulations to Sue Gazzard for her super design for
this new time travel adventure through the ages of world
history Chill to the Ice-age. go romin with Caeser's legions,
shed light on the Dark Ages etc etc We ll be selling this
game mail-order from January 1st

Price: £9.90 each (inclusive)

Level 9 adventures are available from good computer shops,
or mail-order from us at no extra charge Please send order,
or SAE for catalogue, to

LEVEL 9 COMPUTING

Dept A, 229 Hughenden Road. High Wycombe. Bucks
HP13 5PG

Please describe your Computer

36

ACORN USER JANUARY 1984

HINTS & TIPS

EXPERIMENTS IN MODE 7 BY MARTIN PHILLIPS

THIS problem page is a new, regular feature of Acorn User
presented by Martin Phillips. It will present simple hints and
tips and answer readers' queries about the Electron, BBC
micro and BBC Basic. £5 will be paid for a ‘star’ letter, so you
can profit from your problem!

If you have a query concerning some aspect of program-
ming or some technical difficulty, please give sufficient
information and make your question specific. The following
query was received recently:

1 am in the middle of writing a program for an exam project
on my 32k BBC. However, although the program is only just
over 21 k long, when it is run the computer prints up the error
message ‘No room* or Dim space'. I would be grateful if you

could tell me any methods of running the program success-
fully without the need to cut the program up.'

Now, there are any number of reasons why a program will
run out of memory. Without knowing far more about the
program, the style of programming and techniques used,
and whether discs Econet have been fitted, it is impossible to
give anything but general hints on memory saving. It also
helps to know the operating system and Basic.

So please bear these points in mind and include a listing if
possible. Unfortunately, we cannot reply to letters individual-
ly, and are unable to return letters, listings, etc. Send you
letters to: Hints & Tips, Acorn User, 53 Bedford Square,
London WC1B3DZ.

TELETEXT

CHARACTERS

SEVERAL letters have been received from
readers who have tried using teletext char-
acters in mode 7 but been unable to get
them to work.

Mode 7 coloured text is well worth ex-
perimenting with, as eight colours are
available on the screen at once and the
screen memory uses only Ik. It also has a
clear print style with the advantages of
double-height characters, coloured oack-
grounds and flashing letters.

Figure 1 shows how the screen is divid-
ed up in mode 7, teletext mode. There are
1,000 pixel blocks into which a number,
letter, graphics character or control code
can be inserted. A list of the displayed
alphanumeric characters appears on
pages 486-487 of the User Guide , and the
displayed graphics characters appear on
the next two pages. Each character has its
own ASCII code, which is shown on the
charts in the User Guide

Codes 0 to 31 are the normal control
codes that operate in any mode, but codes
128 to 159 are the special teletext codes.
To use them they must be printed in one of
the screen pixel blocks in the same way as
a normal character. In the same way, too,
they take up one pixel space, although a
blank space appears on the screen.

To see how they function, we need some
text on the screen to work with. Program 1
(overleaf) gives three lines of text. Line 10
ensures that mode 7 is selected and clears
the screen too. Lines 20-40 print the same
message on lines 5, 6 and 7, starting at the
left-hand edge of the screen. Now add a
new line 50 and rerun the program:

50 PRINT TAB(0,6)CHR$1 30’ ’

The middle line of text should now appear
in green CHR$130 is the code for green
alphanumeric print; the two apostrophes
are there to move the cursor down two
lines so that it does not interfere with the
printing on the screen

Having run this, there are several points

to note. First, only the middle line has
appeared in green, showing that the con-
trol code affects only the horizontal line in
which it is placed. Second, the first letter of
the middle line has been replaced by a
space. This is because the capital T has
been overwritten by the control code To
work correctly the control code needs to
be inserted in an existing space between
words or at the start of the line. Change line
50 to read:

50 PRINT TAB(1 1 ,6)CHR$130’

Now only part of the line turns green
instead of the whole line. The control code
has been inserted in the space between
the 1 and the rest of the line and so has not
deleted any text. Now we can elaborate on
one of the above points. Only print on the
same line and after the control code will be
affected by that control code. Instead of
CHRS130 in line 50, try the following
codes:

CHRS133 Magenta print

CHRS129 Red print

CHRS136 Flashing print

There are several ways these codes can
be included in programs

• Use CHR$ as we have seen above.

• Use a VDU statement instead, eg, VDU
130 for green lettering

• Include in a string. eg
A$=CHR$1 30 + “Hello”.

• Put the control code directly into the
string, using the user-defined keys To
select green, press SHIFT at the same time
as f2.

Although little used this latter method is the
easiest to use, mostly because it cannot be
shown in listings as the codes are not
printed out. Control characters so pro-
duced must be put inside speech marks.
They will appear in colour in listings as
well, but again only on the line in which
they are printed. This facility of the user-
defined keys is available only with the 1 .2
operating system and doesn’t work with
the 0.1 OS.

To help remember which keys do what, I
have included a full-sized slip (figure 2,
overleaf) which can be cut out or copied
and placed under the plastic strip above
the user-defined keys. You will see that by
using these keys in conjunction with the
CTRL key all the teletext graphics symbols
can be drawn. I’ll have more to say about
this next month

0 39

0

25

NR Each
pixel IS
<n the
proportion
fl high to

5 wirle

Figure 1. Mode 7 screen display grid

ACORN USER JANUARY 1984

37

'The TJata Stcfie

6 CHATTERTON ROAD
BROMLEY
KENT

for the BBC MIC RO
OFFICIA L ACORN DEA LERS

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plus oux personal advice service

MACHINES DELIVERED & SET UP
IN YOUR HOME

PHONE 01 460 8991 (9.30 - 5.30)
ORPINGTON 26698 (Evenings)
(CLOSED WEDNESDAY)

® diamond/oft

A better way of computing

Complete home finance system packed with sensible facilities to
help you maintain up to date records of your BANK. CREDIT
CARD. LOAN and SAVINGS ACCOUNTS. Keep track of
CHEQUES. RECEIPTS. AUTOMATIC BANKERS ORDERS,
BILLS WAITING PAYMENT and much more.

An essential asset for home or club.

A must for every concerned parent of a 6- 1 0yr. old. Makes learning
fun. helping teach ADDITION, SUBTRACTION,
MULTIPLICATION, DIVISION, TABLES and SPELLING.
Incorporates our unique grading feature which grows and
develops with your child.

A cassette based, powerful, general purpose, file handling system
Quickly create, maintain, sort, select, save and print your own
data. Develop complex systems with ease. Invaluable for Home.
Club, Schools or Business Records. Offers the use of advanced
software techniques to beginner and expert alike.

V

Cheques or P.O. to Diamondsoft Ltd., FREEPOST,
Cheadle Hulme, Cheshire. SK8 5YB. Tel: 061- 484 8705
(24 hrs).

J

DIAL SOFTWARE.

PRESENTS*

EDUCATIONAL BANES .

FOR THE BBC MICRO.

Adventure Quiz — Base 10

£4.93p.

BBC Logo — Bertie Bear

£4.95p.

Bells — Curve Stitch Planner £4.95p.

Childs Play Pack -- File Handler

£6.50p.

Fantasy Adventure - Cesil

£4.95p.

Finance Pack — Four-in-a-Roa

£4.95p.

Set the Message — 6olforaaa

£4.95p.

Maths Pack — Nueberhang

£4.95p.

Odds-On Honarchs -- Odds-On inters

£4.95p.

Odds-On Musicians - Odds-On Geography

£4.95p.

Odds-On Inventors - Science Pack

£4.95p.

Plotter — iord Processor

£6.30p.

Tripute — iordsquare

£4.93p.

Uniao

£3.93p.

These can be obtained froai

DIALSOFT, 72 Doanend Road, Doanend, Bristol BS1& SUE.

or send an SAE to obtain our latest Brochure.

Mrs E Harper, 33 Nealands Road, Ruishton

, Taunton,

Mins our free aonthly coapetition for October by

selecting the four top selling progress.

Childs Play, Maths Pack, Tripute, Hordscan.

She sins £30 of Softaare of her choice.

— -

|

■ : ■

TT1TTPTI

—

. v v

m

SPELLWISE

—

IS YORE SPELING REELY ATROSHUS?*
Or is it just a littel bit off kei?

In either case you need
SPELLWISE.

is a spelling checker for use with your BBC
micro and WORDWISE word processor

is a DISC or tape based machine code program
with comprehensive user manuals

contains an expandable dictionary of over 6000
words (disc) or 3000 words (tape)

SPELLWISE diligently checks every word in your
text against the SPELLWISE dictionary. When it has
finished you will be left with a list of words which are
incorrectly spelt or not in the base vocabulary.

The program can be interrupted at any stage
for inspection of the remaining word list and for the
insertion of personal or specialist vocabularies. For
this purpose software is included to enable you to
create your own data files.

SPELLWISE comprises a set of one disc (or two
tapes) plus a complete user manual. The tape version
is limited to cassette recorders with motor control.
SPELLWISE costs £12 on tape, £18 on disc and can
be obtained from:—

DATAWARE FREEPOST SWINDON SN3 4BR

llf

38

ACORN USER JANUARY 1984

Figure 2. User-defined key slip (1.2 OS)

0

Cl

c a

0

CD

D

CD

O

c

CD

3

0)

CQ

CD

3

S’

o

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CD

3

$

ZT

CD

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CD

a

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CD

a

co

CD

0

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CD

O

$

c

CD

3

£D

CQ

CD

3

S

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K

CD

3

$

IT

O

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3

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0

0

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CQ

C

o

c

C/)

MR BAXTER of Bristol has seen several
programs with double-height titles on a
coloured background in mode 7 and would
like to know how they are done.

This requires the us~ of the CHRS141
control code to give the double-height
lettering. Code 157, which gives a col-
oured background, is also needed. The
colour has to be defined in a previous pixel
on the same line

Two programs are presented here in
procedure form (programs 2 and 3) to
show the technique They could be saved
and used in your own programs. They are
similar, except that one gives a back-
ground just wider than the title length
(program 2) and the other gives a full line
background (program 3) Both procedures
will centre the title, which must be shorter

MODE 7

than 32 characters and spaces to fit on the
line correctly

Each procedure is called up using four
parameters: the line-number for the title
(counting from the top)- the background
colour; the foreground colour; and the title
itself, either given directly in speechmarks
or as a string variable The colour numbers
are numbered in the normal way for COL-
OUR and GCOL statements, except that it
is not possible to select black using 0 For
example

red
green
yellow
blue

magenta

6 cyan

7 white

5 p R0Ctitle(2,l,4,"MV TITLE")

3 END j

)

I DEFPROCt i 1 1 e ( vert pos bar l. m i ±

1 P 'EM Double height tit?e , C ° 1,WOrd * )

is Nidth of titie
a- ( o^-LEN <word$) ) /2

FOR N=0 TO j.

pr : "Vcmi ; 1 4 * chr *

PRINTTAEU C 's-y> ? ^O+torecoI >

NEXT N 8 X) * <vertpos+N))CHR*15fc

ENDPROC

Program 2. Colour background wider than title

M0DE7

PROCt i 1 1 e ( :
END

'i 1 5 4, "MY I ITL.E'

)

1 RE” D°ublB 1 hei’"gh: P “;?J CkC ° 1 '' Or,sco1 '"Ortiz/

' S745SKS-,!?-** — - -«•

1 FOR N=0 TO 1

ENDPROC

Program 3. Background to full width

ACORN USER JANUARY 1984

39

3 inch MICRO DISC DRIVE

Cable Colour Monitor 14" screen RGB good resolution
guaranteed for two years £199.50

Disc Drive Unit on its own with technical manual £99.00
Complete Single Drive with cables,

boxed EPROM, manual, utility disc £149.00
Complete Dual Drive with cables,

boxed EPROM, utility disc, free disc £249.00
Single 3” 100K disc £4.95 Pack of 5 100K disc's £19.95

ORDER NOW!

3" Micro Disc Drive
for the

BBC Model B

Random access of mass storage - Compact size
Fully enclosed rigid plastic cassette, with
protect write switch - Smallest disc size in
micro field - Lightweight, low power
consumption only 5 watts when
running - 100K per disc unfor-
matted, supplied with utility
disc for formatting
Requires standard Acorn
disc interface, but

disc filling system
ROM supplied
with easy to
follow

instructions,
sending back
old DFSROManew
disc will be sent free
charge. New ROM will
also read and write to 5 ’A"
disc drives - Powered from
BBC machine -Single drive easily
upgraded to a dual for £99.00
Macro assembler for the BBC micro -
For a more professional approach - On
disc or easy to fit ROM , complete with
instructions and manual - Send for details to:

DDT Software, Southfield House,
1 1 Liverpool Gardens, Worthing, Sussex

Telephone: Worthing (0903) 213174

MO®© 'iOwjdiaiJ

Southfield House, 11 Liverpool Gardens, Worthing, Sussex BN 11 1RY
Please add carrige plus VAT at 15% to all orders

40

ACORN USER JANUARY 1984

*■

t

i

BUILD-UP TO DOUBLE HEIGHT

THIS month s £5 star letter is from Mr
Willgoss of Pocklington, Humberside, who
poses a seemingly simple problem. He
would like to be able to input an entry into
the computer in mode 7 using double-
height lettering.

The double-height lettering facility in
mode 7 requires the use of teletext charac-
ter code 141. In order to get the double-
height lettering to work correctly you have
to print the control code 141 followed by
the lettering on each of two successive
lines. Try the following line and run it to see
the effect:

10 PRINT CHR$(141) “HELLO”

It will print only the top half of the word
“HELLO”. To print out the whole word, the
same line must be entered again:

20 PRINT CHR$(141) “HELLO”

Now when the program is run, it will magi-
cally print out the word “HELLO” in double
height and not, as one would expect, two
top halves of the word. Once the control

code has been written into a line (a Dianx
space will appear on the screen where the
code resides), the rest of that line will
appear in double-height lettering.

It seems a simple job similarly to pro-
gram in an INPUT statement. Program 4
shows just such an attempt - and it does
not work. It prints out the top half of “NAME
PLEASE”, and then prints out the top half of
the name as it is entered. Once the name
has been entered it then goes to line 20,
printing out the bottom half of “NAME
PLEASE”, and waits again for a name to be
entered.

The problem occurs in the use of the
INPUT statement, but all is not lost. Instead
you can make use of the versatile GET
statement to input a simple numeric vari-
able. If GETS is used, a string variable can
be input.

The following short program illustrates its
operation.

A$=GET$:PRINT A$

Unlike the INPUT statement, the GETS

10 MODE 7

PRIN I CHR$ ( 141 ) ; s INPUT "NAME
-•0 PR INI CHR$ ( 1 4 1 ) ; : I NPUT " NAME

Program 4. Problem with double-height characters

PLEASE "namet
PLEASE "namet

PLEASE'

PLEASE'

10 MODE 7
20 name#='"'

30 PR 1 NT T AB (0,2) CHET 141“ NAME
40 PR I NTTAB (0,3) CHE* 141" NAME
50 REPEAT
60 name*~name*+GET*

70 PR I NTTAB (14,2) name*

U0 PR INTI AB ( 1 4 , 3 ) n ame$

/0 LJN I 1 L. R 1 GH T* ( namel , 1 ) =CHR* ( 1 3 )

00 PRINTTAB (0,6) "HELLO
Program 5. Inelegant solution

10 MODE 7
20 namel=" "

30 PROCdouble (0,2, "NAME PLEASE")

40 REF'EAT

50 name$=name't+GETt
60 PROCdouble (14, 2, name*)

70 UNTIL RIGHT* (name* , 1 ) =CHR* ( 17)

80 PRINTTAB (0,6) "HELLO "name*

90 END
100

120 ?o™0 d ?o bl i e<h ° rPO5,VertPOS ’ WOrdt)

140 NE^™ (h ° rP0S ’ VertP05+N)CHR# ( 141 >
150 ENDPROC

Program 6. Double-height characters anywhere on the screen

wordl

statement does not print out the letter as it
is keyed in. This has to be done using a
print statement and the letter can then be
printed double-height.

To input a whole string of letters a loop
has to be made, with a test to see whether
RETURN has been entered - this will stop
the loop. A REPEAT. . UNTIL loop is the
ideal one to use here. Program 5 shows
one way the routine could be made to
work. It is not terribly elegant, and program
6 shows a longer but more elegant way of
achieving the same input. Program 6 has
the advantage that, once defined, the pro-
cedure to print double-height can be
called up at any time to print anywhere on
the screen. (The three parameters follow-
ing the PROCdouble statement at line 30
give the horizontal and vertical screen
positions, as given in figure 1 , together with
the string to be printed.)

Although longer in this short example,
this approach proves quicker and easier in
a longer program if use of the double-
height procedure is made several times
during the course of the program. In both
programs the string assigned to the name,
nameS, is set to a null string (a string zero
characters long) at line 20.

Although not essential in the programs
presented here, it is good practice to do
this as on some occasions each name will
be added into the variable to give one long
string of names if a program is run several
times.

■ Programs are now being made which
incorporate the use of the user-defined
function keys. A slip of paper indicating the
key definitions is supplied with each to go
under the clear plastic strip, but these can
soon be mislaid or get damaged. Here’s a
way to keep them all together, ready for
use in flip-over book form. Find an old
calendar (not too difficult at this time of
year) at least 20cm wide with a spiral
binding. Cut most of the paper off parallel
to the binding 5cm below it and, if neces-
sary, cut it widthways to about 20cm long.
The bottom sheet can then be inserted
under the plastic strip to hold the leaves in
position and the key definitions can be
glued to each page. Now all the pages can
be kept together and be available when
wanted simply by flipping them over. For
extra protection, cover the pages with
transparent book-binding film.

■ If using tne same series of teletext
control codes more than once in a pro-
gram, put them into a string variable at the
start of the program and then call up the
variable each time:

A$-CHR$133 + CHR$157 + CHR$136 +
CHR$133

When printed, A$ will give a magenta
background and any text then printed will
flash blue.

ACORN USER JANUARY 1984

41

£72 TIM TOM MICRO

IF YOU IIA VE THIS
- A PRAXIS 30 or 35 -
TUPS YOU MUST GET

•v i r r c r
- - .. . > '

THE TIMTOM RS 232/432 <

SERIAL INTERFACE

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THE COST EFFECTIVE VAT OF PROVIDING A HIGH QUALITY DAISY WHEEL PRINTER
CAPABILITY FOR YOUR MICRO. SMALL ENOUGH TO STILL ALLOW USE OF THE
CARRYING CASE WHEN FITTED, THE UNIT GREATLY ENHANCES THE PRAXIS WITHOUT
IMPAIRING USE AS A NORMAL TYPEWRITER. THE MICROPROCESSOR BUILT INTO THE
INTERFACE PROVIDES OPTIMUM PRINTING SPEED AND TAKES CARE OF AUTOMATICALLY
ACCESSING KP1/KB2 CHARACTERS - MAKING THE COMPLETE PRAXIS CHARACTER SET
PRINTABLE. (THOSE STRANGE NON -ASCI I PRAXIS CHARACTERS ARE ACCESSED BY
SENDING A SIMPLE "ALTERNATE CHARACTER SET " CONTROL LETTER ) .

THE T1MT0M INTERFACE CAN BE USED WITH ANY COMPUTER WITH A 300 BAUD SERIAL
CAPABILITY AND iTS HANDSHAKING (THE BBC COMPUTER , VIC 20, C64 AND AIMOS T
ALL CP/M MACHINES ARE FINE ) . THE UNIT HAS LOW POWER CONSUMPTION AND
REQUIRES NO EXTERNAL POWER SUPPLY OR BATTERY. MANY UNITS HAVE BEEN SOLD
AND LETTERS BACK FROM CLIENTS CONFIRM THAT FITTING IS STRAIGHTFORWARD,
OFTEN TAKING LESS THAN 30 MINS. (VERY DETAILED AND CHAR INSTRUCTIONS ARE
GIVEN). A SCREWDRIVER AND SOME VERY EASY SOLDERING IS ALMOST ALL THAT IS
REQUIRED. SO IF YOU'VE ONLY WIRED UP A PLUG UP TO NOW YOU SHOULD STILL
FIND THE WHOLE THING FAIRLY EASY, WE THINK !

TIMTOM TIM TOM TIM TOM

ORDERS ■ by Cheque nr P.O. payable In-
TIMTOM MICRO. 39 /M>.\ GWYN, CAERPHILLY. HALES CEB lES.

S.A.E. for further detail s.

TIMTOM

MICRO, 39 BRYN GWYN, CAERPHILLY . WALES CF8 1FS.

A QUALITY LIGHT PEN

SUPERIOR PERFORMANCE

★ Absolutely insensitive to ambient lighting.

★ Responds to different colours and screen intensities without
any adjustment of TV or monitor.

★ Red LED readout showing that data is available.

★ Switch for program control (allows pen to approach
the screen without erroneous data capture)

★ All features are
program accessible.

SUPERIOR
PROGRAMS

★ Good Documentation.

★ Tape storage of your work.

★ User routines provided on tape
and printout.

★ 'Freehand' drawing program.

★ 'Library menu' drawing program (define your own
shapes).

★ Example programs illustrating uses of the pen and

library of
its features.

£25

inclusive of P&P.

Please state Dragon, BBC or Vic20 when ordering, send
cheque or P.O. to: Dept AU1 Datapen Microtechnology Ltd,
Kingsclere Road, Overton, Hants.

Please enclose SAE if requesting technical literature.

We welcome enquiries from dealers willing to demonstrate our
product

Datapen Microtechnology Limited

X

v

WHAT USE IS A HOME COMPUTER?

A very common question. Here is an
answer. It can help to solve the every day
problem of

"WHAT'S TO EAT?"

Let the BBC micro turn a dreary task into
FUN. Let it provide reminders of forgotten
dishes. Let it list the ingredients, let it
produce the shopping list.

Give this program as a gift and the cook of
the house will become a computer convert
— backing your daydreams of extending
your system . . . Discs . . . Printer . . . ?

"What's to Eat?" is simple to operate. By
providing over 20,000 possible combina-
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everyday meals or special occasions.
When the final choice is made the menu is
displayed, the ingredients are listed and a
shopping list is produced.

Available on cassette £9.95 or 40 track
disc £12.95. Add 50p postage and
packing. Prices include VAT.

Don't Delay — Send Today to:

SHUMWARI ASSOCIATES
12 Marlin Court, Marlow
SL7 2AJ

VDU EMULATION

You can harness the power of your BBC
Microcomputer for both problem solving
and as a full function visual display unit. "
Simply plug the Emulator Chip into your
microcomputer and you have facilities such
as direct cursor control, protected fields, full
serial line handshaking and much more.

Two models of emulator are currently
available:

Digital Equipment Corporation
TypeVTIOO £35

Newbury Data Systems Type 8003 £25

Communication software giving full serial
line control by your BASIC program is
available either in its own chip or combined
with an emulator.

Terms -cash with order, cheques payable
to Arts Ltd’. Prices include documentation,
p+pand VAT.

Special emulators and communication
software produced to order.

Applied Real Time Systems ltd

DEPT AU.

PO Box 32. Sunderland, Tyne & Wear SR2 7SN

42

ACORN USER JANUARY 1984

VOICE

SPEAK TO ME

MUCH has been said about the BBC Voice
Synthesiser, but as yet it hasn’t had a lot to
say for itself. The vocabulary of the word
PHROM supplied by Acorn is quite com-
prehensive and includes a number of pre-
fixes and suffixes with which to construct
additional words. Unfortunately, 165 words
has its limitations. You start thinking ‘if only
Acorn had included this word, or that
prefix’. They do intend to extend the vo-
cabulary. The article in the October 1982
issue gave a clue as to what is available;
now it’s time for the nitty gritty. Let’s pull the
speech processor and the word PHROM
apart and see what can be done - with a
little imagination you will be able to get
your BBC to say almost anything.

First, a summary of the more basic
methods of accessing the vocabulary, with
apologies to those already familiar. The
simplest is to use the Basic sound com-
mand with the channel set to -1 and the
second parameter set to a given variable.
This variable can be a ‘word number' in the
range 32 to 291 and these provide the full
range of the standard vocabulary, in-
cluding the part words. For example,
SOUND- 1 ,65,0,0 will produce the letter
‘A’. The last two parameters are always
zero. The lower range 32 to 126, which
corresponds to the ASCII code range, will
produce sounds wherever possible that
associate with the ASCII character. This
provides a second format, for example.
SOUND- 1 ,ASC“A'’.0,0. The sounds in the
lower range are duplicated in the range
127 to 291, so SOUND— 1 .159,0.0 will also
produce the letter ‘A'. The reason for this is
that the upper range provides a method of
directly accessing words in the PHROM by
location. We will look at this shortly.

One of the simplest methods of con-
structing words is to use the part words
provided, and stringing several sound
commands together. SOUND-1 ,207,0,0:
SOUND-1, 264, 0,0:SOUND- 1,131 ,0,0 for
example, will produce the word ‘in- ten -d’.
This provides a very useful method of
construction, but again one with limitations.
To be able to construct almost any word
we must be able to obtain an almost
unlimited number of part words, and the
only way of obtaining these is to pull
existing words apart. To do this we must
first look closer at the sound parameters.

So far we have considered the first
parameter of the sound command to be
-1. From now on we must consider the
value of this in its hex equivalent, &FFFF. In
this two-byte format, it is used to tell the
speech processor exactly what to do with

Limitations on the
vocabulary of the BBC
micro’s speech chip can
be overcome using some
simple assembly
language routines
provided by
Ian Rowlings

the rest of the sound parameters. The first
byte (MSB) is always &FF, but the second
(LSB) can take several values. Consider
the value &FFFx, where ‘x’ relates to the
word PHROM number This nibble (four
bits) can take the value 0 to 15 (&F). and
thus in future up to 16 different PHROMs
could be addressed. For our purposes the
standard on-board PHROM is number 15
hence &FFF(F), which means ‘speak from
the on-board PHROM using the word num-
ber provided’. To access words directly
from the PHROM, and for the purpose of
constructing our own words, we must tell
the processor to use ‘absolute address-
ing’. This is done using the parameter
&FFBx. Hence, &FFBF means ’speak using
absolute addressing from the on-board
PHROM’. Two additional commands.
&FF60 and &FF00 are available, but we will
look at these later.

Absolute addressing is just another
method of accessing the vocabulary where
instead of giving the second sound para-
meter a word number or an ASCII charac-
ter, you give the start address in hex of
where the data for a particular word is
located in the PHROM. Thus the command
SOUND&FFBF,&B5D,0,0 will access the
data at the address specified and produce
the sound ‘A’. All the word numbers, ASCII

equivalents and addresses are specified in
the voice synthesis manual
To recap, all the following commands
produce the sound of the letter ‘A’:

SOUND- 1,65, 0,0
SOUND-1.159,0.0
SOUND-1, ASC“A 0.0
SOUND&FFBF,&B5D.0,0
SOUND&FFFF.65.0.0
SOUND&FFFF, 159,0.0
SOUND&FFFF,ASC“A ,0.0

Straightforward so far, but to continue our
quest we must now look at addressing the
processor in assembly language For
those who only use Basic or who have a
dread of assembly language don’t be put
off. As you will see it’s very easy, and even
if you don't entirely understand it, you can
still use the routines. The standard OS-
WORD call (User Guide p461), can be
used with A=&07, as you would with
normal sounds. First you need to set up the
data block to pass the speech parameters
as in figure 1 .

The command type as discussed earlier
should be &FF when using word numbers,
and &BF when using absolute addressing.
For simplicity let us put these values into
zero page using pling (!) indirection, Pro-
gram 1 shows how this could be done. Of
course, there are several alternatives to
this routine. You could extend it by placing
the CALL in a loop and reading the data
values required, or even passing the data
as CALL parameters Unfortunately, OS-
WORD merely provides an equivalent call
to the Basic sound command and is not
suitable for our purposes. To construct our
own words we need to read and write
directly to the speech processor, and the
only way to do this is to use OSBYTE.

Now we can get down to some exam-
ples. There are two methods of construct-
ing words using OSBYTE. You can if you

Address
XY
XY+1
XY +2

XY + 3

XY+4
XY + 5
XY + 6
XY + 7

Contents

Parameter 1 (LSB)
Parameter 1 (MSB)
Parameter 2 (LSB)

Parameter 2 (MSB)

Parameter 3 (LSB)
Parameter 3 (MSB)
Parameter 4 (LSB)
Parameter 4 (MSB)

Command type
&FF

Word number or Address - low
byte

Word number or Address - high
byte
&00
&00
&00
&00

Figure 1. Data block to pass speak parameters

ACORN USER JANUARY 1984

43

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44

ACORN USER JANUARY 1984

VOICE

wish, by constructing and passing the right
data, create new words from scratch. This
is, however, extremely difficult, takes a
long time and consumes a considerable
amount of memory. I will touch on this later.
A much simpler method would be to create
numerous part words which when strung
together produce the desired effect. This
can be done by instructing the processor
to access a word from the standard vo-
cabulary and then, after a suitably short
delay, issuing a second instruction to
'chop' the word before its completion.
Unfortunately, because of the way in which
the word data is stored, trying to access
the middle of a word with an intermediate
address will only produce garbage. Only
the absolute address can be used, which

PHROM number - 1111 (&F). Figure 2
shows how it’s done.

As you see from the result in figure 2, the
value is &85BE3. In fact, it is even more
simple than it appears. The first three
values will always be the absolute address
in reverse order, and the last value will
always be &03. With a four-digit address,
the fourth value will be the first digit of the
address + &0C. A three-digit address is
the easiest; reverse its order and tack &C3
on the end. We only need to add &40 to
each digit and we have our five param-
eters, &48 &45 &4B &4E &43, to pass to
the processor. Having done this, we then
only need to instruct the processor to
speak with &FF50. Program 2 illustrates the
process.

LSN

&8

0001

&5

1010

& B
1101

&2

0100

0011

0000

1100

MSN (reversed address)
(PHROM number)

0001

1010

1101

0111

1100

(Result)

Figure 2. Format for pence’

DATA*232t , t tS,*25F, 1
*2409,200

660 DATA*4 15, 1 00 , *1 ?5A , 5 5 ,
*3EFC , 45

670 DAT A* 263D , 55 , *25F , 30 ,

*-.315-7,60

680 DATA* 2923, 55, *2 IPS ,40,

*328,100

690 DATA&415, 100,*1C1 1 ,200,
*2321,100

700 DATA* 1483, 22, *3153,63,

*2923,55

710 DATA&25F , 1 ft,?*JCC9, 14,

*25F, 15

720 DATA&31 53, 64 , *.DBD, 60 ,

* IB IE, 48
730 DATA© , 1

And for the poet lovers
among you, (with my
apologies to the author ) :

650 DAT A* 1DCC, 120, *2409, 200,

* 1 CC9 , 22

660 DATA&27E5, 150,*16D7, 170,
*25F , 25

670 DAT A*633 ,65 , ?<36DF , 75 ,

*1240,200

680 DATA*CB3 , 250 , *633 , 65 ,

*36DF , 75

690 DATA*21F5,40,*29DE, 180,
t 124D, 160

700 DAT A*DBD ,110, *2E9 , 50 ,
*36DF,55

710 DATA&329A, 84 , * 1 DCC , 1 50
0, 1

Figure 3. Alternative data for program 5

Voice

Energy Repeat Pitch K1

K2

K3

K4

— 1011

0

101010 11100

00110

1001

0110

Repeat

— 1001

1

000000 —

Space

— 0000

—

—

Unvoiced

— 0101

0

000000 11101

01011

0100

0011

Stop

— 1111

—

. — —

—

f-,,-

K5

K6 K7

K8

100

K9

110

K10

001

Figure 4. Word data frame

limits us to the beginnings of words. Still, I
have found it is possible to construct
complex words and sentences in this
manner.

The relevant OSBYTE calls are not listed
in the User Guide, so it’s down to brass
tacks. With A=&9E or A=&9F we can read
or write directly to the speech processor. In
either state the relevant commands are
placed in Y before calling OSBYTE. At the
moment we only need to write commands,
and the operations to do so are:

Command Operation

&4x Load address

&50 Speak (from PHROM)

&70 Reset (chop!)

The 'x' in the load address command
represents a nibble of the address of the
word we wish to use. Unfortunately, this
command also needs to include the
PHROM number. So to pass both the word
address and the PHROM number, this
particular call has to be made five succes-
sive times. Acorn has confirmed that the
information to do this in the manual is
incorrect, which doesn’t help much as the
method could be confusing. To work out
the format required involves some simple
binary arithmetic and is easy. Let us con-
sider the word ‘pence’ whose absolute
address is &2B58. It must be represented
in a somewhat unconventional manner;
least significant nibble (left) to most signifi-
cant nibble (right). To this is added the

10 REM LISTING 1
20 DIM MC7 10
30 P7.=MC7.

40 COPT 0
50 .SPEAK
60 LDA#7

70 LDX# ( &70 MOD 256)

80 LDY# <&7 1 DIV 256)

Q 0 JSR?vFFFl
100 RTS
110 3

120 ! &70=&B5DFFBF
130 ! &74=0

140 CALL SPEAK

Program 1. Using!

10 REM LISTING 2
20 DIM MC7. 35
30 P7.=MC7.

40 COPT 0
50 .SPEAK
60 LDA#&9F

70 LDY #&48 : J SR2/FFF 4 \

80 LDY#&45: JSR&FFF4 \

90 LDY#&4B: JSR&FFF4 '

100 LDY#?<4E: JSR&FFF4

110 LDY#&43: JSR&FFF4
120 LDY#&50: JSR&FFF4
130 RTS
140 3

150 CALL SPEAK

Program 2. Instructing processor to speak

\ SET A = 7

\ LOAD INITIAL VALUES FROM
\ START OF DATA BLOCK
\ CALL OSWORD

:REM LOAD CONSECUTIVE LOCs
WITH ADDRESS AND COMMAND
: REM FOLLOWED BY
PARAMETERS 3 AND 4
:REM CALL MACHINE CODE

PASS 1st ADDR. PARAM. (LSB)
PASS 2nd ADDR. PARAM.

PASS 3rd ADDR. PARAM.

PASS 4th ADDR. PARAM.

PART OF PHROM No.

PASS PART PHROM No.

PASS SPEAK COMMAND

ACORN USER JANUARY 1984

45

YOU HAVEN’T
SEEN ANYTHING

LIKE THIS ON A

COLOUR MONITOR

BEFORE.

An RGB monitor from JVC offering a resolution of
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For we’ve managed to acquire the sole distribution
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There are two models available: medium resolution
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The units have a 14" screen and are suitable for the
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Delivery is good: your monitor should arrive
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You can order by filling in the coupon below and
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THE JVC

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r,;

MODEL REFERENCE

1302 1 Medium Resolution

1302 2 High Resolution

RESOLUTION

370 x »70 Pixels

580x470 Pixels

CRT

14"

14"

SUPPLY

220 240v. 50 ooilz.

220 24 Ov. 50 6011 /

E.H.T.

Minimum I9.5kv

Maximum 22.5kv

Minimum I9.5kv

Maximum 22 5kv

VIDEO BAND WIDTH

6MI Iz

IOMII/

DISPLAY

80 characters by

2S lines

so characters by

25 lines

SLOT PITCH

0.63mm

0.41mm

INPUT; VIDEO

R.G.B. Analogue

1TL Input

R.G.B. Analogue

TTL Input

SYNC

Separate Sync i >n R.G B.
Positive or Negative

Separate Sync on R G B.
Positive or Negative

EXTERNAL CONTROLS

( )n off; switch and
brightness control

( )n off switch and
brightness control

Opu.s Supplies Ltd., 158 Camberwell Road, London SH5 OFF
Please send me Medium Resolution Colour Monitor(s) at

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I ligh Resolution Colour Monitor(s) at

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Connection lead(s) at £6.00 each

I understand carriage per m< mitor will cost an extra £7.00.

(N.B. A Medium Resolution Monitor including VAT, lead, and
carriage costs £18739- A High Resolution Monitor including VAT,
lead, and carriage costs £279.39.)

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Please state the make of your computer

Name -

1

Address.

46

ACORN USER JANUARY 1984

J

The processor will now access the word
data and execute it. It will in fact continue
to execute the word until either it reaches
the end of the data, or it receives a reset
command (&FF70). All we need to do,
having executed the word, is to wait a
suitable length of time and then send the
reset command to chop the word off exact-
ly where we require. Program 3 incorpo-
rates a double delay loop to allow for a
period of 0 to 255. Again I have used
indirection to set up the delay, but you can
use whatever method suits your require-
ments. This particular example using the
delay value 110 on the word pence’,
produces the new word 'pen’. You will find
that both the values 0 and 255 allow any
word in the vocabulary to be spoken in its
entirety. You can experiment with different
delay values on different words to build up
a library of both complete new words or
additional part words with which to con-
coct new words.

We can now expand this to pass any
number of word/delay pairs sequentially to
construct sentences. Program 4 shows
one method where the calculations for the
five load address commands are done for
you, and where suitable word/delay pairs
are read from data statements within a loop
and passed to a procedure which calls the
machine code. This particular method is
not very elegant, as reassembling the ma-
chine code each time it is called is slow
and does not promote very smooth
speech If we are going to create words
from several chopped part words, the time
between chopping or resetting a word to
the start of the next must be negligible.
Also notice that the area set aside for the
machine code is fixed. If it weren’t and you
had a lot to say a vast amount of memory
would be needed. By the way, there is no
prize for guessing what this example says.

It is a common occurrence in my house,
where I spend too much time at the key-
board and not enough concentrating on
the more basic requirements of life.

A much faster and more elegant method
would be to use a machine code routine
which involves no mathematical calcula-
tions and where the word/delay pairs are
passed as CALL parameters. Program 5
shows just how effectively new part words
can be strung together. In this example the
parameter block set up by the CALL is first
transferred to zero page where the relevant
addresses are initially stored from &70 to
&74. The delay value is then stored in &73,
and subsequent manipulations for the first
four load address commands are stored
from &74 to &77. I don’t claim this is the
ultimate routine for creating speech, but it
works and can be effective. If you want to
try some other examples replace the data
statements with those in figure 3.

There are some important tips to remem-
ber when using the above routines. First,
don’t be tempted to mix the machine code
with Basic sound commands. Their access
speeds are drastically different and they
can easily get out of sync. In many in-

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

*260

270

280

REM LISTING 3

DIM MC7. 60

FOR N7.=0 TO 2 STEP2

F'7.=MC7.

COPT N%

. SPEAK
LDA#8<9F

LDY#&48: JSR2<FFF4\ LOAD ADDRESSES
LDY#?<45: JSR&FFF4
LDY#&4B: JSR&FFF4
LDY#?y4E: JSR2/FFF4
LDY#?/43: JSR&FFF4
LDY#?<50: JSR2<FFF4
LDX&.70
.L LDY#?/FF
■LI DEY

NOP: NOP: NOP: NOP

\ LOAD DELAY FROM &70
\ INITIALISE FIRST LOOP

\ SUITABLE ADDITIONAL

NOP: NOP: NOP: NOP \ DELAY FACTOR

BNEL1 \ LOOP ON &FF

DEX

BNEL \ LOOP ON DELAY VALUE

LDY#&70: JSR&FFF4V RESET TO CHOP WORD
RTS
3

NEXT

REM LOAD MEMORY WITH DELAY
?&70= 1 10
CALL SPEAK

Program 3. Uses delay loop

1 REM LISTING 4
10 REPEAT
20 READ AD7.,DEL7.

30 PROCSPEAK
40 UNTILDEL7.= 1
50 END

60 DEFPROCSPEAK
70 FORN7.=0TO2STEP2
80 P7.=*eD00
90 COPT N7.

100 .SPEAK
110 LDA#2s9F
120 LDY#&40+ (AD7AND?<F)

130 JSR&FFF4

140 LDY#&40+ ( AD7.AND&F0) /&F
150 JSR&FFF4

160 LDY#?<40+ ( AD7.ANDS/F00) /&FF
170 JSR?<FFF4
180 LDY#?<4C+ ( AD7AND&F000 > /&FFF \ 4th LOAD ADDR
190 JSR?v.FFF4

: REM READ ADDR. AND DELAY
: REM CALL M.CODE

: REM FIXED ASSEMBLY ADDR.

\ 1st LOAD ADDR.
\ 2nd LOAD ADDR.
\ 3rd LOAD ADDR.

5th LOAD ADDR.
SPEAK COMMAND

200 LDY#&43: JSR&FFF4 \

210 LDY#2<50: JSR&FFF4 \

220 LDX#DEL7.

230 .L LDY#&FF

240 .LI DEY

250 NOP: NOP: NOP: NOP

260 NOP: NOP: NOP: NOP

270 BNEL 1

2^0 DEX

290 BNEL

300 LDY#?/70: JSR2/.FFF 4 \ r ES ET / CHOP

310 RTS

320 3

330 NEXT

340 CALL SPEAK

350 ENDPROC

355 REM WORD / DELAY PAIRS

360 DAT A?<232 1,115, ?<3573 , 1 20 , ?< 1 F57 , 1 35

370 DAT A& 1 483 , 24 , &2923 ,0,0, 1

Program 4. Calculates load address commands

1
10
20
30
40
50
63
70
80
93
100
1 10
120

REM LISTING
DIM MC7. 105
FOR N7.=0 TO ‘
P7.=MC7.

COPT N7.

. SPEAK

CLC

LDX#4

•L LDA&60 1 , X
STA&70 , X
DEX
BPL L
LDY#0

STEP2

transfer relevant

PAR AMS. TO ZERO PAGE

continued on page 49

ACORN USER JANUARY 1984

47

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48

ACORN USER JANUARY 1984

1

VOICE

a

stances the delay factor you choose will be
critical; a numeric difference as little as two
can have a considerable effect. Unfortu-
nately, we are always left with the sounds
produced from the PHROM data, which
cannot be altered. As such not a great deal
can be done to alter tone, emphasis or
inflection. However, judicious use of delays
between words and individual syllables
can provide close approximations. You
can use chopped values of the two timed
spaces provided in the vocabulary to help
with this. Similarly, where you may have a
choice of standard words which all appear
to provide the same part word, you should
test each one to find which has the nearest
energy and pitch levels for your purpose.
It’s just a case of experimenting and perse-
vering until you get what you want. Don’t
be tempted to rush things. Develop one
word at a time and get it right before going
on to the next or concentrating on inter-
word spacing. Build up phrases gradually;
you can always refine them later.

There is one final method available for
constructing new words from scratch. Al-
though Acorn says it can be used, it is
extremely difficult. You not only have to be
a linguistics expert, but also have access
to very sophisticated speech analysis
equipment. Because of the volume of data
needed to construct each word it can also
consume vast amounts of memory. Few
people will be able to do it properly, so it
will not be of any great value. However,
there are ways to get round some of the
problems.

The method involves constructing the
correct data for any particular word, stor-
ing it in RAM, and instructing the speech
processor to execute it. The word data is
constructed in frames, each 1/40s long,
and containing a number of parameter
types. The parameters are energy, repeat
and pitch, followed by up to 10 vocal para-
meters (reflection coefficients, K1 to K10).
The first three are essential and determine
what others are required. The energy and
pitch parameters have an obvious mean-
ing and ‘repeat’ provides a method of
extending a sound by repeating the pre-
vious frame. The other 10 parameters re-
present special values to emulate the vocal
tract and have a decreasing effect from K1
to K10. Typical frames, showing the num-
ber of bits required for each parameter,
might look like figure 4.

All words can be constructed from these
formats, but you must pack the last value
with zeros to ensure the data will form
complete eight-bit bytes. Having con-
structed the data in bit form, you take a
byte at a time and form the actual numeric
data values ready for processing. The first
two bytes from the above, for example,
would be 10110101 (181) and 01011100
(92), and so on. The next thing to do is read
a byte at a time, reverse the order, and
store it in an array. From the example this
would produce the first two bytes as
10101101 (173) and 00111010 (58). Re-
verse order is necessary because of the

continued from page 47

STORE DELAY VALUE
WORD ADDRESS (LSB)

CALC. 1st LOAD ADDR.

STORE pi AT 8(74

NEXT WORD ADDR. NIBBLE

CALC. 2nd LOAD ADDR. P 2

AT 8<75

NEXT WORD ADDR. NIBBLE
CALC. 3rd LOAD ADDR. p3

STORE p3 AT 8<76

NEXT WORD ADDR. NIBBLE (MSB)

CALC. 4th LOAD ADDR. P 4

STORE p4 AT 8<77

LDA (8(73) , Y
140 STAS' 73
150 LDA (8(70), Y
160 AND#&F
170 ADC#?<40
180 STASt74
190 LDA (8(70), Y
200 AND#?/F0
210 LSRA
220 LSRA
230 LSRA
240 LSRA
250 ADC#&40
260 STAS; 75
270 I NY

280 LDA (8;70) , Y
290 AND#8;F
300 ADC#?v40
310 STA8/76
320 LDA (8;70) , Y
330 AND#?/F0
340 LSRA
350 LSRA
360 LSRA
370 LSRA
380 ADC#.34C
390 STA8<77
400 LDA#8(9F
410 LDX#0
420 .LI LDY8<74
430 INX
440 CPX#4
450 BNE LI

460 LDY#?/43: JSR8;FFF4
470 LDY#S 50: JSR?vFFF4
480 LDX8<73
490 . L2 LDY#8<FF
500 . L3 DEY
510 NOP: NOP: NOP: NOP
520 NOP : NOP : NOP : NOP
530 BNE L3
540 DEX
550 BNE L2

560 LDY#8(70: .JSRS'FFF4
570 RTS
580 1
590 NEXT
600 REPEAT
610 READ AD7. , DEL*/.

620 CALL SPEAK, ADX, DEL7.

630 UNTIL DEL7.= 1
640 END
650 DAT A8<232 1,118, 8c25F , 20
660 DATA&3573, 135,8,415,80

670 DAT AS; 1 483 , 35 , 8(2923 , 220 ,0,1

Program 5. Stringing together new part words

ACORN USER JANUARY 1984

49

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50

ACORN USER JANUARY 1984

-

VOICE

i

a

way the speech processor buffer stores
and sends the data. The final step is to
instruct the processor to ‘speak’ the data
stored in the array. This is where the
remaining two commands arise. You will
remember the command &FFBF to 'speak
from PHROM’; we now need the command
to speak from RAM’ (speak external).
There are in fact two - &FF60 must be sent
with the first two bytes as this also initia-
lises the processor to the required state;
&FF00 is used with all subsequent data
Program 6 illustrates the whole process
and contains the data for the word ‘illegal'.

Having got this far, the only real problem
left is how to work out the required data for
any new word. The answer is, it’s almost
impossible without the right equipment.
However, having said that, all is not lost.
There is a way (if you’re a masochist). The
method requires reading the data for an
existing word from PHROM. reconstituting
the parameters in binary form, taking out
those complete sets of parameters for the
part word you want, and translating these
back into numeric data values that can be
used in the routine (program 6). This can
be used to create new words, or to obtain
part words from any section of an existing
word, not just the beginning. This I will
leave you to experiment with, but as a start
look at program 7 I used it to obtain the
data in PHROM for illegal’. Again, it’s not
too elegant, but putting in the correct
address will allow you to read the data
stored for any word in the vocabulary.
Modifications would also allow you to store
and manipulate the data as you wished. As
you can see. the location of the first byte of
word data is always the absolute address.
However, the location of the last byte of
data is not, as you might expect, the
location prior to the absolute address of
the next word. The last byte(s) of the data
sequence contains the word name(s) of
the next word (Speech Processor Manual,
p29,30). A close look at the addressing
loops in the program should clarify this.

A facility does exist whereby ‘code val-
ues’ relating to standard sets of voice
parameters (energy, pitch etc) can be
passed to the processor, to avoid the
necessity of storing vast quantities of data.
Unfortunately, Acorn cannot shed any light
on how this is done, and I have, as yet.
been unable to discover the information
elsewhere Time will tell.

One point remains. If you are developing
software in which you wish to test for the
presence of the speech processor, this is
quite easy. Just try the following:

A% = &EB:X%=0:Y% = &FF:X% =

(USR&FFF4 AND&FF00)/&1 00
X% will be zero if the processor is not
present, and &FF if it is.

I hope this quest has proved of interest
For those who already have the power of
speech, at least your machine will have
more to say for itself than it does at
present I hope your own experiments will
be fruitful and would welcome any com-
ments or further information as a result •

continued from page 49

\ LOOP SENDING
\ DATA STORED

TO READ,

i»0 JSR&FFF4
30 LDX#0
'0 .LOOP
i0 LDY array:/, X
'0 JSR?<FFF4
10 I NX
0 CPY#0
0 BNE LOOP
0 RTS
0 3

0 NEXT

0 REN CALL PROC.

, _ REVERSE AND SPEaITdATA
3 PROCSPEAK

3 END

a defprocsfeak
a ix— i

3 REPEAT
3 I7.= I7.+ i

5 REM READ EACH DATA VALUE
) READ A7.

1 REM REVERSE .AND STORE

I ARRAYX? 1 7.=USR (REVERSE) AND?/FF
1 UNTIL A7.=0

REM CALL M. CODE TO SPEAK

CALL SPEAK

ENDPROC

REVERSED
IN ARRAY7

0 REM DATA FOR " ILLEGAL "

0 DATA164, 152,50, 149

0 OATA52.230, 132 250 4 28

1 Si • z&i&iSk?"

9 DATA77 ’ f|Kfl ^ , 1 87 , i 1 7 , 188

* DATA 1 76 , 1 1 7 , 20 1 1 £ ’ l^Z

1 DATA 108, 227, 98, 239 1 0 ~

1 DATA195, 82, 190, 143,24 77'^, ’ 8 ^o

DATAU5,172,1 6 L8 Til 54 -,p

DATA225 , 1 56 , 4 1 , 78 , 199 , ^ 'l?', B
DATA8,219, 1 9- 77 -71- A. j6 ’ 101

DATA214, 45,173, I^IIiCto.’b 97 ’ 216

Program 6. Uses data for 'illegal'

30

40

REM LISTING 7
REM LOAD WORD ADDR.

MINUS No. OF LETTERS IN WORD
REM .DAT PASSES A "READ BYTE”

TO ACCESS CONSECUTIVE DATA VALUES

ft,*. 1 *™ 4 ■“

MODE 7 : VDU1 4 , 10,10
DIM MC7. 50
DIM DAT7. 250
FOR NX=0 TO 2 STEP r?

P7.=MCX
COPT N7.

LDA#&9F X L0ads addr - of word required

\ MUST BE WORD ADDR.
MINUS No. OF LETTERS

LDY#?<47: JSR&FFF4

40 LDY#&43: JSR&FFF4
50 LDY#?/4E: JSR&FFF4
S0 LD Y#2:4D: JSR&FFF4
70 LDY#?.;43s JSR&FFF4
30 RTS
?0 1

30 P7.=P7.+ 1 0
0 COPT 0
’0 . DAT

; ® L DA#8e9F:LDY#Stl0: JSRS<FFF4 \ SEND "RFAn p.vtctm
J ?r 9E!j — 4 ' REA ° BY?E PROM PHROM

\ TRANSFER RESULT IN Y TO A
0 Rxs F0R USE WITH USR

0 I

0 NEXT

0 REM CALL TO LOAD WORD ADDR

0 CALL ADDR

7 PR I NT " WORD NAMES : LABELLI (RFVFBQrm «

3 F0RIX=t D lE37 E T07°iE3D RE ^ F0R " 1 LLEGAE "

3 REM CALL FOR DATA IN PHROM
5 PRINT USR ( DAT > ANDS.FF
) NEXT

> PR I NT "DATA

! ™ ’?. DDRE3 ? ES 0E DfiTA FOR "ILLEGAL"

1 > Uh ^ E TC Z i EDA

• PR INT USR < DAT > AND&FF
i NEXT

^i N Ji W0RD NAMES <NEXT WORD! : -MI (RFYFRFFn * '

REM ADDRESSES OF WORD NAMES FOR "IN-" <REVERSED >

FOR 17.-?/ 1EBC TO ?7lEBD

PRINT USR (DAT) AND?vFF

NEXT

END

Program 7. Obtains data from PHROM

ACORN USER JANUARY 1984

51

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The programs are menu- driven and thoroughly error-
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52

ACORN USER JANUARY 1984

GAMES

SNAPPY WRITING

THIS article assumes you have mastered
the art of moving a shape around the
screen, and that you now wish to write a
game. So, take a look at Nick Wilkinson’s
article first if you need to.

There are several ways of writing a
game, or any program. The first is to sit
down with a pencil and paper, and rough
out the outline, ie how the player will be
represented, how the baddies will move,
what shape the screen will be, and so on.
Having done this, it’s time to write the main
loop of the program. This is normally in a
form similar to figure 1 .

Note how long names are used for the
subroutines this aids legibility and the
code becomes self-documenting. Once
this ‘top level’ is out of the way, the writer
can concentrate on the subroutines
themselves.

The next thing to think about is the
‘difficult’ subroutines. Most games have
some speciality which sets them apart from
the others, for example in Scramble ( Rock-
et Raid), the sideways scrolling screen is
the feature, and in Donkey Kong , it is the
large number of different things to dodge,
climb, and rescue. These ‘features’ are
usually the most difficult to program, and
the author must check the idea can be
done on the machine before continuing.
For example, hardware scrolling cannot be
used on the Electron for the smooth
sideways motion required by Scramble,
and thus it is necessary to devise some
other method, or start something else.

First, however, let’s think about structure.
The method just described is a combina-
tion of the 'top down’ approach, and the
‘bottom up’ approach. The terms become
fairly self-explanatory if you think of the
program as a tree, with the main loop at the
top (all trees in computing are upside
down, as the root is at the top, with the
‘branches’ growing downwards!), and the
‘primitives’ (which are the routines that do
the donkey work of looking at the key-
board, plotting a shape, etc) at the bottom.

At a lower level, other things which come
under the nebulous heading of ‘structure’
are parameters, small routines, constants,
comments and look-up tables. First para-
meters. These are a good idea in assem-
bler for the same reason that they are in
Basic — ie they make the routine more gen-
eral-purpose. Parameters can be passed
to a routine in one of at least four different
ways. If there are only a maximum of three
single byte values to pass, the 6502 chip’s
internal registers (A, X, Y) can be used (this
is the method used by the MOS with
OSBYTE calls). Next, X and Y can together
form a 16-bit address, where an informa-
tion block is held - as in OSWORD calls.
Another way is to leave the values to be
passed on the stack (see Joe Telford’s

Jonathan Griffiths,
author of Snapper,
gives away some
Acornsoft secrets
on writing games

article), although this would require careful
removal, as the first two bytes to be pulled
would not be parameters, but would in-
stead be the address to return to. This
method is useful for recursive routines. But
beware, the 6502 stack is only 256 bytes
long, and if this is used heavily, it may
crash (ie wrap around to the start when it
gets too long). Finally, of course, the pa-
rameters can be passed into known
addresses.

Small routines make the code easier to
debug, which is a real necessity, although
often over-looked. If it is possible to read
the whole routine on one screen (without
multi-line assembler statements!), then it
becomes much easier to spot errors.

Constants are a good idea because to
change, say, the number of ghosts chas-
ing you, it would only be necessary to
change one statement in the initialisation
section. Most people write all their con-
stants as numbers, which would mean, to
do the same as before, going through the
entire source code (my latest game, JCB
Digger, has about 110k of source!), and
then changing all the places where the
number of ghosts was mentioned, which
are not always easy to spot.

Comments are nearly always ignored
when people start to program, and it is only
later, when they start to wonder exactly
how that amazing three dimensional plotter
worked, that their value is realised. Also,

.enter

JSR initialise
.mainloop

JSR update

JSR plotshapes

JSR get input

JSR checkcollisions

LDA dead

BEQ mainloop

JMP hi score

Figure 1. Main program loop

many people who are brought up on Basic
think of comments as wasteful, as they
occupy valuable RAM. This point does not
apply to assembler, which may be likened
more to a compiler than to an interpreter,
and the only problem is then how to get the
source code into the machine. This prob-
lem can be solved - see later.

Look-up tables produce fast, and often
compact, code. These can be used to
convert one value to another, whenever it is
needed, and where there is no simple
algorithm to do so. An example might be a
three-times table look-up.

Long variable names, mentioned earlier,
might be felt by some to be impractical in a
micro with only a small memory, but these
memory problems can be sorted out with a
master program which takes the assem-
bler source code in chunks, and assem-
bles them one after the other. This means
that, since all the source does not need to
be there at once, there can be as many
comments and long variable names as you
wish.

The master program could look like fi-
gure 2. This makes use of the fact that BBC
Basic allows more than one program to be
resident in memory at any time. Thus the
master program is always in memory, and
each source file is loaded up when it is
needed. Note also the way of swapping
between programs. Each source file is not
RUN, but is treated as a subroutine to the
main program. This means that all the
variables from all the source files are
known about from the master program,
and each source file is not aware that it’s
fellows are not there, as the information
regarding them is known. A typical mem-
ory map might look like figure 3. Each
source file should only be about 8k long,
and this is the one size that can shrink if the
object code and the storage for the varia-
bles gets too large. Some typical numbers
in the master program (figure 2) for those
with a disc machine would be:

• origin at &1 900.

• if the game uses a 20k graphics
mode (as most do), the area re-
served for the source files would
probably start at &3000

• the master program would start at
about &5000, and the variables
would live from the TOP of this pro-
gram to the bottom of the screen
(&7C00 for teletext)

With an Electron, the only differences
would be that the screen would start at
&6000 instead of &7C00, and you might
need to shunt everything down a little, or
reduce the size of your source files.

Note that I assume a disc-based system
for this program because of the number of
file accesses needed with two-pass as-

ACORN USER JANUARY 1984

53

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ACORN USER JANUARY 1984

10 origin=<start of area for machine-code>

20 file$="ABC"

30 PROCrun ( "I" , <page for source files>)

40 FOR pass = 0 TO 2 STEP 2
50 P%=origin

60 TOR files = 1 TO LEN(file$)

70 PROCrun (MID$ (file$, files, l),<page for source files>)

80 NEXT files
90 NEXT pass

100 PRINT "Object code from ";STR$ 'origin; " to ";SIR$'P%

110 END
120

130 DEF PROCrun ( name$ , start )

140 PRINT najne$

150 OSCLI "LOAD 90URCE"+narre?$+" "+STR$'start
160 PAGE = start
170 QOSUB 0
180 ENDPROC

Figure 2. Example master program

0 REM SOURCEB

.rnd

10

LDA

seed

20 [OPr pass

AND

CO

30 <assembler text>

ADC

#&38

•

ASL

A

•

ASL

A

•

ROL

seed+2

•

ROL

seed+1

1000 ]

ROL

seed

1010 RETURN

LDA

seed

RTS

Figure 4. Format for source file Figure 5. Random number

routine

sembly. You can use it on cassette if you
must, but if you do, it would be a good idea
to insert a line 85, saying ‘PRINT "Please
rewind your tape’’:dummy=GET’, so the
second pass may work. Also, don't forget
to have your source files in the right order,
or it won’t work.

Each source file must correspond to a
certain format for the master program to be
able to assemble it, which is shown in
figure 4. The stipulations are that there
must be a line 0, or the PROCrun routine
won’t find the start of the code, and that the
opening of the assembler must have an
‘OPT pass’ directive, and finally, that at the
end of the file, there must be a ‘RETURN’
statement to return control back to the
master program.

Line 30 makes a reference to a SOUR-

CE!, where the T stands for initialisation. It
is this file which sets up all the tables and
variables that the other source files refer-
ence. Thus all zero page allocations are
done at the start, along with setting up any
constants, and defining data tables. Be-
cause this is only used at the beginning, it
is not necessary to have it in the loop which
does the double pass.

Right, that’s enough theory, let’s have
some useful routines! First, a random num-
ber routine (figure 5). All registers are
ignored on entry, and everything except A
(the accumulator) is preserved on exit. This
routine simulates a 23-bit shift register,
using the three bytes of ‘seed’. On exit the
accumulator, A, will contain a pseudo-
random number. (Note that ‘seed’ must be
given an initial value which is non-zero.)

Start of BASIC *

( &8000 on most

Screen - Smallest mode possible (MODE 7)

configurations)

Variables shared by all source files

Master program

Source files

origin (normally

OSHNM)

Object code

Figure 3. Typical memory map

Next, figure 6 gives a sound player in
assembler. On entry, A specifies the sound
to be played.

There are several interesting points in
figure 6. A look-up table (soundbuffer) is
used. Also, two functions are used (FNIo
and FNhi). These return the low byte, and
the high byte respectively, of the value
passed to them. They are normally defined
so:

DEF FNIo(value)=value AND &FF

DEF FNhi(value)- (value AND &FFFF)
DIV &100

Finally, note the use of a JMP instead of a
JSR / RTS at the end of the routine. This
technique can also be used in Basic,
where a 'GOTO x’ is equivalent to a ‘GO-
SUB x : RETURN’.

Now for a screen handling routine. This
one waits for the cathode ray gun inside
the VDU to hit either the top of the screen
(BBC machines) or the bottom of the
screen (Electrons).

On Electrons, the only sensible way to
do this is by calling OSBYTE with A set to
19. Thus:

.vsync
LDA #19

JMP os byte

On BBC micros, because operating sys-
tem 0.1 does not have an OSBYTE 19 call
implemented, it is necessary to look direct-
ly at the hardware (figure 7). (Series 1 OS
does support OSBYTE 19, so the method
to be described can be ignored if you only
wish to write for new OS machines.)

Figure 7 is very useful for producing

ACORN USER JANUARY 1984

55

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ACORN USER JANUARY 1964

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ACORN USER JANUARY 1984

57

GAMES

.sound

ASL A

Multiply A by 8 to get offset into table

ASL A

(Acorn sounds have 4 tvo byte parameters)

ASL A

ADC #FNlo( soundbuffer)

'soundbuffer' is the table containing

TAX

the sound data. Note carry will have

LDY #FNhi (soundbuffer )

been cleared by ASL A

BCC nohibyte

INY

. nohibyte

LDA #&07

OSWDRD 7 is sound

JMP osword

Make sound, and return

Figure 6. Sound player

.vsync

.vloop

lda #2

STA viaier

BIT viaifr
BEQ vloop
LDA #&82
STA viaier
RTS

This is at &FE4E

This is at &FE4D

Reset flag, such that future pulses generate
interrupts. Note that this nay well knock
out flashing colours.

Figure 7. Screen handling for OS 0.1 (also useful for flicker-free graphics)

flicker-free graphics, as the shapes on the
screen can be updated when the cathode
ray beam isn’t looking. Note that each
vertical synchronisation pulse will happen
every fiftieth of a second (sixtieth on Ameri-
can machines), and may thus be used for
delays.

Now for some Basic routines for use with
assembler programs. First figure 8, a utility
to find a string in a program. This can be
tacked onto the end of all the source files,
and then called from immediate mode so:

PROCfind(“soundbuffer”)

to search for all the occurrences of 'sound-
buffer' in that source file. Note that the
routine will not find tokenised words, and
that to do this, it will be necessary to
reserve the first line of your source file to
hold the string to search for. Thus:

>0DATA

>PROCfind($(PAGE + 4))

would find all occurrences of the token for
'DATA'.

As a final note, the original BBC Basic
has a bug associated with INSTR, so it is
necessary to insert a ‘IF LEN($A%) > =
LEN(A$) THEN' before the ‘IF INSTR(. .
(The way to find out if this is necessary is to
hit break, and then type REPORT. If the
message printed out is '(C) 1981 Acorn’,
you have Basic I).

The differences, as far as the assembler
programmer is concerned, between the
two Basics are:

• no OSCLI on Basic I (see later for a way
around this).

• no assembler directives EQUB, EQUW,
EQUD and EQUS (see Ian Birnbaum’s
Forum Extra in this, and the past two
issues of Acorn User). This can also be
got round.

• no ability to assemble something to one
area as if it were living somewhere else
This is virtually impossible to get round
easily.

The way to simulate the OSCLI command
is to define a procedure to do it for you.
OSCLI takes a string as its parameter,
which it then passes to the operating
system command line interpreter (OSCLI).
A procedure which can be directly slotted
into any occurrence of OSCLI-is shown in
figure 9.

Simulating the assembler directives
EQUB, EQUW, EQUD and EQUS is also

fairly easy. First a description of these
directives which you may not otherwise be
familiar with.

EQUB stands for EQUate Byte, and it
takes a byte value as its parameter, and
sticks the byte into the code at the current
position of the assembly pointer (P%).

EQUW stands for EQUate Word, and is
the same as EQUB, except it takes a two-
byte value, and puts this (low byte first, in
accordance with the rest of the 6502) into
memory at P%.

EQUD stands for EQUate Double word
(four bytes), and is an extension of EQUW
EQUS stands for EQUate String (which
may be 0 to 255 bytes long). Note that only
the characters are put in memory following
this. There is no terminator byte, or length

byte either.

Original Basic versions of these four are
given in figure 10. These can all be called
from assembler using the following:

OPT FNequx(value)

where the OPT statement is used to evalu-
ate the following expression. This is why
each function returns ‘pass’, which should
be the pass number of the assembler. (NB
The equs function does not mimic the
EQUS directive with absolute fidelity. In-
stead, it leaves a CHR$13 at the end of the
string (which will be overwritten by the next
assembler statement) and although I can-
not see how this would be a problem, it
could be avoided by using a loop to write
the string to memory, character by charac-

DEF PROCfind(A$)

Figure 8. Assembler utility
to find a string

Z% = PAGE

REPEAT A% = Z% + 4

IF INSTR($A%,A$)

PRINT Z%?1 * 256 + Z%?2

Z% = Z% + Z%?3

UNTIL Z%?1 > &7F
ENDPROC

Figure 9. Simulating OSCLI
in Basic I

DEF PROCoscli (A$)

DIM X% 256

Y% = X% DIV &100
$X% = A$

GALL oscli : REM This is at &FFF7
ENDPROC

58

ACORN USER JANUARY 1984

GAMES

DEF FNequb ( byte )

DEF FNequw(wurd)

DEF FNequd ( doubleword )

DEF FNequs( string?)

?P% = byte

?P% = FNlo(vord)

!P% = doubleword

$P% = string?

P% = P% + 1

P%?1 = FNhi(word)

P% = P% + 4

P% = P% + LEN( string?)

= .pass

P% = P% + 2

= pass

= pass

- paSS Figure 10. Simulating Basic II routines EQUB, EQUW, EQUD and EQUS in Basic 1

ter The reason I have not chosen this'
method is that it is more cumbersome,
longer, and slower, although all of these
reasons only apply to the assembly pro-
cess, and do not affect the final machine
code.)

If you use this method of functions,
together with multiple source files, you
might find some very obscure errors being
generated at assembly time. To under-
stand these, you must be familiar with the
way Basic handles functions (and
procedures).

When Basic finds a reference to a func-
tion, it compares the name with an internal
table, to see if it has come across this
function before. If it hasn’t, it searches
through the program, looking for a match-
ing name. Having found this, it makes a
note of where the function starts in mem-
ory, so that if Basic is asked to find it again,
it can go straight there, without bothering
with the slow searching method. A side
effect of this is that if you call a function
from one source file, and then also call a
function with the same name from another
source file, then, instead of searching
through the second file, Basic will jump
directly to where it found the function last
time, and thus it might do anything. Of
:ourse, if the second file was significantly
shorter than the first one, there is a fair
:hance the function definition is still in
nemory, and thus everything will work, but
obviously, it is hardly reliable.

The way to avoid this problem is to have
i separate file, which is always in memory,
and which contains all the function defini-
ions used by all of the source files. But
also, this new file must call all the functions
)efore any of the functions are called by
Basic, so the addresses are known. Thus a
unction source file would probably look
ike figure 10. The dummy variable A% is
jsed to evaluate (and thus remember) all
)f the functions. Note that for this dummy
un, the value of P% is just somewhere
vhere it won’t do any damage.

Also, a line will need to be added to the
naster program, before loading any other
source files, to ‘PROCrun( , ‘F",<page re-
served for function library>)’.

And now, as they say, for something
completely different. Screen scrolling is
one of the few subjects that appears to
crop up again and again, and so here is
my version of how to do it.

On both BBC micro and Acorn Electron,
the potential screen sizes (in terms of
memory) are quite large, and thus to scroll
20k of memory fast is no easy task. In fact,

0 REM 30URCEF

10 P%=&8000 : REM Scrnpwhere
in the ROM
20 A% = FNlo(O) + FNhi(O) +
FNequb(O) +

30 RETURN
40

50 DEF FNlo( value) . . . .

Figure 11. Function source file

if one defines a text window to be the size
of the screen in mode 0, by typing;

MODEO

VDU 28,0,31,79,0

and then scrolling the screen, one can see
just how slow it is. To get around this
problem, Acorn decided to incorporate*
hardware scroll, in which a section of the
hardware (the 6845 chip on BBC mach-
ines, and a section of the ULA on Elec-
trons) is dedicated to keeping track of the
top of the screen.

To scroll the screen, one merely changes
the ‘top of screen’ pointer, and the hard-
ware takes care of the rest. Thus on the
BBC machine, to scroll the screen up, one
line, type:

MODE 6

VDU23;12,&0C;0;0;0;

VDU23;13,&28;0;0;0;

and on the Electron, type;

MODE 6

?&FE02 = &A0 : ?&FE03=&30

(This could be implemented using *FX151
to write to Sheila, if you want it to be Tube-
compatible!).

On both machines there are two regis-
ters which together form the high and low
bytes of the address that represents the
top of the screen. On the BBC machine,
one has to divide the memory address by
eight to get the value to put into the
registers, and on the Electron, one must
divide the address by two. In mode 6, the
screen memory normally starts at &6000,
and since each line is 320 (&140) bytes
long, to scroll up one line (ie move the start
of screen up by &140), we must write the
modified version of &6140 into the regis-
ters. Note that the memory which ‘falls off
the end’, in fact reappears at the bottom of
the screen, and thus there is a discontinu-
ity in the memory map, as the memory now
goes from &7EC0 through &7FFF, and then
starts going up again at &6000. This

means that any shape plotting routines that
you have must keep a track of this barrier,
and allow for it when plotting the shape.
Also, if you have an (X,Y) to address
function, this will also have to allow for the
fact that the top-left corner of the screen no
longer occupies a fixed position in mem-
ory, but instead moves about, and also that
there is a barrier on the screen.

A further point to notice is that, since the
value put into the registers is divided by
something, this is the minimum by which
you can scroll at any one time. (The Elec-
tron is in fact worse, not better, than the
BBC machine here, as the bottom five bits
are ignored, so that the resolution of the
scrolling is only to the nearest 64 bytes, as
opposed to eight bytes on the BBC
machine.)

To round off, here are some words about
the palette, which also appears to be a
bugbear for most people.

The palette can be thought of as just a
mapping between two tables. One of the
tables always runs from 0 to 15 (the logical
colours), and the other table can vary:

Logical colour Physical colour

(in memory) (displayed on screen)

0 Black (0)-

1 Red (1)

and so on. To change the mapping, just tell
the machine to make logical colour 1 point
to physical colour green (number 2). Now,
whenever you white something in colour 1
to the screen, it will come out in green.
Note that if you are using mode 2 to
practise this in, you will have two greens,
which you won’t be able to tell the differ-
ence between on the screen However, to
the computer, the colours are different,
and if you use POINT to look at the colours
of the points at (X,Y), then you will notice
there are still two different colours, 1 and 2.

The way this works is that as each byte is
read from the screen memory by the ULA,
it looks up in its internal mapping array
what colour that number should be dis-
played as, and then it tells the cathode ray
guns to display that colour. Thus the mem-
ory isn’t changed when you change the
palette, but instead the hardware remem-
bers the mapping which lets you change
the colour of selected areas of the screen
very fast.

• Jonathan Griffiths is the author of Acorn-
soft’s Snapper, Rocket Raid, and JCB
Digger. His book Creative Assembler will
be published by Acornsoft in the New
Year.

ACORN USER JANUARY 1984

59

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60

ACORN USER JANUARY 1984

ELECTRON

Paul Beverley uses his Electron interface to download software - 14k in 30 seconds!

PARALLEL LINK
TO THE BEEB

LAST MONTH I explained how to attach a
6522 versatile interface adaptor (VIA) to
your Electron to enable you to do some
interfacing and showed you how to make a
link with a BBC micro via the cassette port
for the transfer of software. Here I’ll explain
how to make a parallel connection between
a BBC micro and the Electron to enable you
to download programs at high speed. With
this method it takes less than 30 seconds to
load a 14k program into the Electron.

The hardware described in the Decem-
ber issue is sufficient to enable you to do
this. The only other item you need is a 26-
way IDC connector and cable to link the
6522 VIA adaptor to the printer port of the
BBC.

How does data-transfer along parallel
cables take place? The data to be transmit-
ted between the two computers is carried, a
byte at a time, on the eight data lines from
the printer port of the VIA on the BBC micro
to the eight lines of port B of the VIA
attached to the Electron. But there has to
be some means of synchronising the trans-
fer. For this purpose two control lines are
used, one from the sending computer
(BBC) to say that the data is ready to be
accepted, and the other from the receiving
computer (Electron) indicating that it has
read the data and is ready for the next byte.
To do this the CA2, the strobe’ output of
the BBC printer port, is connected to CB1
on the Electron, and the CB2 output from
the Electron connected to the CA1 input on
the BBC, the acknowledge’ input.

To get the Electron to accept the data
from the BBC it must carry out the hand-
shaking just as a Centronics-type printer
would. Special machine code routines are
needed to carry out the hand-shaking auto-
matically and to put each character re-
ceived into the keyboard buffer. The oper-
ating system then deals with them as
though they had come directly from the
keyboard and enters them as lines into the
program area. It is equivalent to EXECing a
piece of text coming from a file system.

When the BBC sends a strobe pulse it
can be used by the VIA to generate an
interrupt. The response to this interrupt is to
accept the data from the port, feed it into
the keyboard buffer and send an acknow-
ledge pulse to the BBC.

The earliest way of doing this was to use
a single interrupt routine which took in the

data and immediately sent out an acknow-
ledge pulse. The problem was that the
keyboard buffer soon became full, the rate
at which the BBC could send the data being
much greater than the rate at which the
Electron could receive it. Attempts to solve
this problem by getting the operating sys-
tem to generate a ‘buffer full event’ pro-
duced a far more complicated program
which improved performance only slightly.

Then with help from the Advanced User
Guide it was discovered that every time the
operating system removes a character from
the buffer it indirects through a vector at
&22C. If you intercept this vector and send
out an acknowledge pulse only when a
character is about to be taken out of the
buffer there will never be more than two
characters in the buffer at a time; the speed
at which the BBC is allowed to send the
data is controlled by the speed at which the
Electron can store the characters in the
form of a Basic program.

This method seemed to work, apart from
an occasional loss of a single byte of data.
This could have been because the routine
was using the second interrupt vector,
IRQ2V, bringing about delay between re-
ceiving and interrupt from the BBC and
actually servicing it. The interrupt is not
dealt with until the Electron operating sys-
tem has gone through all its own interrupt
routines to find out whether it was an
internally generated interrupt.

The solution is to use IRQ1 V rather than
IRQ2V. This is the vector through which the
operating system indirects before it starts
its own routines. Thus the routine which
you put into the Electron should check
whether the interrupt has come from the
VIA and if so service it, and if not return to
the normal IRQ routines. With this modifica-
tion data transfer seems secure.

Listing 1 shows the source code for the
machine code routines that have to be put
into the Electron. This could be assembled
and put on to a cassette ready to be *RUN
into the Electron. But as we are using a
disc-based BBC computer it is possible to
do without a cassette by linking the cas-
sette ports of the two computers - as
explained last month. All that is needed is
to cross-connect the output from one cas-
sette port to the input of the other and vice-
versa, and add a 1 ,5k resistor to earth on
each line.

Running the program as listed assem-
bles the machine code program and pre-
pares to *SAVE it across to the Electron. It
prompts the user with ‘RECORD then RE-
TURN’, at which point you type in *RUN on
the Electron (or 7 for short), press RE-
TURN and then press RETURN on the
BBC. This will LOAD and RUN the machine
code program into the Electron, and it is
then ready to receive normal Basic
programs.

To send the programs you LOAD them
into the BBC computer from disc and then
use function key 2 to LIST them across to
the Electron. The machine code program in
the Electron itself sets up three of the
function keys to ease the use of the routine
and then puts the letters NEW and a
carriage return into the keyboard buffer to
clear out any old program in the Electron. If
there is already a program in the Electron
using line numbers that are not used in the
new program these lines will be retained.

As long as the machine code programs
within the Electron are active, they are
being used by the operating system every
time an interrupt occurs or a character is
removed from the keyboard buffer. This
causes a marginal slowing down of the
processing speed but, more importantly, if
your program uses the area of RAM in
which the routines are stored it will corrupt
them and the system will crash. Thus by
pressing the BREAK key, which has been
programmed with OLD’, the vectors are
restored to their original values and the
routines are no longer active.

This also explains the use of what might
seem to be a strange area of RAM on the
BBC computer - page &D00. Any other
page of RAM on the Electron may well be
used by one of the programs being sent
across and RUN.

After setting up three function keys on
the BBC, the values of various registers
and vectors are set up (lines 50-100). Lines
160-640 are the setting-up routines used
within the Electron to remove and remem-
ber the old interrupt vector and the old
remove-a-character vector and replace
them with the addresses of the new rou-
tines. Lines 360-400 set up the peripheral
control register and the interrupt enable
register of the VIA, and lines 420-520 set
up three of the function keys on the Elec-
tron by means of the OSCLI routine at

ACORN USER JANUARY 1984

61

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D) FUNNY FACES presents a line up, which one is the suspect?

E) FRED THE FROG needs co-ordinated help to get across the pond.

A) THE POND seems very active today.

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62

ACORN USER JANUARY 1984

ELECTRON

&FFF7. Then at lines 540-640 the word
NEW followed by a carriage return is insert-
ed into the keyboard buffer.

The interrupt routine itself starts at line
670 and involves looking at the interrupt
register to find out whether an interrupt has
been generated in the VIA and, if not,
returns through the indirect jump at line
810. If an interrupt has been generated in
the VIA then, after saving the X and Y
registers, the value is picked up from port
B. By using OSBYTE routine 138 the char-
acter is inserted into the keyboard buffer.
The registers are then restored and the
interrupt routine ended with an RTI.

At line 790 the new remove-a-character
routine starts by sending a zero-one pulse
out on CB2 by changing the value in the
peripheral control register. You then jump
back to the old vector tp continue the
routine that actually removes the character
from the buffer.

The remainder of the routine gives space

to store both the strings used for program-
ming the function keys and the two old
vectors. Finally, the machine code program
assembled within the BBC is *SAVEd out to
the Electron at line 1110.

When the BBC has finished its listing it
sends a *>’ character (the Basic prompt)
down to the Electron. If you then start to
type something into the Electron keyboard,
such as RUN, the prompt character in front
of it will cause a syntax error. So, for
sending out the listing, key 2 on the BBC
has been programmed so that it follows the
listing with a control-A and a control-M. This
sends a single carriage-return to the printer
only’, ie to the Electron, so that although the
prompt character itself generates a syntax
error, the Electron is ready to accept a new
line from the keyboard.

There remains a problem with this meth-
od, which arises when the program to be
sent includes long lines: it is possible by
using abbreviations to type in a program

line of less than 256 characters which,
when listed out as a line with full Basic
keywords, is longer than 256 bytes. Such
output will not be accepted by the Electron
as a line that it can feed into its program.
You must therefore either split the line on
the BBC before sending it, or re-send the
individual line using abbreviations. You will
know this problem has occurred if the
Electron gives a bleep.

If you want to send a single line from the
BBC to the Electron, type control-B, move
the cursor on the BBC to the line to be
copied, press the copy key to copy the line
and then type control-A and control-M to
send a carriage return to the Electron. Then
press control-U to cancel the line on the
BBC and control-C to stop sending from the
BBC to the Electron.

The next project for the Electron will
enable you to drive a Centronics-type print-
er by adding a printer interface to the VIA
and writing a printer driver routine. •

OS PROBLEM

WHILE developing this program, I dis-
covered a slight problem with the Elec-
tron’s operating system. It only be-
comes apparent if you try to *RUN a
machine code program as the first file
system operation after switching on the
machine. There is no problem with
LOAD, or *LOAD.

What happens is that when you come
out of the machine code program which
you have just *RUN, back into Basic,
you get a spurious ’Syntax error’, and
sometimes the system will not allow you
to type in a program without first press-
ing the break key.

It appears that *RUN (or */) does not
set up the value of one of the flags used
by the cassette filing system as it
should. The actual effect which results
depends on the value the flag byte
happens to assume on power-up.

This same ‘feature’ is also present in
the BBC micro’s operating system 1.2,
but because of the consistency with
which its RAM powers up, it has not
previously been noticed.

When using my software downloading
program, or the printer driver routine,
you are likely to want to *RUN the
machine code program immediately
after power-up. To solve the problem
either:

• *LOAD the program and then CALL
&C00 (or wherever you have put it).

• Type LOAD“” creturn >, and < es-
cape , and then you can *RUN the
program as normal. This is because
the LOAD command will have set up
the flag byte correctly.

• Put a single-line Basic program which
consists of 10 *RUN in front of the
machine code program, and then
chain it.

► *KEYO*CAT ! M

1 *KEY1*DISC!M LOAD"
*KEY2LIST ! B ! M ! A ! M ! C

p or t B=&FCCO
PCR=p or t B+ 1 2
i ntREG=portB+13
IER=portB+l 4
IRQ1 V=&204

RemV=& 22 C

FOR opt=0 TO 2 STEP
P'/.=&DOO
COPTopt

RTI
SEI

LDA IRQ IV \

STA oldIRQV
LDA #newIRQ MOD 256
STA IRQ1V
LDA IRQ IV + 1
STA oldIRQV + 1
LDA #newIRQ DIV 256
STA IRQ IV + 1

LDA RemV \

V For NMI's on BBC

Change interrupt vector

Change remove character
vector

STA ol dRemV

LDA #newRemV MOD 256
STA RemV
LDA RemV + 1
STA ol dRemV + l
LDA #newRemV DIV 256
STA RemV + l

continued on page 65

ACORN USER JANUARY 1984

63

Software for the BBC micro

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The Graphic Extension ROM

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Our latest utility ROM includes over 28 new graphics related commands. These can be typed in like any normal commands
and can of course, be included in BASIC programs. The commands are split into 3 distinct areas: -

1. Sprite graphics

These are multi-coloured shapes up to 24 x 24 pixels in size.

Once a sprite has been designed (using in-built routine) it can be plotted at any position on the screen and easily
moved around. A sprite can also be part of a ‘film’ — a sequence of frames allowing animation.Up to 32 sprites or
‘films' can be active on the screen at any time. A 'film' can contain up to 47 frames, each frame being any sprite
image.

LOGO ‘turtle’ graphics

By using simple FORWARD, BACKWARD, LEFT and RIGHT commands a ‘turtle’ can be moved very quickly around the
screen, producing intricate patterns by the most user-friendly means. Including these commands in structured BBC
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The third section consists of a large number of general purpose commands, such as-
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Fast circle and arc drawing

3D graphics routines allowing X, Y, Z co-ordinate plotting
Large character printing in a range of patterns

Scaling — allowing any part of the screen to be expanded or diminished
A rotate command that will rotate all plotting by any angle around the origin

Because this is a ROM, all the commands are instantly available, and has a built-in help menu showing the syntax of
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Available directly from us, mail order only, or from all good dealers

£28.00 plus £1.00 p&p plus VAT

16 Wayside, Chipperfield, Herts WD4 9JJ. Telephone (09277) 69727

ELECTRON

continued from page 63

350

0 LDA #StEE

3 STA PCR

3 LDA #8t90

3 STA IER

3 CLI

\ CB2 = 1 output
\ Enable interrupts on CB1

LDX #keylO MOD 256
LDY #key 1 O DIV 256
JSR &FFF7

Program various keys

LDX #key 1 MOD 256
LDY #key 1 DIV 256
JSR &FFF7 \ OSCLI routine

LDX #keyO MOD 256
LDY #keyO DIV 256
JSR &FFF7

LDA #138
LDX #0
LDY #ASC "N"
JSR &FFF4
LDY #ASC "E"
JSR &FFF4
LDY #ASC "W"
JSR &FFF4
LDY #13
JSR &FFF4
RTS

. new IRQ
BIT intREG
BPL return
TXA: PHA
TYArPHA
LDY portB
LDX #0
LDA #138
JSR &FFF4
PLArTAY
PLArTAX
LDA &FC
RTI

• return

JMP <ol dIRQV)

Put NEW in keyboard buffer

1010

1020

\ Check for CB1 interrupt 1030

1040
1050
1060
1070
1080
1090

920 EQUB 13
930

940 . key 1

950 EQUS "KEY1NEW ! M"

960 EQUB 13
970

980 . keyO

990 EQUS “KEY0CALL&D01 ! M“|
lOOO EQUB 13

If not, return
\ Save registers

\ Get character

. ol dIRQV
NOP: NOP

- ol dRemV
NOP: NOP

Put in keyboard buffer
Restore registers

Restore accumulator
End of interrupt routine

3

NEXT
llOO *T.

1110 *SAVE X D01 DCO DOl
1120 *D.

Send acknowledge pulse

. newRemV
LDA #&CE
STA PCR
LDA #8tEE
STA PCR

JMP (ol dRemV) \ Remove character from buffer

. key 10

EQUS "KEYIOOLD ! M"

Listing 1. Downloading programs from BBC
rmcro to Electron at high speed. Source code
for Electron machine-code routines.

ACORN USER JANUARY 1984

65

Your choice is crystal clear

'The Hobbit'

The Hobbit floppy tape system is the ideal alternative to an unreliable cassette recorder and an expensive disc drive.

This is a professional digital recorder designed specifically for users of micro computers.

The Hobbit is completely under the control of your computer - no more pressing RECORD/PLAY/FAST FORWARD, etc.
Absolutely no danger of accidentally overwriting other files on the cassette. The Hobbit uses an internal filing system similar to
that used by a disc, thus ensuring that there is no redundant space on your cassettes.

The Hobbit is significantly faster than an ordinary cassette recorder (READ/WRITE speed 6000 data bits/sec., ordinary
cassette recorder average 960 data bits/sec.)

Typical file access time is 22 seconds; maximum is 90 seconds.

Up to 5 files may be opened simultaneously. Random access files are fully supported.

Two Hobbits may be connected to your computer to form a dual drive system.

NO COSTLY DISC INTERFACE REQUIRED

No hidden extras - the Hobbit comes complete with everything you need, including one certified digital cassette.

The Hobbit is available now for BBC and NASCOM computers.

Special Features for the BBC

Zero Memory Option The standard Hobbit operating chip sets PAGE to 1C00. With the Zero Memory Option the Hobbit
does not use any of your precious RAM, thus making the transfer of programs from ordinary cassette to Hobbit even simpler.
Power Supply Power is taken from the external power outlet socket on the BBC computer. If your computer is not fitted with
this socket a suitable power supply is available from us.

Special Features for the NASCOM

Microsoft Basic Upgrade Kit Enables you to read and write files from BASIC using PRINT and INPUT statements - no more
PEEKS and POKES! Supplied on a Hobbit cassette.

Operating system available in 2 x 2708 or 1 x 2716.

Normal address D000 - other addresses are available on request at no extra charge.

If you want to know more about the Hobbit before you
make up your mind send to the address below for more
details, or order the manual and see just how sophisticated
the Hobbit really is.

If you have a different make of computer, but are
interested in the Hobbit system, send us a stamped
addressed envelope and details of your computer so that we
can send you advance information of new products when
they become available.

I » 1

x xViV OqC

Available from most good computer shops or direct from:- IKON COMPUTER PRODUCTS, KILN LAKE, LAUGHARNE, DVFED.
Tel. 099 421 515. BBC Hobbit £135.00 + £3.00 p&p. BBC Second drive £120.00 + £3.00 p&p. Zero Memory Option £25.00 (£18.00 if ordered with the
Hobbit). Power Supply £12.00. Manual (ordered separately) £1.50 (No VAT; refundable on purchase of Hobbit). Nascom Hobbit (unboxed) £120. 00. Nascom
second drive £94.00. Basic Upgrade Kit £10.00. Box of 6 cassettes £17.50. Cleaning cassette £3.50. Please add VAT at the current rate to the above prices.
ACCESS AND VISA ACCEPTED.

COMPUTER PRODUCTS

*

{

LESS PEEKING says George Hill

THERE were two ‘naughty but nice' things
in October’s Forum. First, was the refer-
ence to locations for various flags and
parameters which are stored in the nether
regions of memory by the operating
system.

One letter referred to the values for the
co-ordinates of the graphics cursor. Far be
it for me to spoil people’s fun, but I do see a
danger of becoming Pet-style program-
mers, endlessly peeking and poking. All
the information required by John Swift is
available through the operating system.

In fact almost all the information you
could conceivably need is available
through the OS. May I suggest the pur-
chase of the new Advanced User Guide ,
and a deep perusal of the OSWORD,
OSFILE and OSBYTE calls amongst
others.

The parameters Mr Swift required were
those for the X and Y co-ordinates of the
graphics cursor. These are accessible by
a Basic routine (listing 1), which is guaran-
teed to work with any future OS. This
method translates into assembly language
as listing 2. (Note that it gives results which
must be divisible by four in mode 1 .)

It has the advantage that the values of
the cursor positions are produced in loca-
tions which you control, and which are not
subject to change - although it is longer to
write, and slower.

Another set of parameters required in
Forum by Mr R Lewis was the load finish
and execute addresses of a file. The meth-
od suggested by S Munn for OSO.1 suffers
from the same disadvantages as the pre-
vious peek-and-poke method, ie it is not
transportable across OS changes.

Listing 3 shows how to use OSFILE to
obtain the parameters in a similar way to
listing 1 . The method can also be translat-

ed into assembly language The program
uses byte indirection extensively and the
‘decoding’ of the addresses is rather pecu-
liar. This is caused by the fact that, for
Basic files, the addresses are stored with
the 16 most significant bits set ie, address
&1900 appears in the parameter block as
&FFFF1900. This is not true of machine
code or other files.

If you must peek and poke memory,
many of the locations are now documented
in the Advanced User Guide. One which I
have scrupulously avoided using directly is
&355 which contains the value of the
current mode. (Location &387 in OSO.1 if
memory serves!)

THANK you for these elegant routines,
George. As for your comments, they are in
essence similar to a warning I gave, but
they go somewhat further than I would
want. There are two reasons for this. The
first is that not all the *FX calls available in
the series one operating system are avail-
able in OSO.1.

Second, I am not convinced that every-
thing which can be done by direct memory
access (what you call peek and poke
methods) can be done by operating sys-
tem calls. However, one of the reasons for
publishing direct access calls is to stimu-
late readers to respond with methods
using OS calls, if they exist.

To start the ball rolling, I offer the follow-
ing challenge. In my Beeline word pro-
cessing program it'was necessary to move
the cursor to a predefined point on the
screen as if the cursor controls had been
pressed. This allows the copy key to be
pressed at once, without using any cursor
keys first. The code to achieve this is in
listing 4.

page 68 ►

THE Forum’s aim is to exchange ideas,
tips and applications for BBC micro
and Electron. Chaired by Ian Birnbaum,
it enables more experienced
programmers to present ideas, which
must draw on earlier Forums or be
original. In either case, it should be
described clearly and fully, with listings
supplied. At least £5 will be paid for
any tip published. The main judging
criteria are originality, and skill in
implementing a ‘routine. Your
contribution should be typed or
printed, with any substantial listings
on cassette, but only included to
make a point.

SPACE ERROR

TYPE this short program into your
computer:

10 *KEY10 OLDIM RUN!M[space]

20 GOTO 20

Make sure you leave a space at the end of
line 10 - this is important, as you will see.

Run the program and press the break
key. The result will be a 'Key in use at line
1 0' error.

Now copy line 10 without the final space,
and re-run. Then break works as expected,
with no error message.

The error occurs because when run is
activated, part of the contents of key 10 -
namely the space remains to be execut-
ed. Hence, when line 1 0 of the newly re-run
program is executed it fails, because the
operating system will not allow the defini-
tion of a key, part of whose contents remain
in the buffer.

Yet another example of how unwanted
spaces can have unintended effects in
BBC Basic programs!

10

20

30

40

50

60

70

80

90

100

110

120

130

140

RFM GCURSOR

LEM To read the current positon of
the graphics cursor.

OSWORD =?<FFF 1

DIM graphi cs_cur sor 7

A7.=s<D

X'/.=graphics__cursor MOD 256
Y7.=graphi cs_cursor DIV 256
CALL OSWORD

previ ous_cursor= ! graph i cs_cur sor
current_cursor=gr aph i cs__cursor f 4
current_X=current_cursor MOD & 10000
current _Y=current__cursor DIV 0000
PRINT " X= " ; cur rent __X
PRINT" Y* H ; current Y

MODE 1

>M 0 VE 773 , 1089

>RUN

X =772

Y= 1 088

10 REM GCMAC

20 REM To read the current graphics
~‘ 0 REM cursor via assembly languaqe
40 OSWQRD=&FFFl 9

50 DIM space 20
60 P/C=space+8
70 COPT 2

Tind cursor

80

90

100

110

120

130

Ida #8<D

1 dx #space MOD 256
ldy #space DIV 256
jsr OSWORD
rts

Listing t. Graphics cursor from Basic with RUN result

140 CALL Iind_cursor
150 PRINT" X=" ; space ! 4 MOD & 10000
160 PRINT" Y=" ; space ! 4 DIV & 10000
>liODE 1

>MOVE 1 25 , 689
>RUN
X= 1 24

/-68e Listing 2. Cursor from assembler with RUN result

ACORN USER JANUARY 1984

67

BEEB FORUM

Cass

ette

Data : O.S. 1.2

362

53

) FILENAME

3 B 3

4 B

)

364

45

3 B 5

54

>

366

43

>

3 B 7

48

>

3 B 8

0

>

363

FF

3 BR

FF

3 C 2

23

386

FF

3 C 3

88

3 C 4

FF

SBC

FF

\\

3 C 5

FF

3 BD

FF

>

RCA

3 BE

0

> LOAD ADDRESS

3 C 7

r

0

3 BF

19

>

3 C 0

FF

>

308

DB

3 C 1

FF

>

309

0

The

above

i Ti f o r m a t i o n c a n

trans

f ered

10CLS: PF’INTTAB (1,2) " ABCDEFG"TAB ( 1 ,2) ; : IF?kFFFE=
1 64THEN?&36B=S<42 : ?&372=&54: ?&374=&52: ??/.37D=?- IS ELS
E ?&364=2: ?&365=24: ?&D0=66: INPUTTAB < 0 , 5) ,A*

Listing 4. Copy without cursors

> EXEC ADDRESS

7 ) BLOCK NUMBER

DRTfi BLOCK LENGTH

to i r«te 9 er var i ab 1 es as f o 1 1 ows

R " £ * ? & 3 C 6 # 2 5 6 + ? & 3 C 8

< Pro9rarn Len9th >

BX=< « & 3 BE >RND< &FFFF > < Load Address )

C 5 S*< ! S-. 3 C 2 >AND< &FFFF .

! Exec Address >

Table 1. Cassette filing system workspace
from page 67

If you type in and run this listing, you can
use the copy key at once to make a copy of
ABCDEFG into A$ in the INPUT statement.
It will work on both operating systems (the
contents of &FFFE dictate which part of the
code is executed). Can anybody do this
using OS calls only?

Readers who would like to enter the
debate on direct memory access versus
OS calls are invited to write to the Letters
pages.

M/C BASIC

AT THE risk of offending George Hill, I
include this month an answer to Mr Lewis’
question for OS1 .2 from Steven McLean.

Details of the cassette filing system
workspace for OS1 .2 are given in table 1 . It
also shows how the information can be
stored in integer variables as queried by R
Lewis (October, page 57).

by Eddie Atherton

FOLLOWING October’s Forum, I have a
few comments to make.

The article about saving Basic programs
as machine code and then using *RUN to
execute them will only work properly in a
small percentage of cases.

Loading a program using *LOAD or
*RUN will not set the value of the Basic
variables PAGE or TOP. This will result in
the famous 'bad program’ if the program is
loaded at a different location than PAGE is
currently set at. If PAGE was correct, the
chances of TOP (and therefore LOMEM)
being right are even slimmer. The result of
this is that any variables created in the
Basic program will be stored at the wrong
locations in memory, causing a variety of
problems including 'No room’, 'Bad mode'
or even overwriting the Basic program.

The problem of LOMEM can be correct-
ed by including the command END (RE-
TURN) before the RUN in the machine
k code driver, but I can think of no method of
setting PAGE correctly.

QUITE right, Mr Atherton. This unfortunate-
ly escaped my notice on the final checks.
Putting OLD or END before RUN ought to
cure the problem of TOP, but it unfortu-
nately causes other problems. However,
see Ben Clarke’s piece for another
approach.

13

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

1S0

190

200

210

LOAD FINISH and EXECUTION addresses of a file

17

NOD 256
DIV 256

REM FILEADR

REM To read the
OSF I LE=&FFDD
DIM osfile parameters
DIM filename 10
INPUT"Fi lename" , f i 1 enamel
f i 1 ename^=LEFT^ ( f i 1 enamel , 7 )

$f i 1 ename=f i 1 ename^+CHRI 13
osf i le_parameters?0=f i lename
osf ile_parameters?l=f i lename
A7.=5

XX=osfile parameters MOD 256
Y7.=osfile parameters DIV 256
CALL OSFILE

I oad_address=osf i 1 eparameters?2+256*osf i 1 eparameters?

e, ‘ ec — a<= idr ess=osf i 1 epar ameter s76+256*osf i 1 e _par ameter s?

1 enqth=osf i 1 epar ameter s?l 8+256*osf i 1 e parameter s? 1 1

f 1 ni shpddr ess=l aad_address+l ength

FFINT Load ad dr ess= " ; ""1 oad_address

PR I NT “Execution addre ss=" ; "exec ad dr ess

PRINT Finish address— “ ; ""finish address

a

>RUN

F i I ename?F I LEADR
Load arfdr ess=1900

Execution address-80 1 F
Finish address=lBCl

Listing 3. Using OSFILE to obtain parameters with RUN result

ACORN USER JANUARY 1984

68

-

LOCKED FOR PROGRAM PROTECTION by Ben Clarke

£20

WHILST prodding around in the darkest
depths of OS1.2, I found the enigmatic
message ‘Locked’ , which appeared to be
concerned with the loader code. Further
investigation showed it was dependant
upon the least significant bit being set in
the 'Block flag’ byte of the cassette header
( User Guide , page 399). If this bit is set, the
only way the program can be loaded,
without the ‘Locked’ message appearing,
is via ‘RUN. It also proved to be the case
that programs loaded via this mechanism
acted as though ‘FX200.3 had been ac-
tioned, ie, the escape key was disabled
and RAM was cleared from &400 upwards
when break was pressed.

This all looked pretty good for program
protection but for two problems: getting the
Locked bit set on a save, and how to make
a Basic program start after ‘RUN (machine
code is OK).

Looking even deeper into the operating
system showed no obvious way of setting
the locked bit, so, in the end, I resorted to
'stealing' the relevant save code from ROM
into RAM and then modifying it to do what
was required. Then all I had to do was alter
the OSFILE vector to point to my doctored
code.

However I couldn't find a convenient
point in Basic for a direct entry so I had to
arrange to obey OLD followed by RUN.
Putting them both in the keyboard buffer
didn’t work, as it gave syntax errors. How-
ever, putting &F9 (the code for RUN)
followed by a carriage return into the
buffer, and putting carriage return into the
‘Run time buffer’ (at the address pointed to
by &B/C modified by &A), then jumping to
the code for OLD worked fine. Basic ac-
tions the OLD then looks in the buffer for
the next command, where it finds RUN.

All the above has to be obeyed after the
program has loaded, of course, so must be
present when it is recorded by a ‘SAVE. 1

The Basic is upset by finding REMs con-
taining characters less than &1F, so line 0
jumps around line 1, which is a REM into
which the machine code is assembled.

All that now remains is to ‘crashproof’
your program. Make sure there are no
ends or stops laying around, and add:

ON ERROR GOTO 5 and
5 CALL&D9CD

to force break and clear store (make sure
you’ve got all the bugs out first - debug-
ging a program which deletes on error is
nasty!).

The result of all this is a program which
can only be loaded via ‘RUN, so immedi-
ately RUNs itself, cannot be broken into,
and, if break is pressed, clears the whole
store - about as tamper-proof as you can
get.

There are seven stages to go through.

• Type:

FOR l% = &C00 to &CFF:?I%-
l% 9 &E600:NEXT

This relocates the save code to COO to CFF
(it can be moved if required)

• Type:

?&CE4 = &A9:?&CE5=&81 :

9 &CE6=&8D

This modifies the code to add in the locked
bit.

• Add to program:

20 *Fx 5 fi R Phillips & R Ward
30 VDU2*21
40 PRINT"

50 VDU6 , 3

IF ADVAL-4=63 THEN 90
70 *FX 15 , 0
80 *FX5,0

90 REM Begin output to printer

Listing 6. Tests printer buffer

20 RES £T^ liSt 311 — *evs

40 FOR N KX=0TO15 ter * P “* remainin 9 : "j255-?&B10

de-ffne^:GOTO 0 ?80 %)=? * ,B10 ™ EN PRINT " Ke V "*KX,» Un
60 S%=? (&B00+K%) +1
70 E%=?&B10
80 FDR I7.=0TO15
70 L%=? ( &B00+ I % )

mxr'i? “ D LKEX TH “

120 PRINT "Key ” ;KX;” " ■

130 F OF IX=0TOE7.-SX
140 L%=? (?^B00+S7+iv )

x<> EX T;L L PrTS°.™ EN PRINTCHR *<L7.) ; ELSE IF S7. + I
160 NEXT 17.

170 PRINT
180 NEXT KV.

190 END

Listings. Prints out function key definitions

OGOTO 10

1 REM followed by at least 23 spaces

• Type:

P% = &E0E:[LDA#&8A:LDX#0:LDY#
&F9:JSR&FFF4:LDY#&D:
JSR&FFF4:LDA#&D:LDY&A:
STA(&B),Y:JSR&8A3D]

Note that this must be typed as one line.
The code to insert the characters into the
buffers is assembled into the REM line,
ready for saving

• Type:

9 &213 = &C

This alters the OSFILE vector to point to
the modified code

• ‘SAVE “progname”E00 xxxx EOE
Where xxxx is the top of Basic store in

hex. (Typing PRINT ^ !0 gives an eight-
digit hex number, the last four of which
give the number required.)

• Type:

9 &213 = &F2

This reverts the vector to normal

Try loading the program by LOAD, CHAIN,
‘LOAD You should get ‘Locked 1 to all
three. Then try ‘RUN when the program
should load and run. 1

FUNCTION LIST ^

LISTING 5 from John Nelson provides a
way of printing out the function key defini-
tions without having to press the keys
themselves. The program prints the num-
ber of characters remaining in the buffer
and then the current definitions for the 16
keys (red keys 0 to 9, break key, four
cursor keys and the copy key).

The operation is as follows. Key defini-
tions are kept in page &B, ie from &B00 to
&BFF and the address of the last occupied
byte is found in &B10 - all addresses are
within page &B. The first 16 bytes are
allocated one to each key beginning with
red key 0. If the key is undefined, the
address stored for that key is the same as
that in &B10, otherwise the address is one
less than the start of the key definition. The
program then scans the first 16 bytes to
locate the end address of the key definition
and prints the characters. Characters with
ASCII values less than 32 are treated as a
signal for a new line.

PROGRAMS which output to a printer will
hang up with a full printer buffer if the
printer is not on-line, connected and
switched on. Many programs therefore use
a ‘Do you want a print out?’ option. Listing 6
avoids this by testing the printer buffer. If
the buffer is being emptied, output pro-
ceeds normally, but if it is not being emp-
tied, the printer sink command is executed.
This routine came from Richard Phillips
and Robert Ward.

ACORN USER JANUARY 1984

69

As Reviewed in July Acorn
User and July Laserbug

MICROVOC

AS SUPPLIED TO
SCHOOLS & COLLEGES

Yes it's here! A complete sound system for the B.B.C.

Micro, realistically priced at £21 (Inc. V.A.T.) plus £2 post and packaging.

Using the BBC's own po wer, M I C R O VO C /s suitable for use with either Speech Synthesis or
computer produced music, and will fill the average sized room with a sound you will not have
belie ved possible!

The external speakers can be disconnected at will leaving MICROVOCs volume
control to operate the internal speaker of the BBC micro.

Or your own headphones can be plugged in for persona! use.

r ooo^ca^ ~
T musica^ a „ £ j

PAID foP ‘

Mm

.. m

NOW in stock: The SYNTH from Musicsoft. This program allows you to input your favourite
tune via the keyboard, and then to record it for posterity.

THE SYNTH can mix all four channels including the Noise channel for Percussion! Cymbals
and Drums).

Extremely versatile and extremely easy to use and a snip at £8.50.

Complex melodies which once took hours to program can now be entered in minutes by
a complete novice!

OUR GUARANTEE — None of the original components of the BBC micro,
including the cabinet need to be modified in any way to install 'MICROVOC'.

Our prime concern whilst designing 'MICROVOC' was to ensure that your BBC
micro warranty would remain unaffected.

MICROVOC can easily be fitted in five minutes and requires no drilling, soldering,
or any technical expertise whatsoever. It can just as easily be removed, leaving
your BBC micro in its original condition.

MICROVOC simply plugs into existing fittings on the BBC micro and makes use
of the 'Reset' and 'Econet' apertures at the rear of the machine.

If your BBC micro suffers from the infuriating Buzz' then you will also need
'Buzzgo'. 'Buzzgo' simply plugs into the IMhz Bus to eliminate the infernal buzz.
BUZZGO COMES FREE WITH MICROVOC! For separate purchases , BUZZGO costs

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MICRO-ADVENT (A subsidiary of Advent)

Ashlyn House, 113 Writtle Road, Chelmsford, Essex.

Opening hours 9.30am - 3pm Monday - Friday.

Telephone: 0245 59708

70

ACORN USER JANUARY 1984

GRAPHICS

Malcolm Banthorpe grows his own crystals with some eye-catching programs

LIFE VARIATIONS

MANY readers will be familiar with J H
Conway’s game of Life. In its simplest form,
Life is a simulation of a group, or groups, of
cells whose existence is governed by three
simple rules. The world in which the cells
exist consists of a rectangular grid, each
division of which can either be empty or
contain one cell. The existence of a cell
and the ’birth’ of new ones is determined
by the contents of the eight locations which
immediately border the location under test
(figure 1). The three rules are:

• a cell survives to the next generation
if it has either two or three
neighbours;

• a cell dies if it has less than two, or
more than three neighbours;

• any empty location which has exact-
ly three neighbours gives birth to a
new cell.

These simple rules can lead, after a few
generations, to complex patterns which
would be difficult to predict.

Most Life programs are designed to
study small groups of cells, but the same
rules are applied here to larger groups, by
using a higher resolution display than is
generally employed.

A requirement of any Life program is that
the nine neighbours of every screen loca-
tion be examined before the status of any
location is changed. Any changes which
were made during the examination would
affect the inspection of subsequent loca-
tions and effectively change the rules. It is
therefore generally necessary to store the
next generation, without changing the dis-
play, until the examination of the whole
field is complete. This is normally done
ifeing an array, so the size of the field is
limited by the memory available. Thus most
programs use a fairly low resolution display
of about 1000 locations; 40x25 being
typical, as it matches the text screen for-
mat of many small computers.

My initial attempts at a high resolution
program were on an ITT 2020 (Apple)

computer, which had a potential 69,120
locations on its 360x192 display. Clearly
the use of an ordinary integer or real array
to store the next generation was out of the
question. Other than storing the next gen-
eration on disc, it would be necessary to
store the status of each location in a single
bit (just as the high resolution screen buffer
does in an Apple). The Apple has two high
resolution screen buffers, either of which
can be selected by software for display. A
program was therefore devised which
would solve the problem by displaying

alternate generations on alternate high res-
olution screens. The sequence of events
was: set up initial sequence on screen 1 ;
display screen 2, examine screen 1 and
plot next generation on screen 2; display
screen 1 , examine screen 2 and plot next
generation on screen 1; go back to the
second stage.

As might be expected, Basic was too
slow. For every generation, each of the
69,120 cells and its eight immediate neigh-
bours had to be examined, requiring no
less than 622,080 iterations of the routine

□ □

_ TO

C 3 -* -

rcD

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CH □

~n U

^fosoiui

..*Oid ! =l1 pi

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□

□

Figure 2. Results of applying program 1 to random square pattern (generations 0-3)

ACORN USER JANUARY 1984

71

GRAPHICS

and probably taking several hours.
Machine code speeded this up to about 1 8
minutes per generation.

A similar dual screen approach could
have been used for the BBC micro be-
cause, although not a commonly used
technique, the operating system does al-
low the re-mapping of screen memory so
two separate screens can be generated
and displayed. The approach used here is
easier, and four or more generations can
be viewed simultaneously. This makes it
possible to follow the progress of a pattern
without resorting to hard copy of each
successive generation. In program 1, the
screen is effectively divided into four sepa-
rate windows, each having a resolution of
160 by 128. The program generates the
following sequence of events:

• set up initial pattern in window 1 ;

• examine window 1 and plot next
generation in window 2;

• examine window 2 and plot next
generation in window 3;

• examine window 3 and plot next
generation in window 4;

• examine window 4 and plot next
generation in window 1 ;

• go to stage two.

This approach relies on the VDU29 com-
mand which allows the graphics origin to
be redefined. This means a particular loca-
tion can be examined and the next genera-
tion plotted at the corresponding location
in the next window without the need to
recalculate coordinates. The program is in
BBC Basic, making use of the built-in
assembler for the time-critical part, and
takes about two and a half minutes to
process one generation. The machine
code part of the program makes use of
OSWORD and OSWRCH operating system
calls to set the graphics origin, return the
value of a pixel, and to plot a pixel. This
saves a considerable amount of coding
but execution time could be improved if the
screen memory were addressed directly.

Lines 300 to 350 of PROCdesign can
define any initial shape. The graphics ori-
gin (coordinates 0,0) of each window is at
its bottom left-hand corner. The program
will continue to run, with successive gen-
erations proceeding clockwise around the
screen, until the ‘H’ key is pressed. The
program then halts at the completion of the
current generation and awaits a further
key-press: either ‘C’ to continue or *Q' to
quit.

Figure 2 shows the result of applying
program 1 to a random pattern of squares.
The initial pattern is in the top left-hand
corner and the next three generations
follow in a clockwise direction. Figure 3
shows generations four to seven.

Program 2 is entirely in Basic but never-
theless runs reasonably quickly owing to
the application of a technique which helps
to eliminate the redundant processing of
empty locations. The object of using Basic
was to allow the rules governing the evolu-
tion of the cells to be easily changed; any

Figure 9.

potentially interesting combinations could
then be incorporated into a program simi-
lar to the first listing. In this situation it is
sufficient to process relatively small initial
cell groups. The feature of being able to
display several generations simultaneously
has been retained, which makes it easier to
see how a pattern is evolving. The rules
incorporated in this program are:

• each cell survives for exactly three
generations and then vanishes;

• only the bordering locations shown
in figure 1 as 1, 3, 5 and 7 are
examined;

• any empty location with an odd num-
ber of neighbours gives birth to a
new cell.

The first rule requires each location to have
four possible states:

• empty;

• containing a first generation cell;

• containing a second generation cell;

• containing a third generation cell.

Each pixel therefore needs to be capable
of exhibiting three values as well as zero.
This condition is achieved in graphics
mode 1 on the BBC micro by assigning

one of the four logical colours to each pixel
to represent the state of each location.

When processing a single small shape,
only those locations within the shape and
immediately bordering it need be exam-
ined. This fact is used to optimise speed
and allow the display of a large number of
generations simultaneously. In effect, each
window is made just big enough to accom-
modate the current generation. With most
algorithms of this type, the overall shape
tends to expand and so a larger area must
be allotted to each successive generation.
Consequently the time required to process
each generation increases, but the overall
saving in time is considerable.

Figure 4 shows the program applied to a
single cell, while figure 5 starts with five
cells arranged in the shape of a cross (if
figure 1 is taken to represent the centre of
the display grid, locations 2, 4, 6, 8 and the
centre location would initially be occu-
pied). In figure 5 the condition for the
creation of a new cell is that there is just
one neighbour. Line 30 sets logical colours
1, 2 and 3 appear as white for a mono-
chrome display (leave out for a colour
monitor). This has the advantage of giving
a clear indication of the generation of each
dell.

It is possible to explore the effects of

72

ACORN USER JANUARY 1984

GRAPHICS

Figure 8. Results with different cell groupings

Figure 7. Approximate hexagonal symmetry

2

1

3

X

6

4

5

Figt

ire 6. H

lexagoi

nal gric

i appro

►ximatii

an

changing the rules and cell patterns by
altering program 2. The variable, ‘count%’
holds the current number of neighbouring
cells, ‘colour’ is the logical colour of the
current generation and 'thisceir is the logi-
cal colour of the current location. Line 290
defines the conditions for the creation of a
cell and lines 190 and 200 determine the
locations, relative to the current location, to
be taken into account. As before, ‘PROC-
design' can be altered to generate any
desired initial configuration. In this case
the graphics origin is at the centre of each
window. If the initial cell group has a width
or height greater than three pixels, the
initial value of L% in line 40 (which deter-
mines the initial size of the window) will
need to be increased to accommodate it.
L% is automatically incremented as the
program proceeds.

So far we have been concerned with
cells on a rectangular grid. The next listing
attempts to apply a set of rules in which the
state of a location is determined by six of

the neighbouring locations arranged in the
hexagonal form (program 3). As the screen
locations are arranged in a rectangular
matrix, it is not possible to simulate a
hexagonal grid perfectly, but a reasonable
approximation can be achieved (figure 6).
For each potential cell location, the relative
locations 1 to 6 are examined. Figure 7
shows this is good enough to approximate
hexagonal symmetry, and the first 18 gen-
erations are shown. As might be expected,
many of the six-sided shapes are reminis-
cent of snowflakes. The initial pattern is a
square block of nine cells. Again, each cell
survives for three generations and the
creation of a new cell is dependent on a
location having an odd number of
neighbours.

Figure 8 shows the same rules applied to
slightly different cell groupings. The rules
have also been changed in the third frame
so that only one neighbour is required to
create a new cell.

If a further change to the rules is made
such that third generation cells are ignored
for the purpose of the neighbouring cell
count, it is possible to use the whole
screen to display a single generation. This
variation removes the need to leave the
display of a particular generation unaltered
while the next is being determined. Figure
9 shows generation 14 of such a display
and was generated using program 4. The
individual cells are represented by 3x3
blocks of pixels (as defined in PROC-
block), giving an effective resolution of
80 x 64 and a larger display which is more
suitable for the UHF input of a television
receiver. The PAL television system is
unable to give a satisfactory rendering of
colour detail at the level of a single mode 1
pixel. Hence some colour detail will be lost
if listing 3 is run into a domestic receiver
rather than an RGB monitor. Once again,
any initial pattern of blocks can be incorpo-
rated in the definition of PROCdesign. The
initial value of L% in line 40 will need to be
increased in increments of 16 to accom-
modate larger initial patterns.

I hope the examples given will stimulate
further experimentation in the generation of
patterns by the repeated applications of a
few simple rules to various ‘seed’ shapes •

73

ACORN USER JANUARY 1984

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Telephone (0253) 55282

74

ACORN USER JANUARY 1984

10

PROCassemble k

20

MODE 4

30

VDU29 , 0; 512;

40

PROCdesi gn

50

REPEAT

60

PROCsource (0,512) : PROCdest i nat i on (

640,5

12)

70

CALL life: PROCkey

80

PROCsource ( 640 ,512): PROCdest i nat i o

n (640

,0)

90

CALL life: PROCkey

100

PROCsource (640,0) : PROCdest i nat i on (

0,0)

110

CALL life: PROCkey

120

PROCsource (0,0) : PROCdest i nat 1 on (0,

512)

130

CALL life: PROCkey

140

UNTIL FALSE

150

END

160

170

180

DEF PROCsource (X7, Y7)

190

?SXL=X7.M0D256: ?SXH=X7.DI V256

200

?SYL=Y7.M0D256: ?SYH=Y7.DI V256

210

ENDPROC

220

230

240

DEF PROCdest i nation ( X7 , Y7. )

250

?DXL=X7.M0D256: ?DXH=X7.DI V256

260

?DYL=Y7.M0D256: ?DYH=Y7.DI V256

270

ENDPROC

280

290

300

DEF PROCdesi gn 1

310

FORI7.= 1TO20

320

MOVERND (13) *40,RND (9) *40

330

PLOT 1 , 80,0: PLOT 1 , 0.80: PLOT 1 ,-80,0:

PLOT 1 ,

0,-80

340

NEXT

350

ENDPROC

360

370

380

DEF PROCassemb 1 e

390

oswor d=&FFF 1 : oswrch=2<FFEE: pi x el =&7

8: XO=2<79: Y0=?'7A: col our=?/85

400

XBL=&70: XBH=&7 1 : YBL=S<72: YBH=8-.73: XL

=&74: XH=2<75: YL=&76: YH=&77

410

cel 1 count=8<7B: thi seel 1 =&B4: SXL=&7C

: SXH=&

:7D: DXL=&7E : DXH=?<7F

420

SYL=&80: BYH=?:B1 : DYL=8<82: DYH=&B3: TX

L=2/86:

TXH=?<87 : TYL=&B8 : TYH=8<89

430

DIM life 400

440

FOR PASS=0 TO 3 STEF' 3:P7.= life

450

COPT PASS

460

OLD: LDA#2: STA XBH:LDA#112:

STA XBL

470

. 1 oop4 LDA#1 : STA YBH: LDA#240: STA

YBL

480

. loop3 JSR source: JSR cell:JSR de

st : LDA#0: STA colour

Program 1.

plots four generations continued on page 77 1

ACORN USER JANUARY 1984

75

ELBUG ELBUG ELBUG ELBUG ELBUG ELBUG ELBUG ELBUG ELBUG ELBUG ELBUG ELBUG ELBUG EL

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packed with News, Reviews, Hints, Tips,
Programming ideas, Major articles, plus Regular
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1. SPACE CITY. Defeat the invading Aliens with your laser, and save
the city

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3. RACER. Guide your racing car to victory, avoiding other cars and
obstacles on the track

4. 3D MAZE. In this challenging game, you must escape from the
maze - The screen displays a 3D view from inside the maze

5. PATCHWORK A multicoloured display of continuously changing
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6. KEY SET ROUTINE. A program to set up the user function keys

7. MEMORY DISPLAY. An efficiently written utility to display the con-
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this useful utility for use in your own programs.

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*

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Figure 5. Five-cell cross with program 2

► continued from page 75

RTS

LDA#0: STA cell count : LDA#12

490 LDA thi seel 1 : BEQ nocell:LD

A cel 1 count : CMP#2: BEQ newcell

52)0 .nocell LDA cel 1 count : CMP#3: BNE sh
ow

ol0 .newcell LDA# 1: STA colour
520 .show LDA#1S:JSR oswrch: LDA#0: JS
R oswrch: LDA colour:JSR oswrch

530 JSR plot: SEC: LDA YBL:SBC#4

: STA YBL: CMP#252: BNE loop3

540 LDA YBH: BEQ here: DEC YBH: J

MR loop 3

550 .here SEC: LDA XBL: SBC#4: STA XBL:
CMP#252: BNE loop4

560 LDA XBH: BEQ end: DEC XBH:JM

P loop4
570 . end
580 .cell
: STA XO

590 . 1 oop2 LDA#12: STA YO:CLC:LDA XBL:
ADC XO: STA XL

600 LDA XBH: STA XH:BCC loopl:I

NC XH

610 . 1 oop 1 LDA YBL: ADC YO:STA YL: LDA
YBH: STA YH:BCC cont2: INC YH
620 . cont2 LDY#0:LDX#XL
630 LDA#9 : JSR osword: LDA#8: CMP

XO: BNE cont : CMP YO: BNE cont

640 LDA pixel :STA thiscell:LDA

XL: STA TXL: LDA XH:STA TXH

650 LDA YL: STA TYL: LDA YH: STA

TYH: JMP cont 1

660 .cont LDA pixel: BEQ contl: INC ce
1 1 count

670 .contl
E 1 oop 1
680

E 1 oop2: RTS

690 . dest LDA#29:JSR oswrch: LDA DXL:
JSR oswrch: LDA DXH:JSR oswrch

300 LDA DYL:JSR oswrch: LDA DYH

: JSR oswrch: RTS

710 .source LDA#29:JSR oswrch: LDA SXL:
JSR oswrch: LDA SXH:JSR oswrch

220 LDA SYL:JSR oswrch: LDA SYH

:JSR oswrch: RTS

730 .plot LDA#25: JSR oswrch : LDA#69: J
SR oswrch: LDA TXL: JSR oswrch

740 LDA TXH: JSR oswrch: LDA TYL

: JSR oswrch : LDA TYH: JSR oswrch:RTS:l
750 NEXT : ENDPROC
760
770

780 DEF PROCkey
790 A*=INKEY$ (0)

800 IF A$="H" REPEAT A$=GET*: UNTIL A*
="C" OR A$="Q"

810 IF A*="Q" END
820 ENDPROC

page 89

SEC: LDA Y0:SBC#4:STA YO: BN
SEC: LDA X0:SBC#4:STA XO:BN

ACORN USER JANUARY 1984

77

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78

ACORN USER JANUARY 1984

GAMES

BATTLE PLAN

WHILE developing a games program in
Basic for my BBC micro, I thought it might
be useful to keep track of the stages of
development to see how the finished game
came about.

The game in question, Defencecom, is of
the Missile Command type, although the
finished product bears only passing re-
semblance to the arcade original. The final
program is written entirely in Basic without
recourse to indirection operators, so if
you’ve invested in a second processor,
you’ll be delighted to learn that it should
still run via the Tube.

The first step was to develop short,
dummy-run programs to reproduce key
aspects of the game. These checked from
the start that the speed available from BBC
Basic was sufficient to ensure that the
completed game would be a challenge to
play. These short programs developed into
procedures used in Defencecom.

PROCmissiles is used to advance the
incoming missiles. It consists of a loop
which DRAWS a small section of each line
in turn to build up the tracks of the missiles.
The x and y coordinates of the tracks at
any time are calculated using proportions,
as the start and finish points are known and
the y coordinate is altered by a set amount
in each loop.

It is important that as much calculation
as possible is carried out before the start of
the main game loop. This system seemed
to work satisfactorily, although it is slightly
amended within the final program.

PROCscreen sets up the backdrop of

Fresh from his defence
of the cities from
missile onslaught,
Simon Williams tells
in this extract from his
Defencecom memoirs
how he set the enemy
up using Basic tactics

the game using a variety of different back-
ground colours. At this stage most of the
user-defined graphics were worked out.
This may seem early to be considering the
niceties of the eventual screen image, but
it normally ensures the game will be visual-
ly attractive.

PROCsights (line 5010) moves the de-
fence missile sights around the screen.
This program should surprise nobody as it
makes use of simple INKEY statements,
using negative parameters to ensure the
machine scans the keyboard and not the
keyboard buffer. This method means that
the micro can detect more than one key
depression on each pass of the control
loop, making possible, for instance, diag-
onal movement around the screen.

Having checked that the major elements
of the program could be made to work, the
next stage was to devise a main control
loop to run the program.

To do this a flow chart, figure 1, was
drawn up. This sequence of actions can be
adapted to most video games. Whether it

is Space Invaders, Pac-Man, Frogger or
Missile Command, the progression of
events is much the same and essentially
simple. In a high-level language it is a
straightforward step to translate this flow
into the main control loops of the game
itself.

Programs really are easier to follow if
they don’t involve the use of GOTO state-
ments for loop control. For this reason a
system of REPEAT. . .UNTIL loops and
named procedures was employed with, as
near as possible, the direct translation of
the flow chart into the main control pro-
gram. This can be seen in lines 10-180 of
the final game listing 1 .

Each procedure was programmed to
perform a specific task within the game,
and the titles of the procedures reflect
these tasks. In some cases they call further
procedures or levels of procedures and so
build up a four-tier hierarchical structure. A
brief run-through of the first level of called
procedures and their actions should illus-
trate how the program is built up.

PROCinitialise dimensions arrays for the
positions of incoming missiles (X3%(1 2)
and Y3%(12)), the increments of their
movement (DX%(12) and DY%(12)), and
the x coordinates of the six cities (C%(6))
The various user-defined graphics are set
up and allocated to strings for easier
subsequent handling. Note that, in line
1110, the explosion string EX$ is drawn as
a clockwise spiral, which gives a fairly
realistic explosion. Variables which need to
be set up for replays as well as for the first

ACORN USER JANUARY 1984

79

GAMES

Figure 1. Flowchart outlining the sequence of actions found in
most video games

INTEGERS

A% — Ammunition left
B% — Number of current background
colour

C%— Cities left

D% — Duration of note in fanfare
DIF% — Current level of difficulty
DPX% — Movement increment for projectile
E%— Explosion delay counter
EX% — x coordinate of explosion
EY% — y coordinate of explosion
ENTRY% — Entry variable
F% — Frequency of note in fanfare
HS% — Current high score
L% — General-purpose loop counter
M% — Missiles in flight
N% — General purpose loop counter
NX% — New x coordinate for sights
NY%— New y coordinate for sights
NX3% — New x coordinate for current
missile

NY3% — New y coordinate for current
missile

P% — Projectile type/in flight flag
PCX% — x coordinate of next undestroyed
city

PX% — Current projectile x coordinate

S% — Size of title

SC% — Current score

T%— Time delay parameter

TS%— Temporary score variable

TX% — x coordinate of title origin

TY% — y coordinate of title origin

X% — x coordinate of sights

Y% — y coordinate of sights

XI % — x coordinate of missile start

X2% — x coordinate of missile finish

FLOATING POINT

TX — Current x coordinate of title
TY — Current y coordinate of title

STRINGS ? .

AMMO$ — Ammunition graphics

B$ — Bomber graphics

BASES — DEFENCECOM base graphics

CITY$ — city graphics

EX$ — explosion graphics

P$ — projectile graphics (B$ or SAT$)

SAT$ — satellite graphics

ARRAYS

C%(6) — x coordinates of cities
DX%(12) — increment in missile x
coordinates

DY%(12) — increment in missile y
coordinates

X3%(12) — Current x coordinate of missiles
Y3%(12) — Current y coordinate of missiles

Figure 2. List of variables

80

ACORN USER JANUARY 1984

GAMES

I

playing of the game are devolved to
PROCreset. The four sound envelopes are
set up in lines 1 1 30 to 1 1 60.

PROCinstructions first calls PROCtitle,
which draws the game’s name, DEFENCE-
COM, in high-res graphics from x.y data
pairs. The size and position of this title can
be controlled via PROCtitle’s parameters.
PROCfanfare plays a short introductory
tune and the first page of instructions is
then displayed. This is followed by scores
and bonuses, before the procedure exits
and after input from the user, at line 2200.

PROCIevel increases the level of difficul-
ty, DIF%, and then uses this value to
establish the rates of descent of incoming
missiles. The values of flags P% and PX%,
used by PROCprojectile, are then reset.

PROCscreen, as weir as drawing the
backdrop to the playscreen, also prints the
score and remaining ammunition. B% is
allocated the colour of the current back-
ground by reading it directly from the string
“41367” in conjunction again with the level
of difficulty variable, DIF%.

PROCsights incorporates line 6050,
which calls PROCfire to set up an explo-
sion. The conditional test for firing originally
employed negative parameters to the IN-
KEY statement, but because PROCmis-
siles takes a significant time to complete,
the program would occasionally not re-

spond to the space bar. By reading the
keyboard buffer instead, the key will al-
ways operate, although sometimes after a
short delay.

PROCmissiles includes several tests for
hitting a defence missile, the ground or a
city. The destruction of a city is handled
separately by PROCcity, and satellite and
plane attacks are also handled from this
procedure by calling PROCprojectile.

PROCbonus calculates and displays the
bonuses for cities saved at each level and
for unused ammunition. It calls PROC-
pause, a parameter-driven delay loop.

PROCgameover handles the final screen
display when all cities have been de-
stroyed by missiles or plane or satellite fire.
It requests input for a replay and, if neces-
sary, calls PROCreset to reset variables.

At the lower level, PROCprojectile acts
as a separate game by moving a satellite
or plane across the screen to attack one or
all cities. It calls respectively PROCsearch
to establish the first eligible city for its
attentions, and PROCshoot, which acts
similarly to PROCcity.

The incorporation here of the systems of
development may help you to produce
games programs more easily, if not more
quickly. It should make them easier to read
and, if necessary to modify. I hope you
enjoy playing Defencecom. •

1 REM DEFENCECOM by S. Williams
- REM Acorn User January 1984

10 MODE 2
20 PROCini tial ise
-.-•0 PROCi n struct i ons
40 REPEAT
50 REPEAT
60 PROCIevel
70 PROCscreen
80 REPEAT
90 PROCsights
100 PROCsights
110 PROCmissiles
120 PROCsights
130 UNTIL MY.=0 OR C7.=0
140 PROCbonus
150 UNTIL C7.=0
160 PROCgameover
170 UNTIL ENTRY7.=78
180 MODE 7
190 END
999

1000 REM #** JO INITIALISE VARIABLES/

in,,™ USER CHARACTERS etc

1010 DEF PROCini tial ise

) !?%(6? IM X3 ' /,a2) ’ Y3%<12> *DX-/.<12> ,DY-/.U2

23 - 2 24,B,B,8,62,8,8,8,0,23 2-5

*0*0, 0,^4, 24 , 60 , 1 26 , 255 *

1 040^ VEMJ 23 226,1,1,3,19,87,119,247,255

’ — ' * l^ 8 , 152, 152, 156,220,222 -54 ->55

1050 VDU 23,228,0,2,2,2,2,77s 0
0,0,144,220,127,28,16.0 ’

, 255

255 , 255 , 255 , 255 , 255 , 255 ’ 255 , 25'7-55' t
1070 VDU 23 , 23 1 , 255 , 254 , 252^252 ,25 7 -48
, 1 92 ,192, 23 , 232 , 255 ,127 1 -7aTa3 1 - ’ t »

1 080 VDU 23, 233,1, 15,

g 5 ’ 2> ’ 20,4 » 1 92 , 248 , 252 , 252 , 254 , 254 , 255 , 25

1090 S$=CHR*224: BASE*=CHR*225- ciT'/T-r
HRS226+CHR*227 LIT.T-C

rU00 AMM0*=CHR*22B: B*=CHR$229: SAT$=CH

1 + X HR^« R ^uD 5+CHRi:255+CHR * : 1 0+ CHR*e+C
R * B+C HR*255 + CHR*8 + CHR*S + C
^to- H p $8+CHR$1 1+CHR*255+CHR*8+CHRT 1 1
+CHR^2o3+CHR^255+CHR^234

0; 1120 PR °Cresets HS7.=0: VDU 23;8202;0;0;

, 0 !?L!s 0 ELOIiE 4 - 0 . 0 , 127 ,- 1, -1

— Ti70 ENDF'ROC

continued on page 83

ACORN USER JANUARY 1984

81

SPRITE-GEN is an amazing and revolutionary piece of
software. You can create multi-coloured fast-moving sprites
quickly and easily without machine code. Until now, only
experienced machine-code programmers could produce ‘Ghost
Gobbling Monsters’ and ‘Light Speed spacecraft'. With SPRITE
GRAPH ICS any character or object you imagine are at your
command, moving smoothly at any speed in any direction.
Supplied on cassette it can be used on disk.

Look at these features:

v tacn i l actually nas i wu images wnicn given sngni
differences wil I achieve the animation effects when the two are
alternated. Or, if you choose, give the two images totally different
designs and you have created two SPRITES out of one, usable
alternately. Thistechnique can also be applied to the CLONES
which means thatall 32 SPRITEScan beanimated, multi-
coloured, moving objects!!!

* Once you have completed the design of your SPRITES using the
simple grid-based generator utility, they and the high speed
machine-code routines that control their movement are secreted
into RAM and the BASIC system is ready to accept your own
program lines through which you can direct the SPRITES to
appear, move, disappear or just remain stationary.

* Up to 32 SPRITES on screen at any time.

Limitless SPRITE design using the SPRITE Generator program
included in the package, allows ALL SIXTEEN logical colours "In
each SPRITE" if desired. Full operating system capability of
logical/actual colour assignment.

* SPRITEScan be linked together in pairs or groups to produce
large scale animation. Of course, if you wish they can be as small
asa single pixel.

* Your own creations can move in front of each other with no loss of
detail.

* There can be up to EIGHT different SPRITE DESIGNS active at
onetime, each of which can have up to THREE “CLONES” (copies
of the primary SPRITE but each with individual movement
control).

With SPRITE-GEN you can use your imagination and micro to the
full for fun and profit. Ideal for Schools and Colleges. Comes
complete with two brand new sample games and fully illustrated
instruction manual at just £17.95 (U.S. $49.95)

SUPER - 7

The best value in arcade-type games available today. Seven
exciting machine-code games in full colour and sound.
Space Pilot Test, Guns of Navarone, Creatures of the Deep
(COD), Fire Chief, Space Rescue, Chopper Chase, Bouncer.
(BBC B Only) Only £8.95.

■

To DACC Limited, 23 Waverley Road,

Hindley, Nr. Wigan, Lancashire WN2 3BN.

Please rush me:

qty. SPRITE-GEN at£17.95each

qty. FLIGHTSIMULATORSat £9.95 each

qty. SUPER 7 at £8.95 each

Please state machine.

I enclose a cheque/PO to the value of £

Name

Address

747 FLIGHT
SIMULATOR

Now Electron!

BBC * Dragon * TRS 80 C/C * Electron
Exactly reproduces the flight deck of a

. Postcode _

-j

747, 21 real dialsand 25 other actual screen photograph

indicators. You select passenger level,

fuel loads and flight plan. Random emergencies make this one of the most
exciting and taxing programs even written.

Your controls operate throttle, ailerons, elevators, flaps, slats, spoilers,
landing gear, reverse thrust, brakes etc. Runway shown in true
perspective to position, indicators show distance and bearing: Operates
with two joysticks (optional) and keyboard.

“A real simulation, not just another game” (Your Computer, April ’83)

Cassette £9.95 inc VAT (US $27.95)

DACC Limited,

23, Waverley Road,
Hindley, Nr. Wigan,
Lancashire WN2 3BN.

In US order from sole distributor:
Frank Ashton, PO Box 7037,
Chula Vista, CA 92012-7037.
(California residents add 6%)

82

ACORN USER JANUARY 1984

k

continued from page 8 1

19??

20 00 REM XXX TO DISPLAY INSTRUCTIONS
2010DEF PROCinstructions
2020FOR LX=50 TO 945 STEP 128
2030PROCt i t 1 e(50 ,LX, 1?)

2040NEXT : PROC-f an-f are

2050VDU 24,0;0; 1270;815; : CLG : GCOL0.7
2060MOVE 32,500: PRINT" <c) 1983 S.Williams"

20 70PROCpause( 200) : CLG: SOUND 1 , 3 , 0,100

2080VDU 4: COLOUR 9: COLOUR 128: PRINT TAB< 2 , 7) " ALERT - HOSTILES"
2090COLOUR 2: PRINT TAB< 2 , 10) » Destroy incoming mxssiul! pfanes

"fire from DEFENCECOM"
<-l eft >-r i gh t "

silo. Move sight
Space bar-fire":

"-200

- 10 "

;CITY* TAB< 13, 15) ; AMM

F’l ane wi 1 1 try

satellites"''''" with qround to air
2 100 PRINT 1 ' " A-up" 2 -down" " •

OUR 3 : PRINTS" Press S for scores";

2 1 10 REPEAT UNTIL GET= 83 : CLG

2120 COLOUR 6 : PRINT TAB< 7 , 8 ) " SCORES'" TAB< 7 , 1 3 ) " BONUSES"

2 130 COLOUR 1 : PRINT TAB< 2 , 10) " -50 -150 - 300 " TAB (6 15 )

2 1 40 GCOL 0 , 2 : MOUE 80 , 700 : DRAW 112,670

2 1 50 CGLOUR 2 : PRINT TAB ( 7 . 10 ) ; SAT $ T AB ( 14 , 10 ) ; B$ TAR< 4 , 15 )

U*

f J p 1 " PR1Mr TAB(1 > 19 > "Satellite will hit" TAB< 8 , 21 ) "one city""'

2 170 COLOUR 11 : PRINT TAB< 9 , 28 ) "ALL"

2 180 COLOUR 3 : PRINT TAB< 2 , 30 ) "Press S to start"-

ImIeSpROC UNTIL GET " 83: UC,U 2<i ’ 5: C0L0UR COLOUR 136
2999

30 00 REM XXX TO SET UP VARIABLES FOP

30 10 DEF PROClevel - - - NEXT LEVEL OF PLAY

3020 1 F DIFX <5 DIFX=DIFX+ 1

3030 FOR NX =1 TO 12

EL5E 12W

3080 X 3 X<NX)=X 1 X: Y 3 X<NX )=1023
3070 DYX(NX) =DI FXX 3 +RND< 10 )

3080DXX<NX)=(XlX-X2X)X-DYX<NX)/823

3090 NEXT

3100 EX= 0 : PX =0 : PXX =-84

31 10 ENDPROC
3999

4000 REM XXX TO SET UP PLAY SCREEN
40 10 DEF PROCscr een

CLO: GC 0 L 6 ,2

4040 MOVE NX , 1 70 +RND( 20 )

4050 MOVE NX+ 100 , 170 +RND< 20 )

4060 PLOT 85 ,NX, 0 : PLOT 85 , NX+ 100,0
4070 NEXT : GCOL 0 , 0 : FOR NX = 1 TO 6

^%^ E F x T c rsr3S 8 % E eff^;Mf^ SE p , R,NTc,TYi

4 a 6 0 SoL 6 . : 3 - R ™ « S “ RE " ,SC< TAB < = . 30 >-flMHUN.T,ON-, UOU 5

4120 MOVE 55 XNX. 30 : PRINT AMMO*

4 130 NEXT

4 140 XX= 840 : YX= 700 : NXX=XX: NYX=YX
4 150 GCOL 3 , 7 : MOVE XX, YX: PRINT S*

4 180 ENDPROC
4999

50 00 REM X** TO MOVE SIGHTS AND PROCESS

5010 DEF PROCsights EXPLOSIONS

5020 IF AX =0 ENDPROC

= f ^NX’X^XX-BBX^NKEYC- 103 ) X(XX> 127 ) + 80 X 1 NKEY < - 1 0 4 ) X < XX < 1 is?}

RR,NT s * ! n0VE »

5090 ENDPROC GC ° L3 ' 7 ’ D6! ' E ' rX ' PRINT B >0 ELSE IF EX >0 EX-EXM

59 ??

•S 000 REM XXX TO MOVE MISSILES AND OTHER PROJECTILES

and

continued on page 84

ACORN USER JANUARY 1984

83

O '.ft

GAMES

continued from page 83

6010DEF PROCmissiles
6020NX=0: MX= 0 : GCOL 0 2
60 30 REPEAT: NX=NX + 1

6040 IF Y3X<NX)=0 UNTIL NX= 12 : ENDPROC

SSSK-- ™ - — —

6080MOL-E X3X<NX> ,Y3X<NX> : DRA^N^Zvl UNTI . L N 7.= 12: ENDPROC
6090MX=MX+ 1 : UNTIL MX =5 OR NX=12 ' 3/,: X 3 X<NX> =NX3X : Y3X<NX)«NY3X

6 1 1 ©FNDPRnr PR0Cprojectl ' e ELSE IF RND< 30) <DI FX - 1 PROCprojec t i 1 e

70 00 REM *** TO CALCULATE AND DISPLAY

7010DEF PROCbonus bPLAT BONUS SCORE

7020CLG: PROC t i t 1 e< 50 , 800 , 1 ?>

70406COL3 ' 7 • Mmr 480 ’ 700 ! PRINT" BONUS"

7050MOVE 352,300; PR I NT " SCORE^ ■ SCX ■ ^TSX~SCX ^ 160 ’ 4501 PRINT“AMMO"

7060GCOL0,2: MX=316: FOR NX =1 TO 6 TS/ '“ SC/

e.S^PROCpluieJL) 1 ^ 7 ^ 136 ’ M0UE MX, 550: PRINT CITY*: SCX=SCX+200: SOUND 1,-12, 3

70?0tSIsCX: °gc6l 0 , 2^MX=370 ^FOR^X-j MWE 736 > 300 « PRINT ; SCX

'ZglLiSy™*' SCX=SCX+ 10 : SOUND 1,-12,50,2: P

7120AX=AX+12? L ?F 7 AX>20 E AX=20 300! PRINT;TS * ! MWE 736,300: PRINT; SCX
7 130PROCpause( 300)

7 140ENDPROC
7999

f 000REM *** T0 han dle end of game/

80 10DEF PROC game over REPLAY ETC

8020GCOL0 , 128: CLG : MX=6 1 1
8030FOR LX=5 TO 17 STEP 4
8040PROC t i 1 1 e< 50 , MX , LX)

80 50MX=M'<+ L'/.X 7

8060NEXT : VDU 4 : COLOUR 128- ppnr-fani

80 /0 PR I NT TAB< 10 , 16) "GAME OL^ER" TAB* - 1 2&^"Y

R TAB<1 ’ 20> Your score ";SCX TAB( 1 , 22) - Hi oh score
8080COLOUR 3: PRINT TAB*' 1 ha 4 ...

8090REPEAT • ENT R Y v- rrT . ?? Ar, °ther game?<Y/N> "

8 100 1 F ^ T ‘ L ENTRV ' / -- 78 °» ENTRY*. S R

81 10 IF ENTRYX=89 PROCreset
8 120ENDPROC

899 ?

^Of T . 0 S .T /RESET ' N,T,flL >*LUES

fImoifxIb A y- 20 ’ ‘ 426 ' cy ' , ‘»- 7 ^- c*<5>-87<s, CZ<«- 102 F
9040COLOUR 7: COLOUR 130: OdU 5
90 50 ENDPROC
9999

SScIf.fS^™

%s%rz<ro 7 n,° cDL °-* ! ' move

1 0040READ TX,TY

10060NEXT X ' ^ PL ° T 1 > TX *SX,TYXSX ELSE TX=TX- 10 : PLOT 0 ,TX*SX,TY*SX
, 16,-1, ©^7^5 Te fe T- e 0 f-if 2 _ e ’a 3 -!?’ L 1 ’ 1,0 » 5 ^ i;5 ' e ' l- 5, -2, 0,-1 ,-1.5, -2, -1.5,0

.2, 2,3, 0 , 0, - 1 , - 2 . 5, 0 ,:, -1^-2, 0,0,-2^^0 : 0, - 1 ,- 5 , 0,17,2,0,3

continued on page 87

84

ACORN USER JANUARY 1984

YOUR PARENTS DID THEIR BEST
FOR YOU. . .WILL YOUR CHILDREN
BE ABLE TO SAY THE SAME?

*

In the last five years, the

MICROCHIP HAS EXTENDED ITS
REVOLUTIONISING INFLUENCE TO OUR
SCHOOLS. TODAY, EVEN THE YOUNGEST
CLASSES TAKE COMPUTERS AS MUCH FOR
GRANTED AS WE DID OUR WOODEN
RULERS.

With these implications
IN MIND, good housekeeping
SOFTWARE WAS CREATED; ITS AIM
BEING TO DEVELOP A COMPREHEN-
SIVE RANGE OF CAREFULLY
STRUCTURED EARLY LEARNING SOFT-
WARE FOR YOUR HOME COMPUTER.

"Now... I’ve got two oranges in my
left hand and one in my right, how

many oranges.

y

A NEW WAY TO
FLAY AND LEARN

Designed not

JUST BY SOFTWARE ^

SPECIALISTS, BUT ALSO BY EDUCATIONAL EXPERTS. EACH
PACKAGE GOES FAR BEYOND THE POPULAR IMAGE
OF COMPUTER ASSISTED LEARNING.

It provides a framework for

YOU AND YOUR CHILD TO LEARN AND
PLAY TOGETHER. It ALSO ENCOURAGES
YOUR CHILD TO DISCOVER THE REWARDS
OF INDEPENDENCE AND CONCEN-
TRATION AS HE OR SHE EXPLORES THE
PROGRAM ALONE, OR WITH A FRIEND.

Each package includes
cames But unlike most other

SOFTWARE FOR CHILDREN, THESE ARE
NEITHER TRIVIAL NOR COMPETITIVE.

They are designed to encourage

LEARNING THROUGH STRUCTURED
PLAY, COLOURFUL EYE-CATCHING
GRAPHICS OF THE HIGHEST QUALITY,

AND A VARIETY OF REALISTIC
SOUND EFFECTS.

YOU CAN ALSO ADJUST THE
SPEED AND DIFFICULTY OF EACH
GAME TO SUIT YOUR CHILD. Or LET
THE COMPUTER ADJUST ITSELF
AUTOMATICALLY AS YOUR CHILD
PROGRESSES.

LEARNING WITH

MRT

MR T, GOOD HOUSE-
KEEPING'S LIVELY ANIMATED
CHARACTER, WILL HELP YOUR
CHILDREN EXPLORE ALL SORTS OF

SOFTWARE PACKAGE S THAT I HAVE INDICATED

Mr t tells the time

£ 1345 EACH

Mr r s money box

£0.115 EACH

Mr I S ALPHABET GAMES

£i2.Y5 EACH

Available

Mr i s number games

£ll<»5 EACH

Mr i s measuring games

£1345 EACH

Mk TS SHAPE GAMES

£ti<H EACH

Total

DHC MICRO 8

PREVIOUSLY DIFFICULT EDUCATIONAL AREAS NOW THEY CAN LEARN
TO TELL THE TIME, OR COPE WITH REAL MONEY IN AN EXCITING AND
ENTERTAINING WAY.

Mr t will also help your children come to terms

WITH THE WHOLE IDEA OF COMPUTERS AS AN INTEGRAL PART OF
THEIR FUTURE LIVES.

THE PARENTS' HANDBOOK

A PARENTS’ HANDBOOK IS INCLUDED IN EACH PACKAGE,
CONTAINING SIMPLE OPERATING INSTRUCTIONS AND A STEP-BY-STEP
GUIDE TO HELP YOU AND YOUR CHILD GET THE BEST OUT OF EACH
PROCRAM. It ALSO CONTAINS a WEALTH OF FOLLOW-UP ACTIVITIES
FOR YOU BOTH TO ENJOY AWAY FROM THE COMPUTER.

YOUR CHILDREN’S FUTURE
BEGINS HERE

Put your home computer to work

FOR YOUR CHILDREN NOW. SEND FOR YOUR
GOOD HOUSEKEEPING EARLY LEARNING
PACKAGES BY CUTTINC THIS COUPON.

ii OR ABOVE

Hardware compatibility bbc micro b ro.i
Sinclair spectrum «uk commodore 6a
Available at leading computer stores and specialist computer

DEPARTMENTS OF MAIOR HIGH STREET RETAILERS

»Xl<u»MRv. . m.

blN< I.AIR
SPECTRUM

Signed

Dati

Name mr mrs m<
BLOCK LETTERS

Address

Commodore m, versions available ism

I ENCLOSE MY CHEQUEJPO FOR THE AMOUNT ABOVE INCLUDING VAT AND PAP. MADE
PAYABLE TO EBURY SOFTWARE Or CHARGE MY ACCESS/VISA/DINERS/ AMERICAN EXPRESS

Totai number OF PACKAGES ORDERED _

Remittance should be made payable to ebury software and shall hi heldon yo
BEHALF IN THIS ACCOUNT UNTIL THE GOODS ARE DESPATCHED P| EASF ALLOW UP TO It
DAYS FOR DELIVERY OFFER APPLIES TO U K AND EIRE ONLY

Ebury software a division of the national magazine co ltd.

Registered number iuost

GOOD HOUSEKEPING SOFTWARE • EARLY LEARNING

Published by ebury softwarf a division of the national magazine co ltd: for good housekeeping national magazine house broadwick street London wiv :bp

Mike Chalk and Kansas bring you the first of the

NEW GENERATION Arcade games

PINBALL ARCADE

The absolute in arcade games

Wr

m

Going are the days of squashing frogs , killing gorillas and
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Create your own Pinball machines— save them to tape

to play whenever you like

Yes, the ’levels’ problem is solved at last
—literally a thousand games in one!

There are six pages’ of shapes for you to create a Pinball board.with each shape capable of
being placed in any position required. K K

Targets, Slings and Bumpers can be moved into any required position anywhere on the board,
with the actual 'bounce' being adjustable.

There is total control of the firing spring, with realistic action depending on amount of
time taken to press control bar. The strength of the flippers can also be varied.

There is highest score, last and current score and ball count.

The actual tilt of the board can be altered, with amount of ball speed and bounce coresponding.

It's not just a

s an education!

But take warning — it will make you dissatisfied with common Arcade games

Pinball Arcade literally 'stole the show' at the PCW Show, easily outselling every

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Available by our famed first class return post service with every program of course carrying the Kansas
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ACCESS OR BARCLAYCARD TELEPHONE ORDERS ACCEPTED WITH PLEASURE

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cfcansas

* Kansas City S

Recognised Brand Leader in microcomputer software

Kansas City Systems, Unit 3, Sutton Springs Wood, Chesterfield, S44 5XF. Tel. 0246 850357

86

ACORN USER JANUARY 1984

continued from page 84
10110DATA 17,-1 0 s „

10120ENDPROC ’ 1 - 5 *- 1 ,0 ,-l , 1 , 5f 0 ,1 I \ « ^ ’ 14 ’ “ 3 » 0 * ? , 1 ■ 5 , 0 , \ -2*1 o'l’i’

10999 ’ 1,0 9 ** l 9*f 1 '5 f

UiSiS£°gM°‘" F0R Nx “ T0 15

11 040 SOUND 1 . - 1 S pv nv
1 1050NEXT SOUND 1,0,1,]

1 1 060 DATA 33 1 oo « cr^ -

53,4 ’ ’^’ 49 » 1 > 53 > 1 ,61 ,2,53, 1 ,61 , 1 69 2 A\

11070ENDPROC * I *«,2 f 61,l,5 3(lt49f2>4

11999 ’ ’

12000Re;/v| x%% TO DESTROY riTv r-

JT™ . "

,5 ^- <c,KUO * *“ M0UE «««,.*,. PR , N

3S- SE-fSTi?!."*

iiHEH c s^F* TELUTE/BmeER

sir rssr?sssiis: ■ proc

•°ENDP R ir 9 ' 5 ' PRINT P* ; sou

S- p., Pxx. m . DPX ; 8, ' sc " wu 51 — —

13080 ENDPROC 1 P$

13999

140 10DEF PROCPi>r iRE DEFENCE MISSILES

14020 IF EX=0 'eJXxx, rvy = YV . r , r , „ ~ AND SET UP EXPLOSIONS

E X*: WiWl MOVE <540,248* D

140 30 ENDPROC 6CUL0,2: MOVE 55*AX,30 : PRINT AMMO

14999

15000REM *** TO DELAY FYrrn-rr -

150 10DEF PROCpause^Tv> E ECUTIUN F0R SET

15020TIME=0 • RfpfIt ,JL. TIME

15030 ENDPROC EAT UNTIL TI ME>TX

15999

16010DEF PROcIearch ECT CITY/IE S FOR

1 6020PCXX= 1 280 : NX= 1 . repeat ATTACK

iSS5K£JSS?° >e pc,=n,

1 <50 60 ENDPROC^” 7 ° R PCX X <12 80
! 2 ei0D R E E F ?ROcIh 7 oot OOT/DESTR ° Y CITY

170200001.3,3: MOVE PXX + 32,PYX-1, : DRAW PXX + 32 200* MOVE p

170306COL0 , 8 s MOVE PCXV ?00 PCIf ' p XX + 32,PYX-16 : DRAW PXX +

^12,2,50,20 ,2W0: PRI NT CITY** if CX<PCX)>0

F 040IP p ' x -=2 PROCsearch ELSE Pry 0! Cy ‘~ Cy -~ 1 : SOUND

170 50 ENDPROC tLbE Pcxy -= 1 280

End of Defencecom Listing

ACORN USER JANUARY 1984

87

‘The professional graph program for the BBC Micro 5 (Model B only)

INDUSTR IRI OUIPIM

a

V'h'f'w'f'r'f h!f WfWrV r Y r r'n r fl'rn Y r ji T i :

70 ?1 7 2 7 3 / 4 / 7 & / / 7 8 1/9 8 8 81 8 2 8 3

1^2 VEttRl V RUI-RRGES
This is what A&B Computing said about the cassette version of EASIPLOT
(December 83 issue):-

“ EASIPLOT . . has many options . . its very easy to use yet very
comprehensive and very useful to people from small businesses to schools etc . .
in conclusion this is a very good package . . Ratings . . value for money 85% . .
overall 92%. ”

NOW EASIPLOT is on DISK and is EVEN MORE POWERFUL with
extra facilities and an additional program, DATA PLOTTER (a share price/
general purpose indicator program with selectable moving average curve, colour
select and graph magnification facilities).

At a price of £19.95 the disk version must represent EXCEPTIONAL value
for money!

FACILITIES:-

EASIPLOT 1 (CASSETTE ONLY) . . 3 comprehensive programs . .
LINES, BARS & PIES— 3 simultaneous graphs per program— AUTOMATIC
or MANUAL scaling, sort and labelling— Full cassette save, load and cat

v m;<NL*!J a h ; i a*** :um a»i n

z~ BNSLI> ON
1938 BflSE
OF 1 00

wot 1 d
war

2

_l_

uor 1 d
war

1

_L_

L.

18/5 1900 1925 8 950 19/5 2000

VEflR

options— 100 characters of fixed description per graph— Choice of 10 different
line types, 5 different bars— 8 different colour combinations— Full EDIT and
MERGE capabilities— GRID option— SCREENSAVE facility— Powerful
OVERWRITE Mode-MENU driven-COMPREHENSIVE 40 PAGE
MANUAL— Machine code screen dumps for EPSON (entire range), SHINWA
(CP80) and SEIKOSHA (GP 100A & GP 80A) printers.

EASIPLOT 2 (DISK ONLY) . . additional facilities include— single and
selectable file handling— scatter charts— 5 mergeable graphs— powerful
overwrite memory— bar/line interchanges— up to 200 chars of fixed description
per graph and DATA PLOTTER (see above).

EASIPLOT is useful, educational and is also ideal for householders and
investors.

We are convinced that this is by far the best BBC graph package available . . .
If after using EASIPLOT you do not agree, we will refund your money.

EASIPLOT is guaranteed for 12 months and programs are normally
despatched within 24 hours of receipt of order.

Send remittance for £15.95 (cassette version) or £19.95 (disk version-40 track) to

SYNERGY SOFTWARE, Dept AU, 7 St Andrews Close, Slip End, Luton LU1 4DE.

What is the "Beasty"?

What is a Servo?

the Beasty connected

The Beasty is the interface which connects
directly into the BBC microcomputer and
enables the computer to accurately control up
to four servos. The Beasty comes complete
with all connection cables, a demonstration
program and comprehensive instructions.

A servo is a precision geared motor with a feed
back mechanism to give positional information.
The servo rotates an output arm through
1 00° and allows you to twist, turn, push, pull,
lift, lower, open, close almost anything.

The standard servo is a FP-S1 28, which
develops 3.5 Kg/cm torque with 1 00° range.
There is also a range of servos available for
almost any application.

Your introduction to Microrobotics

How Many Servos Do I Need?

You can start with just one and buy more as
you need them. A Beasty can run up to four
servos. All you have to do is decide on your
movement requirements and select the
number of servos you need.

Which Micro Do I Need?

The Beasty is designed for a BBC Model B
microcomputer, (though a 32K Model A with
a user port upgrade will suffice) fitted with OS
Version 1 .0 or above. Most of the Futaba
range of servos can be driven from the 5v
1 .25A DC auxiliary power output from the
BBC microcomputer, though the more
powerful ones may require an external power
supply.

What About the Software?

The Beasty is supplied with a demonstration
program on tape which allows sophisticated
control of up to four servos directly from the
keyboard. For those who wish to program the
servos, the machine code driver occupies less
than 256 bytes of relocatable code (so it can
be stored at any location in RAM). From
BASIC, instructions are of the form:

X% = Channelnum: Y% = Newvalue: CALL Driver
From Assembler, it's equally straightforward:
LDX 4 ; Servo number 4, for example

LDY NEWVAL96 ; Newval% is the new position
(between 0-255)

JSR DRIVER ; Call Driver routine

—More Details?

C©MM©TI©N

COMPUTER OPERATED MOTION

241 Green Street, Enfield, Middx EN3 7SJ Tel: 01 804 1 378

88

ACORN USER JANUARY 1984

-

r

16

► continued from page 77
10 M0DE1

20 VDU29 , 64 ; 900; : CX=64: DX=900
30 VDU 19, 1 , 3 ; 0 ; 1 9 , 2 , 5 ; 0 ; 19,3,6; 0;

40 C=2: col our=3: L7.=12
50 F’ROCdesign
60 ROW=l : AX=108:BX=900
70 REPEAT

80 LX=LX+8: C=C+1 : col our=C MDD3+1
90 PROCmain <CX,DX, AX, BX)

100 CX=AX : DX=BX : AX=AX+2*LX+20
110 IF AX+2*LX > 1 270 AX=LX+2S: BX=BV
X~72:R0W=R0W+1
120 UNTIL R0W=4
130 END
135

140 DEF PROCma i n < S X , S' Y , D X , D V )

150 VDU29 , SX ; SY;

160 FOR XX=— LX TO LX STEP 4
170 FOR YX=-LX TO LX STEP 4
180 count X=0

190 FOR ;<%=XX-S TO XX+8 STEF
200 FOR yX=YX— 4 TO YX+4 STEP S
^10 IF F 0 1 NT X , yX) >0 countX— cgupLX+1
220 NEXT
230 NEXT

240 FOR yX=YX-8 TO YX+8 STEP 16
^50 IF POINT ( XX , yX) >0 countX -count 7 + 1
260 NEXT

270 thiscel l=POINT(XX, YX)

280 IF thiscel I >0 THEN IF thrscellOcc
lour PROCpl ot (thiscel 1 )

290 IF thiscel 1=0 THEN IF countXM0D2=l
PROCpl ot (col our )

300 NEXT
310 NEXT
320 ENDPROC
325

330 DEF PROCplot (C) GCOL0,C
340 VDU29 , DX ; DY ; : PLOT 69 , XX , YX : VDU^o sy
;SY; ^ ’

345

350 ENDPROC

-'60 DEF F’ROCdesign

370 MOVE— 4 , -4: PLOT0 ,8,0: PLOTS 1 , -8 , 8* P 1
0T81 ,8,0 *

380 ENDPROC

Program 2. Neglects empty locations

13 MODE 1

20 VDU29,64; 900; ; CX=64: DX=900
30 VDU 1 9 , 1 , 7 ; 0 ; 19,2,7; 0; 19, 3, 7; 0;

40 C=2: colour =3: LX=12
50 F’ROCdesign
60 ROW=l : AX=108: BX=900
70 REPEAT

80 LX=LX+8: C=C+1 : col our =C M0D3+1
93 PROCmain (CX,DX, AX, BX>

100 CX=AX: DX=BX: AX=AX+2*LX+20
110 IF AX+2*LX>1270 AX=LX+20: BX=BX-^*L
>:-72:R0W=R0W+l
120 UNTIL RQW=4
130 END
135

140 DEF PROCmain (SX ,SY,DX ,DY)

150 VDU29 , SX ; SY ;

160 FOR XX=-LX TO LX STEP 4
170 FOR YX=-LX TO LX STEP 4
180 count X=0

190 FOR xX=XX— 4 TO XX+4 STEF 8
200 FOR yX=YX-4 TO YX+4 STEP 8

"^0 NEXT^^ countX=countX+l

230 NEXT

270 thi seel 1 =POINT ( XX , YX)

280 IF thiscel 1>0 THEN IF thiscel lOco
lour PROCplot (thiscel 1 )

290 IF thi seel 1=0 THEN IF countXMQD2=l
F’RQCp 1 ot (col our )

300 NEXT
310 NEXT
320 ENDPROC
325

330 DEF PROCplot (C) SCOL0 , C

340 VDU29 , DX ; D Y ; : PL0T69 , XX , YX : VDU29 , SX
; SY ;

345

350 ENDPROC
•j.60 DEF PROCdesign
370 PLDT69 ,0,0
380 ENDPROC

Program 3. Hexagonal variation

10 MODE 1

20 VDU19, 1,3;0; 19,2,5; 0; 19,3,6;0;

30 VDU29 , 640 ; 5 1 2 ;

40 C=2: col our =3; L%=64 : G= 1
50 PROCdesign

60 REPEAT G=G+1 ; VDU30: PRINT"generat i o
n " ; G

70 C=C+1 ; col our=C MOD3+1
80 PROCmain : LX=LX+32
90 UNTIL FALSE
100 END
105-

110 DEF PROCmain
120 FOR X7.--L7. TO L7. STEP 16
130 FOR Y7.=-L7. TO L7. STEP 16
140 countX=0

150 FOR x 7.= X 7.-32 TO X7.+32 STEP 64
160 FOR yX=YX-16 TO YX+16 STEP 32
170 f ^ =poi NT (:<7. ,yX) : IF P'/.< >col our AND
P4>0 counf/.=count7.+ l
180 NEXT
190 NEXT

200 FOR y7.=Y7.-32 TO Y7.+32 STEP 64
^10 FX=POINT(XX,yX) : IF P7.<>colour AND
P.O0 count7.=count7.+ l
220 NEXT

230 thiscel 1 =POINT (XX, YX)

^40 IF thiscel 1 = colour GCOL0,0:PROC
block (X7.,Y7.)

250 IF count/C MOD2=l AND thi seel 1=0 GC
OL0 , col our : PROCb 1 oc k ( X7. , YX >

260 NEXT
270 NEXT
280 ENDPROC
285

290 DEF PROCb 1 oc k <X,Y)

300 MOVEX-4 , Y-4: PLOT0, 8 ,0: PL0T81 , -8 3-
PL0T81 ,8,0

310 ENDPROC
315

320 DEF PROCdesign
330 FOR XX=-16 TO 16 STEP 16
340 FOR YX=-16 TO 16 STEP 16
350 PROCb 1 oc k ( XX , YX )

360 NEXT
370 NEXT
380 ENDPROC

Program 4. One generation displayed

ACORN USER JANUARY 1984

89

Gateways to the World Outside

The CST PROCYON opens a lot of doors to your BBC microcomputer - lifting it
right out of the ‘ home computer" league. The CST PROCYON provides full
IEEE 488 interface, enabling your BBC micro to operate professional plotters
and printers, frequency counters, voltmeters, disc drives etc, and to communicate
with other IEEE-ported machines, such as Commodore, Sirius, Osborne.
Hewlett-Packard or Tectronix computers.

The CST PROCYON comes with a highly efficient IEEE filing system, supplied
in EPROM, and responds to any high level language, including LISP. FORTRAN,
FORTH. APL and BASIC. A specially-written Commodore data-exchange
routine, allows you to link your BBC micro to CBM machines and disc drives.

At 70k bytes of information per second, the CST PROCYON channels data
quickly and efficiently between up to sixteen devices, responding to standard
system commands as well as specialised filing instructions. Its capabilities are
fully documented in a straightforward but comprehensive manual

• Full multiple controller implementation

• Extensive “HELP” facilities

• Interactive debugging

• Visual Display of operating status

• Internal switched and socketed power supply

• Comprehensive error checking and indicating

The CST PROCYON from
Cambridge Systems Technology
30 Regent Street, Cambridge
Tel: (0223) 323302

ENQUIRIES FROM DEALERS WELCOME

Isn’t it time you started taking your BBC micro seriously?

CHALKSOFT

37, Willowslea Road,
Worcester WR3 7QT
Telephone: 0905 55192

Special thanks to

* Good computer shops everywhere

* Access * Adtel ansaphones

* Webster and other imaginative
software distributors

* Simon stables Rejajl Time Tape
Duplicating Company.

EDUCATIONAL SOFTWARE

SPECIAL
CHRISTMAS
OFFER

Buy two or more and get £ 1 off each.

Take this coupon to your
local dealer or post direct.

TITLE

XMAS

PRICE

MACHINE

TICK

HERE

PUNCMAN 1 & 2 Animated
punctuation game. Can you help
Puncman beat Nosher...?(7-1 2 years)

BBC ‘B’

£8.25

Spec 48 K

STORY A - SPANISH GOLD

The first multichoice illustrated
story book on screen. (6-1 1 years)

£*S5

BBC 'B'

£6.95

Spec 48 K

PIRATE Simply the best
^adventure game for young people

J(7 to adult) illustrated. Compulsive.

BBC ‘B’

£8.25

Spec 48 K

ff LETTERS Let your micro teach
your child to write! Draws lower-
case letters ....

BBC ‘B’

£10.25

Spec 48 K

INKOSI Be an African King!

• Simulation. Can you look after the tribe
and defeat the WITCH DOCTOR...?

BBC ‘B’

£5.95

Spec 48 K

Tick at least two. Remember, if you
only buy one you pay the old price.

Prices include VAT and p&p.

To: Chalksoft Ltd.

37, Willowslea Road,
WORCESTER WR3 7QP

Please send me your new
1 6 page colour catalogue

Please rush me the tapes I’ve ticked.

I enclose a cheque for £_
or debit my Access no:

Name.

Address-

Postcode _

90

ACORN USER JANUARY 1984

THE TR Al N

WRITING action-packed arcade games in
Basic poses problems - objects have to
move fast, you want lots to be happening
and to know when things collide.

Machine code gives plenty of time to do
all the calculations, but Basic runs a hun-
dred or more times slower and is bulkier
into the bargain. So you're limited in both
time and space.

The suggestions in the BBC User Guide
help, but not a great deal. Deleting REMs
relieves the space problem, of course, as
does putting several statements on one
line and keeping identifiers short. Watch
out for trailing blanks at the end of lines -
they don’t show on the listing but can add a
few hundred bytes to a long program.
However, all these ‘improvements' are at
the expense of readability. And neither
they nor using integer variables help much
with speed. The Basic interpreter is spend-
ing most of its time working out what the
line means.

One solution is to have lots of ‘active’
objects, but few moving at any time. A
pinball simulation is a good example. You
can have lots of active objects - the ball,
bumpers, flippers and so on - but only the
ball is constantly moving. In The Train
Game we have lots of points, passengers
and trains waiting in the engine shed, but
only four trains are allowed on the track at
once.

Next, don’t print characters at the graph-
ics cursor (VDU 5) or use plotting, as both
are very slow. For speed, use nothing but

GAME

Peter Balch challenges
you to enroll for his
crash course in running
a railway network

characters printed in the normal character
locations.

Finally, there’s the problem of knowing
whether two objects have collided. You
could search a table of object locations to
see whether they have come close, but
that would take forever. Similarly, using the
POINT command is slow. Instead, keep a
separate ‘map’ of the screen in an array.
Every time you move an object into a new
square you can look at the map to see if the
square is occupied. A total of 1,280 inte-
gers (40 x 25 characters in mode 1 ) is a lot
of bytes so you can’t use an array. But you
can use a byte for each character by
declaring, for instance,

DIM board 1280

Then you can access each byte by, for
instance,

board ? (row * 40 + column)

But remember that the interpreter doesn’t
check that (row * 40 + column) is within the
bytes called ‘board’ - it’s quite easy to
overwrite your Basic program and lose it if
your program has bugs. It’s best to use a
single function which works out
board + row * 80 + column
and stops the program if row or column get

out of bounds. You can take out the
bounds check when the program is
debugged.

The best way to debug The Train Game
(or any listing) is to type it in carefully then
get someone else to read it from the
magazine while you check the TV screen. If
you still have a bug - or you want to modify
the program - this section tells you some-
thing about the layout. All this information
could have been given in REMs - but there
just wasn’t enough room.

You’ll notice that the game loads as two
programs. The first gives the rules and
initialises the character set and some en-
velopes. Then it loads the second one -
the game proper. If you don’t run the first,
you’ll find the characters are not defined;
the game will run but won’t give the correct
display.

The total number of characters in the
cnaracter set exceeds the capacity of the
user-defined character space (&C00 -
&CFF). I didn’t want to expand this area
(using *FX20) as that doesn’t work with the
older operating systems. So I put the
second half of the character set in the
section &D00 - &DFF (but remember this is
used by the disc system). The two sets are
swapped as necessary. If you press break
(or the program crashes) while the other’
set is in then the track will be drawn as
pieces of station and vice-versa - don’t
press break while the stations and towns
are being drawn.

The main program starts with various

£8 COftLi £82?

ACORN USER JANUARY 1984

91

GAMES

initialisations and declarations BRD is the
‘map’ of the screen mentioned above. It is
always accessed by

? FNBD (X,Y)

FNBD gives the address of the byte in BRD
corresponding to co-ordinates (X.Y). If the
program has a bug so that X or Y are not in
the right range then ?FNBD (X,Y) will be
outside the BRD area and you might end
up writing over the Basic program (and get
a BAD PROGRAM error) While debug-
ging, replace FNBD with a function which
STOPs the program if X or Y is invalid.
When the program works, use the faster
version of FNBD given.

A similar routine - FNNM accesses the
names of the eight best scores in a differ-
ent byte area. Using strings would have
been simpler but the BBC micro doesn't
seem to recover the bytes from old strings
properly.

The CONN array gives the input and
output connections of each type of track
square. Imagine each track square as a
miniature Union Jack - the track connects
just two of the marks (I won’t call them
’points’) on the periphery. For instance, a
curve might connect the South mark to the
North-west mark There are 12 different

The Train Game is for the BBC model B
with either operating system. In it, you
control up to four railway trains running
round a complex network of track. The
track connects five stations to the en-
gine shed and it’s your job to run a
passenger service between the
stations.

You play the part of the signalman
and can start, stop or reverse each
train, and change the points on the
track. When you stop at a station, you
pick up and drop passengers, and the
ones that get off pay a fare. When all
the passengers are where they want to
be, a new, more difficult, ‘sheet’ starts.

A stock of coal is provided at the
start of each sheet, which the trains
burn continuously - whether they are
moving or not. If coal runs out before all
the passengers are delivered the game
is over. Each successive sheet gives
you more trains, more coal and more
passengers. It’s more difficult with
more passengers because the trains
have only a limited capacity.

The trains can crash into each other,
the engine shed, or points which are
set against them. When that happens,
you lose the train and all its passen-
gers. The train will be replaced by
another from the engine shed either
one of yours or, if there isn’t one left, a
‘Demon’.

Demon trains are not under your
control - they run around changing
points, crashing into you and generally
getting in the way.

See overleaf for listings ►

track squares in all. The CONN array and
some others - are initialised by the
INITPCS procedure.

The BRD map specifies which type of
track square is located in each position.
The track type will fit into the lower four bits
(nibble) of a BRD byte. If a square holds
points then the lower nibble specifies how
the points are currently set and the upper
nibble specifies the alternative direction.
When the points are changed by the
CHGPTS procedure - the nibbles are
swapped

The TX, TY, TD, TP and TS arrays specify
the location and status (Demon, stationary,
direction etc) of each train. The ST array
gives the locations of the five stations. The
P array specifies how many passengers
each train is carrying for each destination
and the array holds the highest eight
scores.

After the declarations and initialisations,
the program enters three nested loops -
for each game, for each sheet and to move
the trains by one square.

The TRAINS procedure moves all the
trains by one square. When a train moves
to a new square, it makes a note of the type
of track in the new square, puts a ‘Train’
byte at that position on the BRD map and
draws a train pointing in the appropriate
direction (the DRAW procedure). To move
off, it replaces the track on the map and
uses the OUT routine and the CONN array
to see where the exits from the square are.
It knows from which direction it entered the
square and thus that the other one is the
exit The TRAINS procedure also worries
about checking the keyboard, changing
the points, picking up and dropping pas-
sengers and stopping and starting trains.

The TRACK procedure generates a new
track layout at the start of each game, as
described above The STATIONS and
TOWNS procedures of course draw the
stations and towns

The program starts a game by putting in
the forests and generating a layout for the
track. The track starts at the engine shed
and at each end of every station in turn.
(The engine shed is drawn only when the
track has been laid.) The track grows from
its free end until it hits something. If it hits
another piece of track at a reasonable
angle (and away from the engine shed) it
will form points and is considered com-
plete. If it hits anything else, it will back up
by an amount depending on how much it
has hit recently.

When the track is complete, the engine
shed, stations, towns and passengers are
drawn. No check is made that the points
are put in to join the various sections of
track together, so it might not be possible
to get to every station. If you can’t, press
SHIFT while the track, stations or towns are
being drawn.

A new track is drawn only at the start of
the game - not for each sheet.

At the start of the game, you have four
engines in the engine shed. On the first
sheet you get a few minutes to practise

l

_L

92

ACORN USER JANUARY 1984

GAMES

driving after the first engine has come out
and before the second one emerges.

You have a maximum of two trains on the
track on the first sheet. On subsequent
sheets you get up to four (more than four
makes the whole game run very slowly).
Whenever you crash a train, another
emerges from the shed - if you haven’t got
any more, the new one is a Demon. You’re
not allowed to run a rail service with fewer
than two trains - the game would then be
over.

You can control only one train at a time.
Select the train by pressing ‘Z’ this will
make each train in turn ‘light up’ (appear
on a white background). You can stop the
selected train by pressing but if it was
already stopped it will start moving in the
opposite direction. After about 20 sec-
onds, a stationary train sounds its whistle
and starts by itself.

If you press the 7’ key the selected train
will turn red (on a white background a
Demon is red on a green background).
This means that just before the train
reaches that next set of points it will
change them - and turn back to blue on a
white background. The points also change
whenever a train leaves them - they make
a sort of ‘kerchunk’ sound so you can tell
when it's happened.

Demon trains are not under your control.
They run around, changing direction when-
ever they hit anything and changing any
points they meet.

The object of the game is to deliver
passengers. At the start of each sheet
there are passengers waiting at each sta-
tion - you can see them standing on the
platform. Every passenger wants to go
somewhere else and pays his fare only
when he gets there.

About ten seconds after you stop a train
in a station all the passengers on the
platform will get on and those who want to
alight there will get off and pay their fare

The top left corner of the screen shows
the destinations of the passengers on the
selected train. The number in the first
coach shows the number of passengers to
be delivered to station A, the number in the
second coach shows how many for station
B and so on. A coach can hold only 99
passengers so in later sheets some may
be left waiting at the station you’ll have to
go back for them.

When all the passengers have been
delivered, you go onto the next sheet. At
the start of each sheet you’re given a
certain amount of coal. You have to deliver
all the passengers before the coal runs out.
If it does, the game is over.

Your score is shown on the top line of the
screen. Each passenger you deliver gives
you £10. At the end of each sheet, the
amount of unused coal is added and £500
subtracted for each train you crashed. You
get a bonus train as your score exceeds
certain values.

At the end of the game, the ten best
scores are shown and if yours is among
them you can write your name.

ACORN USER JANUARY 1984

93

could ther^
none mor

Microvitec Cub 452 is by far the

largest selling colour display for the

BBC microcomputer:-

WHY?

* It is the only colour monitor
approved and recommended by
both Acorn and the BBC.

* 95% of schools have chosen Cub
452 under the Department of
Industry Micros in schools
scheme.

* Cub is designed and manufactured
in the U.K.

COLOUR DISPLAYS

See your local dealer or contact:
Microvitec Sales Dept.

Futures Way, Bolling Road, Bradford,
West Yorkshire BD4 7TU.

Telephone (0274) 390011. Telex 517717

The name to look for

Ry|SgH

1

■

■

94

ACORN USER JANUARY 1984

^:EM *♦**♦**♦*******.*****.*.*.**.* ***.*.
REM * *

REM * THE TRAIN GAME *

REM * *

REM * (C> Peter Balch, 1983 *

REM * *

REM *■*#**--*■** -*■*-*# *■ *♦********.*.*.*.*.¥..¥.

10
20
30
40
50
60
70
30
90
100
ns — "

110 VDU 31,26,9,148,106,32,104,60,71.'
6 , 10 , 1 48 , 111 , 63 , 111 , 63 , 1 35

120 PRINT"- around the track without cr
ashing. You will crash if you. hit poi
nts that are againstyou, another tr air o
r the Engine Shed. M

GOSUB650

PR I NT : PR I NT "Try to drive your

Tr ai

130 PRINT: PRINT" You can control

one

ain at a time. You can stop or r ever :
£? a t or change thopoir.ts you are aproaci
i ng"

140 PR I NT : PR INT M The object of the qame
is to make money. Each passenger you del
i yer to thei^ destination pays a far

e. But they must get there before your
coal runs out.";

150 A= INKEY (6000)

160 REM==- ==== = = = ===== = =

170 GOSUB 650

180 PRINT" If there are passengers wait
station, you will see them s
the platform. When you stop
station, they will get onto

"The top line shows the
the passengers on the

"mean •
to B

#--14-0-21-4-30"

14 passengers to
21 to C, 4 to D

passengers will
stops at their d

ing at a
tanding on
at the
your train.

190 PRINT: PRINT
destinations of
selected train. "

200 PRINT: PRINT
210 PRINT: PRINT
station A, none
and 30 to E. "

220 PR I NT 5 PR I NT" These
Qst off when the train
estinat ion. "

230 GOSUB 1330
240 A=INKEY (6000)

250 REM================

260 GOSUB 650

270 PRINT" In later sheets, you will fi
nd there is a limit to the number of pas
sengers in each coach - so you may have
to make several trips. "

280 PRINT: PR I NT "When there are no more
P assen 9 er ^ to deliver, you will get

a new, more difficult, sheet and m

aybe a bonus Train. "

^-90 F*R I NT: PR I NT "Each Sheet gives you m
ore Trains - up to a maximum of 4. Th
e Trains come out of the Engine Shed and
if you. haven't enough for the Sheet,
they will come outas Demons. A Demon Tr
ain is not under your control.^";

300 A= INKEY (6000)

310 REM================

320 GOSUB 650

j c0 PRINT"The Game is over when you ha
ve only one Train left or have run out o
f Coal or Money. "

340 PRINT: PRINT"Somet i mes , the track m
ay have stations you can't reach. If t
hat happens, you won't be able to clear
the Sheet . "

350 PRINT: PRINT"To get a new track, ho
Id down the SHIFT key while the program
is making the tract or is putting ir

the towns. "

360 PRINT: PRINT" (There just wasn't eno
ugh room to get the program always to
make connected tracks. > "

370 A= I NKEY ( 6000 )

330 GOSUB 650

390 REM================

400 PRINT "Here are the di x ferent kinds
of Tr ains: " ' ' " " ;

41S VDU 148, 106,32, 104,60, 135: PRINT "

420 VDU 143,111,63,111,63,135

4c-0 PRINT" One of your Trains" ' ' "

I* .

440 VDU 157, 148: PR I NT" _ : : VDU 156-

PRINT ' “

450 VDU 1 57 , 1 4 3 : F R I NT " 2 pc w " ; : VDU 156,
135: PRINT" The Selected Traift" ' " " •

460 VDU 157, 148: PR I NT "4 + ' " ; ; VD’J 156*
PRINT""

470 VDU 157, 145: PR I NT" _ " ; : VDU 156,

1c 5: PRINT" T h 0 Selected T rair w .. 11"

?

480 VDU 1 57 , 1 45 : PR I NT " 2 pz w " ; : VDU 156.
135: PRINT" change the next points"'" "

490 VDU 1 57 , 1 45 : PR I NT ” + ' + * " ; : VDU 156,

135s PRINT" just as i t reaches them

•« .

500 VDU 145,106,32,104,60,135
510 PRINT" A Demon Train, not unde

r " ' " " ;

520 VDU 145,111,63,111,63,135
530 PRINT" your control";

540 A= I NKEY (6000)

550 REM================

560 GOSUB 650

570 PR I NT "Control Keys -"

530 PRINT : PRINT" Z Select Train

* Stop Train o
stationary t

? Change next
just before

590 PR I NT: PR I NT"
r start a
rain in reverse"

600 PRINT: PRINT"
set of points
hitting them"

610 GOSUB 780

620 PRINT : F’RINT"Loadi r.g TRAINS2"
630 CHAIN " TRAINS2"

640 REM================

650 MODE 7

continued on page 97

ACORN USER JANUARY 1984

95

Microware presents

the latest news -

on BBC.

N.B. 40/80 Format Switch — call for information

ZL DISK DRIVES

Microware, the authorised
dealers for BBC, ACT and IBM are
still making news. The new ZL range of
disk drive subsystems is the best available
— yet compare the prices. The new Double Density

Disk Controller is
another first from this
company, which con-
tinues to write the
headlines. ’Phone
today for details/

\ 1 * ^ —

Type

Capacity

Capacity

Power

No. of Files

Dual unit

Acorn DFS

with DDFS Supply

Acorn DFS

Price

ZL 241 BH

200K

400K

62

£199-00

ZL 242 BH V

400K

800K

124

£375-00

ZL241H Expandable

200K

400K

V

62

£229-00

ZL 242 H \/

400K

800K

V

124

£395-00

•ZL281BH

400K

800K

62

£250-00

•ZL282BH V

800K

l-6Mb

124

£445-00

•ZL281H Expandable

400K

800K

V

62

£290-00

*ZL 282 H V

800K

l-6Mb

V

124

£490-00

j All prices quoted exclude VAT. All cables included in price

*40/80 Format switch and Manual available

No. of sides per drive

r

No power supply, must be
iwercd by BBC

Range identifier -ZL 241 BH Half height unit

/ //// ' No. of drives per subsystem

No. of tracks per
side (4=40, 8 = 80)

PRINTERS

Epson FX 80 £375.00

Epson RX80 £275.00

Epson RXFT .... £320.00
Epson FX 100 ...£425.00

Star 80 £257.25

Star 100 £313.95

Shinwa CP80 ....£257.25
Juki 6100 £399.00

1 ■ 4 ‘ ,

lllll

MONITORS

12" Green Screen

Sanyo £99.00

BMC £99.00

Amdex £135.00

14" Colour

Microvitec

Luxor

High Resolution

,£257.00

£450.00

(D Microware

Showroom: 637 Holloway Rd London N.19
Telephone 01-272 6398/6237. Telex 297598

A

AMES

continued from page 95

660 VDU 31,9,1, 146
tn™ PRINT "PPPPPPPPPPPPPPPppp"

.3“

690 PRINT "The TRAIN Game"

,53?®34 DU 31 ’ 26 ’ 3 ’ 146 >1 0 6,31,8,4,141,146
710 PRINT"The TRAIN Game"

T1 72 ® ^ 31 ^26,4, 146, 10 6 , 3 i ,9,5, 146,53,
-■1 , -7, j, 106,31 ,9,6, 146,53, 133
730 PRINT” (c)Peter Balch"

75 S prin?"- 26 ’ 6 ’ 146 ! 106 : 3 ?! 9 ’^

760 RETURN ‘ FRINT

770 REM=========== === __

780 REM TRACK

III . VDU 23 * 224 .0,0,68, 255, 68,0,0,0
800 VDU 23,225,8,28,8,8,8,28 88
810 VDU 23 , 226 ,3,3,4, 24 , 24 32 19^

820 VDU 23,227,192 192,32:24^4 4’^
830 VDU 23,228,5,78,122,160 0 000’"

8 840 ™ 23, 229,8, 48:24,; 6 ,32?i?2^ fl 2

850 VDU 23,230,1,6,3.4 4 1^ a o
860 VDU 23,231,8,6, 12, 4, 4 , tTi

III VDU 23 * 232 *0,0, 0,5, 6, 90 , 96 , 1 60
B 880 VDU 23 ’ 233 ’ 128,96, 192,32, l^^B,

890 VDU 23,234,0,0,0,160,96,90 6 5
900 VDU 23 , 235 , 208 , 50 , 46 i 5,0,0 | 0 ! 0
10 VDU 23,236,208,50,46,5,0,0.0 0

930 REM=S=~I= 0 ’ f: 0 :^ 0 ’ 96 ’ 90 ’ 6 ’ 5
940 REM LOCOMOTIVES

j2 950 VDU 23 .238,8, 112,230,247,253,30,30
960 VDU 23,239,28,20 o 8 70 a- ao

„ ™ 0 ™ 23,241,64, 71 , 70, 2 5S, 2=5,

„ 990 VDU 22 ,243,2, 22 6 , 98 , 255 , 255 ,102,0,

1000 VDU 23,244,25,54,30,143,95,120,120

1010 VDU 23,245,34,62,62,62,20 ig
3 1020 VDU 23,246,152, 108,

1030 REM========= ====== _ == __ ===

1040 REM PASSENGERS
1050 VDU 23,253,0,24,0,60,24,24,24,0

1070 REM HOUSE

1080 VDU 23,254,0,0,0,24,60,126 ^55 755
_1090 VDU 23,255, 1 26, 1 26 , 1 26 [ 1 26 II26 *0^0

1100 PROCSWOP

1110 REM========= ===== _________

1120 REM TREES, STATIONS, ETC

Jl40 VDU 23 1 226 * 0 * 224^240 1 248 J 252^254^2

^1150 VDU 23,227,255,255,255,255,255,255
5II60 VDU 23,228,0,255,255,255,255,255,2

0 1170 VDU 23,229,4,14, 31 ,63,127,255,255,

1180 VDU 23,230.0,0,0,129,195,231.255 0
255 , '0 VDU 2 3 ’ 231 ’ 32 . 1 12,248,252,254,255,
^1200 VDU 23,232,255,255,255,255,255,255

1210 VDU 23, 233, 0,8, 42, 23, 73 , 47 eg g
1220 PROCSWOP ,

1230 RETURN

1240 REM========== =======

1250 DEF PROCSWOP

Sw °P the cha r set with the
1 a 70 REM user routine space.

1280 FOR I-&C00 TO &CFF

1290 J=?l ; ? 1= I 22567 I 7256= J

1300 NEXT
1310 ENDF’ROC

1320 REM========== ===== _

1330 REM EFFECTS
1340 *FX9,3
1350 *FX10,3

1360 ENVELOPE 1,1, 0,0, 0 , 1 j 0 A . _
128,-128, 105, 0: REM cAuFF ’ ’ ’ ’

1370 ENVELOPE 2,1, 96,0,0, 100,l00,i 00<
1-7, 1,-1, 1 26 , 0: REM POINTS

1380 ENVELOPE 3,3, 120,0,0, 20,20,20, 9
V ’ 1 » *, 126,0: REM PASSENGERS

4 ' 4 ’ “’°’ 0 ' 32 --'-

1400 RETURN

TRA?uc 1 |. TyPe ' S and save “ '^mediately as
TRAINS . It prints the screen instructions and sets up

r iOU l 9ame Shapes usin 9 VDU commands. Listing 2
hw H«t 98 °"" ards) ,s ,he second part which is chained in
by listing 1. Save both listings separately.

tra^k f n u y: *** in ,is,in9 1 and save « “> disc as
,k Cha " 9e line 630 as This automatlcal-

lL#». u the V h ° ® 9ame d ° wn in memory from A 1900
(defau't page for DFS) to AEOO when it is run. Do not run

overwritten 0 "" 1 b °* h " aV6 bee " S3Ved ’ as m emory will be

?4F00 MOLD ! MRLIN M ” " 00 : N - ! M*T APE ! MPAGE=

continued on page 98

ACORN USER JANUARY 1984

97

V

continued from page 97

10 DIM BRD 1 239 , CONN (12) , TX (4' TY(4>

t D c4., t p„,, ts „ ) , ST(5 . 2)i p; 4j

20 GO3UB2630

-•0 FOR I = 1 T03 : SC ( I ) =— i 003 : NEX T
40 $NM=STRING* (12B,CHR$13>

50 REPEAT
60 *F X 9 , 3
70 #FX 10,3

80 FORX=0TO1239: BRD?X=0: NEXT
90 MODE 1
100 VDU 23;8202;0;0;0. 12

: BG=1 NS=4: p ‘ / - =0: BT=2500: MAXP=10

—r * 2 ® VDU 19, 0. 2; 0; 19, 1,1.0. 19,2, 4; 0; 1?

- t 13 ?r P TM CSTATI0NS: PROCINITPCS: PROCTRA
CK: IF INKEY- 1 THEN S0
140

150 TC=0: TT=0: MX=MX-(MX<4) : sy =1 . Ty

(MAxp<20a) = c-/.=600+maxp

d™ x Ti\ T0 M%! TS(N, ~ is next
BG ir T HEN B ? 7 r 6+1 1 IF BG=1 ° R BG = 3 ° P

180 VDU 19,0, B6; 0;

190 PROC TOWNS: IF INKEY-1 THEN 80
200 REPEAT

230 PROCTRA I NS
240 TX=TX-(TXO0>

250 REPEAT: UNTIL TIME: 60: TIME=0
260 UNTIL TT+NS.2 OR PS=0 OR C‘'< 1
270 REM. . . .

=B?f? X = Py - + C-/--TC: IF X>BT THEN NS=NS+1:BT

290 FOR N=1 TO MX

300 IF TS (NX >— 1 THEN GOSUB l-?30
310 N3=NS- (TS (N) >0)

320 NEXT

330 IF PS=0 AND X>0 AND NS>1 THEN P7=X
: GOTO 140 A

340

350 REPEAT : UNTIL TIMEX300
360 MQDE7
370 3=0

380 GOSUB 2630
390 *FX21 , 0

400 FOR 11=7 JO 1 STEP -1

T T 4 1 cr / t T 1 1 " IF X>SC(II > T HEN 1 = 1 1 + 1 ; J=

‘ ( 1 > _sc '■ *FNNM ( I ) =t FNNM ( J >

AB ( 27 , 1 +8 J ; SC a 8 ’ 1 +S > 5 1 5 " " 5 * FNNM ( 1 > * ' 1
430 NEXT

440 PRINT TAB(0, 18) "FARES : ' " ; PX ' "COAL
;CX "LOST TC '' "PROFIT- ’ *• - y

450 SC(J)=X ’

460 IF J THEN PRINT TAB (27 , J+8) ; X; TAB (

B, J+8) ; J; CHRS133; : FOR 1=0 TO 14: A*=GET
*<FNNM<J>+I>=A* ! PRINT At;: 1^1-99*^
$=CHR$ 13) : NEXT ELSE A=GET <A

470 UNTIL FALSE

480

490

500 DEF PROCTRA I MS

510 FOR N=1 TO M/C

520 IF TSCN}<>-1 THEM 540

. IF TX<>0 0R 7FNBD (EX , EY) =255 THEN

1040 ELSE T7.= (M7.=2>*99-8: TX(N>=EX- TY(M
)=EY: TP ( N ) = 1 : TD(N)=3: FOR 1=1 TO 5 . £

s-llzV rx x I; ? QSLJB 1170: IF NS>0 then N

TT ~ T T+1: TS (N) =0: GOSUB 2530: £;
St TS (M) =-256

.540 X=TX (N) :D=TD(N) s Y=T Y ( N )

550 IF 7FMBDCX,Y)<>255 THEM 1020

560 IF TS (N) <0 THEM 8^0

570

580 J=INKEY(0): IF J-0 THEM 6^0

OCDRA W !ax? =90 THEN AX=G-/ - : GDSUB U40: PR
600 IF JO-58 THEN 620

iTS(SX) AND 63) =0 THEN TS(SX)=T
ELSE Ta (SX) = <TS (SX) AND 128! OF:

28

OR (TS (N) AND

610 IF

S (SX) +30
64

620 IF J=47 THEN TS (SX > =TS ( SX) + 1 '

630 PROCDRAW(SX)

640

650 IF (TS (N) AND 63) =0
64) THEN 820

660 TS (N) =TS (N> — 1

ip 6 I?o I Tl™ ( = > AND 63: IF 1=1 THEN SOUND

680 IF 1015 OR TP (NX >17 THEN 1 030
690 SOUND 17,3,1,12
700 I=INT( 1 . 6+Y/B. 7) : K=0
710 X=ST (1,1): Y=ST (1,2)

720 FOR J=l TO 5
730 1 1 =FNBD ( X , Y- 1 ) — 1 + J ■

740 K=K+ (A>0>

750 P ( N , J ) =P ( N , J ) + A
760 a=P(N,J)-99: IF A: 0

(N , J ) =99: ?I I=A ELSE ^11=0
770 NEXT

PX=PX+ 1 0*P ( N , I ) ; PS=PS— P ( N . I ) :

A=?I I

THEM K=K+9: P

780
, I )=0
790
800
810
820
830
840

MD 128

P(N

IF K<0 THEM GOSUB 2570
GOSUB 1170: GOTO 1030

GOSUB 1230
SOUND 16,1,4,5
IF TS (N) AMD 64 THEN
D=8-FNQUT (TPCN) )

TS(N)=TS(N) A

B50 D=FNOUT C TP ( N ) )

860 IF T7. >0 THEN 1040

: GOTO 1 ^" 1 THEN PR ° CCHGP TS<X,Y, T P(N),
880 :

890 X 1 =X : X=X+DX: Y1=Y: Y=Y+DY

900 P1=?FNBD(X,Y) : IF Rl>17 AND t S (n>

IZ^ND T 127 PR0CCHGPTS( X,Y,P1): TS(N)=T

910 TX (N) =X : TY (N) =Y: TD(N'=D

920 IF FNOUT ( 2FNBD ( X , Y ) ) >— 1 THEN 1020

930 IF PI >15 THEN PROCCHGPTS ( X , Y , PI )

continued on page 101

98

ACORN USER JANUARY 1984

ORLANDO’S BACK!

IIIIIHINIIIIHIIIIIIIIIIIIIIIIIlIHlWHIIIIIHinilinillllHIIIIIIIIHIIIIIIIHIHIHIIIIIIIIIIIIIIIinllllllNIIIimillUlHlllimillllllllHIIIinilllllllHIHIimiUlHMIllllllUMmilUll

ZALAGA

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIUIIIIIIIIIII^

Aardvark Software, creators of tbe Ultimate Atom

Games, bring you NOW

THE ULTIMATE BBC SPACE-GAME

Seated at your computer, streams of multi-coloured aliens swirl past your laser-base
into formation. The first squadron appears harmless, but later waves will avenge
the deaths of their comrades with increasing ferocity. To combat the swooping bomb
dropping meanies, you may try to link up a pair of laser-bases and double your fire
power! Your progress through successive phases will be rewarded by challenge
stages, where large bonuses may be earned. The game builds up to a dizzying
crescendo of high speed motion where instant reflexes and pure technique are your
only hope of survival. . .

One or two player game • Keyboard or joystick • Sound on or off • Escape facility
• Works on all OS’s and Tubes • Ten name Hi-score table • Mode S full colour
graphics • Continuous rolling twinkling stars • Multiple missiles • Full screen
action • Attractively packaged in a collectable library case • High quality
cassette • Full instructions • For BBC model B or A + 3SK •

Send cheques/P. O.s for £6.90 to
Aardvark Software,

100 Ardleigh Green Road,

HORNCHURCH, Essex.

FRAK coming soon . . .

ACORN USER JANUARY 1984

99

THE AFFORDABLE TABLET

£125

+VAT

FOR

if OUR BBC
MICRO

iDAPTORS for other home computers to follow

BRITISH MICRO

k HEGOTRON GROUP COMPANY

ritish Micro, Penfold Works, Imperial Way, Watford, Herts. WD2 4YY Tel: Watford (0923) 48222/43956

Qty

Item

Item

Pnce

Item
Pnce
inc VAT

Totals

Grafpad complete

£125.00

£143.75

C.A.D. Program

£18.00

£20.70

IMPORTANT"! ~ D ,

Tick Below Postage & Packing

£5.00

BBC MODEL 2

SINCLAIR SPECTRUM
COMMODORE 64

Total

To: British Micro, Unit Q2, Penfold Works, Imperial Way,
Watford, Herts WD2 4YY

I enclose cheque PO Order £

Please charge my A CCESS/BAR CL AYCARD/ AMERICAN EXPRESS/ DINERS CLUB

Card No LI — I — I I I | I 1 I I I I I I I

Signarure
Name
Address

Tel No

IF S7.=N THEN

NEXT

continued from page 98

940 IF TS (N ) <0 THEN 1000
950 GOSUB 1190: TS(N )=-1
GOSUB 1140
960 TC=TC+500
970 T‘/.= 0 : TT=TT — 1
980 FOR J = 1 TO 5: PS=PS~P(N J)

990 GOTO 1040 '

1000 TX (N) =X 1 : TV (N ) =Y 1
1010 TD (N) = 8 -TD (N)

1020 I=FNBD(TX(N> ,TY(N) ): TP<N>-*>I- ^r =

' ■ 1

1030 PROCDRAW (N)

1040 NEXT: ENDPROC
1050
1060

1070 DEF PROCCHGPTS(X,Y,P) : if p < 2 55 th
EN 7FNED< X V,.p DI „ ^ „„„ ™

L I 9 , , 1 7 , 129+ (P=l 7 ) 3 i v Y ^ 3 +P/ia 1-7

12 * z IF P>17 THEN SOUND IB Si ->5
1080 ENDPROC ’

1090

1100 DEF PROCDRAW (N): VDU 17,2: IF gv-w
VDU E 17^ U 17,131: IF TS(N) AND 128 THEN
1110 IF TS (N ) <0 THEN VDU 17 l

8: 1 <N) ’ TY (N> - ™ <"» +238 > 12

1130

1140 1 = 0 ; REPEAT: 1 = 1 + 1 : S7.=S7+1- tf qv
>M7. THEN S 7 .= l ‘ 1- IF S/>

1150 UNTIL TS (S%> >=0 OR I>M%

1160 IF I >M 7 . THEN ND=M V

T , ?™.^V a 3 0 jf 7 -2:"> lF "> •-! TO S: PR, N
T , .PIS/., I), .NEXT: PRINT- - , RETUR

1180

11^0 SOUND 16,4,6,255: VDU 19,0,15-0-.
FORJ=1TO900: NEXT : VDU 19,0,B6:0- "

-RNn 0 *" RNO(1000) * VDU5: FOR j=l Tn 2: A
-RND(-o): FOR 1=1 TO 150 STEP 3 - GCOL -
RND(3): MOVE X1*32+RND<I)-I/2,104-Y1*34

PR,NT "-" : — =N6?r 4 ^;;r-

1210 RETURN
1220

1230 7FNBD < TX <N> , TY <N > ) =TP (N'

1240 IF TP (NX 15 THEN VDU 17 3 +i T Xfw,

TyIn^T^NX + 223: ELSE PROCCH0F TS(ix(N);
1250 RETURN

1260 DEF FNBD(X,Y)=BRD+X+Y*40-40
1^70 DEF FNNM ( I ) =NM+ 1*1 6-16
1280
1290

1300 DEF PROCTRACK

!Im p* E n-f V TO ¥ i so ’’ ! BOSUB 1470

1330

AX-ST (11,1): AY=ST (

1340

FOR XX=AX— 5 TO AX-1

1350

?FNBD(XX,AY)=0

1360

NEXT

1370

FOR XX=AX TO AX+4

1380

VDU 31, XX, AY, 224

1390

NEXT

1400

SX=AX— 1: SY=AY : SD=r

1410

FOR XX=AX+5 TO AX+9

GOSUB 1470

1420 2FNBD ( X X , A Y ) =0
1430 NEXT

1450 NEXT A><+5: SY=AY: SD=5: G0SUB 1470
1460 ENDPROC
1470

1480 X=SX : Y=SY : D=SD: WF;ONG=0
1490 DX=0: DY=0
1500 F'=RND (12)

1510 IF FNOUT (P) =- 1 THEN 1500
1520 IF INKEY-1 THEN ENDPROC
1530 SOUND 17,-12,1 1

1540 ?FNBD(X,Y)=P: VDU 17,3 31 v Y
P: X=X+DX : Y=Y+DY ’ , -1 , X , Y , ++3+

1550 IF X >39 OR X<1 OR Y>30 OR Y<2 THEN

1560 BXY=?FNBD ( X , Y> : IF PXY=0 OR ARSfRv
-X) +ABS (EY-Y) <12 THEN 1620 S<EX

1570 IF B X Y > 1 0 THEN 1630
1580 I=D: P=1

1590 IF FNOUT (P) =— 1 THEN 1610

( _ IF PNOUT(BXY) >-l THEN 2FNBD

(X, Y)-BXY*16+P: VDU 17,129,31 X V 'vjt+p
17,128: RETURN ’ ’ ’ Y t -^+F ,

Jfi® ?Z I: P=P+1: IF p <13 THEN 1590
»= SSra iS™'” ™ EN **I^ONG=WRONG+ ' WRONG >0
1630 WR0NG^WR0NG+2

D-3*DY) -4 = ° =8 ~ D: DY=IN TtD/3)-l: DX=INT(

Jf 5 ® ^ X+DX: Y=Y+DY: P=?FNBD(X,Y)

16o0 SOUND 17,1,200,99

1670 IF F*=0 OR P > 1 6 THEN 1470

P == FNOUT (P) : VDU 31,X,Y,32: 7FNBD ( X

Ivll ^8-D : ^ I<=WR0NG/2 ™ EN 1650

1710 GOTO 1500

1720

1730

1740 DEF FNOUT (P>

j 1 750 P=P AND 15: IF P> 12 OR P=0 THEN =-

^1760 C 1 = I NT ( CONN ( P ) / 1 0 ) : C2=C0NN (P> -Cl*

J 77 ® 1F 81=8-0 THEN C>=C2: GOTO 1800
1790 i^! 02-8-0 THEN D=C1: GDT0 1800

1810 BY=INT(D/3)_1: DX=INT(D-3*DY)-4
1820
1830

1840 DEF PROCINITPCS
1850 :

1860 RESTORE 1900
1870 FOR 1=1 TO 12
1880 READ CONN ( I )

1890 NEXT

g 1900 DATA 53,17,26,8,23,16,27,18,56,7,3

1910 ENDPROC

1920

1930

1940 DEF F'ROCST ATI ONS
19^0 DATA 8,3,27,6,10,16,8,27,27 70
1960 GOSUB 2510

continued on page 1 14

ACORN USER JANUARY 1983

101

RING FOR SAMPLE PRINTOUT, FULL SPECIFICATIONS & LATEST PRICES
WE WILL NOT BE BEATEN ON THE PRICE OF STAR OR JUKI PRINTERS

JUKI 6100

DAISYWHEEL PRINTER

STAR GEMINI 10X

UPRATED

STAR

DP510

One Year Warranty

1 8 CPS : BiDirectional & Logic Seeking
1 0, 1 2, 1 5 & Proportional Spacing
Wordstar Compatible
2K Buffer : 13 Inch Platen
Underline : Backspace f Lots more
Centronics Interface Standard
RS 232 Interface £54.00 + VAT Extra
Tractor Feed £99.00 + VAT Extra

JUKI 6100 £369.00 + £55.35 = £424.35

BBC/ORIC or DRAGON Package
JUKI 6100 + Cable +

24HR Delivery & VAT £440.00

STAR DP8480

RS232 INTERFACE STANDARD
7x9 Character Matrix (7 Needle Head)

80 CPS Bidirectional & logic seeking
5, 6,8.5, 10,12, 17cpi
40,48,68,80,96,1 32 cpI
Friction & Tractor Feed: 10 Inch Platen
Hi-Res option with Software £10.00/15.00
DP8480 with RS232 Int. £208.70 +

£31 .30 VAT = £240.00

Package prices for BBC/Newbrain/Epson HX20
DP8480 + Cable + Hi-Res + 24Hr Delivery &
VAT = £250.00

SERIAL PRINTER CABLES

BBC to 25 way D type £9.50

EPSON HX20 to 25 way D type £9.50

NEWBRAINto25 way Dtype £12.00

25 way D type to 25 way D type £15.00

One Year Warranty
T rue Descenders 9x9 Matrix
120 CPS Bidirectional & Logic seeking
5, 6, 8.5, 1 0, 1 2, 1 7 cpi 40,48,68,80,96, 1 36 cpI
Italics, Emphasized, Double strike, Supers Sub Scripts
Hi-Resolution & Block Graphics
Continuous Underline, Backspace
Downloadable Character Set
Friction or T ractor Feed
Internal Buffer Expandable to 4K
Centronics Int. Std. RS232 Available

GEMINI 10X (10 CARRIAGE)

£300 including VAT

STAR DP515 ( 15 " carriage) £280 Inc VAT.

PACKAGE FOR BBC/DRAGON/ORIC
GEMINI 10X + CABLE + DELIVERY
BBC SCREEN DUMP SOFTWARE & VAT
£315 including VAT

RING FOR LATEST PRICING

ACORN ELECTRON £199.00

BBC Micro Model B £399.00

BBC Micro Model B with Disc Int £469.00

Large range of Accessories including Disc Drives, Printers,
Monitors always in stock

Printer Cables

BBC to 36 Way Centronics Type Connector £15.00

Dragon to 36 Way Centronics Type Connector £1 5.00

Oric to 36 Way Centronics Type Connector £15.00

Torch to 36 Way Centronics Type Connector £20.00

FullA>B Upgrade Kit £58.00
Ram Upgrade Kit £23.00

Blank C15/C30 Cassettes Ten for £4.50 ANY MIX
Send SAE for Full Price List

VAT INCLUDED WHERE APPLICABLE
PHONE/CREDIT CARD ORDERS WELCOME

Postage 50p per order or as stated
24 HR Securicor Delivery for Printers/Disk Drives £8.00

P I F

Dept (AU), 78 BRIGHTON RD

Microcomputers 5°£gg „„„ 2m

(0903) 213900

102

ACORN USER JANUARY 1984

. s *,' i, »,

GAMES

MACHINE CODE GRAPHICS

FOR FAST graphical displays in games,
you not only need the speed of machine
code, but also to put your characters
directly into screen memory. Although this
is termed ‘bad programming' it does give
the necessary speed, detail and colour in
the most efficient way (and all the good
games do it). The ‘official’ way to do it with
user-defined characters provides only two
colours (foreground and background) and
you need to mess about with MOVE and
VDU 5 commands. Directly addressing
screen memory allows for any size of
character with up to 16 different colours
(counting the eight flashing variations)
within that character. To use this method
we first need to know how the screen is laid
out in memory, hence figure 1 shows the
top left hand of mode 2. (Mode 2 because
of its advanced colour facilities.)

Figure 1 is actually offset by &3000,
meaning that location 0 is really located at
&3000 0 = &3000 and location 1 297 is

located at &3000 + 1297 = &3511. Look-
ing at any location, eg 1263, the location to
the right is 1271 , a difference of eight, and
this is true of any location (except of course
the extreme right hand column). Listing 1 is
a simple FOR . . . NEXT loop which puts a

If moving shapes
around quickly has
you stumped, then
Nick Wilkinson
has some answers

white block into each screen location and
at certain times a delay factor is intro-
duced, to enhance the layout shown in
figure 1 .

The screen memory of mode 2 starts al
&3000 and runs to &7FFF (a massive 20k).
In mode 2 there are 16 different colours,
represented in binary from 0000 to 1111,
so each colour is represented by four
binary digits. Each screen location is re-
presented by one byte and holds the
necessary information for two colour
codes, meaning there are two pixels in on6
screen location. Table 1 shows the deci-
mal, hexadecimal and binary representa-
tions of the 16 available colours.

We now know how screen memory
(mode 2) is laid out, and that you can get
two colour codes in one location, giving the
resolution of 1 60 by 256. We now need to

know how the colour is organised in the
bytes of screen memory.

Figure 2 shows a possible byte value
and this seems to suggest the two colours
represented are yellow and magenta: how-
ever, the two colours in figure 2 are in fact
blue and white. Resorting to binary nota-
tion will help us understand how the col-
ours are organised. The binary values of
blue and white are 0100 and 01 1 1 respec-
tively, and careful examination results in
figure 3a. Bit 3 of blue goes to bit 7 of the
result, bit 2 to bit 5, bit 1 to bit 3 and bit 0 to
bit 1 . For white, bit 3 goes to bit 6 of the
result, bit 2 to bit 4, bit 1 to bit 2 and bit 0 to
bit 0. The diagram is easier to understand
so I suggest you remember it that way! We
can check this organisation with the exam-
ple from listing 1, where we put a white
block into each location, with the white
block being represented by &3F. Figure 3b
shows the calculation.

Having dealt with how the screen and
colours are organised, we can design
multi-coloured characters. Let’s start with a
simple space invader. To take maximum
advantage of the resolution we will need to
design two invaders, because there are
two pixels in one location. When designing

0

8

16

24

608

616

624

632

1

9

17

25

-»

609

617

625

633

2

10

18

26

-♦

610

618

626

634

3

11

19

27

611

619

627

635

4

12

20

28

612

620

628

636

5

13

21

29

-

613

621

629

637

6

14

22

614

622

630

638

7

15

23

623

631

639

640

648

656

-

1256

1264

1272

641

649

657

1257

1265

1273

642

650

658

1258

1266

1274

643

651

659

1259

1267

1275

644

652

660

1260

1268

1276

645

653

661

—

1261

1269

1277

646

654

662

1262

1270

1278

647

655

663

1263

1271

1279

1280

1288

1296

1896

1904

1912

1281

1289

1297

1897

1905

1913

Figure 1. Top left corner of mode 2 screen memory

Colour

Decimal

Binary

Hex

Black

0

0000

0

Red

1

0001

1

Green

2

0010

2

Yellow

3

0011

3

Blue

4

0100

4

Magenta

5

0101

5

Cyan

6

0110

6

White

7

0111

7

Flashing black/white

8

1000

8

Flashing red/cyan

9

1001

9

Flashing green/magenta

10

1010

A

Flashing yellow/blue

11

1011

B

Flashing blue/yellow

12

1100

C

Flashing magenta/green

13

1101

D

Flashing cyan/red

14

1110

E

Flashing white/black

Tablet.

15

1111

F

Possible byte
value"*

0

0

1

1

0

1

0

1

&35

Figure 2. Possible byte value

ACORN USER JANUARY 1984

103

Another devastating new game from the fabulous Postern range.

The colourful Postern range is available on a variety of micros. Wtite
quantity of each game required in the boxes provided.

Please

I send
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. Fire Hawks
1 Snake Pit
I Shadowfax

Spectrum C64/Vic 20 BBC B'

£6.95

£6.95

£6.95

£6.95

Siege
3 Deep Space £7.95

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Name _
Address -

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OR PHONE: Northleach (04516) 666 Telex 43269 Prestel 37745
^Postern is always on the look out for any new games you might have developed.

POSTERN

the characters it becomes helpful to have a
border around it, so no matter what direc-
tion it moves in we won’t need to worry
about erasing any bits left behind.

The invaders are shown in figures 4a
and b.

Once designed, the invaders have to be
translated into numerical values. We could
translate each block, but that would be
time-consuming and boring. Another way
is to create a look-up table of all the colour
combinations in figure 4. Translation would
then be a simple task of comparing col-
ours. Table 2 shows all the different combi-
nations from figure 4.

Now we have the relevant data, all we
need to do is whizz through a couple of
FOR . . . NEXT loops, read the data, and
plonk it into memory. Listing 2 does just
that (there is only one set of data as we’re
not bothered about moving it around yet).
Line 40 starts a repeat loop and waits for
an input of four hex digits (no need to use
the & prefix). Line 70 calls the dump
procedure with parameters declaring
height, width, data line number, and mem-
ory location.

The height in this case is eight, the width
five, the data line number 190 and the
address is the evaluation of eight plus your
input, ie hex value. Line 80 keeps the
program going until you press either break
or escape keys. Lines 90 to 180 read the
data and put it row by row into the appro-
priate memory locations. The crucial line
here is line 160 where it says S%=S%+1.
This relies on the statement that the differ-
ence between two locations (one on top of
the other) is one, which of course it is not,
eg beneath &3007 is &3280 certainly not
a difference of one. The program is fine
only if that boundary gap isn’t crossed. For
example, an input of &4000 is fine, but
&4005 is not. If we could produce a
formula to work out the relevant memory
location from an X and Y co-ordinate, we
wouldn’t need to worry about the boundary
gaps.

Looking back at figure 1 , we see that it is
laid out in blocks of eight, and the differ-
ence between each block corner is 640.
From this the Y contribution is (Y DIV
8)*640 - this specifies which block of eight
the Y co-ordinate is in and Y MOD 8
indicates the vertical position in that block.
The X contribution is simply (X DIV 2)*8, as
each location has two pixels and each
horizontal co-ordinate is eight away from
the next. So our formula for obtaining a
specific memory location from an X and Y
co-ordinate is:

&3000 + (Y DIV 8)*640 + Y MOD 8 + (X
DIV 2)*8

where &3000 is the offset.

Not forgetting that our aim is machine
code graphics, we shall have to translate
that formula into machine code, which
looks horrendous. One way around all
those MODs and DIVs could be to write our
own integer multiplication and division rou-

GREEN

RED

RED

GREEN

0010

0001

0001

0010

\ /

00001001 = 809

00000110 = 806

BLACK

BLACK

GREEN

GREEN

0000

0000

0010

0010

\ x

00000000 = 800

00001100 = 800

GREEN

BLACK

BLACK

GREEN

0010

0000

0000

0010

00001000 = 808 00000100 = 804

Table 2. Data values from figure 4

ACORN USER JANUARY 1984

105

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*

1 ^ 0 REM Nick Wilkinson program 1
20REM Acorn User January 1984
30REM Program 1 puts white block

50*TV255 tO m ° de2 SCreBn locatiDns -
60MODE2

70VDU23; 8202; 0; 0; 0;

80FOR IX=0 to 1300
90 I %?&3000=&3F
1 00PR I NT TAB ( 1 , 3 ) ; I %

110i p I X< 27 OR IX >620 AND IX<667 PRflC
DELAY (50)

120NEXT 17.

1 30PRINT ETC " : END

140DEF PROCDELAY ( XX)

150T I ME=0: REPEAT UNTIL TIME‘>X'/
160ENDPROC

Listing 1. Puts white blocks on screen

1^0 REM Nick Wilkinson program 2
20 REM Acorn User January 1984
'0 REM Key in hex number . eg . 4000
40 REM to plot invader
50 M0DE2

60 REPEAT INPUT BASE*

70 B ASE X=EVAL ( " & " +B ASE* )

80 IF BASEXC 8/3000 OR BASEX >8/7FFF THEN 100
90 PROCDUMP (8,5, 190, BASEX)

100 UNTIL FALSE
1 1 0 DEFPROCDUMP ( PX , QX , RX , SX )

120 RESTORE RX
130 FOR IX =0 TO PX — 1
140 FOR JX =0 TO OX -1
150 READ T$

160 ? (SX+JX* 8 ) =EVAL (

170 NEXT JX
180 SX=SX +1
190 NEXT IX
200 ENDPROC

210 DATA 00 , 00 , 00 ? b 0 ( 00

220 DATA04,04,00,0B,08
230 DAT A04 , 0C , 0C , 0C , 08
240 DAT A04 , 09 , 0C , 06 , 08
250 DATA00,0C,0C, 00,00
260 DATA00, 08, 00,04,00
270 DATA04,03,00,04,08
280 DAT A00 , 00 , 00 , 00 f 00
Listing 2.

10 REM
20 REM
30 REM
40 REM

Nick Wilkinson program 4
Acorn User January 1984
Cursor keys display and move
wall of multicoloured invaders

n , w A * W i CT Li X ft

u0 PROCASSEMBLE : PROCCODE I N • MPD^
60 VDU23; 8202; 0; 0; 0; s *FX4 1
ora YX=0: REPEAT FX=0s REPEAT

90 IF INKEY— 26
X*/.< 0 THEN X7.=0

100 IF INKEY-58 THEN
YV<0 THEN Y7.=0

110 IF INKEY-42 THEN
Y:0184 THEN Y%=184

IF

THEN

X7.=X7.-2:F7.= 1: IF
Y7.=Y7.-2:F/:=1: IF
Y7.=Y7.+2:F7.= 1: IF

120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
490
500
510
520
530
540
550
560
570
580
590
600
610
620
630
640
650
660
670
680
690

UNTIL FX-1 : CALLi nvade: UNTIL
DEFPROCASSEMBLE
FORI7.=0TD1 : F'X=S/C02
C0PTIX*2
-invade STX8/79
STY8/75 : LDA#7 : STAS/7 A
. nexrow LDA8/79: STAS/74
LDA# 1 0 : ADCS/75 : STA8/75
LDA# 1 0 : ST AS/7B

. nexcol LDA#10: ADCS/74: STAS/74
LDA8/75: SBC#8: STAS/75
JSRdump : DEC8/7B: BNEnexcol
DECS/7A: BNEnexrow
RTS

. dump LDA#SA: STAS/76 : LDA#6: STAS'- 7

JSRqetX: LDX#0

-rep JSRgetY: LDY#0

LDAS/77: STAS/78

-again LDAS/0CA4,X

STA (S/72) , Y : INX

DECS/78 : BEQnex tr ow

TYA: ADC#8: TAY

JMF'agai n

. nextrow DECS/76: BEQret
INCS/75: JMF’rep
-ret RTS

. get X LDA#0: STAS/71
LDA8/74: AND#S/FE
ASLA: ROLS/71
ASLA: ROLS/71
STAS/70: LDA#S/30
CLC: ADCS/71 : STAS/71
RTS

-getY LDA#0: STAS/72
LDAS/75: AND#S/F8
LSRA : LSRA : ST AS/73
LSRA: LSRA: PHF'

CLC: ADCS/73: ADCS/71 : STAS/73

PLF': RORS/72

LDAS/75: AND#S/7

CLC: ADCS/72: ADCS/70: STA8/72

LDA#0 : ADCS/73 : STAS/77

RTS

] NEXT: ENDPROC
DEFF'ROCCODEIN
FORIX=0TO59

READZ*: IX?S/CA4=EVAL ( "S/" + Z^ ) :NEXT
ENDPROC

DAT A00 ,00,00,30,00,00
DAT A00 ,00,00,00,00,00
DAT A00 ,33,33, 33 ,33,00
DATA00 , 23 ,03,33,13,00
DAT A00, 23, 0F,0F, 13,00
DAT A00 , 23 , 4F , 8F ,13, 00
DATA00 .23,03,03,13,00
DAT A00 , 33 ,33,33,33.00
DATA')' 7 ) ,00,00.30,00,00
OATA00 ,00,00,00,00,00

FALSE

Listing 4. Code can be relocated by altering
P% in line 110 and call at line 90. To change
location of data, alter D70 in line 440 and
0D70 in line 160

page 109 ►

ACORN USER JANUARY 1984

107

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108

ACORN USER JANUARY 1984

tines, but they would be too slow for
graphics. Another way would be to search
through the Beeb’s ROM to find the said
routines, but they probably wouldn’t be any
faster. So it seems we’ll have to translate it
ourselves. Well, first note that:

(Y DIV 8) *640 = (Y DIV 8)*8*80

(figure 5 explains why this is helpful).

Figure 5 shows that (Y DIV 8)*8 is the
same as setting the first three bits to zero.
This is achieved by logically ANDing with
&F8, so all that’s left to do is multiply by 80
to achieve (Y DIV 8)*640. We could add it
to itself 79 times, but that would be too
slow. Alternatively, we could multiply it by
64, then by 16 as:

Y*80 = Y*(16 + 64) = Y*16 4- Y*64

(You’ll see why this is helpful in a minute).
But before that, just a little footnote: to
multiply by two in binary, just shift left one
place, putting a zero in at bit 0. To divide
by two, shift right one place, this time
putting a zero in at bit 7.

To multiply by 64, we could shift left six
times, but that would result in vital informa-
tion falling off the end. An easier way would
be to shift right twice divide by four (no
need to worry about bits falling off the end
for we have already masked off the first
three bits), then store this as the high byte
of the result - which is the equivalent of
multiplying by 256, hence achieving a
multiplication of 64 for (Y/4)*256 = Y*64.
So far the program looks like this:

LDA # 0
STA YLB
STA YHB
TYA

AND # & F8
LSR A
LSR A
STA YHB

This section gives us (Y DIV 8)*8*64 and
has to be added to (Y DIV 8)*8*16 to
achieve (Y DIV 8)*640. Still in the accumu-
lator meanwhile is (Y DIV 8)*8*64, so all we
have to do is shift it right twice because

((Y DIV 8)*8*64)/4 = (Y DIV 8)*8*16.

Remembering back to the beginning we
cleared the first three bits, then shifted
right twice, leaving only the first bit clear.
Well now we want to shift right twice again.
The first shift will be OK, but the second
shift will cause bit zero (possibly contain-
ing vital information) to fall off the end.
However, if we use that very useful LSR
operation again, bit zero will be put into the
carry. A way around this is shown below.

LSR A
LSR A

So far we have stored (Y DIV 8)*8*64, and
in the accumulator at the moment is (Y DIV
8)*8*16. Needless to say, we add the two
together with:

n p

ADC YHB
STA YHB

Now we can worry about that loss bit with:
PLP

ROR YLB

So, stored as a two-byte number in YHB
and YLB, we have (Y DIV 8)*640. All that’s
left of the Y calculation is Y MOD 8, and
from figure 6 it can be seen that Y MOD 8 is
equivalent to Y AND #7. The next section
does this and adds the offset of &3000 to
complete our Y contribution:

TYA

AND#7

CLC

ADC YLB
STA YLB
LDA#&30
ADC YHB
STA YHB

The X contribution can be tackled in a
similar manner. First (X DIV 2)*8 = (X DIV
2)*2*4. Figure 7 shows that (X DIV 2)*2 is
equivalent to masking off the first bit -
done by ANDing with &FE. This done, we
now need to multiply it by four, which can
be done by two shift lefts. There are, of

X (205)

X DIV2 (102)

(X DIV2)*2 (204)

&FE

X AND#&FE
Figure 7.

&70]
&71 j

[x contribution + offset of &3000

i

&72]

&73j

^True address

&74

X value

&75

Y value

&76

Height

&77

Width (permanent)

&78

Width counter

Figure 8.

course, complications, eg if X was 205
then X AND #&FE = 204, followed by two
shift lefts will cause information to be lost
(but with ASL, bit 7 pops into the carry).
Because of this complication we will need
to represent the answer over two bytes.

LDA #0
STA XLB
STA XHB
TXA

AND#&FE
STA XLB
ASL XLB
ROL XHB
ASL XLB
ROL XHB

The section above completes the X contri-
bution, so to complete the whole calcula-
tion we only have to add the two with:

CLC

LDA XLB
ADC YLB
STA RLB
LDA XHB
ADC YHB
STA RHB
RTS

ACORN USER JANUARY 1984

109

10
20
30
40
50
60
70
80
90
100
1 10
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
490
500
510
520
530
540
550
560
570
580
590
600
610
620
630
640
650
660
670

KEM Nick Wilkinson program 3
REM Acorn User January 1984
REM Use cursor keys to move around
REM screen and plot X Y numbers
PROCASSEMBLE: CLS: X7.=0: Y7.=0
VDU23; 8202; 0; 0; 0; :*FX4, 1
REPEAT

IF INKEY-26 THEN X7.=X7.-1:IF X7.<0 THEN X7.=0
IF INKEY 122 THEN X7.=X7.+ 1 : IF X7.M59 THEN XV = 159
IF INKEY-58 THEN Y‘/.=Y7.+ 1 : I F Y7.>255 THEN Y7.=255
-f V 42 THEN Y7.=Y7.-1: IF Y7.<0 THEN Y7.=0

n^;^^^ IV8,#640+<VX M0D8 >*< X * DIV2, *8: T1=TIME

PRINT TAB (1,3) " X = •' ; X7. y = • Y7 ••

PRINT " BASICS." ;~TLC7.;", TIME=";T1 ’

PRINT'" M/CODE=8t”5~!RLB ANDS/FFFF : " , TIME="-T'’

UNTILFALSE ’ lnt ’ rZ

DEF PROCASSEMBLE
YLB=?,70: XLB=?v.72:RLB=?v74
VHB=?,71 : XHB=?<73: RHB=?.75
DIM CODE 70
FOR I7.=0 TO 1:P7.=C0DE
COPT 1 7. #2

LDA#0 \ CLEAR STORAGE SPACE,

STA YLB \ BY PUTTING ZERO INTO,

ST A YHB \ LOCATIONS TO BE USED.’

TYA \ RUT Y VALUE INTO ACCUMULATOR t H fn

hND#^F8 \ LOGICALLY AND TO PRODUCE (Y DIV8)*B.

| L fc" n DIVIDE BY 2 TWICE, ACHEIVING DIVISION BY 4

CTO Cum x THEN ST0RE AS HIGH BYTE THUS MULTIPLY BY 256
-.A YHB \ NET ACHEI VEMENT IS <Y DIV8)*8*64.

l~cc ? ^ DIVIDE BY 2 TWICE THEREFORE DIVIDE BY 4

LSR A \ ACHEIVING (Y DIV8)*8*16

F'HP \ SAVE CARRY FLAG.

CLC \ CLEAR CARRY (IN CASE IT WAS SET'

ADC YHB \ ADD (Y DIVB) *8-464 TO (Y DIV8>*6*16

PLP YHB \ cCro, U , CING <Y DIV8) * 0 * 80 .THEN STORE ’rESULT.

FLP \ RECALL SAVED CARRY AND,

TYA YLB \ put A C E ul, T , ,1° L ° W BYTE C0MPLET ING <Y DIV8>*640.

p tt7 X ™ * VALUE INTO ACCUMULATOR THEN,

AND# \ LOGICALLY AND TO PRODUCE Y MOD 8.

CLC \ PREPARE FOR ADDITION,

ADC YLB \ ADD Y MODS TO LOW BYTE OF (Y DIV8>*640

LDA#?^0 \ Ann ^ T ° RE AS FINAL Y CONTRIBUTION LOW BYTE.

LDA#../ _.0 \ ADD HIGH BYTE OF &3000 (?<30) TO

ADC YHB \ HIGH BYTE OF Y CONTRIBUTION AND,’
oTA YHB \ STORE AS FINAL Y CONTRIBUTION.

LDA#0 \ CLEAR,

STA XLB \ STORAGE,

STA XHB \ SPACE.

T™ N PUT X VALUE INTO ACCUMULATOR THEN

AND#J?,FE \ LOGICALLY AND TO PRODUCE (X DIV'?)*'?

STA XLB \ STORE (X DIV2>*2

Rrn yur , pnTflTc*" V (X DIV2 >* 2 BY 2 EQUALING (X DIV2>*4.

^ R0TATE POSSIBLE OVERFLOW INTO HIGH BYTE.

ROL xHFt \ pnTaTc* Y <X DIV2) * 4 BY 2 EQUALING (X DIV2>*8.

ROL XHB \ ROTATE POSSIBLE OVERFLOW INTO HIGH BYTE
\ PREPARE TO ADD X TO Y.

LDA XLB \ LOAD X LOW BYTE,

ADC YLB \ ADD TO Y LOW BYTE,

STA RLB \ STORE AS RESULT LOW BYTE.

LDA XHB \ LOAD X HIGH BYTE,

ADC YHB \ ADD TO Y HIGH BYTE,

STA RHB \ STORE AS RESULT HIGH BYTE
RTS \ FINITO BENITO'

INEXT 17.

endproc Listing 3. Machine code can be relocated by
simply altering P% in line 180

Listing 3 shows the end product. It enables
you to use the cursor keys to alter the
values of X and Y, and compare the
accuracy and speed of Basic and machine
code. The timings however mean very little
as the TIME function is only in hundredths
of a second. I can assure you though that
the machine code version is considerably
faster.

Looking back through the program
again carefully, can reveal some space
saving and statements that aren’t needed.
See if you can sort out how to save space.
To give you a pointer: there is no need to
store the result in a new location because it
could be stored in either XLB/XHB or
YLB/YHB as they aren’t needed again. This
has saved two bytes. Space • and time
saving are both important if you want
maximum speed from the least amount of
memory.

The routine is now complete, and it only
remains to provide a screen controller
program. Listing 4 is just that and has been
written for maximum speed. This is why the
calculation routine has been split into two
sections. We only need to calculate the X
contribution plus offset once, the Y contri-
bution is then added and stored as the
answer which points to a screen location.
The data is loaded and stored and then the
answer is incremented by eight, thus it
points to the next location, ie immediately
to the right. This continues until the row is
finished. The Y value is then incremented
and the new Y contribution is added to the
X contribution plus offset and stored as the
answer, etc.

In listing 4 (which takes up 12 zero-page
locations - figure 8) you use the cursor
keys to manipulate the position of a whole
wall of multi-coloured invaders The pro-
gram uses Basic only for key detection (so
as not to bog you down with code) and is
written in such a way that the code is only
called if you press one or more of the
cursor keys, which reduces flicker to virtu-
ally zero.

The first machine code subroutine
whizzes through a couple of loops dump-
ing each invader individually. The following
pseudo-Basic program will hopefully clari-
fy the technique.

REPEAT

REPEAT

UNTIL KEY PRESS
FOR | = 1 TO 7
FOR J = 1 TO 10
DUMP INVADER (I, J)

NEXT J. NEXT I
UNTIL FALSE

where DUMP INVADER (I, J) means dump
a single invader at position I, J. The only
thing that isn't global about listing 4 is the

address of the data. This can be rectified
with the following routine (where DATED is
the address of the data):

.CHANGEADD

LDA # (DATAD MOD 256)

STA again 4- 1

LDA # (DATAD DIV 256)

STA again + 2
RTS

This effectively changes the program by
storing a different value in the program
area. Although this is also considered bad
technique, it is in fact the fastest and most
efficient way of enabling different charac-
ters to be drawn.

Hopefully you will now be able to write
your own machine code graphic simula-
tions and games, so good luck!

110

ACORN USER JANUARY 1984

WE STOCK THE BBC MICRO. ELECTRON. DRAGON 32,

The following titles are available for both the ^

BBC Micro and Electron: Killer Gorilla £7.95/

Moonraider £7. 95/Bandits at 3 o'clock £6.95/

Croaker £7. 95/Felix in the Factory £7.95/

Felix and the Fruit Monsters £7. 95/Chess £7.95/
Escape from Moonbase Alpha £7. 95/Draw £9.95/
Swoop £7.95. BBC only (at present):

L Martian Attack £7. 95/Demon Decorator £6.95/

I Asteroid Storm £7. 95/Laser Command £7.95/
■Galactic Commander £7. 95/Time Trek £7.95/

'Danger! UXB £7.95/Cowboy Shootout £6.95/Wall £5 95/|
Alien Swirl £6. 95/Labyrinths of LaCoshe £7.95/ Jk
Adventure £7. 95/Caveman Adventure £6.95/

Filer £9.95/Beebmon £7. 95/Barrage £7.95/

Chemistry £6. 95/World Geography £6.95/ ySVyJ
Where? £6 95/Junior Maths Pack £6 95/^Cjjitfh)rj
Constellation £6. 95/Physics £6.95

ORIC AND SPECTRUM.

All cassettes are fully guaranteed and
contain two recordings.

All prices inclusive of VAT.

Mail Order Please add 55p per order
to cover P Er P.

COMMODORE 64.

WE’RE EXPANDING!

oom: Mail order:

vood House Dept. VH

Street 8/8a Regent Street

scar Chapel Allerton

LS7 2AA Leeds LS7 4PE

532) 458800 Tel: (0532) 683186/696343

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VERSIONS AVAILABLE FOR BBC

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MICROAGE - LONDON’S PREMIER

More an experience than a computer shop.

• A library of books that give
specific or general
information.

The Acorn Expert

If you are thinking of buying a BBC
Micro or the amazing new Electron,
then come to Microage and benefit
from our experience. We have
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paper and cables. Free carriage.
Normal price £1,843. Save £244 .
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• A complete range of games,
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BBC Machines

Model A, 32K RAM and
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Disk Drives

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disk drive (100K) £235

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disk drive (200K) £389

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Verbatim single sided

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Some of our books

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Programming for BBC £8.95

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and FORTH all at £7.50

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Monitors

14" RGB Microvitec
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(As used in BBC
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dramatically reduced to
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to

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12" Zenith High res.
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The new model at

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BNC Cable

£4.95

112

ACORN USER JANUARY 1984

HOME COMPUTER DEALER

If you are interested in joining the home computer revolution or adding to your
present system, then come along to Microage. In a relaxed atmosphere you can
browse through the best selection of computer products and peripherals in
London. Helpful assistants who really know about the products offer unbiased
advice to help you choose a personal computer or get the best out of your own.

,9l S ,P9PHTCARD

5 / discount

Space Station,
you’re always in command. Sit
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There’s room for your printer,
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• Business computers too!

Printers

Seikosha AP - 80 A now
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Epson FX - 80
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All printers include
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Printer Cable

10" listing paper, 2000

sheets

Miscellany

RH Electronics colour
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BBC Compatible
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Official joystick per pair
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£189

£215

£430

£460

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• A complete range of
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Computer Users Data File

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All items subject to availability.

Institutional and
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Microage offer very competitive
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POSTAGE RATES

Small items such as Ribbon, books
and software:- 1 item £1.00, 2 items
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BY COURIER TO YOUR
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mkCRDflGE ELECTRCiniCS

135 HALE LANE EDGWARE MIDDLESEX HA8 9QP
TEL: 01 959 7119 TELEX 881 3241

ACORN USER JANUARY 1984

113

GAMES

continued from page 101

1970 :

1980 VDU 17,2

ll+RND(9??23^3l 0 R MS : (i y? U 31 ,24 + RND ( 1 1 , ,

2000 EX=29: EY=14

EY+lf ^FNBD7v X v) 1 -.ZL EX r tp : F0R V=E Y'2 TO

2020 RE^SRE’^f 51 NEXT: NEXT

2030 FOR 1=1 JO 5

2050 5du°i 7*3*3l' T X = 64 + l T ( 1 ’ 2) =Y

: 2 St™ XX ' X ™ ***= ™ «.XX,»M,227

28" 8 Sex? R XX - X " T ° » 3 ‘ VDU 31,«x,y-i, 2

2090 VDU 17,1,31 X+l , Y— 2 229
2100 VDO 31.X+2 V-n> ’£,

F0R A=40 T ° 1 00 STEP 25 ^ + 7 Y ~ 2 ’ 23 *

2 1*232, 4^°^ 18,0,3 ’ 5 ’ 25 ’ 4 ’ X *32+A;1056-Y*3

2130 'next

2140 FOR XX=X— 5 TO X+9
2150 ?FNBD(XX,Y)=17
2160 NEXT

2170 FOR XX=X TO X+4
2180 FOR YY=Y-2 TO Y+l
2190 ?FNBD(XX,YY)=17
2200 NEXT
2210 NEXT
2220 NEXT
2230 GOSUB 2510
2240 ENDPROC
2250
2260

2270 DEF PROCTOWNS
2280 GOSOB 2530
2290 PS=0

2300 FOR 1 1 = 1 to 5
2ol0 X=ST (11,1); Y=ST(Il,->)

FOR 1=1 TO 40

IF = y IT*’ ~ 3: yy =V+RND(7) -5
2400 ’ ° R XX>39 0R Y Y<2 OR YY>3
J=FNBD (XX , YY)

VDin^f 88 J?40 >0 THEN 2400

> j -• 1 , X X , Y Y , 254 ,17, 3, 31, XX,

2320
2330
2340
0 THEN
2350
2360
2370
YY+1 ,255

23B0

2390

2400

2410

2420

2430

2440

2450

2460

2470 NEXT
2480 ENDPROC

?J=255: J?40=255

NEXT 1NKEY ~ 1 THEN ENDPR °C
FOR XX=X TO X+4

J=1-RND(MAXP>* (XXOX+II-i)
?FNBD ( XX , Y— 1 ) =j l *

PS=PS+J
NEXT

GOSUB 2570

2490
2500

•§£

vSu l; r 7 ;; 2 b then ™ else

2550 NEXT: RETURN
2560

2570 REM PASSENGERS
o=o„ F ° R A=36 T0 100 STEP 20
Y*32; 253^4 18 ’ 3 ’ 2 * 5 > 25 , 4 , X*32+A; 1020+36-
2600 NEXT
2610 RETURN

is! 3i -’.^'3osub 2650

2650 VDU 141,134

-a™ RR ^ NT " The TRfiIN Game"

+670 RETURN

cS ? 2 ivs S“” ?„ 4 ™r t s ^,?sT

niove it down one linp if anw i “HEAK • will

if R '"" mb * r «• °™» three

z- switches control between trains
/-changes pojnts ahead of train under control

stops tram. Pressing it twice will reverse direction

LiP'ss

hope you like it.' S 3 ^ d,fferent and or '9'nal game. We

14

ACORN USER JANUARY 1984

Add

to your BBC

micro in

five minutes

— ARIES- 620 —

Features

★ Adds 20K of useable HAM to
your BBC Micro

★ Run programs up to 28K long in
ANY SCREEN MODE

★ Extra memory can be used
directly from BASIC I and II,
VIEW 1.4, FORTH, LISP, and
many other existing programs

★ ARIES- B20 is compatible with
all correctly written BBC Micro
software, on cassette, disc,
sideways ROM or cartridge

★ Don't be deceived: this product
is unique - no other expansion
unit has these capabilities

★ Complete compatibility -ARIES-
B20 uses only documented
MOS facilities

★ Fitted in 5 minutes using only a
screwdriver

★ Simply plugs in inside the case

★ No soldering or cutting

★ (Unlike some add-on products)
will cause no damage to your

BBC Micro - can be
removed at any time
Incredibly simple to
use

Patent applied for

★ Designed in Cambridge by
BBC Micro experts

★ Top quality manufacture

★ Unquestionably the most
important add-on ever
produced for the BBC Micro

★ Top software houses are racing
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★ 1 year guarantee.

★ Available mail-order only

★ Official purchase orders
accepted from bona-fide
educational establishments, all
other trade cash- with- order

Price £99.95 including post,
packing and VAT
If not completely satisfied with
your purchase, we will refund
your money in full providing you
return the ARIES- B20 in good
condition in its original
packaging within 14 days

Machine requirements:

★ BBC Micro model B

★ MOS 1.2 or later

★ Plugs into CPU socket and 1
sideways ROM socket

Also available IEEE-488 interface.
Coming soon: Compatible ROM
expansion board.

How to Order:

Send cheque or postal order
made payable to: Cambridge
Computer Consultants Ltd and
forward to:

Cambridge Computer
Consultants Ltd, FREEPOST,
Cambridge CB1 1BR
Telephone Cambridge
0223- 210677

Please send me (Qty) ARIES- B20(s) at £99.95 (incl. p.p. & VAT

I enclose a cheque/ postal order made payable to

Cambridge Computer Consultants Ltd for £

Signed

I Name (block letters)

* Address

Post Code

■ s Cambridge Computer Consultants Ltd, FREEPOST Cambridge CB1 1BR
I < Telephone Cambridge 0223-210677

WHERE TO PUT
MACHINE CODE

MANY people are still unclear about how to
store machine code after assembly on the
BBC micro and the Electron. There are six
main ways: four of them use areas above
the Basic program that assembles the
machine code: the other two use areas
below Basic.

Putting the code above Basic

P%^ TOP + 1000 TOP gives the next
free location above the Basic text, so by
adding 1000 to it we leave space for any
dynamic variables used in the program,
and assemble the code above that.

LOMEM = LOMEM + 250 LOMEM con-
trols the position of the first dynamic vari-
able. By setting it 250 above its default
value (which is TOP) we reserve 250 bytes
for our machine code program. It is impor-
tant, however, to execute this statement
before any reference to a dynamic
variable.

DIM P% 250 This reserves the next 250
bytes in the free area above the Basic text
and any dynamic variables used, and
automatically sets P% equal to the address
of the first location in this reserved block.

HIMEM = HIMEM 250 This reserves the
‘top’ 250 bytes below screen memory. It
should be the first statement in the pro-
gram and there should be no mode
changes from a mode requiring less mem-
ory to a mode requiring more (eg, Mode 4
to Mode 0).

Putting the code below Basic

PAGE = PAGE 4 256 This instruction
must be performed before loading the
Basic program. You can then set
P%= PAGE -256 within that program.

Ian Birnbaum looks at
storage options above
and below Basic and
considers advanced use
of the OPT command

Using memory below &E00 The loca-
tions &900 to &AFF are used by the cas-
sette system with OPENUP, OPENIN and
OPENOUT commands, but not when load-
ing and saving programs. These are also
used by the RS423 port, and &9C0 to &9FF
are additionally used by the speech syn-
thesis system. Thus, &900 to &AFF may be
safe areas in certain circumstances, espe-
cially when using discs.

&C00 to &CFF are reserved for user-
defined graphics, so if you do not intend to
use these in a particular case your ma-
chine code can be stored there.

&D01 to &DFF are safe locations only if
you are not using discs and do not have
sideways ROMs (eg, BCPL) fitted. With
BCPL, &D90 onwards may be unreliable
&D00 itself is always unsafe with series 1
OS and above (and this includes the Elec-
tron), since 64 is always deposited there
on break.

Most other locations should not general-
ly be used for the storage of machine code
programs, unless you are prepared to take
great care.

As a general rule, DIM P% 250 is to be
preferred, except when stand-alone ma-
chine code programs are required. In this
case, using &C00 onwards is probably

best (or &900 onwards if more than 256
bytes of storage are required)

Advanced use of OPT

You may want to use your BBC micro (or
even your Electron) as a development
machine to produce machine code pro-
grams which you want to put on EPROMs

To do this you will need an EPROM
programmer add-on. But this won’t be
enough. You will want your programs on
EPROM to occupy memory locations
above &8000, the usual ROM and EPROM
locations. However, there is usually no
RAM in this area, so how do you write code
which uses the correct addresses 9

The answer is to use OPT4 to OPT7
These are the equivalents of OPTO to
OPT3, except that you now have two as-
sembly location variables at your disposal
P% is still the program counter, but 0% is
now also available: 0% indicates where
the assembled machine code will physical-
ly go in your computer. Hence you can set
P% above &8000 with 0% at a usual RAM
location.

As an example, type in listing 1 and run
it. You should obtain the display in figure .1
Note that all addresses refer to &9000
onwards, the initial value of P%, and in
particular that BACK is &9002.

Nevertheless, running the one-liner in
figure 2 will prove that the machine code is
physically stored in START onwards,
START being an address just above the
Basic text, and certainly in RAM. Thus we
can store the code in RAM while referring
throughout the address locations in
ROM — precisely what we require for our
EPROM development work'

>F0RI7.=0 TO 8 s

PR I NT^ST ART? 1 7. : NE X T

A5

70

69

5

C9

9000

0PT7

10NUM=St70: DIM START 50
20P%=&9000 : 07.=START
30C0PT7

40LDA NUM

C8

9000

A5 70

LDA NUM

50. BACK

90

9002

. BACK

60ADC #5

FA

60

9002

69 05

ADC #5

70CMP #200

80BCC BACK

9004

C9 C8

CMP #200

90RTS : 1

Figure 2. Machine code

9006

90 FA

BCC BACK

stored in RAM

9008

60

RTS

Listing 1. 0% indicates where the assem-

Figure 1 .

Display from listing 1

bled machine code will physically go

116

ACORN USER JANUARY 1964

Draw with the BBC micro

and show the true potential of your machine

Fill shapes in one of 23 colours (Mode I)

Draw points, lines, rectangles, ellipses and circles

Smooth curves

Wire frame diagrams

Hidden line removal

Draw in perspective

Measure scaled distances

Ekta sketch lines, Half tone facility

Mirror images

Repeat images, SS, enlarged, reduced, stretched

Actual colour displayed

Store up to 1 0 ellipses or circles in memory

Redraw any one of these at cursor position

Change any actual colour for one of 8 others

Clear screen, load screen, save screen

Print characters or numbers at any pixel point

Error messages for incorrect input

Fully comprehensive manual

356 496 • j~j •••

designs

This programme has been purpose designed by professional Graphic Designers
for simplicity and ease of use, and is undoubtedly the most versatile drawing
programme on the market at this time. There is no need to input any numerical
data, as all judgements are made visually. The BBC Micro is the finest drawing
machine in its price range. Find out what it can do.

The A.B. Designs drawing programme costs only £35 for over 70 functions (Model B). New AB2 Program, available on disc (price £60.50)
and cassette (price £50.50). When ordering send Cheque/PO and include 50p for P&P. Please include phone no. with all correspondence.
For further information send SAE and phone no. to A.B. Designs, 81 Sutton Common Road, Sutton, Surrey. 01-644 6643 (closed all day
Thursday).

Keeping in touch with the
changing methods in
education is a must for
any progressive
teacher. And that
means knowing about
computers. And that
means knowing about
Acom Computers -
the leading
manufacturer of
computers in use in
today.

Acorn Education Exhibition gives you a unique
, to get right up to date with ail the latest
developments in hardware, software peripherals and services. Over 60
leading suppliers of Acorn related products will be there, as well as Acorn
themselves.

This is an ideal opportunity to listen to informative talks, try out
systems, watch demonstrations and collect literature away from the
interruptions of students.

The Central Hall, Westminster is in Victoria Street, almost opposite
Westminster Abbey, one minute from Parliament Square.

Buses: 11, 24, 29, 70, 76 and 88
Mainline: Waterloo, Charing X and Victoria
Underground: St. James Park, Victoria
Parking: NCP, Abingdon Street.

Admission is by ticket only and is limited to educationalists over 18.
Every educational establishment in the country is being mailed with
tickets, but if you would like more just write to: Ticket Office,
Computer Marketplace (Exhibitions) Ltd., 20, Orange Street, London
WC2H 7ED, stating your requirements.

ACORN
w EDUCATION
EXHIBITION

Central Hall, Westminster
London S.W.1.

Wednesday January 25th 10a.m.-6 p.m.
Thursday January 26th 10a.m.-8 p.m.
Friday January 27th 10 a.m.-5 p.m.

to Computer Marketplace (Exhibitions) Ltd,

20 Orange Street, London WC2H 7ED

Please send me tickets for the

ACORN EDUCATION EXHIBITION.

NAME

ESTABLISHMENT

ADDRESS

POSTCODE

ACORN USER JANUARY 1984

117

FINANCIAL GAMES

Three great games, enjoyed by thousands of BBC
owners throughout the world'

Join them - don't delay order today.

GREAT BRITAIN LIMITED - £5.95

Ever thought you could run the country better?

Here is your chance!

As Prime Minister and Chancellor (of the party of your choice), you
have to guide the country through its social and economic ills for 5
years, then put yourself up for re-election.

"Great Britain Ltd is easily as exciting and certainly more satisfying
than any game of space invaders" - Micro User.

"A must for all budding politicians " - Computer Answers.

"Thoroughly enjoyable and worthwile decision making activity and as
such can be thoroughly recommended" - Educational Computing.

"Highly enjoyable" - Acorn User.

"A dream for Megalomaniacs" - Micro Update.

INHERITANCE — £5.95

Have you ever wondered what you'd do if you came into some
money? Would you be able to invest it and watch it grow, or maybe
start a small business and become a millionaire. With Inheritance you
have the chance to find out.

"A great game, really two games for the price of one" — Micro User.

"Well presented and good value for money" - Personal Computer

World.

WORLD TRAVEL GAME -£6.95

A game for 1 or 2 players. Rush around the world collecting souvenirs.

Keep your head and try to avoid Hijacks, Strikes, Thieves, Cash
shortages, Bankruptcies, Bad Weather etc.

"Exciting, competitive and even educational - not to be missed"

ALL THREE GAMES NOW AVAILABLE IN A SPECIAL PRESENTATION

PACK - AN IDEAL GIFT

£17.95 complete

A vailable from your local computer shop or by 24hr despatch from:-

SIMOIM W. HESSEL SOFTWARE

(Dept.clL 15 Lytham Court, Sunninghill, Berkshire.

Telephone: Ascot 25179

Please add 30p P&P on orders for single games - UNLIMITED GUARANTEE.

Dealers - Reserve your Christmas stocks NOW.

Schools and Education Authorities - special deals on multiple orders.

1 18 ACORN USER JANUARY 1984

SCHOOLS

Charles Bake recounts his exploits with Roman togas and five-line programs

DATA IN ROME

IN APRIL’S Acorn User I described how
two programs, Animal and Explore , were
used with a class of vertically-grouped
lower junior children. But apart from using
the available software I also wanted to
show the children how a micro could be an
extremely useful tool and in particular how
it could sort information rapidly. I looked at
the Factfile program supplied as part of the
MEP software package for schools but did
not think it would suit my purposes. It was
not a particularly powerful handler of data

- 10 headings would allow for just 25
children per file and I wanted to expand my
files to include the children in other classes

- and, more important, it reinforced the
'black box’ image of the micro. I wanted to
find a way of showing what the computer
was up to which would allow the children to
discover that if inaccurate data were
stored or if a query were not precise then
the resulting answer might well not be what
was wanted.

Fortunately, I had not only read an article
about data handling by Frank Gregory in
the Micro Primer reader, but had also
heard him speak on the subject. Briefly, for
those who do not know of his work, he
describes how he used a six-line Basic
program with middle school children to
classify data - in this case data about an
imaginary crime. In addition to this, he had
also used punched cards to demonstrate
how children could sort data and so check
the answers given by the computer. His
work was the inspiration I was looking for.
His article explores the classroom possi-
bilities of data handling in far greater
depth.

This seemed an exciting idea, but I was
unsure how eight and nine-year-old chil-
dren would cope, so I decided to limit my
experiment to the children in my class
rather than start amassing data about the

Figure 1. Celia’s fact card. Each child picked a
Roman name and decided on their character-
istics. Hence, Celia had brown hair, drove a
chariot, had a scar and was seen at the Forum

whole school. At the time we were en-
gaged on a topic about the Romans and
had begun to deal with the career of Julius
Caesar. His ultimate assassination seemed
an ideal subject on which to try out Frank
Gregory’s ideas.

Each child in the class picked a Roman
name: Publius, Helena, Billius and the like.
Then we discussed what sorts of informa-

tion would have been useful to the Roman
authorities following Caesar’s murder in
their search for the culprits (we imagined
that the real villains were not Brutus and
Cassius after all but as yet unidentified
Romans). Various ideas were forwarded
and after further discussion a final list of
fields, or questions, was agreed upon:

A was the assassin a man?

B was he/she tall?

C did he/she have brown hair?

D did he/she drive a chariot?

E was he/she wearing a red toga?

F did he/she have a gold brooch?

G was he/she carrying a sword?

H did he/she bear a scar?

I or a tattoo (!)?

J and was he/she seen at the Forum on
the Ides of March?

Shorthand versions of these questions
were written on punched cards and each
child thought what characteristics its Ro-
man alter ego would possess. The children
then cut away the holes on the cards which
referred to those questions to which they
would answer 'yes’. (Celia’s card is shown
in figure 1.)

Celia’s card shows she is:

not a man (the hole left intact indicates

‘no’),

not tall,

has brown hair (the slit cut away

indicates ‘yes’),

drives a chariot,

was not wearing a red toga,

was not wearing a gold brooch,

was not carrying a sword,

did have a scar,

did not bear a tattoo,

was seen at the Forum.

I then explained to the class how punched

Figure 2. (a) Plastic rod is
inserted to remove the ’No’
cards. In this case, all the
women’s cards are being lifted
away; (b) Rod used to remove
cards of women not wearing
red togas. Hence cards left
behind give women wearing
red togas

ACORN USER JANUARY 1984

119

■ The complete AMS disc drive package, tailored to your
BBC micro, is compatible with all disc interfaces and
includes cables, a comprehensive manual and utilities
on disc and EPROM. Housed in a steel case, matching
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■ The 3" disc is totally enclosed in rigid plastic and a
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■ The disc is "flippable" like a cassette tape and has a
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interface). A neat plastic switch can be flicked back
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■ The AMS disc drives are completely hardware and
software compatible with 514" drives which can be
used in parallel so allowing easy transfer of software.
Consequently the 3" drives will operate with all the
standard floppy disc interfaces. They take their power
from the outlet provided by the BBC micro- there s no
onboard power supply to corrupt data.

■ The AMS package includes utilities on both a disc and
an EPROM for formatting and verifying discs. The
EPROM, which is easily fitted, offers a simple to use
and permanent alternative to using the utilities disc.

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Name

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CLS

10 FOR suspect=l m o—

20 READ names* a pVn rr
30 IF A=1 AND ^0

40 NEXT suspect FRINT name ^

60 DATA

70 DATA Marcus 1 ’ 1 ’ f' ’£ 1 ’ 1 ’ 1 ’ 0 » 1 , 1

cards could be used to sift through infor-
mation about the possible ‘suspects’ and
we tried several trial sorts to see how the
system worked. For example, to find out
which ‘Roman women’ were wearing red
togas it was necessary first of all to sort out
those cards which referred to women. A
plastic rod was inserted through the holes
and slits of Question A and the ‘No’ cards
we wanted lifted away (figure 2a).

This operation was then repeated for
Question E and this time the ‘Yes’ cards
required were left behind by the sort (figure
2b).

The next step was to introduce the
children to the data handling program they
would be using (listing 1). It was not easy
to do this without falling in to computer
jargon but I persevered and the children
began to see that altering line 30 would get
the micro to look for different bits of infor-
mation in much the same way that inserting
plastic needles through the punched cards
at various places would elicit different
names.

For example, if line 30 reads:

IF A=1 AND C=1 THEN PRINT name$
then the identities of those Roman men

with brown hair would be revealed. Similar-
ly, if line 30 were changed to

IF A=0 AND G = 1 AND H=1 THEN PRINT
names$

then the computer would look for women
carrying a sword and bearing a scar.

Each child then typed in its own line of
data - not easy for lower junior children
when the slighest error in syntax would
make the program crash. Nevertheless,
they checked their own work and that of
their friends and, after a couple of hours, all
the lines of data had been incorporated
into the program. This was then saved on
tape.

I now took on the role of Roman ‘Dun-
geon Master’. I had decided that there
would be two murderers and had used the
punched cards myself to discover what
information I would have to reveal to the
class so that just two names would be left.
Over the next few days I gave clues as to
the assassins’ identity.

I did not do this openly but made a game
of it by hiding information round the class.
So the children would come across a
scrawled note Sellotaped to a plastic tray
or pinned to a display board informing

them that 'The man had a tattoo . . . from a
witness’. Other work would stop and this
new information added to that already
known. The punched cards would be used
to see which suspects had now been
eliminated and, as soon as the micro was
available, the program was used to check.
Sometimes we worked the other way
round, using the micro first before resorting
to the cards. Progress of the ‘investigation’
was recorded by the children in the form of
Roman newspapers. These contained
imagined interviews with witnesses, pleas
for help and witnesses from the Roman
authorities and news of the latest discover-
ies. Eventually the culprits, Livia and Bil-
lius, were unmasked.

We are now engaged in a larger project
involving sorting data about houses in our
local area (see December’s Acorn User).
Interest has spread among the staff and I
hope to involve all five lower school
classes in the work.

My first experience with simple data
handling had been a great success: ‘When
are we going to do it again?’ asked the
children. And ‘Can you be the one that gets
killed this time?’ - and I thought they liked
me! •

RALLY TIME

MAPS and time are the two disparate
subjects covered by Bourne in two new
programs. The first uses a car rally as
the excuse for learning about co-ordin-
ates and compass bearings: the second
teaches telling the time and follows on
from an earlier program.

Map Rally is aimed at 7- to 13-year-
olds, and includes a printer option. The
child has to find a series of hidden
checkpoints against the clock, or an
opponent.

Timeman Two is for 4- to 10-year-olds
and covers six options for telling or
setting minutes to the hour, and the 24-
hour clock.

Map Rally and Timeman Two each
cost £7.80, or £9.55 for discs (plus VAT).

Bourne Educational Software B °urne Educational Software

Distnbutad ty^CORNStFT •

timeman

, TWO

for the SBC Microcomputer

,o m

ACORN USER JANUARY 1984

121

SOf^

PENGO

3 C O R f a

* ** •

a B

One of the most sophisticated full colour, 100% machine code game
software. This arcade game will give hours of fun. You (Pengo) are
being harassed by the devouring Snobees (Snow Beasties) whose diet
is the ice-cubes and an occasional juicy Pengo!! Your only means of
survival is to hurl the ice-cubes at the marauding snobees and crush
them into the snow. Beware, as you crush them to death the remaining
snobees turn even more vicious. Each act will bring a new species,
even more aggressive!!! All is not lost; Bonus points are won by lining
up the three indestructable DIAMOND cubes. Progressive levels of
difficulty. Bonus Pengo at 30K points. A MUST for all BBC Micro
owners.

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SCHOOLS

Robin Ward examines the Oil’s awareness pack, and gives her opinions

TECHNOLOGY IN CONTEXT

Micros in Schools: an awareness pack for
teachers (BBC micro edition P540, £20),
Micros in Schools Project, The Open Univer-
sity, Walton Hall, Milton Keynes, MK7 6AA

THE Open University has produced a se-
ries of awareness packs designed to help
teachers to understand, with practical ex-
perience, the use of micros in schools. The
project is funded by the Microelectronics
Programme (MEP) and the packs are avail-
able in five editions to cover machines
commonly used in schools. All booklets are
easy to read, with a clear, simple style.

The BBC model B pack consists of a
Study Book, a Case Studies Book, a Pro-
ject Book and four cassettes of useful and
interesting software.

The Study Book is designed for individ-
ual users or groups. The suggested study
sequence is flexible enough to allow much
individual choice and the integration of
other materials into the programme is pos-
sible. Unlike the other two books, it is
specific to the BBC micro.

By following the instructions for setting
up and running a micro, the novice should
soon become competent. Suggestions for
loading and running programs and a
troubleshooting guide for error messages
are helpful and easily understood.

The Case Studies Book covers 13 pro-

Study Book - one of three books and four tapes in the awareness pack

grams on a variety of topics in the human-
ities, sciences, arts and mathematics.
Teachers will find a comprehensive and
useful coverage which should illustrate the
ways they can use micros to improve the
learning experiences of the pupils. Each
case study is well set out and follows the

project*

p " H ’ b

interpretation

Sample pages
from the three
manuals

In order to (j*i
,, ^ 'houJd prrM proKrjm '

* ' he ‘ imr mbtt

37. uvin g only £? > * rdm ‘ *' 1

* y in > Whm you ru '" •

Firui*

SHsS® 1 “--rassSg-*

P"W.m „

f *rtwtty * ' j Do

to look

12 live limns 4.

key «t the top right-hand end ol t
topmost row vt key* on the keyboard You
should hr bark to the hist message shown when
the computer is twitched on - now minus the
32K. as shown m Figure 16
If you have used the WELCOME tape, rewind 11
and e)e»M it from the machine

1 1 Vi.ir

rt the *

Check that you have got exactly the same

spelling as shown in Figure 17 (Don't forget that

you can use the OtiliK key to erase typing

mistakes 1 When the screen looks like Figure 17

press the RffuRN key

Find the cassette containing the prograjn

EUREKA, included with this pack, which Is used

for Proj«ct l in the Project Book Insert it In your

cassette player and rewind it to the start

Type BBBMBBBlIBBBgP

Ensure the screen looks like Figure 16, and then

ptess the Bcfjwit key. followed by the PLAY

button on your cassette

You will see Figure 19, followed by Figure JO,

and then the program EUREKA will begin

Figure 17

Trilwgrt

I he tvmputrr

/Hayrres

Figure 18 Instructing the computer
EUREKA

Mils the microcomputer back
virtually to the state when It is lirst switched on.
You may read elsewhere that it is possible to
recover the program you are running at the time
fef£&J is pressed by typing in {SCGSlfittUfW
Unfortunately, this is not the case with the
programs used in this Awareness Pack. U you
press the key, you will need to reload the

program from cassette as shown In step 7 below.

upgraded machines (see step 9, right- hand
nn). the program EUREKA is too big lo fit
into the available space In the main memory (the
RAM part - see page 14). We have designed an
additional program to tell the computer how to
regam space in the main memory that has been
reserved for the upgrading This is what
happens in the first phase of loading The main
program is then loaded into the memory in
phase two All of the programs for this pack,
except TELE2, swill work in the same way
Don't worry it vuur computer has not been
upgraded for example by fitting a disk or
ECONET interlace - your program will run just

Stop the tape, rewind it. and put it back in its
bos (The program is now loaded into the
computer * main memory You will only need
the tape again it you have lo repeat the loading
process for some reason )

Figure 19 PfcBsr

icmpulrrs main m
the nght hand column )

It is a good idea to get into the habit of
rewinding a tape and putting it away as
soon as a program has loaded It ran save
a tape from accidental damage.

«<• tuv nf the ImJuiK openitbn.

same structural pattern - an introduction,
how the micro was used and a critique by
the teacher. The programs are well chosen
and cover a number of subject areas,
some not ordinarily connected with the use
of micros. The ‘details’ which are included
in each case study are important, as fur-
ther information such as worksheets or
instruction sheets can be obtained from
the teachers who produced them.

The Project Book covers precise instruc-
tions for the four programs on the cas-
settes. Eureka (see Acorn User, March
p48), Turtle (a Logo program), Interest/
Tele2 (illustrates how a program works),
and Service (shopping simulations) are
presented in a detailed and graphic fash-
ion. There are various levels of difficulty in
these programs and the most complex,
Service, includes games, worksheets and
ideas for additional activities.

The roles of simulations in different disci-
plines are described in the Project Book
and should help to stimulate interest in
many areas. There is also a glossary.

The examples given for most subjects
are easy to understand and teachers will
be quite excited by what is available to
them. The pack is suitable for both primary
and secondary school teachers as the
material covers a wide range. Technology
is very important and computers should
not be seen only in information technology
classes or in computer studies. Students
need to be shown as wide an area as
possible so they can see the relevance of
technology in their everyday lives.

• Mrs Robin Ward is assistant director
of the IT Project at the Davidson Centre
in Croydon, London.

ACORN USER JANUARY 1984

123

^ J IM ^

Software News

INNN

BBC SOFTWARE

rom the professionals

MAXI ■ GRAPH

Maxi-Graph is a graph drawing program for the
BBC Model B which features not only extreme ease
of use, but also sophisticated graph drawing
facilities. Both the curve and the background
colours can be individually set and, as can be seen
from the illustrations, up to three curves can be
drawn on the same graph. As you can also see, bar
graphs are available, in addition to curves. The
latter can be linked or unlinked. Background grids
may be displayed or not (they are not, in the tree
growth graph). The starting point of the graph
need not be in the bottom left hand corner and
magnification of sections of the graph may be
carried out, by restricting the plot range to a
certain section of it.

Data may be saved to disk and loaded from disk.
Three types of graph labels may be defined on the
X axis. The first is monthly, the second is yearly
and the third is a numerical general purpose
definition.

Maxi-Graph is disk orientated, it is not available for
tape, and gives an excellent graph representation.
As can be seen by the illustrations, the graph which
the user constructs can be sent to the printer, in
addition to the screen. It should be compatible with
most dot addressable printers and has been tested,
and is guaranteed, with Epson MX80 Model III,
FX80, RX80; Star 510/525; Seikosha GP100A
or GP80A.

Maxi-Graph (Disk) £14.00 plus VAT £16.10

Plus 75p P&P

RRINFBLL 19/0

M J J
MONTHS

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124

ACORN USER JANUARY 1904

PRINTERS

BUDGET DAISYWHEEL

THE Juki 61 00 is the first reasonably priced
daisywheel printer I have come across.
Imported and distributed through Micro
Peripherals, it sells for around £350, which
brings it within the home computer user’s
budget and makes it a contender as a low-
cost business printer.

A daisywheel printer has a printer
mechanism with many moving parts, each
of which has further to travel than those of a
dot-matrix printer before a letter is printed
(details of the process were covered in the
March issue in the first of my printer
articles). The result is that daisywheels
tend to be bulky, noisy and slow, but these
disadvantages are offset by the fact that
they produce print of the highest quality,
not quite matching up to a printing press
but certainly as good as that of the best
electric typewriter.

How does the Juki measure up to other
daisywheels and to dot-matrix printers in
its price range?

On first handling it you are struck by its
weight - at 12.5kg it is certainly not to be
put on a card table. It is also large, having
a 13in carriage, which enables it to handle
A4-size paper sideways if required. Thus
tables of results or other data can be
printed legibly, unrestricted by the limita-
tions of an 80-character line. It takes up a
lot of space, however, and requires a large
desk or a separate printer station.

It has a Centronics parallel interface,
which connects via a standard cable (not
supplied with my printer) to the printer
socket under the Beeb. An RS232C inter-
face (compatible with the Beeb’s RS423) is
available as an optional extra.

The speed is an unremarkable 18 char-
acters per second, to some extent com-
pensated for by the rapid linefeed (‘bi-
directional, logic seeking, etc - which
means that it prints more or less continu-
ously with the carriage moving in either
direction). It is still slow compared with
even a moderate-speed dot-matrix. It takes
about 35 minutes to print a full page,
though it would be quicker for program
listings.

The print quality is superb. Obviously the
style depends on the daisywheel in use,
but I found the Courier 10 wheel supplied
very much to my taste. Even the best dot-
matrix printers cannot compare, and if your
principal need is to impress clients with
beautifully printed letters the daisywheel
mechanism is unrivalled.

The Juki 6100 is friction-feed only. This
means that it is at its best dealing with rolls
or cut sheets of paper. I could find no
reference to a roll-holder or cut-sheet feed-
er in the manual. Either would be an
expensive extra but probably necessary to

At £350, the Juki 6100
is well priced for
business and home,
says George Hill

translate this into a satisfactory business
machine. You have to feed the paper
manually, or if you’re using fanfold paper
continually adjust it as it creeps across the
roller.

The printer makes a lot of clattering and
whirring noises while printing, and there is
a continuous soft high-pitched whine
which might get on your nerves in a quiet
office. It is quiet by daisywheel standards
though.

An impressive set of features are built in,
though some of these are not very con-
venient to use - they seem to derive from a
typewriter ancestry, when a printer had a
keyboard attached.

They include proportional spacing, hori-
zontal and vertical tab, underlining, bold
printing (or bolt printing, as the manual has
it), shadow (double-strike) printing, setting
of left and right margins, super and sub-
script, variable character spacing and line-
feed, an international character set selec-
tion (if you use Juki daisywheels), and a
graphics facility.

The proportional spacing mode enables
the narrow letters to take up less space
than the wide, in the manner of handwrit-
ing. This type of printing has been avail-
able only on the more expensive daisy-
wheels until recently. It is excellent on the
Juki, though it must be cancelled if lists are
to be printed, otherwise they won’t align.

Emphasised modes of type are set ancl
cancelled by simple escape sequences.
The bold type isn’t bold enough to be
noticeable, and I had trouble with the
shadow sequence, which failed to cancel
on some occasions. The super and sub-
scripts are also simple, the paper being
fed half a line up or down in response to
ESC U and ESC D.

The horizontal tab and the left and right
margin settings are somewhat idiosyncrat-
ic, apparently deriving from a printer with a
keyboard attached, and are set at the
present carriage position by sending ESC
1. This is difficult to accomplish as the
carriage can be moved only with the print-
er enabled, and then the escape sequence
must be sent without being printed. The
awkwardness of these settings led me to
write program 4 which allows you to set the
horizontal tab positions before starting
work.

You can move the carriage directly to a

fixed position along the line, which is more
useful. This is done by sending ESC
CHR$9 n (where n is the number of the
position to move to).

I’m sure someone will tell me why there
are complex vertical tabbing arrange-
ments on all printers, but I have yet to
discover a use for them, and there is no
way to demonstrate them in a magazine
article.

The graphics facility is really an exten-
sion of total carriage control. The carriage
can be stepped horizontally and vertically
in steps of 1/60 and 1/48 of an inch
respectively, and any character can be
printed at any point. I have used the facility
to write a graphics dump made up of dots
printed from the full stop. Other characters
could be used to produce shading and
other interesting effects. I shudder to think
what the long-term stress on these over-
used spokes of the wheel would be, and
wheels are expensive to replace.

A note in the front of the manual says that
this glossy booklet is only a temporary
issue. It was quite clear, despite being
obviously a translation from the inscrutable
(for instance, item 6 is ‘Setting a Paper on
the Printer’). It suffers from a complete lack
of programs and I hope that mine will help
you.

You will notice that I still work in VDU1
terms for all escape sequences. I still find it
safest. The use of VDU21 or *FX3,10 still
generates results I don’t expect.

The sample printout (figure 1) demon-
strates the facilities a' ailable.

Program 1 is for users of Wordwise, and
sets the function keys as stated in the
REMs. The strip down the eage of the page
(figure 2) can be insertea under the per-
spex cover over your normal Wordwise
strip. The keys operate when SHIFT and
CTRL are held down and the function key
pressed.

Program 2 is a fun program which con-
verts the Beeb/printer combination into an
advanced typewriter. The function keys
have actions similar to those in program 1 ,
though the sub- and superscripts apply to
individual characters rather than to strings.
The main program could apply to any
printer, with slight modifications according
to the linefeed/carriage return arrange-
ments.

Program 3 is the graphics dump, a
simple on/off dump that has been used to
print the mode 5 monochrome picture
illustrated in figure 3

My overall impression of the Juki 6100
was of a very well engineered product
which requires more thought to make it
user-friendly. It produces beautiful printed
output, though.

ACORN USER JANUARY 1984

125

YOUR MICRO COULD TEACH YOU
ATHING OR TWO ABOUT THE FRENCH

...OR THE GERMANS...OR THE SPANISH

■ ■■

A home computer is an expensive toy; and, if playing
games is all you do with it, a toy is all it is.

Now, using the New Personal Computer
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your micro and learn something at the same time.

PCSS language courses comprise 12 lessons on
3 audio cassettes used in conjunction with a fourth
software cassette, to add a new dimension to learning.

Initially the software package enables you to see
the words you’re learning; then, as your vocabulary
develops, it will test your skill in your new language.

Anyone can learn this way - no previous knowledge
of the language is required. The unique PCSS method
develops your overall learning and memory skills in a
way thats both relaxing and enjoyable.

Each PCSS language pack - French, German or
Spanish -contains a comprehensive booklet detailing

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I COMPUTERISED EDUCATION SYSTEMS I

the 1 2 audio lessons and the function of the interactive
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At only £29.95 per pack PCSS costs less than other
home language courses yet it offers much more in
terms of education and enjoyment.

Complete the coupon below and try PCSS for
yourself -you’ll be amazed what your micro can
teach you.

(PCSS software is compatible with the ZX81 (16K). ZX Spectrum. BBC Micro.
Acorn Electron Micros )

Each pack comes with a full money back guarantee if not completely satisfied

Send your cheque or Postal Order for £29.95 made payable to:

MDA Modon Associates Limited, 561 Upper Richmond Road West,
London SW14 7ED. (ZX81 users £26.95)

or, alternatively phone Teledata 01 200 0200 now, lines open 24 hours
and quote your Visa, Diners Club, Access or American Express number.

Tick which Audio/software package you require. (Prices include VAT.
Add £1.45 for postage and packing on each order.)

Please supply the following Audio/software Packages
FRENCH □ GERMAN □ I

Machine Type:

_ Memory Size:

HARRIS McCUTCHEON SYSTEMS

are pleased to release

HMS HOME ACCOUNTS £28.75

HMS VAT TRADER'S LEDGER £21.50

HMS BASIC ENVIRONMENT £14.50

to BBC Microcomputer users with a mininum configuration of 1 x 40 track single sided disc and a 8" 132-column (condensed mode) printer, to a maximum
configuration of 2 x 80 track double sided disc and a 15" printer. The programs allow user allocation of each file between * DRIVE 0, 1, 2 or 3, thus making full
use of the disc space available.

All our products work ONLY on disc systems ! ! I When did you last have four data channels open simultaneously ? ? ? By popular demand we bring you

HMS VAT TRADER'S LEDGER

Are you AFRAID of your VAT return ? ? ? Buy HMS VAT TRADER'S LEDGER and fear no more ! ! ! Better than a full-time accountant in your wardrobe I I !

HMS HOME ACCOUNTS

Does your BANK MANAGER send shivers down your spine ? ? ? Do you stop answering the phone in case it is a debt collector on the other end ? ? ? Spend £28.75
on HMS HOME ACCOUNTS and bring bankruptcy a little closer still I ! !

HMS BASIC ENVIRONMENT

Can t read your own BASIC programs ? ? ? Write them with l-o-n-g-e-r variable names (and some of our code procedures) and see what improvements can be
yours ! ! I Be the envy of your local user group ! ! ! THEY may be good at copying tapes, but YOU can write your own systems and UNDERSTAND them ! I I
Why bother having a disc drive if you don't do things the cassette wallahs CAN'T DO AT ALL ? ? ? Show off in style ! ! !

The disc, manual and information contained are sold under license subject to the condition that they are for single user single site application by or on behalf of the
purchaser, are not for resale in whole or in part either as originals or copies, and may not be supplied to a third party as part of a package or used as part of a package
supplied by a third party to the purchaser, without the written consent of the copyright holders. Damages will be claimed where this occurs, with revocation of license.
Purchase indicates acceptance of license terms.

I enclose £ for the following products (tick and delete where appropriate)

HMS HOME ACCOUNTS (£28.75)....

HMS VAT TRADER'S LEDGER (£21.50) ....

HMS BASIC ENVIRONMENT (£14.50)....

Please supply on 40/80 track disc. I have VIEW/WORDWISE; OS 1.0/1. 2; BASIC I/ll

Name

Address

Vat, disc, manual, post
and packing inclusive.

The credit card companies
4% take precludes our
offering their service.

Postcode

Telephone Date

Please send with cheque or postal order to: Harris McCutcheon Systems, 40 Huntingdon Street, London N1 1 HM (01-609 3207)

126

ACORN USER JANUARY 1964

PRINTERS

This is to illustrate the normal print style

THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
The quick brown fox jumps over the lazy dog

Now in proportional spacing

THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
The quick brown fox jumps over the lazy dog

This illustrates the TAB function.

12345678901234567890123456789012345678901234567890
~POSl ~POS20

Any word or fetter may be underlined or printed
in bold type or in shadow printing.

Good for Chemistry and mathematics.

2NaOH + H 2 S0 4 Na 2 S0 4 + 2H 2 0

N 2 + 3H 2 2NH 3

(a + b) 2 = a 2 + 2ab + b 2

Figure 1. Juki 6100 output demonstrating some of the machine’s facilities (note there is no
difference between I and 1)

^ m

§1

a

5

o u -

m LL

c n

o

CO

©

c

= li-
eu LL

?°

D

©

c

-O '

c

D

<s it

o O
tr o)

0 .g

II

1 £

<0 2

0.0

e a

Q _ c />

©

© £
© ~
Q

n

Cl

g

O)

©

c

©

CL

Figure 2. Function-key strip
for use with
Wordwise

ACORN USER JANUARY 1984

127

Whether its your first computer or whether you’re already an
enthusiast, LVL COMPUTERTOWN offers you the quality of
service you expect from experts. If you invest money, you go to
a bank or a broker - a specialist who can guide and advise you
on the best return for your capital. At LVL COMPUTERTOWN
we’re specialists too. We’re there to help guide you through
the micro maze, keep you up to date on innovations, help you
get the best value for money, whether your computer is for
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Come and talk to the experts and move into micros with LVL
COMPUTERTOWN

An example of superior technology, total reliability and outstanding
performance, combine to produce the LVL Disk Drive Family.

Truly professional units designed to work with the BBC Microcomputer.

LVL 03 100K Single 40 Track Drive £265.00
LVL 02 100K Dual 40 Track Drive £389.00
LVL 04 200K Dual 40 Track Drive £573.85

(including VAT)

BBC

MICROCOMPUTER

MODEL A £299 MODEL B £399

-(INCLUDING VAT)“

MONITORS

DECCRCOLOUR

14”

COLOUR MONITOR
£247.25

(including VAT)

MKROVITEC

14”

COLOUR MONITOR
£247.25

(INCLUDING VAT)

© SANYO

12 ”

GREEN SCREEN
£102.35

(INCLUDING VAT)

SOFTWARE

DESIGNED FOR THE BBC
MICROCOMPUTER

GAMES

Monsters £9.95

Snapper £9.95

Planetoid £9.95

Arcade Action £11.90

Rocket Raid £9.95

Meteors £9.95

Arcadians £9.95

Sliding-Block Puzzle £9.95

Cube Master £9.95

Starship Command £9.95

Snooker £9.95

Super Invaders £9.95

Hopper £9.95

Colditz £9.95

Doctor Who £10.00

White Knight II £10.00

Missile Base £9.95

Draughts & Reversi £9.95

ADVENTURES

Philosophers Quest £9.95

Castle of Riddles £9.95

Countdown to Doom £9.95

Sphinx Adventure £9.95

LANGUAGES

LISP £16.85

FORTH £16.85

GENERAL

Desk Diary £9.95

Creative Graphics £9.95

Graphs & Charts £9.95

Tool Box £21.00

Record Keeper £13.80

Magic Garden £9.95

EDUCATIONAL

Business Games £9.95

Tree of Knowledge £9.95

Peeko Computer £9.95

Algebraic Manipulation .... £9.95

Word Sequencing £11.90

Missing Signs £11.90

Number Balance £11.90

Word Hunt £11.90

Density Circuit £11.90

Chemical Analysis £13.80

Chemical Structures £13.80

Jars £11.90

Vu-Type £16.10

BOOKS

ACORN

Creative Graphics

. . £8.63

Graphs and Charts

. . £8.63

Lisp Book

. . £8.63

Forth Book

. . £8.63

BCPL Manual

. £17.25

BBC

The Computer Book

. . £7.76

The Book of Listings . J . .

. . £4.31

COLOUR UGHTPEN

The lightpen is compact, reliable
and comes in a nigged metal case
providing physical and electronic
protection. Its sensitivity can be
adjusted to match any make of TV
screen, giving the highest levels of
accuracy.

The lightpen package consists of
the lightpen, an interface unit,
introductory software on cassette
and a user guide.

PHICS SVSTEfTl

An easy to operate, complex
graphics system with new and
very advanced software giving a
versatile CAD System Complex
picutres and diagrams, or original
designs can be quickly, easily and
accurately reproduced. The system
consists of the ‘GRAPHIC
DIGITISER’ incorporating a 256mm
x 205mm tracing pad, the ‘Control
Program’ (tape or
disc). Instruction
manual, key card
and quick
reference card.

* IT’S A PORTABLE
COMPUTER TERMINAL!
* IT’S A LETTER QUALITY
COMPUTER PRINTER
* IT’S A FULL FEATURE
ELECTRONIC
TYPEWRITER

NEVER BEFORE, AT ANY PRICE, HAS THERE
BEEN AN INNOVATION LIKE TRI-WITER! AND
AT THIS LOW-COST, IT’S ALMOST UNBELIEVABLE P
NOW EVERYONE CAN HAVE ALL THREE FUNCTIONS

IN ONE MACHINE, AND AT A COST BELOW

WHAT YOU WOULD EXPECT TO PAY FOR A SINGLE FUNCTION
MACHINE!

The items featured represent a very small selection
from our vast product range.

Further information of both product and services
available can be obtained by telephoning or visiting
your nearest LVL Computertown Dealer.

CHESHIRE

C-TECH SOFTWARE
184. Market St.

HYDE

Cheshire
061 366 8223
‘ COMPUTER CITY
78. Victoria Rd
W1DNES
Cheshire
051 420 3333
OAKLEAF COMPUTERS
100. Boughton
CHESTER
0244 310099

CUMBRIA

THE COMPUTER SHOP
56/58 Lowther St.
CARLISLE

Cumbria
0228 27710

THORNGUARD
46. Pensby Rd,
HESWALL

The Winal.
Merseyside
051 342 7516

9. Bank St

RUGBY

Warwickshire
0788 65275

ESSEX

A.C.L.

1. Northman

GRAYS, ESSEX

0375 79834
BROADWAY MUSIC
AND VISION
Woodford Green

ESSEX

01 504 7500

LOMAX
8. Exchange St..

St Annes Square.

MANCHESTER

061 832 6167

WORCS

SPURTREE COMPUTING
LTD.

Council Buildings,

Teme Street.

TENBURY WELLS,

Worcestershire
0584 811353/811304

Trent Boulevard

WEST BRIDGFORD

Nottingham
0602 819713
S P ELECTRONICS
48, Linby Rd.

HUCKNALL

Notts.

0602 640377

LEASALINK VIEWDATA Ltd
230. Derby Rd

STAPLEFORD

Notts

0602 399484 •

OXFORD

ABSOLUTE SOUND
AND VIDEO (Oxford) Ltd.

1 9. Old High St. Headington

OXFORD

0865 65961

Msassm wm

K & K COMPUTERS
32, Alfred Street,

WESTON

SUPERMARE

Avon

0934 419324
COLSTON COMPUTER
CENTRE LTD.

The Colston Centre.

1 1. Colston Ave.
BRISTOL
0272 276619

WEST MIDLAND

RICHARD MORRIS

523. Bearswood Rd.

Smethwick

WARLEY

021 429 1161

JBC MICRO SERVICES

200 Earlsdon Ave.

Nth. Earlsdon
COVENTRY
0203 73813

WILTSHIRE

WILTSHIRE MICRO

CENTRE

Unit 6.

Central Trading Estate.
Signal Way.

Old Town,

SWINDON

0793 612299

§

BUCK

HI-VU ELECTRONICS
38. Church St. Wolverton

MILTON KEYNES

Bedford
0908 312808

SUSSEX

C.J.E. MICROS
78. Brighton Rd

WORTHING

West Sussex
0903 213900

ISLE OF WIGHT

EXCELL
4. Foreland Rd
BEMB RIDGE

Isle of Wight
098 387 2578

YOUR

LOCAL

DEALER

HEREFORD

SALOP

a

LANCASHIRE

KEMPSONS
26, St. Owen St..

HEREFORD

0432 273480

KENT

KENT MICRO
57. Union St

MAIDSTONE

Kent

0622 52784
GRAVENSEND
COMPUTERS
39. The Terrace.

GRAVESEND

0474 50677

NORTHANTS’

M A ELECTRICAL
7. High St

IRLINGBORO

N'Hants
0933 650133

MEDUCOTT BROS
53. Mardol

SHREWSBURY

Shropshire

| 0743 3060

10, Market Place

BUNGAY,

Suffolk
0986 2141

IRELAND

EVERYMAN COMPUTER

SERVICES

BALLYMONEY

Co- Antrim

N. Ireland

026 56 62658

NEWBURN

ELECTRONICS

BALLYCARRY

Co-Antrim.

09603 78330

P V MICROS
38A Water St.

ACCRINGTON

Lancs

0254 36521
Home & Business
Computers Ltd.

54. Yorkshire Street.
OLDHAM
06 1 633 1608
Home & Business
Computers (RCH) Ltd
73, Yorkshire Street.
ROCHDALE
0706 344654

WALES

63. Blaby Rd 1

WIGSTON

Leicester.

0533 785033

* OAKLEAF COMPUTERS
121. Dudley Rd.

GRANTHAM

0476 76994

LONDON

CANNONBURY RADIO
185 Upper St.

ISLINGTON N1

London
01 226 9392
PAUL ELECTRICAL
250/2 Grand Drive.
Raynes Park,
LONDON SW20
01 542 6546
WOODS RADIO
257. Lavender Hill.
Battersea.

LONDON

01 228 1768

NAL

18. Salter St..

STAFFORD

0785 3420

KIRKLANDS

City Rd.. Fenton.

STOKE ON TRENT

0782 415787

COMPUTE RAMA

59. Foregate St

STAFFORD

0785 41899

SURREY

HASLEMERE COMPS
25. junction Place.

HASLEMERE

Surrey

0428 53850

P & H ELECTRONICS

5. The Parade.

Reading Road,

YATELEY

Surrey.

0252 - 877 222

* Spectrum Members

BULWALK RADIO
5. The Bui walk
Brecon.

POWYS

0874 2974

BUCON

18. Mansel St.

SWANSEA DY FFD

0792 467980

SIR.

91. Whitchurch Rd.
Cyncoed

CARDIFF

Wales

0222 621813
P & P COMPUTERS LTD.
41. The Hayes.
CARDIFF,

Wales.

0222 26666

SCOTLAND

COMMSCOT
30 Gordon St.

GLASGOW

041 226 4878

NORTH LAND

NEWTONS
Main St.
SEAHOUSES

0665 720307

I® d EM JUKI key settings
^0 REM paragraph
30 *KEY0 ! M ! f ! TI6 ! ! "

40 REM delete line
50 *KEY1! ! !L! I#!!!... j LI ,

70 *

80 *KEY3 ! f 0C27 , 83 J » "

90 REM underline ON and OFF
100 *KEY4 ! ! ! 0C27, 69 ! ' "

1 1 0 *KEY5 ! ! ! 0C27 , 82 ! ! "

IS «EV6;*?Sc27^“- 3 “ “ 0FF

1 50 *KEY7 ! ! ! 0C27 ’ 38 ; j «

17^ *KrvnV l i’ erSCript and subscript
170 *KEYB! ! !0C27,85! ! *'

1 80 *KEY9 ! ! • 0C27 , 68 ! J "

Program 1. Function keys set up for Word-
wise users

OFF

10 REM TYPEWRITER

20 REM A program to make a printer be
have like a typewriter

30 REM G. B. HILL <c) 1987

40

6100 0 REM KEY Settin 9S are for the JUKI
60

70 REM *** main program **-*

80

AS CU values 1156 fUnCti ° n key = to return
100 *FX225 , 128,0
110 REM adjust display
120 *TV255,1
130 M0DE3

140 1 i nel ength=80: count=0
150 REM reset printer
160 VDU2, 1,13,3
170 REM ESCAPE key to exit
180 ON ERROR GOTO 350
190 CLS

-00 REM * main typing loop *

210 REPEAT P

220 count=count+l
230 A=GET

2 f® ^ M A function key pressed
-o0 IF Ax- 127 THEN ON ^A-1^7) GDRI

’ 510 * * ’ 530 * ’ 540:560 ' A=0:’

x.60 REM backspace pressed

unt -2 IFA=127 THEN VDU2,8,3:A=0:count=co

280 REM return key

= 0 290 IF A=13 ™ EN VDU2 >A,10,3:A=0:count
300 REM line end reached - sound bell

continued ►

320 VDU2,A,3
330 UNTIL FALSE
340

350 M0DE7
360 *FX225 , 1

PRIN?-"af- E ^ R<>B . AN ° ERR<>17 THEN REPORT:
r ki NT ; at line " ; ERL

380 END

390

400 REM ♦subroutines*

410

4*:0 REM KEY0 paragraph

430 VDU2, 13, 10,32,32,32,32 37 ^7 7

440 REM KEY1 nothing

450 RETURN

□nToff" KEVB 213 "--portion., =P.ci„ g

S SS:l:S:i:S:S!Eas

* nd 0FF

d off RE " KE« 7 ;^ a ;A«o RT B ™„ tln9 ON

-am mn’ 1,27,1 ’ 87,3:RETURN

--m o™^’ 1,27,1 ’ 38 ’ 3!RETURN
JJ 0 RE M KEYS subscript

>-j<S0 A —GET : VDU^- 1 1 o~7 i qc « 1 __

: A=0: RETURN ’ 1 »*»^ / » 1 »68,3

-j70 Rem KEY9 superscript

= A=0 8 fRE A T = U G R E N T: VDU2 ’ 1 ’ 27 ’ 1 ^B,A, 1 ,27, 1 ,85,3

Program 2. Beeb/printer combination as ad-
vanced typewriter

1000
1010
1020
1030
1040
1050
1060
1070
1080
1090
1100
1110
1 120
1130
1140
1150
1160
1170
1180

REM JUDUMP

REM G.B.Hill (C> 1983

REM dump for the JUKI 6100

DEFPROCDUMP

REM Enable printer

VDU2

0 E f!T*: initia lise printer
VDL'l ,-7,1,26,1 , ASC" I "

REM clear paper

VDU 1,13,1,13,1,13

FOR YX-1023 TO 0 STEP -4

REM ESC 3

VDU1 ,27 ,1,51

REM centre picture
FOR IX=0 TO 89:VDU1 ,32:NEXT
for X7.=0 TO 1279 STEP 4
IF POINT ( XX , Y7C ) >0 THEN VDU 1 , 4 6

continued ►

130

ACORN USER JANUARY 1984

PRINTERS

1190
1200
1210
1220
1 230
1240
ep

1250
1260

Program 3. Graphics dump

VDU1 ,32
NEXT

REM Linefeed
VDU 1,10,1,13
NEXT

REM Reset printer, disable and be

VDU1, 27, 1,30, 1,9, 3f 7

ENDPROC

10 REM JUTAB

20 REM Set horizontal tabs on JUKI 61
00 printer

30 REM G. B. HILL (C) 1983

40 REM *** Main Program ***

50 DIM num ( 78)

60 M0DE3
70 PROCsetup
80 REPEAT
90 PROCinput
100 UNTIL num=0

110 PRINTTAB(5, 17) "Please wait"

120 PROCsort

130 PROCset _pr inter

140 PRINTTAB (5, 17) "Printer now set to
tab at positions";

T:PR?NT° R 1 = 1 T ° N:PRINT ’‘” *' j num ( I ) ; : NEX

160 PROCtest_tab
170 END
180

190 REM *** Procedures ***

200

210 DEFPROCsetup

220 PRINTTAB (0,3) "Type in positions fo
r TAB stops."

230 RRINTTAB (0, 5) "These should be numb
ers between 2 and 79"

240 PRINTTAB (0,7) "Type RETURN when you
have finished"

250 N=0

260 FOR 1=1 TO 7: PRINTTAB ( 1*10-1 , 10) . T
; : NEXT ’ ’

270 PRINTTAB (0,11);

-i80 FOR 1 = 1 JO B0:PRINT;I MOD 10;:NEXT

290 ENDPROC
300

310 DEFPROCsort
320 REM SORT
330 spare=0
340 REPEAT

continued ►

0

350 sorted=TRUE
360 FOR 1=1 TO N-l

370 IF num ( I ) =num ( 1+1 ) THEN num(I+l)=8

^90 NEXT Um<I> >nlJm<I + 1> THEN PR0Cswa P

400 UNTIL sorted

410 N=0

420 REPEAT

430 N=N+1

440 UNTIL num(N+l)=80

450 ENDPROC

460

470 DEFPROCi nput
480 REPEAT
490 N=N+1

500 INPUTTAB (0,14) "Type in numbers now
s > numl

510 num=VAL (num$ )

520 OK=(num=INT (num) AND num>l AND num
<79) OR num$=" "

530 IF NOT OK THEN VDU7:N=N-1 ELSE num
(N) =num

540 PRINTTAB (20, 14) ; "

550 UNTIL OK

560 IF r>um$="" THEN num (N) =80 ELSE PRI
NTTAB (num (N)— 1,12) ; "

570 ENDPROC
580

590 DEFPROCswap

600
610
620
630
640
650
660
670
680
690
700
710
720
730
740
750
760
770
780
790
NEXT
800
810
820
830
840
850

spare=num ( I )
num ( I ) =num ( I + 1 >
num ( I + 1 ) =spare
sorted=FALSE
ENDPROC

DEFPROCset _pr inter
VDU2, 1 ,27, 1,50
FOR 1=1 TO 80
FOR J=1 TO N

IF num ( J ) =1 THEN VDUl.27,1,49

NEXT

VDU 1 ,32

NEXT

VDU3

ENDPROC

DEFF’ROCtest _tab
VDU2, 13

FOR 1=1 TO 80: VDU1 , (48+1 MOD 10);
PRINT

FOR 1=1 TO N
VDU1 ,9, 1 ,94
NEXT
VDU 13,3
ENDPROC

Program 4. Horizontal tab positions set

S

ACORN USER JANUARY 1984

131

Available NOW. . .

jjp :]

iff p

BF :

ME.

mmiNm

3 programs
on ONE CHIP
Used with
DISC or TAPE

FfSSEfTlELEN A full 6502, 2-pass MACRO

assembler using standard Mostek mnemonics. It has the facilities
you would expect on an assembler for a much larger machine.
Features include MACROS with LIBRARY facilities ; nestable
CONDITIONAL ASSEMBLY ; flexible LISTING OPTIONS ; hex,
decimal, binary and ASCII data formats; full range of ARITHMETIC
and LOGICAL OPERATORS ; symbol table sort and dump ; file
chaining ; 29 powerful PSEUDO-OPS. Source and object programs
are kept on disc so NO LIMIT ON PROGRAM SIZE or location.

DEE1JS5EK The famous SPY DEBUGGING MONITOR!

Instantly available for inspecting, modifying, debugging and dis-assembling
machine code programs. Features include easy-to-read COLOUR display;
hex, ASCII or DIS-ASSEMBLED display modes ; SINGLE-STEP ;

BREAKPOINT ; MEMORY SEARCH ; DIS-ASSEMBLER and
much more!

EDITEK A dynamic TEXT EDITOR with WORD
PROCESSING CAPABILITY! Designed with the programmer
in mind to produce both programs and documentation.
Features include SCREEN EDITING and DEFERRED EDIT
modes ; MACRO commands ; NO LIMIT on document size ;
sideways SCROLLING ; COLOUR display ; full use of
FUNCTION KEYS. AfullySTRUCTURED COMMAND LANG-
UAGE makes this editor THE MOST POWERFUL YET
DEVISED for the BBC Micro.

gii» i

FOE

is a COMPLETE PROGRAM DEVELOPMENT PACKAGE for assembly
language programmers. Comprehensive user guide includes TUTORIAL and REFERENCE
sections as well as details on how to code your own ‘sideways ROMs’.

FREE disc of example programs, MACRO library, and source code for text formatter and
librarian oroarams.

£60 including V.A.T.

16 k Firmware
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Coming next month. ..SPY2... even more debugging features -f- relocator +
'sideways ROM/full disc recovery routines. Still only £21 +VAT

Please enclose cash with order or an official order form.

Dept A 12 Collegiate Crescent Sheffield S10 2 BA

LET YOUR ATOM DO THE WALKING

.

SINGLE key entry of Basic seems to be in
fashion these days - even the Electron has
it. Personally, I think it just encourages
laziness - which is why I’ve written the
routine in listing 1 . It allows you to set up
the Atom so that pressing SHIFT and a
letter key inserts a keyword into the input
buffer at #100, where it is treated as if it
were entered at the keyboard. The
keywords are entered into strings A to Z.
Thus, after running this routine, you may
type, for example, $A=“ABS” and this
word will appear any time you press
SHIFT-A.

Of course, you may not now enter shifted
characters into your program. If you want
to do this, you must BREAK and OLD, to
restore normal vectors. To resume single-
key entry, type !#20A=#8400 (or wherev-
er you assemble the code to). Once as-
sembled, the program is not needed, but
don’t overwrite the object code.

LABEL SEARCH

IF YOU are writing a long program, it
makes sense to use labels to speed up
execution. However, it’s all too easy to lose
track of your labels and what the labelled
routines do. Listing 2, when run, prints out
in full every labelled line in the target
program.

It assumes that the target program is at
#2900, but you can alter this by changing
the value of P in line 10. Simply, it looks
through memory until it finds a (CR), fol-
lowed three bytes later by an inverse
character. If found, it jumps to sub.p and
prints that line. Line 40 converts the line
number into decimal, and lines 45 and 50
format lines so that they are printed in the
same way as a LIST instruction. Line 20
checks for the end of the program (#0D
followed by #FF).

DIFFERENT LOGIC

IN a previous Forum we briefly touched
upon ‘logical operators’. Page 31 of the
manual seems straightforward enough, but
try this:

A=3; B=4; P.(A=B),(AoB)

Note the value of the first statement (false)
and the second (true). Now, repeat the
exercise but make A=-3. Oh dear! Now
we get values of -255 (false) and -256
(true). This can be very disconcerting, as I
found out once, when I used a logical
operator as part of a calculation. If you
printed the result in hex, you would see that
the result was calculated using ‘two's com-
plement’ arithmetic and the solution is to
AND (&) the result with 1 . This now returns
false = 1 and true = 0, but it’s at least
consistent, regardless of the sign of the
operators.

Interestingly, Acorn does not regard this
as a ‘bug’ - just different.

As written, the program occupies just
under ik in source form. The machine code
begins at #8400 and the keyword strings
are stored at #8600 onwards. I have re-
stricted string length to 1 5 characters, but
this may be altered by changing the ADC
instruction in line 25. Once you have de-
fined your strings, the whole could be
saved by:

*SAVE“KEYWORDS” 8400 87FF
Remember to alter the vector, as above,
after reloading.

How does it work? Briefly, location #322
to #33B and #33D to #356 hold the low
and high bytes of the various string point-
ers. The routine first sets these to begin at
#8600 ($A), and, if a shifted character is
detected (lines 35 and 40), looks up the
string (lines 50 and 55) and passes it
down, character by character, to the buffer
at #100 (lines 60-70), which then executes
the code.

Barry Pickles hosts this cash-for-tips
column. Here’s a chance to show off
your talents — and earn some crinkly
green stuff into the bargain. There are
reckoned to be some 40,000 of you out
there and, bearing in mind that the Atom
has been around for more than two
years, you must have accumulated a fair
amount of expertise.

What we’re looking for are those little
routines, tips and hardware mods
you’ve discovered. Don’t worry if your
little wrinkle seems too simple — it’s
probably just what someone else has
been looking for. The same rules apply
here as in Ian Birnbaum’s Beeb Forum.
Short, sweet and as original as possible
is the name of the game. I’ll start you off,
but this is your page, so let’s hear from
you!

Send your ideas to Atom Forum,
Acorn User, 53 Bedford Square, London
WC1B 3DZ. If you want it returned,
enclose a SAE. It should be typed or
printed, with programs on cassette (with
listing if possible).

j REM : Single key entry
3 P=#8400; PRINT:£21- E

; LDA#8;. S s?fl»?i n L ^T ii STfl * 81 ’ LD *®°

s TA#ooD,X; LDA#80; STA #3r?2 Y
' 5 LC ! ADC@16; STA.80; BCC P+4 ’

1 INC#81; INX ; CPX©27; BMI p~2^
JSR#FE94; CMP097; BMI P+9
CMPQ123; BPL P+5; JSR P+4; RTS
SEC; SBCS97; STY#AD; TAY

LDA#S-n b DX o AD; LDA#32 2, Y; STA#AE
LDA#._._>D, Y; STA#AF; LDY©0; imy

LDA(#AE) , Y; CMP© 13; BEQ P+16

DEY; LDA (#AE) , Y; STA#100 ,X

INX; INY; JSR#FE52; JMP P-ia

LDA(#AE) » Y ; CMP© 1 ; BNE P+4
LDh@13; STX#AE; LDY#AE; LDX#AC- RTS
3: PRTInjt*a ’ HL ' Krs

I; PRINT$6
'#20A=#8400;

END

-istlng 1 . imitates Electron's single-key entry

EE N: Label finder
j® S=0 ; PRINT*14; DO F-P.l

‘a IFP?1 <>255 SOSUBn

-0 UNTIL . P=13 AND p^l^s^

25 @=8; PRINTS 15; END

30n IFP? 3 >96; IFP?3<123 SOSUBn
35 RETURN UUSUBp

40p L=P? 1 *256+pT>2 • p=p++

S r,i 0 ? 00; 00 IFL<N. PRINT" "

-»0 N=N/10; UNTILL >N

55 PRINTL , tP ' ; P=P+LE N P— 1 ; RETURN

UM "S 2- Print, out J.Mled

ACORN USER JANUARY 1984

133

CUBEFLEX

6809 2nd processor for the BBC micro

CUBEFLEX for education and software development

CUBEFLEX is supplied with a number of useful
machine code handling facil'ties, and FLEX itself
comes complete with a text editor and machine code
assembler for 6809

However, the real strength of FLEX is the enormous
range of other software to run under its operating
system

Cross assemblers and macro facilities exist which
allow the CUBEFLEX to develop object code for all the
68 range from 6801 to 68000. all the 80 range, and the
Z80 The CUBE ROMULATOR can be added to the
spare slot in the CUBEFLEX. and so emulate the
developed software in a target system.

COMPILERS

PL/9 is a high level compiling language whose
structure resembles BBC BASIC However, when
compiled into machine code it runs four times as fast.

"C ", Pascal and 6809 extended BASIC are all also
available, and allow the user to employ the language of
his choice.

6809 + FLEX - the ultimate in 8-bit systems

The BBC microcomputer is already so good, how can it be improved? FLEX is the only truly machine
independent operating system for 8-bit processors. Even CP/M (for Z80) is machine specific to a
significant degree. But take any standard 5 1/4" FLEX diskette and it will load on CUBEFLEX. All
variations of double or single sides, 40 or 80 tracks (if 80 track drives are fitted), and even double
density (if an appropriate disk interface is fitted on the BBC) are automatically catered for.

CUBEFLEX connects to the BBC via the TUBE, and uses the standard BBC disk interface and disk
drives. All BBC facilities are unimpaired by the addition of CUBEFLEX, and can be called up or
returned to at any time. The FLEX configuration parameters are held in EPROM, and the
unconfigured FLEX diskette is read in and initiallised upon entry of the start-up command.

CUBEFLEX 6809 2nd Processor unit £299
Unconfigured FLEX diskette + manual £130

Send for
our free 150
page catalogue.

All prices exclude VAT.

I rede enquiries welcome.

Control Universal Ltd

Anderson’s Court
Newnham Road,
Cambridge CB3 9EZ.
Tel 0223 358757

The BBC Microcomputer
Specialists

GUILDFORD COMPUTER CENTRE offers
a complete range of Computers for
Home, Business and Educational
applications.

Large stock of additional equipment
available includes:- Printers, Hard/
Floppy Disc drives, Monitors etc., for
most makes.

An extensive range of Business software
(Accounts, Stock, Payroll, Word
Processing etc.).

Drop in for a frank discussion and expert
advice on your requirements or arrange
a demonstration. We give a full and
expert backup to ALL our sales.

Stockists of:- BBC/Acorn, Torch, Oric,
Olivetti, Hitachi, TRS-80, Commodore,
Dragon, Sharp, Sirius, Osborne, IBM,
Newbrain, Epson, Seikosha, Cumana,
etc.

GUILDFORD

Qz commodore

Olivetti

HITACHI

cSoter mrnn trs-so

COMPUTER

-E-N-T-R-E

1 The Quadrant, Bridge Street,
> Guildford, Surrey.GUl 4SG
Telephone (0483)578848

134

ACORN USER JANUARY 1984

ATOM FORUM

| KEEP A TAG

ON LABELS

LINE labels are used to speed program
execution - and very useful they are, but it
helps to know how they work. When a
program is first RUN, the interpreter, on
encountering a line number followed by a
label, stores the address of that line in a
table.

Label @ is stored at 38D/38E and other
labels consecutively. So, after the first
encounter with the label, the interpreter
simply looks up the address and performs
a jump.

As you can see, if a label is used only
once, there will be no saving in execution
time. However, since the label vector is
reset every time a labelled line is encoun-
tered, it means that if you take care with the
structure of your program the same label
may be used more than once. The follow-
ing trivial program should help clarify this:

10 C=0

15a REM- FIRST USE OF LABEL
20 P."X”; C=C+1; IFC <10 G.a
25a REM- SECOND USE OF LABEL
30 P.'T’; C=C+1; IFC <20 G.a
35 RUN

Finally on this subject, there is an undocu-
mented label. This is [ . The reason why it’s
not mentioned by Acorn is that, on BREAK,
the label vector area is initialised to zero,
so that jumps to unlabelled lines generate
a search for the label. Label [ is not
initialised, so take care if you use it. The
vector is stored at 3C1/3C2.

FOLLOWING my look at the BBC Basic
conversion board, Keith Williams of Wol-
verhampton has been PEEKing at various
locations and found that PRINT $32775
gives a copyright message, which has him
confused.

A string is a series of characters ending
in a carriage return (hex D). The number
32775 is 8007 in hex format, which is a
location in the Basic interpreter ROM,
where you might expect to find a copyright
message. A disassembler reveals that this
message is followed by a carriage return,
so the Atom looks at it as a string.

Odd PEEKs and POKEs like this do no
lasting harm but, as you might expect, if
you do something that you’re not sup-
posed to do, you get unusual results! If you
find a ‘real’ bug, I’d certainly like to know
about it, but let’s not get involved in the
‘Sinclair bug' syndrome that covers the
letters pages of other mags.

Now to a more serious matter. Mr
Howell-Pryce of Faringdon writes that,
while his machine obeys COS commands

HAVE you tried using the READ/DATA
simulation in the manual? Painful, isn’t it?
Listing 3, adapted from the ‘Son of Word-
pack’ program given in a previous Forum
(July issue), provides a better solution.

Data must be entered, each item on a
separate line, after the end of your
program.

Two subroutines, r and n, are given, one
for strings and one for numbers. As an

normally in Atom mode, switching to BBC
mode disables the ‘CAT, ‘LOAD and
‘SAVE options. This is not normal.

While diagnosis at a long distance is
difficult, I'm 95 per cent certain that he has
a faulty MOS ROM. The following program
produces a unique checksum for the ROM.
It takes 20 seconds to run and, if the ROM
is OK, should produce the answer 7DB40.
If it doesn’t, the whole unit should be
returned for examination and repair. The
ROM address is held in A% (line 20) and
the end address is contained in line 50.

It’s worth while running this routine on
every ROM and keeping a note of the
checksum, in case the machine fails at
some future date. The checksum for the
Basic interpreter should be: 1 B36F8

10 REM: CHECKSUM (BBC BASIC)

20 A% = &F000: B% = 0
30 REPEAT

40 B% = B%+(?A%): A% = A% + 1
50 U. A% > &FFFF
60 P.“CHECKSUM IS B%

added bonus it also saves memory since,
normally, strings are stored twice - once in
the program and once in the string storage
area, after the program text. If you wish to
store string arrays, then, after DIMension-
ing, allocate the value of the pointer Q to
each element of the array, using a FOR
. . . NEXT loop. The array will thus store
only the address of each element rather
than the string itself.

NEGLECTED MODE

MODE 0 is a neglected graphics mode on
the Atom, but some interesting effects can
be obtained with it. To plot in grey, just type
the following, after CLEAR 0:

F.L=#8000 to #8200 S.4;

!L=#C0C0C0C0; N.

All white lines will now appear in grey. To
plot black on grey, alter the above line
making !L= -1 .

The 6847 video chip has two colour
palettes, the alternate one being selected
by ?#B002=8. Try drawing something in
mode 0 as grey on black, then add the
following line.

DO ?#B002=8; LI.#FB8A; ?#B002=0;

LI.#FB8A; U.O

You should see your drawing flashing dark
and light and on a colour Atom you’ll see it
change colour rapidly. Plotting black on
grey has an even more dramatic effect,
since it is now the background which
flashes.

Inverse characters will also flash, but
you really need a colour board to appreci-
ate the difference.

10 REM Initialise
20 0=718*256; DO Q=Q+i
•-■0 UNTIL?Q=13 AND Q'?3=CH"d"

40 0=0+4; P=Q. GOTo r
50 REM Restore
60s Q=P; RETURN
100 REM READ Demo
U0r DIM T (32) ; DO T=Q

III REM N ^ a ! 0=B+l - EN( T)+3i UNTIL?GMCH".»,en

160d JANUARY
170 FEBUARY
180 MARCH

190 *; REM Terminator

numbers

,T(3

220 FORN=0 TO 2; NN(N)=Q
--■0 0— O+LEN (Q) +3j NE y T
240 FORN=0 TO 2; T=NN(N'
250 PRINW; NEXT; END

Listing 3. Better for data

WAY ROUND A PAINFUL SIMULATION

ACORN USER JANUARY 1984

135

The BBC Sideways RAM System

The BBC Sideways RAM:

The most exciting add-on for the BBC micro, which many have been waiting for Acorn to
produce!

Neater, more reliable and far more economical than plugging in more ROMs into your
BBC!

What is the Sidways RAM?

The sideways RAM is a 16K (upgradable to 128K) memory board which fits into the
rightmost ROM socket on your BBC micro. The sideways RAM is an essential piece of
hardware for any BBC computer. Strategically integrated into the BBC system, the system
is capable of:

Running Any Languages, Wordprocessor, Electronic Spreadsheet:

The sideways RAM allows you to run any software normally available in ROM such as
WORDWISE, VIEW, BEEBCALC, BASIC2, FORTH, PASCAL, BCPL, EXMON, DISK
DOCTOR, NET FILING SYSTEM, ENHANCED 16K DISK FILING SYSTEM, SPEECH
ROM etc. . . These programs can be saved on disk or tape and loaded later in seconds
into the sideways RAM.

Giving 27K Bytes Free with Acorn Disk Filing Ststem:

The sideways RAM can also be used to increase available memory for BASIC,

BEEBCALC, WORDWISE, VIEW etc. by moving disk workspace into sideways RAM.

PAGE is then set to the lowest possible value, i.e. &OEOO.

Creating and Maintaining a Silicon Disk on your Computer:

If you have 128K of sideways RAM, 1 12K of it can be turned into a silicon disk. The
system will address your floppy disk as drive 0 and the silicon disk as drive 1 but with a
difference! The silicon drive has the capacity to load a 32K program faster than you can
remove your finger from the RETURN’ key with no clicking noise, no on/off LED, no wear.

It can make you a backup floppy in 15 seconds from the original. The sheer speed of
sideways RAM makes 3D-graphic look like a movie picture. It’s life in the fast lane!

Free Software with Every Sideways RAM System:

The Sideways RAM comes complete with lots of free software, now and with future
updates. The free software includes “ROMCOPY” to move sideways ROMs to disc (or
tape), STL0E00 to move disk filing system workspace into sideways RAM thus giving 3K
bytes extra memory to BASIC, WORDWISE, VIEW, BEEBCALC, etc., STLDISC to create
and maintain a SILICON DISK on your system with extra disk facilities and demonstration
programs.

Future releases include our own DFS (JAN. 84) and SILICON 100K DISK BASIC
(MARCH 84). All sideways RAM system software is given in basic source code. Users are
encouraged to personalise and benevolent contributors will be rewarded with free
hardware gifts.

Increase the Computer Power by Increasing Sideways RAM:

The BBC comes with 32K of RAM and has access to a maximum of 3 languages. The
BBC with 1 6K sideways RAM has 48K of RAM and has access to a wealth of languages.

The BBC with 32K sideways RAM can run 2 loaded languages at the same time. The BBC
with 128K sideways RAM can run 8 loaded languages at the same time. The power of the
BBC relies on its intelligent use of software where several sideways ROMs execute
different tasks such as filing, processing, debugging etc. The bigger the sideways RAM,
the bigger the task the computer can handle.

The sideways RAM is such a powerful and promising device that ACORN HAS PLANNED
to release a similar system on the ELECTRON.

Rather than being a software piracy aid, the Sideways RAM system is the key solution to
selling more software to BBC computer users. This is because powerful sideways
software can be shared by users of the same network and sold cheaper on tape, disk or
by electronic mail.

Beautifully Designed, Easily Installed, no Soldering Required:

The sideways RAM was first introduced and the first issue sold out at the ACORN USER
SHOW (Sept. 83, London). The new issue has been exhibited at the PCW SHOW
(Oct/Nov. 83, London) and will be on general distribution release at the BBC USER
SHOW (Dec. 83, Westminster, London). The system can be installed in 2 minutes by
yourself or most BBC dealers and requires no soldering.

HERE IS HOW:

Open the computer case, plug into the rightmost sideways ROM socket the cartridge base
unit (see picture 1). Install your sideways ROMs, one at a time, onto the mini ROM
cartridge (see figure 2), insert the cartridge into the base unit and CHAIN ’’ROMCOPY”.

This program will save your sideways ROM on disk or tape. Locate S20 and S22 jumper
blocks on the computer board. Replace the jumpers with control wires from the base unit.
Install the sideways RAM card in place of the mini ROM cartridge. Switch on the computer
and ‘LOAD any program saved with ‘ ROMCOPY”. Press the BREAK key. Call up your /
sideways software as usual. For example, ‘WORD etc.

Further upgrading to 32K or to 128K is very simple: from 16K to 32K is by / cX
straight exchange (cost: £12 + p&p), from 32K to 128K is by plugging in the / ' r TO
SOLIDISK extension (see figure 3) onto the 32K sideways RAM. It costs '
just £76 plus p&p. / / r y

OTHER PERIPHERALS FOR THE BBC MICRO: / &

We are stockists of the EPSON range of PRINTERS, the SANYO range of * 'V
COLOUR MONITORS, disk drives from various manufacturers and /

floppy diskettes (WABBASH, VERBATIM, DATALIFE, DYSAN etc.). /

Ring us for a quotation. /

MADE IN ENGLAND /

BY SOLIDISK TECHNOLOGY LIMITED /

17 SWEYNE AVENUE SOUTHEND-ON-SEA /

Essex SS2 6JQ
TEL: SOUTHEND (0702) 354674

THE CARTRIDGE BASE THE ROM CARTRIDGE

muur

THE SIDE WAY RAM CARD

THE SILICON DISK EXTENSION

INSTALLING THE CARTRIDGE BASE

/

/

USING THE ROM
CARTRIDGE TO TRANSFER
SOFTWARE ON DISK

THE SIDE WAY RAM /
NOW REPLACES THE y
ROMS j '

/

* /

/

/

THE SOLIDISK SUPER
FAST DRIVE IS NOW /
INSTALLED /

/£'

/ Jo '

CHRISTMAS ADVENTURE

IT WAS a mild August evening, as we sat in
the bar of the Cunard Hotel, sipping cau-
tiously at our Electron cocktails. A tall gent,
carrying Covent Garden in a glass, passed
by.

‘What on earth is in this thing 9 ’, ex-
claimed Bruce. ‘Dunno’, said Jeremy, ‘but I
think they left the ULA in mine 1 ’

‘It gets better after the fifth one,’ said the
floor We looked down. It was the man from
the BBC.

‘Where’s Tony 9 ’ asked Mad Alex, alias
the guy from Acorn. ‘At the printers,’ we
chorused 'What again?' came the retort
A tall gent, carrying Covent Garden in a
glass, passed by

Any ideas for Christmas?’ ventured Pat.

‘Well,’ said Joe, ‘we could dress Tony in
a Santa suit and send him off down Oxford
Street, with a pile of Trek tapes.’

‘I heard that,' came a voice from behind

Barry Pickles
looks at the funny
side of Acorn User
and produces a
special program

It was Tony. 'And I don’t care how hard up
we are, you’re not going to get me in a
funny red suit and a false beard!’

‘Oh, I don’t know,’ remarked Kitty, eyeing
Tony’s funny red suit, 'it looks rather fetch-
ing, especially the beard.’

‘Ho, ho, ho!’ replied Tony, fishing some-
thing out of his pocket. Kitty ducked.

‘Mmnnff,’ agreed Joe, removing the re-
mains of a 3in disc from his mouth. ‘Hmm’,
he mused, ’the ultimate benchtest!'

‘Well, we’ve got to do something,’ inter-
rupted Pat.

’Look,’ hissed Mad Alex, ‘I don’t know
why you’re bothering. They'll all be too
busy playing with their second processors
to care about your miserable jottings!’ As
the laughter slowly subsided, a tall gent,
carrying Covent Garden in a glass, passed
by, a smile flitting across his face.

‘Besides,’ said Tony, attempting to bring
some order into the proceedings, what
about our Atom readers?'

At the mention of the magic word, my
brain began ticking over, slowly . . . very
slowly. A tall gent, carrying Covent Garden
in a glass, passed by . . .

And so, gentle reader, was conceived
an idea, the fruits of which you are reading.
(Well, I did say that my brain worked
slowly.) It’s a 'find the treasure’ game, the
scenario being set out in the title page. The
idea is to ask the computer questions,
such as 'Is it in Western Samoa?’, which

5REM xmasaduenture
6REf1 B. PICKLES - i 983

10GOS.m;$T="EEE EEE EGCD"

20P. $]2 ; > > > 5 > > ) »•

xms HDUENTURE"’
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60P. HE WAS DUE TO DELIUER LOTS OF" ’

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press TJ° FIND m "”'

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260 ? P. ? p ,i ; p.p, 1 . ? T , ?Tf , L
270qU. F= 1 ;P= 12291 ;R.

280REM-mu s i c
290mP. $21 ;P=#2800;n=P;[

300LD y @ 0 ;S t Y# 83 j ld ^28A8,Y;LDX@0

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370CL r °'pRri BnlP + 57 5CnP ® #48 JBPLP+53
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380LDA#28A9,Y ; criP @ «23,-BNEP,4 ?nx L
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it,n 9 I- Takes un , J ,IN> ,K 1

Listing 1 . Takes un >'* .

you type it in P 2 '° Wer ,ext s Pace. Be very careful how

ACORN USER JANUARY 1984

137

CAMBRIDGE
PROCESSOR SERVICES
LIMITED

Britain's No. 1 independent
service centre for
the BBC Microcomputer

# 1 S’ 2 year service contracts for the BBC
Microcomputer all models including
annual service and testing.

# All upgrades carried out - please
telephone for availability.

# Fast turnaround - micros repaired,
tested and returned within 5 days of
receipt.

# While you wait service — please
telephone for appointment.

# If micro already faulty - immediate
repair and service carried out including
a service contract for small extra charge.

ATomic.

ympcHinecoDC

A book containing 23 fully explained machine
code programmes for the Atom.

DATA SORTS# MODE 4 CHARACTERS#
GAMES # POOLS PREDICTION • TOOL KIT#

Over 5CK of programmes in 1 book for £5.75 inc.
Book and Cassette (source code) £15.50.

Book and Cassette (ready to run) £15.50.

Cassette only £1 1.50.

TOOLKIT

20 useful programmes for the BBC on one cassette.

BAD PROGRAMME LIST • BAD
PROGRAMME FIX • FIND PROCS#

FIND DEFPROCS • DISPLAY MEMORY#
BIG LETTERS • FIND BYTE# FIND
VARIABLE # AND MANY OTHERS.#

£3.95 inc.

ECCE Productions, 3/73 Station Road,

Sidcup, Kent. DAI 5 7DR.

Tel: 01-302 1667. (Mail order only)

# The only extra you pay is carriage and
insurance to our premises subject to
contract.

12] Please tick service required

□ I enclose ,£29.90 for a 1 year Service Contract
] I enclose £39. 1 0 for a 2 year Service Contract

[2| I enclose £40.25 for a 1 year Service Contract
and immediate repair

□ I enclose £48 30 for a 2 year Service Contract
and immediate repair

SIGNATURE

INITIAL

SURNAME ( MR MRS)

POSTCODE
TEL

If paying by Access-Card Number

Serial No:

Send remittance and micro ( if applicable ) to:

Cambridge Processor Services Limited,
Unit 3, Trinity Farm Industrial Estate,
Nuffield Close, Cambridge CB4 1SS

L

If you wish to order by telephone using Access, please
telephone (0223 ) 313245

If for any reason you are not satisfied with the contract please return
within 14 days of receipt for full refund. If you have also sent your BBC
Micro for repair and testing a charge of <£28 75 wfil be retained by us for the
repair and handling Your statutory rights are not affected.

j

CURE FUNCTION KEY
PAPERITtS WITH RIPSTRIP!
ONLY £1.49 im

The function keys are one of the best features of the
BBC Micro except when it comes to labelling them for
each program.

Now instead of all those scraps of paper creeping to
the back of your machine, you can add one FLIPSTR1P
- 10 strips in one spiral-bound package. Write on
FLIPSTRIP yourself or stick on the strips supplied with
software.

Only £1.49 + 26p post and package - or order 5 post
free! Send cheque or P.0, made payable to FLIPSTRIP
to the address below: £1.75 for 1; £7.45 for 5, post free

EDUCATIONAL AND TRADE ENQUIRIES WELCOME

PL

C

s

T

CP

18 Greek Street, London W1V 5LF. 01-437 1674 ®

138

ACORN USER JANUARY 1984

can only elicit a yes/no response. The
computer won’t actually answer yes or no,
but it will tell you if you are close. When you
actually find it, you will be greeted by a
special message, and a seasonal tune.
The key may be found anywhere in the
Universe — or even outside it! But beware
of black holes. The computer can respond
to any input, in any language (although it
replies in English), as long as it is preceed-
ed by ‘Is it’ or ‘Can l‘.

You may repeat the game and the key
will, usually, be found somewhere different

from its previous location.

Because this type of game is often spoilt
by reading the listing as you type it in, the
crucial section has been encoded, so be
very careful how you type it in. The pro-
gram takes up 3ik and listing 1 should be
entered in the lower text space, as normal.
Once this is done, type: ?18=#30 (CR)
and then enter listing 2 (the coded one).
Break and OLD before running the whole
thing. I’m not going to tell you how it works,
this month, but I warn you against breaking
out of the program while it is running. This

may wreak havoc on your carefully typed
listing! Wait until the 'Game ended’ mes-
sage appears.

Finally, a word about the routine that
produces all those musical effects which I
cannot claim credit for. It is a modified
version of a routine published about two
years ago in Your Computer. I used it
because I had it and knew how to use it
easily.

Next month, I'll give you a ‘decoded’
version of listing 2 and explain how it all
comes together.

10SFN2 2 2 fi J TUJOH23

2^ EJNB75<2>B/S/8<6 ’ 2 <F>B/S/&21 , 26 <D> J

30Q/#PL 2X1 buc tsuifsgjstusruftljjpo#c
40t JO/*B <n>HFOB <R>BCT jri. F* <*B> *B , 6

50JGR>1 2D>D, 2<JGD>22H/f
PUIFS!XBl«C<H*t POtU!UOEFSTLIBOE ' USJ! ' ,LI!BO

20 J G 2 B/S/&6 1 > 24 2 *U> #D 2 B 2 # <H/z

80Q/#J 2BN#*BC#N22TFOTPST2 JOEJDBUF 0 # C
*o.H :»™' N Q ^ !BSF5 " ,sz!DnpTF * [ — b

.BDH, 0 <mJ” B ° ER ' 7!a2 * EPU!BSF!BnpTF * [ <«J>
110JGR?62BOER=222Q/#2PU2BSF2TPNF°EJTLIR

ODF2BXB2#C <*U>#D2B#<I1J/N
1 20JGR721 2Q/#0PUI JOH#C <t1J/N
1 30Q/"4tX I BU 2 OPX@# C <H/t

140<Q^23CC#2FT #CC<G/0>2UP4

1 50*U>#B$D$G# <U> LJ , [1F0U <@U> :5<^3U, 2*>#B
$/GD$# <U>$39B9 >4 * B

1 60H J /N <0/ <*U> #B$# <n J /N

^170Q/# 2p ^239# i buf#^2334» 9P v,oe^239#j u

HBJ0^#C^C c'^^^* EP ^ F " # ^ TB0UB * DBB * CSFBLJIF *®
1S0G/O>2UP21 1 <XBJ LI <0/ <Q/# J PF1E 2 P0///V# [
200Q/#j 2 IBWF2B2NFTTBHF2DPNJOH2JO////# c

210@U>:5a3U,2*>4<HHH2H2H2HH2H2HHOH#<U>

$33B9 <G/0> 2UP5 <MJ /N <0/ <U>

220SFN2 2n f ttbh f

CC

230Q^23#UP2Bnn2PUS2bu P n2SFBEFST///^#

^ 240Q/# 2 2 2XF2 IPQF2UIBU22PU2IBLIF2B2LJSUM2
u 250Q/#IBQQ2SDISJ TUNBT-2BOE2XF2XJTI22PU

# 260Q/1 *QFBDF 2 BOE 2 DPOLIFOUNFOU 2 U I SPUH I PUU

270Q/#UIF2DPNJOH22FBS/#C

280Q^UIBOL22PU2GPS2SFBEJOH2bd P so#*239

t s 4? C

290Q/# 2222222222,. #C C

# 300Q/# L)PO2SRUJOOS 2 2 2 2 2 2 2 2 2 2LJUU22NJMOF

31 0Qz# o o oooooo 2CBSS22QJDLI1FT# C
320Q/# o o 2 BOE 2 BFIf1 2 BU 2 2 BEE J TPO. XFTI1F2# C
330*Ll> #DG2 GHGFE 2B$2 2EH2H#<U>U, HFOU <@U>

# o

340^1U,2*>#B/HGF2D2D2#<U>U,nFOU<@U> :5

39B9 J ° ’ 2;t:> #B *° B ° *° B/HG *° E S 2 DDE 2 H 5 F 2 G# < U > $

360snj 2 N<nj/N<Q/#QnFBTF2XBJU/ 2 #( <@23>$

o • \o/

370zQ/4r 2 3#PIo EFBS ,. flUEUFS

BDFXBSQ-2JCUF#C *ur*tJ.bbf-BL2TQ

380Q/#nBOEFE2PO2UIF2QnBOFU2PG2USBnri4tC
390Q/#. BOE2XF2Bnn2LOPX2XIBUCT2UIFSF- 0 0
EP0CU2XF@/z//z#c hbF **

s*U239#c f bt u4U23 : C <H/s

Listing 2. The coded listing

ACORN USER JANUARY 1984

139

and this is my story. A story
of beautiful mermaids,
bored robots and dank, dark
dungeons; A story that Q&,
started one muggy day . RcJ
in New York, and like ^aSf‘
the Big B£ple, it’s . M \

rotten, to the core. jnSRcgl

17 OTorfollc Road, Brighton, Bast Sussex, BN1 3AA.

Look out for Dan Diamond’s next Adventure Series “Franklin in Wonderland” Available Spring 1984

140

ACORN USER JANUARY 1984

REVIEWS

FIVE PACK
WITH FLAWS

Utilities Pack, Salamander, model B. £9.95

SOUND and envelope editor, Epson
screen dump, teletext screen editor and
analyser, and a disassembler come cour-
tesy of Salamander in one box.

All these programs are in a form where
copying to disc is possible, but the sound
and Epson programs are too large to run in
the available memory. The latter can be
corrected by changing page to &1 100, but
the former needs page to be at &0E00, and
so needs shifting, or loading from cassette
with page set to &0E00. Neither of these
facts is mentioned in the manual.

The sound program is pretty standard. I
copied a similar one from Personal Com-
puter World about a year ago - though I
then spent the best part of a week de-
bugging it and correcting the algorithms!
You can change all the various parameters
for sound in one section, and for envelope
in another, and a graphical display is
provided to show the current pitch and
amplitude envelopes, and the current val-
ues of the parameters. The instructions are
rudimentary, and the user is referred to the
User Guide for help - not that the beginner
will get much from that source!

The Epson screen dump is very versa-
tile, dumping any part of the screen in any
mode. The section of the screen to be
dumped is selected by pressing
T,B,L,R,H,W to alter the top, bottom etc
sections of a flashing box on the screen.
This is an excellent feature, but the keys
sometimes do more than you expect. Un-
fortunately, the quality of the resulting
dump is pathetic in anything but mode 0.
The patterns selected are simple stripes,
and produce a distorted and ugly output.
The program is actually a hybrid, using the
Basic section to set various parameters, so
you must have a text window of at lest three
lines for operation to be possible, and
page must be reset to &1 100 if the dump is
to operate from disc in modes 0, 1 or 2.

The best program is the teletext screen
analyser and editor. This allows you to
examine the mode 7 screen, detecting all
the control characters, and the ASCII
codes of all printed characters (including
graphics) by moving a cursor around the
screen. The characters are displayed at
the bottom left of the screen, and the
current x and y coordinates, and the ASCII
code at the bottom right. You can edit,
draw and save pictures, and recall them
from memory. Drawing your own pictures
seems restricted to the normal ASCII al-
phabetic character set, and to the non-
systematic graphics characters with codes
less than 128. These are rather tricky to
use! (A detailed diagram of the graphics
set is included in the User Guide.) Peculiar
things happened to the cursor at the cor-

ners of the screen. This program trans-
ferred directly to disc without trouble.

The disassembler is in machine code,
designed to sit at the top of memory in any
one of modes 0 to 2, 6 and 7 (but not
modes 3, 4 or 5). It suffers from the usual
problems with any disassembler, ie, lack of
friendliness,* and an inability to make a
sensible decision as to where to start
disassembling. If you start in a data table
for instance, you are most unlikely to get
sensible disassembly of the subsequent
program.

To summarise. A good package of use-
ful programs, all of which are, unfortunate-
ly, slightly flawed.

George Hill

KONG VARIANT

Escape from Orion, Hopesoft, BBC B, £8.95

THIS (almost) non-violent game is a vari-
ation in the Donkey Kong genre, ie, a little
man climbs ladders, jumps gaps and mov-
ing hazards to collect objects (by jump-
ing), all against the clock (a decreasing
bonus).

In this game you’ve made an emergency
landing to pick up tools, water, fuel rods
and oxygen. When you’ve collected a
screenful, you pop back to your flying
saucer only to fly into another screen. But
you never actually escape from Orion -
when you’ve cleared the four screens (fast
missiles, lifts, conveyor belts and electri-
fied doors) you start again at the next
difficulty level (maximum of nine). You can
start the game from any of the four
screens.

This is a fun little game that can also be
used with a joystick. It has pleasant graph-
ics, albeit spindly, and reasonable sound
effects. Jumping gaps is sometimes diffi-
cult, as is often the case with this type of
game. But persevere. Verdict: fairly bland
- save up for Killer Gorilla.

Alan Pipes

THREE PRACTICAL
GOODIES
FOR THE ATOM

■ Atom ROAM board, Timedata, £35

■ 6502 Assembly Language Program-
ming by Lance A Leventhal, Osbor-
ne/McGraw-Hill, £11.95

■ Practical Programs for the BBC Com-
puter and Acorn Atom by David John-
son-Davies, Sigma Technical Press,
£5.95

GREAT stocking-fillers they may be, but
where do you fit yet another Atom utility
ROM? An ingenious solution is Timedata's
ROAM board, a combination of ROM se-
lector board and 4k RAM expansion. The
concept is simple: put your three favourite
ROMs into the sockets provided for easy
access, and keep the less common ones
on tape or disc, to be loaded into RAM
when needed. The RAM, at #A000, can
also be used for more general data
storage.

You could even modify the features of
ROM-based software by moving it into the
RAM first, or develop your own super
toolkit, with the best features of all the
others.

If learning machine-code is high on your
list of New Year resolutions, an excellent
book to consider is 6502 Assembly Lan-
guage Programming by Lance Levanthal.
Each 6502 instruction is briefly but ade-
quately covered, but the author really
scores by providing a host of useful rou-
tines (seven chapters' worth!) for common
programming tasks, with exercises to test
and stretch your understanding. Interface
chips, interrupts, design, debugging and
documentation all receive the same thor-
ough treatment.

The book is not machine-specific, but
don’t let that worry you. It’s a fine reference
work, which you’ll consult time and time
again. A wealth of information for your
money.

For those who’d like machine-code effi-
ciency without tears, take a look at Practi-
cal Programs for the BBC Computer and
Acorn Atom by David Johnson-Davies. The
final chapter (worth the price of the book
alone) details a complete, if modest, com-
piler for SPL, a Simple Programming Lan-
guage. This takes high-level statements
and converts them painlessly into fast,
compact machine-code. For the more am-
bitious, the author also suggests ways of
expanding the compiler.

Other chapters cover games, graphs,
and words and numbers, presenting seri-
ous concepts in an entertaining and easily
digested form. In all, a welcome blend of
theory and fun.

Vincent Fojut

ACORN USER JANUARY 1984

141

HARDWARE AI>,D
SOFTWARE

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103 LEDGER Complements CASHBOOK with ageing & analysis f 7 95

105 MAILING Holds 218 addresses Alpha & post code sorts, fasi search

any format labels & delete, add and amend £ 7 95

106 PAYROLL In 2 parts to handle weekly or monthly (state which) PAYE &

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106a Manual 30 page A4 manual with examples Extra No VAT £ 2 50

107 MEMO-CALC Database 'Calcsheet with up to 255 columns, string or

numeric data, sorts, searches, calculations, with automatic
fully formated printout facility f 9.95

107a Manual 20 page A4 manual with examples Extra No VAT £ 2 00

201 GAMES 1 5 Card. Minefield. Darts. Pontoon & Mrmidon £ 4 95

203 HANGMAN Word game in English. French, German. Italian. Spanish £ 7 95

301 BANNER Print large text and graphics on paper for displays £ 2 95

302 DISTANCES Three graphic maps of U K . EUROPE & the WORLD

Calculate the distance between any 2 places £ 4 95

303 FLAGS 98 full colour flags of the world with questions £ 4 95

304 STATPAK Statistics package giving over 30 results £ 9 95

504 PROCAID includes SEARCHBAS to search a BASIC program and alter

it, PROCVAR to list variables in a BASIC program A
PROCFLUSH to clear resident integers in RAM £ 3 45

505 UTILITY-A Our best selling tape includes PROCAID.

DEFCHR to design, display & store graphic characters.

SORTM C a very fast machine code numeric sort.

SORTBAS The undisputed fastest BASIC sort routine £ 5 95

600 FORTH 79 FORTH second language ROM for either OS £34 74

601 LOGO FORTH Advanced Turtle Graphics Language ROM £55 00

602 PASCAL T Structured language ROM with compiler interpreter £55 00

603 XCAL Computer Assisted Learning ROM £65 00

605 WORDWISE Superb fast & easy Wordprocessor in ROM £34 74

606 BEEB CALC ROM based spread sheet with floating point maths £32 50

607 DISKDOC ROM for disk problems in format, search, files etc £27 50

700 BOOKS Various titles for the BBC Micro from £ 6 95

801 CASSETTES Cl 2 Computer quality tapes boxed in 10's £ 4 50

810 5 25 " DISCS MEMOREX Soft sectored 40 track S/S discettes £19 95

900 SEIKOSHA GP700A NEW 7 COLOUR dot matrix printer 50cps £369 00

901 EPSON RX 80 Superb printer lOOcps. 3 fnts. graphics, tractor £269 00

901a EPSON RX 80T/F Same as above, with Tractor and Friction feed £TBA

902 EPSON FX 80 Magmficient 1 60cps 6 founts, graphics. F/T Roll £379 00

910 DISCDRIVES Slimline TEAC or MITSUBISHI with power supply. 100k

800k format disc cable and excellent manual From £199 00
920 VDU STAND Stainless Steel Support protects your micro £19 95

930 COLOUR TV 14 Colour Monitor lOMhz 430 pixels £189 50

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FRENCH ABROAD £7.95

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Epson FX-88 Printer £379

NEW Seikosha Colour Printer £360
PflVROLL (Meekly or Monthly) £17.95

The nost successful Payroll for the BEEB

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OISIT us on Stand 35 at the flCORH EUICMIOH Shoo in Januaru

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‘The Record Changer’

32K £19.95 Cass. £24.95 Disc.

for indexing, membership lists, directories, inven-
tories, budgeting, etc., etc.

don’t buy a database in the dark -
check the spec!

‘The Wordsmith’ 32K for Centronics 737/739

AND NOW FOR EPSON FX80:

£19.95 Cass. £24.95 Disc.

For Reports, Essays, Thesis, etc., etc.

Forget control codes - let Wordsmith’
realise your printer’s potential

Options Timetable 32K
£14.95 Cass. £19.95 Disc.

A must for every secondary school. This programme
helps with the timetabling of pupils’ 3rd year option
choices. Try the effect of any changes to your
Options Timetable and let the micro do all the
donkey work.

Simple Word Processor 32K
£9.95 Cass. £14.95 Disc.

Picture Maths
£9.95 Cass. £12.95 Disc.

An arithmetic practice Program for primary schools.
Uses the BBC Graphics to keep the pupils' interest.

Venn Diagrams
£9.95 Cass. £12.95 Disc.

Solve the Venn Diagram problems. Primary/junior
pupils.

Tape Catalogue
£5.95 Cass.

Catalogue all your tapes using this program and
never lose one again.

Copy Disc
£9.95

Copy disc to tape, tape to disc M/C, Data or Basic.
Forget HEX addresses this program does it all.

ROM Read

£8.95 Cass. £11.95 Disc.

A machine code program to read the contents of
any ROM socket and copy to RAM, tape or disc. Not
to be used for illegal copying.

Machine Code Disassembler
£5.95 Cass. £7.95 Disc.

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inc. Send for details.

Epson Printers
FX80 £370+ VAT
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142

ACORN USER JANUARY 1984

REVIEWS

TV START
FOR USEFUL
TRACKMAN’S TOOLS

BBC Micro Toolbox by Ian Trackman, BBC
Publications, BBC model B (series 1 OS), £21

TOOLBOX is an extremely useful collection
of 25 utility routines. They are all written by
Ian Trackman, whom many of you know
from the BBC series Making the Most of the
Micro; and indeed, it seems that most of
the routines were written to help him pro-
duce programs for the series.

The routines fall into two groups: the first
consists of 13 routines which are designed
to be incorporated into your own
programs.

For example, there are six sorting rou-
tines: a circle draw and fill; two double-
height character generators (one for
modes 0, 1 and 4 the other for modes 2
and 5); a machine code graphics dump for
the Epson MX80; and a generator to output
numbers through the speech chip. All of
these can be used in programs without
breaching the copyright.

The second group consists of programs,
all but two in machine code, to allow
various testing and debugging operations
on Basic programs, or to allow you to
globally alter your Basic programs. For
example, there is a cross referencer, which
will output lines containing a specific
keyword and text (ie it is equivalent to a
‘find’ utility); a replacer, which will change
any part of a Basic program into anything
else (eg it will change VARI% to V%
throughout the entire program); a packer,
which will squash as many lines as possi-
ble together into a single line (this is one of
three 'squeeze' utilities - the others are a
space remover and a REM remover); and a
variable dump, which outputs all variables,
including arrays, used in your Basic pro-
gram except the static variables (ie A% to
z%) - but the program has to be run and all
the relevant variables created, for the utility
to be used to maximum effect.

The software (on tape) comes with very
comprehensive documentation: a 208-
page book with full instructions for each
utility, full listings for each utility (for the
machine code ones, the source code), and
clear details on where in memory to put the
routines for both tape and disc machines.
There is also a section on how to relocate
the machine code programs, which unfor-
tunately proves to be a rather messy op-
eration in most cases.

This is a very well-produced and well-
thought-out package for the serious pro-
grammer, and is highly recommended. I
look forward to the second part which is in
preparation.

Ian Birnbaum

CHIP COCKTAIL

Transistor s Revenge By Chris Butler, Soft-
spot, model B (any OS), £6.95

TRANSISTOR’S Revenge is beautiful to
watch, has nice sounds and is mindless to
play. It’s a game that really shows BBC
graphics at their best.

In the centre of the screen is a large
integrated circuit labelled ‘6502’. From this
radiate printed circuit board tracks to the
edge of the screen. Various electronic
components move slowly and smoothly in
along the tracks and occasional fast volt-
age spikes zip in. You control a cursor in
the 1C and fire your own spikes along the
tracks to blast the components. The con-
trols are responsive and fast, and, with
practice, you can send impressive groups
of spikes along adjacent tracks.

If any component reaches the 1C or an
incoming spike hits the cursor, the 1C
explodes. To add to the interest, every so
often, bonus tools appear at the edge of
the screen: hammers, spanners, pliers and
something like a cocktail cherry on a stick
with a piece of gherkin - perhaps it’s a
software tool.

After you’ve lost three ICs, you get the
chance to either stop or carry on. In fact,
it’s easier to carry on which adds to the
game’s mindlessness - you stop caring if
you get hit. If you do decide to give up, you
can enter your initials.

The transistors, capacitors, resistors,
LEDs, spikes and explosions are a joy to
watch but unfortunately, the game hasn't
much else to offer. Your responses are so
limited, there’s little to develop in the way of
tactics or strategy - it’s all a matter of
refining your skill. Transistor's Revenge is
really just a version of space invaders with
the aliens coming in on tram lines. It’s a
wonderful implementation of a poor game,
but I look forward to the programmer’s next
product - I’m sure he’s capable of a lot.

Peter Batch

SAVE YOUR MONEY

Mr T’s Money Box, Ebury Software, BBC
model B (series 1 OS), £12.95

THE Good Housekeeping magazine has
presumably given its seal of approval to Mr
Ts Money Box from Ebury Software, but it
does not have mine!

First, I found it very tedious to load - 15
tape sectors are apparently taken up in just
producing the title picture in a ghastly pink
colour, and installing the loader. After three
minutes loading machine-code programs
(tiny print tells you to *RUN the program,
not chain it) you are expecting great
things, up to Snapper standards!

What you get is two games designed to
assist the very young in recognition of
coins, and in a very elementary way to
assist them with money values.

My own experience was that this subject
was picked up only too fast by my children
without a computer’s assistance! There is
some supplementary value in the abstract
shape recognition involved, but I cannot
help feeling this is better learned using real
money, or a Mothercare toy shape box.

A program of this simplicity and length
should not need an instruction manual to
help the parent set it up. All the menu
programs should be self-explanatory. Clar-
ity has been sacrificed to Mr T’s graphics.

There are odd quirks too. One is that
though copper coins appear as red in the
full display, both copper and the gold £1
coin are yellow when you have to match
them. Now we all know the £1 coin is close
in size to both 1 p and 2p coins, but it is not
difficult to distinguish by eye. Yet Mr T
expects you to distinguish between yellow
circles differing in diameter by less than
1 mm. Another annoyance was a seemingly
meaningless collection of coins and Mr Ts
which kept appearing at the end of a
game. I was unable to discover why.

The graphics are dull, the sound is
pathetic. I preferred the failure sounds to
the success ones - surely a disastrous
teaching point! No, parents. Save your
money! Put it in your own money box, not
Mr T’s. George Hill

ACORN USER JANUARY 1984

143

Atom:

Full hardware and software support.

BBC:

Model A £299

Model B £399

Memory up-grades £21.99

Repair service and component supply.

Printers:

SeikoshalOO £215

Epson MX80FT/3 £385

SCM Daisywheel £485

Cassettes:

Matched Cassette Recorders

Monitors:

12" Green Screen
(Hitachi/Phoenix)

12" Colour (Kaga)

14" Colour (BMC/Cable)

Discs:

TEAC 40-track
Shugart twin 40-track
TORCH dual disc drive with Z80
processor, 64K RAM, CP/M and
FREE software
Eprom programmer:

Specially designed for BBC. Programs
12 different Eproms including 27128.
Includes screen software £95

(dealer enquiries invited)

Add 15% VAT to all prices. Carriage extra.

£26

£110

£255

£255

£199

£299

£780

The London ACORN-BBC Centre
Suppliers to Schools and Colleges
Maintenance Contractors

Tapes:

Top Tape: see adverts in Radio Times.
OFF Records beats all published prices.

Stationery:

Moore Paragon main agents. Large
selection of continuous stationery,
forms and labels.

Books:

Browse through the Computer Book
Department for educational, scientific
and business applications.

COMPUTER HOUSE
58 Battersea Rise
Clapham Junction
London SW11 1HH
Telephone 01 -223 7730

BR Clapham Junction

Easy Puking

4 Minutes from BR Clapham Junction

Bus 19. 37. 39. 45. 49. 68. 77. 170. 249
Tube: Clapham Common

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(A3. SOUTH CIRCULAR)

BATTERSEA RISE. SW11

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Open Daily 9 30am 6 00pm

New Showroom:

OFF Records would expect you to buy
best value. Spend some time in the
relaxed atmosphere of our new
showroom to find out exactly what you
are getting for your money.

OFFware:

CHARAID for the design of a block of 4
characters in any graphics mode
including mode-7. Outputs VDU23
commands, teletext commands and
printer commands to screen or printer
together with actual design. Substantial
software with more than 20 well-
documented commands. Indispensible
for graphics work.

£7.50 p.p. &VATincl.

ATILITYcontains seven essential
routines for the disc based Atom :
•COPY, *COPYT, *COPYD, ‘RENAME,
‘PURGE, ‘BACKUP. ‘AUTORUN.

£25 p.p. & VAT incl.

Vacancy:

OFF Records are looking for a bright
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EDUCATIONAL SOFTWARE

For children ages 4*11 —

Fifty my m ded b y

-! rrV ^mmenae _

on the

on the

ZX81

with

SPECTRUM

SUPPLEMENT

op ap Paperback
ID.yO 122 pages

(All programs suit IK ZX81)

BBC

MICRO

(Model A and Model B)
WITH COLOUR, SOUND &
OTHER ENHANCEMENTS
PROGRAMS WRITTEN IN
STRUCTURED FORM
07 QC Paperback
Z. f m%j%j no pages

These programs cover a wealth of basic concepts every
child will meet in primary education. They are produced by
professional educators and have been thoroughly tested in
a primary school. Designed to go beyond drill & practice
they promote learning through interaction and discovery.
Programs range from counting and simple arithmetic to
ones dealing with volume, balance and direction, mostly in
form of games. Each program is short but powerful and
comes with full documentation.

To:

Please send

“I

copies Educare s SO on ZX81 /Spectrum. J
copies Educare's 50 on BBC Micro. |

EDUCARE
139a Sloane St.
London
SW1X 9AY

I enclose cheque/postal order tor E

Name

Address

v

Let your child benefit early — Send now

EC

BBC/ELECTRON SOFTWARE

QUALITY SOFTWARE PRODUCED BY PROFESSIONALS

EDUCATIONAL

Our educational software is used in hundreds of schools throughout Great
Britain.

EDUCATIONAL-1 BBC/ELECTRON £8.00

Hours of fun and learning for children aged 5 to 9 years. Animated graphics
will encourage children to enjoy maths, spelling and telling the time. The tape
includes MATH1 , MATH2, CUBECOUNT, SHAPES, SPELL and CLOCK.

An excellent mixture of games, offering various levels of

difficulty and speed of response. Entertaining enough to keep young
children's attention and, on the whole, well-designed enough to help them

learn while enjoying themselves Persona! Software—

Autumn 1983.

EDUCATIONAL-2 BBC/ELECTRON £8.00

Although similar to Educational-1 this tape is more advanced and aimed at
7 to 12 year olds. The tape includes MATH1, MATH2, AREA, MEMORY,
CUBECOUNT and SPELL.

FUN WITH WORDS BBC/ELECTRON £8.00

Start your fun with alphabet puzzle in GUESS A LETTER. Continue your play
as you learn about VOWELS, know the difference between THERE and
THEIR and have games with SUFFIXES. After working so hard reward
yourself with games of HANGMAN. Complete with graphics and sound. The
tape includes ALPHA, VOWELS, THERE, SUFFIXES and HANGMAN.

★ ★★ SPECIAL OFFER ★★★ BUY ALL 3 CASSETTES AND DEDUCT £4 00

ADD 50p per order postage and packing.

Cheque/P. O. to Golem Ltd, Dept. A

77 Qualitas, Bracknell

Berks. RG12 4QG. Telephone (0344) 50720

FOR FULL CATALOGUE GIVING DETAILS OF GAMES AND
UTILITIES SOFTWARE (BBC/ELECTRON) APPLY TO THE ABOVE
ADDRESS.

144

ACORN USER JANUARY 1984

REVIEWS

LAND OF THE
BOFORS GUN

3D Bomb Alley, Software Invasion,
model B, £7.95

3D Bomb Alley from Software Invasion puts
you in charge of defending a fleet of ships.
After the title page and instructions have
loaded, the main game is loaded.

First, a background graphics screen
appears which shows a harbour surround-
ed by hills, cliffs and a blue sky. When
loading is completed the game announces
itself with a tune.

To play the game, you have to control
the sights of an anti-aircraft gun and shoot
down approaching enemy bombers. I
found it easy to use the keyboard controls
and in no time was hitting planes. When the
game begins, you have three ships in the
harbour and are awarded a new ship for
every 10 planes hit.

At first, the planes approach one at a
time and are easy to destroy, but as the
game develops more planes appear
. . . and then your problems start. If you fail
to destroy a bomber, it will drop its deadly
cargo and sink one of your ships. The
game is over when all your ships have
been sunk.

The ships and planes are well defined,
with the planes increasing in size and
definition as they draw nearer. They first
appear as dots, but soon take shape. The
aircraft drone matches the graphics and
gets louder as the planes approach the
ships.

Keyboard options include sound on/off
and a freeze game key, always useful. One
minor bug is that if a plane is destroyed at
the side of the screen, the explosion spills
off screen and re-appears on the opposite
side, which detracts from the realism of the
game.

That point aside, I found Bomb Alley an
enjoyable game which is well presented
and should provide a few hours of fun.

Paul Richard

MAGIC SQUARES

Number Puzzler, by Mike Thorne, ASK,
London House, 68 Upper Richmond Rd,
London SW15, £9.95

NUMBER Puzzler loads easily and reas-
sures the user by initially reading a header
block which displays the title on the
screen. It is important that loading is
straightforward because four minutes is a
long time to wait to get a ‘Bad program’
error message.

The program begins with a menu which
offers choices of playing Addition, Sub-
traction, Adds and Subs or doing a self
test. All responses are by single-key en-
tries except where the user’s name has to
be input.

Addition is played on either a 3x3 or
6x6 board. The aim is to get three num-
bers in a line by either using the two
numbers given or their sum. Squares are
coloured to show who has won them. The
screen display is clear and instructions are
unambiguous. Numbers seem to be cho-
sen to produce a result and the machine
checks for faulty addition. Entries can be
changed and the delete key works as
normal, even though the characters are
plotted as enlarged.

In Sub! r action a single number can be
used as it is, or be split into any two
positive numbers which sum to it. This is
more interesting and produces better tac-
tics than the simple addition version. Adds
and Subs allows a mixture of both games
with either the numbers being used, or
their sum or the components of either. This
is played on a 6x6 board (really four 3x3
boards arranged in a grid), and is quite
difficult.

The skill level in the next stage, Magic
Square, is much higher as the program
gives a partially completed square. The
user enters the remaining numbers and
scores by how many horizontal, vertical or
diagonal lines add up to the constant for
the square which can be deduced from the
original diagram. This game can be used
at a variety of levels since almost everyone
can complete some correct lines and more
careful planning is needed to complete a
magic square. It is a pity the arrow keys
cannot be used to alter values and that
there is no way to allow pupils to experi-
ment without being trapped in the proce-
dure of trying to score more than a hun-
dred for the three games.

The self-test is disappointing because
the time taken to plot the characters inter-
feres with even a moderate typing speed.
A fast typist is either frustrated by the time

delay or penalised for ‘incorrect’ answers.
This part of the program does not match
the standard of the rest.

The program is specified for children
between four and 12, although it could
easily be used with low-attaining older
pupils. The whole package is professional-
ly presented with an attractive instruction
booklet and a simple mechanism to set the
sound level to one of five values.

Although Puzzler will never be a wildly
popular program, it is well worth the money
for primary and secondary schools.

Paul McGee

WORD ROLLER

Wordhang, Bourne Educational Soft-
ware, 32k, £8.97 (£10.99 disc)

HANGMAN programs proliferate for every
micro, but Wordhang is the Rolls-Royce of
them all.

There are several modes of play: individ-
ual word entry; use of list files supplied on
tape; use of list files created using the
Wordstore program supplied.

The program is menu-driven and allows
the user to choose the length of guessing
time. There is also a progress monitoring
option to keep a record of the child's skill in
spelling and comprehension.

As the child begins to play, the gallows
appear - which alarmed some users who
were used to having them built as and
when they make mistakes. The mystery
word is displayed as a series of dashes
and a running list of letters already
guessed is maintained for the child to see.
For classrooms, it would have been an
improvement to use double-height teletext
characters, but this is a minor criticism.

Use of the same letter twice is not
allowed and all illegal keyboard entries are
ignored. As the word nears completion,
encouraging messages are displayed and
the man grows from head downwards as
each error is added to the previous one.

The graphics are particularly good— if
gruesome! The man smiles all the way up
to the last mistake. As his final foot is fitted,
his expression changes, his lip quivers
and, with a most realistic bouncing, he
drops and turns blue! Unfortunately, as is
often the case with this sort of program, the
reward for failure is more entertaining than
that for success.

The child may guess the word at any
point during the program, but a wrong
guess incurs a three-stage penalty in the
man’s development.

This is an excellent version of an old
chestnut and has obviously been well test-
ed. Apart from the break key, there isn’t
much to threaten its robustness. Its flexibil-
ity in use is going to mean that many
people who have used this type of pro-
gram, especially in the classroom, will
have one to cover all their needs.

Nick Evans

ACORN USER JANUARY 1984

145

LOYNES

COMPUTER CONSULTANCY

For the best prices on quality printers and other
products for the BBC Model ‘B’ microcomputer

EXAMPLES

StarDP510 . . 100CPS. . 9X9 Matrix £246.72

Shinwa CP80 . . 80 CPS £246.72

Star DP515 . . 100CPS . . 15" carriage £291.00

Star STX80 . . 80 col thermal printer £136.90

Juki 6100 . . Daisy Wheel £390. 19

MCP40 Printer Plotter £1 10.26

Olivetti JP101 . . Parallel . . (Inkjet) £254.91

Hermes 612B. . 200CPS. . 18 PinHead. . . . £1596.63
Hermes 612 C. . 400 CPS. . 18 PinHead. . . . £1778.76

Star DP5 10/515 Ribbons £2.30

Thermal Paper 2 rolls £6.35

Daisy Wheels Assorted £17.46

BBC- Centronics cable £9.00

Pens for plotter . . 8 pens . . box of 10 £46.35

Discs . . SS-SD . . Per 10 £17.00

2000 Sheets Fanfold . . 80 col £12.00

100 Disc Lockable box £19.00

All prices fully includes. Add £7 p & p on Printers ,
5% of cost otherwise (up to a maximum of £7)

Send large S.A.E. for extensive full lists and data
sheets at the same level of discount to:

LOYNES COMPUTER CONSULTANCY,

Dept AU2, 30 Woodfield,

Briston, Norfolk. NR24 2 JY

HOME STUDY COURSES

30 Hour BASIC

A beginner's BASIC programming course.
Standard, ZX81 and Spectrum editions.

Structured Programming in BASIC

A second stage BASIC programming course.

Beyond BASIC

6502 Assembly Language Programming

MICROTRUST SOFTWARE

All Fingers Go!

Ultra fast touch typing course for BBC
Model B. 2 cassette tapes boxed with
instruction booklet.

£14.95 inc VAT (post free).

30 Hour BASIC

2 cassette tapes containing 62 programs from 30
Hour BASIC, for BBC and Spectrum Micros.
Boxed with instruction booklet.

£11.96 inc. VAT (post free).

Crossword Puzzler

Programs to create and play puzzles plus
4 sample crosswords, boxes with instruction
booklet. BBC Model B and Spectrum editions.
£5.00 inc VAT (post free).

Further information from:

NATIONAL EXTENSION COLLEGE
Dept 45, 18 Brooklands Avenue,
Cambridge CB2 2HN

NEWARK VIDEO CENTRE

PRESENTS

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16" B3404/RGB with remote control & Teletext option £350.00
26" B8400/RGB with remote control & Teletext option £465.00

All prices include VAT, a 12 month
guarantee, a 6 Pin Din lead, a mains plug and
carriage to your door. All are Grundig TV’s supplied
with Grundigs consent.

Educational and quantity discounts are available.

What ‘What Micro’ said:

i The colours are just unreal like 4 A very reasonable comparison
the simulated’ pictures in TV could be made with colour
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TELEPHONE: 0636 71475

Open 9 am - 6 pm Monday - Saturday

146

ACORN USER JANUARY 1984

WORDPROCESSING STARTER FOR SCHOOL AND HOME

M ~ ■ - - - y V J.- >.

Beeline by Ian Birnbaum, EARO Resource
and Technology Centre, Back Hill, Ely, Cam-
bridgeshire, for Cambridgeshire Educational
Computing, BBC model B, £16 (cassette)

TAPE-BASED word processors, by their
very nature, are limited and cannot hope to
compete with disc or ROM-based pro-
grams. However, use of good program-
ming techniques and a little thought can
result in a remarkably flexible compromise.
Compromise it must be, because of the
limited memory space available after the
WP program has grabbed its workspace.

Different solutions to the problem can be
seen in the approach adopted by UK’s
Wordpro and H&H Software’s Alphabet.
The former uses an 80-column mode and
limited facilities, the latter uses 40 columns
but includes a number of useful block
operations and printer facilities.

Beeline adopts a different stance alto-
gether. It comes complete with a detailed
manual, a set of instruction cards and the
cassette-based program. Disc users need
not groan because the publishers have
adopted a very positive attitude, providing
detailed instructions on how to transfer the
program to disc. When used with discs,
Beeline provides some extra functions.

The Beeline system comprises three
modes of operation: input, edit and output,
which are summarised in figure 1 .

Text can be input via the keyboard or the
tape (disc) filing system. Before this how-
ever, the line length and/or tabulation stops
are set (figure 2). This done, an input menu
is presented displaying the input selection.
Keyboard input takes place initially on a
blank screen, and this is where Beeline's
technique becomes apparent. No screen
rulers, or on-screen formatting here; in-
stead the screen acts as a 10-line page’,
each line being given a number in the left-
hand margin. This is a little disconcerting

Documentation is a feature of Beeline package

at first, but not to worry, all carriage returns
are taken care of.

Long lines automatically break and con-
tinue in the correct position - no need to
bother with a carriage return (figure 3). As
text is entered a new (numbered) screen
appears. There is room for about 2500
words, after which the file must be saved
and a new one started.

Editing the text is simplicity itself. Press-
ing the shift and * keys together allows
entry into the edit mode. A selection of edit
commands appears beneath the text
(figure 3), and several useful commands
are available. All editing requires the line
number(s) to be given so the system can
locate the necessary text. The copy key is
used to reproduce the line to be edited and
the delete key works as usual. Characters
may be moved, inserted or deleted in the

middle of a line. This is achieved by
‘cutting’ a line and afterwards ‘squeezing’
(compressing) the text.

Text may be moved in blocks to another
part of the document. Markers are not
used, instead the line numbers must be
specified. Up to 256 lines may be moved at
a time. The edit mode allows for a limited
search-and-replace facility. A locate com-
mand allows replacement with another
word of the same length or shorter. To
some extent this is selective, giving the
option of altering the search string or not
OUT allows escape from the edit mode
and the output menu appears on the
screen (figure 4).

If all editing is complete, the text may be
printed (option 1). The program asks a
number of questions at this point: whether
the text has been squeezed, if a printer is

INPUT EDIT

Figure 1. Summary of input, edit and output modes

ACORN USER JANUARY 1984

147

3D SOFTWARE

FOR YOUR BBC MICROCOMPUTER

3D TENNIS

Full feature, one or two player game.

Fully detailed on screen scoreboard You'll feel
you’re playing at Wimbledon.

3D GOLF

It looks a long way down the fairway.

Trees to the left, out of bounds on the right and a
stream crossing through the middle.

All the fun of the fairway rough.

MELODY LINE

Not 3D, but an excellent music programme
offering rhythm generator metronome, envelope
design, 4 channel simulator tape recorder.
Turns your computer into a piano keyboard.

DOVES

Certainly not a peaceful game.

Fast arcade action. Will you get the bird?

Large list of other proprietory software.

Send a large sae for list
TORCH DISK PACK WITH FREE SOFTWARE
£ 730.00 + VAT

West Coast Personal Computers

47 Kyle Street. Ayr HA1 IRS Tel: 0292 285082

The puzzle

(hat needs a computer

Allen present the ultimate in word
puzzles - 30 integrated crosswords
which form a cube

All locations of this 3 dimensional
A \ puzzle are contained m the
a \\ computer programme and you
w A can complete any part vou

wish using the display on your
_ TV and computer keyboard

trst \\ Understanding all the
»d \1 relationships between the

crosswords is not possible without the
computer but as you proceed you will
discover new routes to help achieve
the solution

Features Solution Store, instant
Display. Anagram Function, character
Location In memory

This is a toudr puzzle with a degree
of difficulty - Its the ultimate but it’s
not impossible Full instructions are included
with the programme

PRIZE '

rtf™***.

Please mail me □ cone of the Alien Ultimate C mwword
uu72le programme at £ 14 95 nercouv me P & P for the

I I BBC Model B ! 1 Commodore M spectrum «8K

i enclose f or my AccesvVisa Card No is

The New Dimension

\ mac

| y Please allow 14 days for delivery

i V

Alien, the New
dimension present...

The first programme which
demonstrates true 3D effects on your TV . ,

All the information you need is provided /
in the programme to create your own
graphics in 3D.

Just imagine the games that
could be written using this
technique. Hours of fun and
really dramatic visual effects. \
bbc model b only The New Dimension

PliuM- Jliuw 28 At Sj» <***«vy

AU

The Alien. Arndale House, Church Street. Blackburn. Lancs . BB7 5AF Tel Blackburn (0254) 52638

A

FOR THE

BBC MICROCOMPUTER

OVER 200 PAGES INCLUDING

• COMPREHENSIVE CIRCUIT DESCRIPTION.

• FULL UPGRADE DETAILS INC. DISC ♦ SPEECH.

• SERVICING DETAILS.

• EXPLANATION OF ALL LINK FUNCTIONS.

• CRAMME0 WITH HINTS ♦ TIPS ♦ MODIFICATIONS.

( MANY PREVIOUSLY UNPUBLISHED)

• CIRCUIT DIAGRAMS INCLUDED.

• MANUFACTURERS DATA SHEETS ON ALL MAJOR IC’S.

AN IDEAL CHRISTMAS PRESENT
ESSENTIAL FOR THE ENTHUSIAST AND
ADVANCED USER ALIKE

SEND CHEQUE OR R0. FOR £l1 95*95p PR (UK ONLY)

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HULL INNOVATION CENTRE, GUILDHALL R0A0,
QUEENS GARDENS, HULL. HU11HJ.

PLEASE ALLOW 28 DAYS FOR 0ELIVERY

148

ACORN USER JANUARY 1984

REVIEWS

attached and paper correctly positioned.
Printer line length and margins are set and
the options of emphasised printing and
right justification of the text are given.
Initially, the program is configured to Ep-
son printers. (However, the publishers
positively encourage the user to alter the
program, and provide details of how to
convert it for other printers.) The text now
printed may be saved on cassette (or
disc), or returned to for further editing.

The program works well and does all it
purports to do. I could not uncover any
bugs and my overall impression was how
friendly the system is. One very pleasing
point is that all operations which are fairly
drastic in consequence are trapped by a
routine which politely asks 'Are you sure?’
to minimise accidental loss of text. The
author has also (sensibly) trapped the
break and escape keys for the same rea-
son. The problem then arises however, of
how to leave the program. The only solu-
tion is to switch the machine off and back
on again. I would have preferred an exten-
sion to option 5 (clear memory), to include
an exit from the program.

Colour highlights various actions in the
edit mode and as Beeline is written in
mode 7, all text is clearly visible on a
television set. Menus are displayed in large
characters and are simple and clear. The
BBC micro’s editing facilities are put to
good use, but apart from one instance (key
fO to save cassette files), the function keys
are neglected. It would be better if these
were programmed to perform some of the
edit functions or allow the user to program
them with commonly-used words and so
on.

The standard of the documentation in-
cluded is very high indeed, with every
instruction covered in a section of its own.
The author has thoughtfully included a
tutorial in the back which takes newcomers
through the whole process one stage at a
time. The inclusion of sturdy, laminated
instruction cards is an excellent idea.

The program’s author, Ian Birnbaum, is
no stranger to Acorn User readers. He has
written a very neat package which should
satisfy most of your needs. Such is the
simplicity of Beeline’s operation and the
clarity of its approach it is ideal for children
to use as an introduction to word process-
ing. Indeed, I worked through the program,
with a 12-year-old who experienced few
problems writing a story once the initial
learning difficulties were overcome. The
limitation of not being able to see the
formatted text on-screen will exclude seri-
ous applications, but then that is not where
the package is aimed. It is a matter of
‘horses for courses’. If you require the
sophisticated functions of ROM-based
programs, you pay your money and take
your choice. As an introduction to word
processing however, Beeline really does
offer value for money and can be thorough-
ly recommended - for schools or in the
home.

Chris Drage

Maximum

< , ™ o*' ' 7. /*v v?* 7; 1 . \ ■ t

lina length <73 or less>??0

How

many TABs (max 10710

* - Enter them in numerical order

I Column :j

positions are between i and 70

TAB

no.

175

TAB

no^

2710

TAB

no.

3715

TAB

no.

4720

TAB

no.

5725

TAB

no.

6730

TAB

no.

7735

TAB

no.

8740

TAB

no.

9745

TAB

no.

10?

Figure 2. Setting line length and TAB stops

0 This a demos t ration of how BEELINE be
haves in the EOIT mode. Although

1 it uses a 40 column display, each )in
e is given an automatic carriage

2 return after the preset line length i
s reached.

• 3

n 0

4 New paragraph. . . .

O

Edit Insert Cut Delete Move Squeeze
O Locate forward Backward Out 13

>This is where 1 pressed the RETURN ke

y i-v'

Figure 3. Automatic carriage return

\ 1 Print

text :

; ' . 2 Save’

text

3 Edit

4 Input

text pf

\ 5 Clear

II'

Type a

....

Figure 4. Output menu called by OUT command

ACORN USER JANUARY 1984

149

More than just a joystick

A superb joystick and a keypad for the price of
either. Plus the software to integrate it into the
computer's systems.

♦ 1 2 Months Guarantee.

♦ 7 day Money back Guarantee (on Hardware)

DELTA DRIVER on cassette or disc. Two programs on each cassette or disc One diverts
machine code programs from the keyboard to the joystick or keypad, with adjustable sensitivity
on the joystick and will run on any O.S The second program (needs O.S. 1 .0 or later and an adaptor
box) duplicates any keyboard keys on the keypads, in the operating system, so that it can become a
numeric keypad or will take on the function keys

DELTA 14b HANDSET £12.95 DELTA 14 b/l ADAPTOR BOX £13.95
DELTA DRIVER CASSETTE £5.95 or DISC £8.95 Prices include VAT and P & P

V/oftmace Ltd

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Tel: (0462) 894410

Callers welcome at the factory - Monday to Friday

Complete

control at your fingertips.

• Nylon encased - Steel shafted joysticks with ball
and socket joint
• Fast spring return to centre
• Graphite wiper linear potentiometers

One handset will work on it’s own in the A/D port as a joystick and two Fire
buttons. Joystick is immediately compatible with ACORNSOFT and similar
software.

The adaptor box joins together the analogue and the user ports to use the
full keypad giving a total of 24 user definable keys. The adaptor box can
also be used as a splitter for the A/d port to take two items at the same
time, e.g. joystick and lightpen.

SHARPSHOOTER

PACKAGE

s

We have a limited number of high
quality light sensitive guns for use with
your BBC Micro. Each of these highly accurate
guns is supplied with a challenging machine-code
program to test to the limit your skills as a marksman.
Features include waddling ducks, bouncing targets,
bonus time for high scores, 6 skill levels and rankings of
the highest scores.

Be on target — ORDER NOW!

SUPERIOR SOFTWARE

Dept Gl, 69 Leeds Road, Bramhope, Leeds.
Tel. 0532 842714

150

ACORN USER JANUARY 1984

REVIEWS

BOOKLETS ARE
ONLY GRUMBLE

Scales and Transverse Waves, Five Ways
Software, BBC, £12.50 each

DESCRIBED as suitable for children of 11
and over, Scales is designed to teach
pupils how to read a thermometer, a mea-
suring cylinder, a burette, an ammeter, a
stop-watch, a vernier and a micrometer
screw gauge. It should provide an essen-
tial skill for those taking science and some
craft courses.

The program loads easily and gives the
user a menu from which to choose the
required measuring device. Although the
accompanying booklet - there is one for
both programs says that the cursor is
moved up and down using the U and D
keys, the arrow keys work just as well.

A diagram is drawn for each device and
the user is asked to input the reading to the
correct level of accuracy. Incorrect or null
answers (by pressing RETURN) produce
an explanation, and pressing fo gives the
current score and the chance to change
device.

' The vernier and micrometer gauge dis-
plays are particularly helpful. The measur-
ing cylinder, however, is hard to read on a
monochrome monitor and this certainly
demands a different physical skill from that
needed to read the real thing. The notes
make the point that pupils should have
seen the real device in use and should be
aware that although the program does not
demand units every real application will.

The program is intended for both class
display or individual use. For general class
use the numbers seem rather small, but the
layout, mode of operation and helpful cor-
rections make it ideal for small group use.
The program will be a boon to teachers
who have found progress of practical work
slowed down by pupils who cannot read a
scale and who need individual attention.

Transverse Waves is for pupils following
Physics courses at O level or above. The
program covers interference, reflection
and beats, all of which can be displayed
with a varying number of points, varying
speed and the ability to freeze a frame by
pressing the spacebar. It is an excellent
program that gives endless possibilities for
pupils of average and above-average
ability.

These programs are robust, the screen
displays are clear and uncluttered and
they both meet worthwhile educational ob-
jectives in an appropriate way. My only
criticism is that the brief booklets don’t give
the average teacher sufficient help to get
the best from the programs. A few helpful
sample runs showing some of the advan-
tages of using the computer would have
been helpful, particularly in the Waves
program.

Neither booklet gives much educational

HAPPY

LETTERS

l« tttr recognition and matching program
with optional speech
for the BBC Microcomputer

Bourne Educational Software

Distributed tyvtCORNSAFT

philosophy and the user has to learn a lot
by trial and error For example, it would be
useful to know how Scales responds to
errors. Does it immediately repeat a ques-
tion thinly disguised or wait a few turns
before repeating it - or ignore the error
altogether?

The programs incorporate the Five Ways
Software security systems to prevent copy-
ing or listing.

Paul McGee

VOICE CHIP

MAKES ENTRANCE

Happy Letters, Bourne Educational Software,
BBC, £8.97.

HAPPY LETTERS is a comprehensive let-
ter-matching program for the three to five
year age-range. Both upper and lower
case letters are matched with other upper
and lower case letters on the screen or with
the keys on the keyboard. An additional
facility is the use of the voice synthesis
chip (if fitted to your machine) which pro-
nounces each letter to be matched as it
appears. It is the name of the letter rather
than its sound that is produced, which
some teachers of reading would frown
upon The program works without the
sound option.

The letters to be matched are produced
in sixes, alphabetically, from a pre-select-
ed part of the alphabet. This means you
can control which area the child concen-
trates on. The six letters, or words begin-
ning with them, appear in a column and the
first letter to be matched jumps down the
right-hand side of the, list, begging to be
matched. The child responds with the
return key when the letters match.

Several attempts are allowed, the final

ones prompted by a flashing box around
the correct answer. The correctly matched
letter then moves into a box on the left of
the screen and six angry-looking fish on
the right gobble up the letters as they are
chosen. The fish return smiling, ready for
the last stage of the program.

When all attempts have been made and
the fish are either full or still angry, along
comes the crocodile The fish, replenished
by the diet of letters, have the energy to
swim away while those unfed become the
crocodile’s meal, usually to the delight of
the player. Another amusing feature is the
mystical tune from Close Encounters of the
Third Kind, the audible reward for a correct
choice.

Some problems arise when the key-
board choice is used Here the child
matches letters on the screen with the
corresponding key. My 3j-year-old found
that the mode 5 letters did not match the
keys at all. For a non-reading beginner this
is not only confusing but illogical, though
with practice the child would soon learn to
pair them correctly

Generally speaking, however, the pro-
gram is well-written, well-controlled and
entertaining for the beginner or the reader
with letter-indentification problems.

Nick Evans

QUALITY BYWORD

Approximation, Estimation and Standard
Form, Five Ways Software, £14.38.

THIS professional, well-tested program
comes from a company that has become a
byword for quality educational software. In
terms of presentation and clarity of instruc-
tion there are few competitors.

In each of the three options one is able to
select a difficulty level and, in the case of
Estimation , an accuracy level. Although it
is menu-driven, there is a summary of
special keys which affect the operation of
the program, all of which are clearly indi-
cated in the handbook and program.

As is so often the case with this sort of
software, one is often in difficulties decid-
ing whether it should be for class demon-
stration use or for individual experimenta-
tion Obviously it lends itself to both, but in
a classroom one needs a very big screen
for single-height teletext characters.

In terms of the actual operation of the
program, the student is expected to be
able to develop his ability to estimate
based on increasing success with the tests
given to him. A clear indication of his level
of accuracy is shown by a bar chart on the
right of the screen.

Approximation may be performed to a
top level of five decimal places and five
significant figures. In Standard Form , the
student may be asked to convert floating
point to standard form or vice-versa.

A straightforward, practical and useful
tool for the mathematics classroom

Nick Evans

ACORN USER JANUARY 1984

151

Dodgy Dealer

"You'll be hard pressed to find a better business game for the
BBC Micro than this grand effort" - (TV Choice Nov. 1983)

A captivating game emulating the real business world.
As boss of a small manufacturing company, you are
required to make executive decisions to enable your
company to survive and even prosper in the face of
strong competition.

The game is dynamic: the more your skills improve the
greater the competition becomes. £6.50

★★★★★★★★★★★★★★★★★★★

One of the biggest attributes that a computer has is the
capability to sort vast amounts of information.

But have you ever wondered how a computer carries out
the sorting process?

SORT ANIMATOR

is the first in the Computer Tutorial series by OIC,
explaining visually and in detail how a selected variety of
sorts work.

Also includes routines that can be used in your own
programs. £6.50

★★★★★★★★★★★★★★★★★★★

All products supplied on cassette for the BBC B 1 .2 o/s
All prices include VAT & P+P

The complete OIC product range will consist of:

Text games Early learning

Adventure games Computer tutorial

Graphics games Tools & utilities

Business applications

Products available soon for the
Electron CBM 64 VIC 20 Spectrum

WATCH PRESS FOR ANNOUNCEMENTS

Products available from your local computer store or direct from:

OIC Ltd., Dept. OPD/AU2, FREEPOST, Camberley,
Surrey GU15 4BR

Dealers/Distributors

Contact Richard Edwards on (0344) 773229

152

ACORN USER JANUARY 1964

REVIEWS

GLUTTONY IN
THE GARDEN

Caterpillar, Gemini, BBC 32k (any OS), £9.95

ARNOLD is yet another lovable(?) charac-
ter to arrive on the software scene. He is a
caterpillar with a voracious appetite. We
find him in a walled garden full of lettuces
(which he likes very much) and coloured,
poisonous mushrooms (which he definitely
doesn’t). Your job is to see he gets fed by
moving him around the garden. You must
of course avoid the mushrooms and the
garden wall which are both fatal. (Every-
body say Ah!) By the way, he’s a rather
noisy eater and he gulps his food.

He has three lives at the start of his
journey and you have to guide him through
10 different screens or gardens. The first
four are as described above; you get
points for the number of lettuces he eats
and a bonus if you survive for the time
allocated to each screen. As you progress
he grows longer (what else would you
expect from a glutton?) and he gets faster
(presumably from all that energy he
stores). This can make the task of keeping
him alive very difficult. While you are look-
ing for the next lettuce to aim for it is quite
easy to bump into a mushroom or even the
wall.

There are no mushrooms in screen five,
just a mass of lettuces. Here you just have
to eat as much as possible within 30
seconds (which suits Arnold down to the
ground). It might sound easy, but by this
stage Arnold has almost attained mach 1
and the walls loom larger than life. If you
survive this of course you get a special
bonus.

Screens six to ten are identical in format
to the previous five, except you now have
Charlie to contend with. Charlie is not
Arnold's best friend, in fact he’s a rather
aggressive customer (which isn’t surpris-
ing as you are now eating his dinner).
Avoid him like the plague or it’s the kiss of
death.

The game is well presented, playable
and enjoyable. It has good sound and
colour, and the animation is very smooth. I
would like to have seen a joystick option,
as the game lends itself readily to it.
However, just four keys are required to
control the game and the only thing to
remember is that you can’t turn back on
yourself. Presumably if you did Arnold
would bite his own tail off. I was a little
frustrated at the response to the keys when
Arnold was travelling at a rate of knots. On
occasion it didn’t seem to pick them up
quickly enough, and I’m sure I pressed the
right ones.

In all, it’s not just another caterpillar
game, although that’s obviously where its
roots lie. Caterpillar could be described .as
an adaptation of various themes, and in

this respect it somewhat lacks originality.
However, it’s a novel little game and for
those who like the type it should provide a
lot of pleasure.

I never did get through to the final screen
(my reflexes must be slowing with age), so
I don’t know what delights await. Hopefully
you are suitably rewarded. My only ques-
tions are: does Arnold ever turn into a
butterfly? (he should do with the amount he
eats); and will Charlie ever have a change
of heart?

Ian Rowlings

NO APPLAUSE FOR
CRICKET FLAWS

Owzat?, Virgin Games, BBC 32k, £7.95

WHEN I was a schoolboy we used to play a
cricket game with a scorebook and two
metal dice which you rolled to determine
the outcome of each ball. It was my habit to
ensure that Ted Dexter, aided and abetted
by me at the other end and controlling the
dice judiciously, invariably got a double
century.

This game is a computerised version of
that one. You can select your own teams or
use the English/Australian ones provided.
You can have automatic bowling and bat-
ting or do these yourself (fairly crudely)
using the keyboard. You can also decide
whether you want a limited-overs match or
a full game.

The screen display represents a view
from approximately the stands at the mid-
wicket boundary, which becomes a close-
up. if you’re doing your own batting. At the
end of each over you get the bowling

analysis, and at the end of each innings the
full scorecard.

Although as a cricket enthusiast I ap-
proached the program with some eager-
ness, I rapidly found it not only dull but
downright irritating: what is missing is the
attention to detail which cricket fans love. If
you’re batting and you miss the ball, you’re
automatically bowled. There is no provision
for extras, no column showing maidens in
the bowling analysis, no fall-of-wickets on
the final scorecard, no run-outs allowed
The bowlers don’t change ends after each
over and the Australian fast bowler Jeff
Thomson needs a ’p’. I grew tired of the
large number of sixes scored over the
head of third man.

Attention to detail is also missing in other
areas. There are no sound effects (why not
the sweet sound of willow meeting leather
or of the crowd applauding a fine shot?)
and you need a magnifying glass to read
the instructions.

Virgin got into the software business with
a big splash and rapidly acquired a lot of
dissatisfied customers. Judging from this
offering they still have a long way to go to
improve.

Simon Dally

ARCADE MUST

Missile Control by Nicholas Tingle, Gemini,
BBC 32k (any OS), £9.95

A FAITHFUL rendering of the arcade fa-
vourite where missiles track and branch
down the screen. They’re after your cities
and your missile launchers. You have three
bases perched on mountains left, right and
centre, plus six cities to protect. You aim
missiles by placing the cursor in the path of
one or more enemy missiles and selecting
the appropriate fire base using fO, fl or f2
(or if you press shift the program selects for
you the nearest base to the target). The
cursor is moved using the arrow keys; A
and Z can optionally be used for up and
down.

As you can gather, some degree of
manual dexterity is called for, but if you
have a joystick, select J and life’s a lot
simpler.

At the end of each raid, the surviving
cities and remaining missiles are totted up.
On wave two, planes and satellites fly by
dropping more missiles in their wake; on
wave six, smart missiles that dodge your
missiles make an appearance. The game
ends when all six cities have been knocked
out, and you’ll have to endure a nasty
stroboscopic ‘the end' display that seems
to last for hours. Get on the scoreboard
and you’re treated to a famous Cliff Rich-
ard tune (not Summer Holiday). Up to four
players can play together in turn. A must
for arcade action freaks, it’s also available
for the Electron.

Alan Pipes

ACORN USER JANUARY 1984

153

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BBC EXPANDABLE CONSOLE

A professional console to house
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Coming soon a bolt on extra
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Also available a matching printer
stand, yes stack your paper
under the printer.

PRINTER/VDU STAND

BBC owners who only need a
VDU stand will find the stand
slips comfortably over the BBC
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PRICES :

BASIC CONSOLE as shown
only £39.99 + £4.00 p/p
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24 hour
ansaphone

Please allow 28 days for delivery

154

ACORN USER JANUARY 1984

REVIEWS

OVERPRICED AS
CLASSROOM AID

Chemical Analysis, Acornsoft, £13.80 (£17.25
disc).

THIS suite of three programs, designed for
the 14 to 16 age range, deals with the
major areas of chemical analysis in broad
terms: elements, inorganic and organic.

The basic format for each of the pro-
grams is the same; the machine randomly
chooses from a data list the substance
upon which tests may be made. A list of
possible tests is put on the screen for the
student to make his choice. As each test is
performed a small amount of text, record-
ing the result of that test, is put into the
answers’ section. Every time a further test
is made, the results of the previous tests
are still visible. It is possible to give up by
pressing the escape key and then the
choice of quitting the program entirely,
starting again or seeing the answer to the
previous test is given.

The problem with the programs is that,
although similar, they are not identical in
operation. Now it’s unlikely that a student
will study all three at once, but it is confus-
ing when conventions accepted in one
program do not apply to another. For
example, when a test had been performed
on a substance, that test was highlighted in
green to make it obvious the choice had
already been made. Apart from the fact
that green makes no noticeable difference
on a green monitor, I was surprised to
realise that this rule did not apply in Ele-
ments. Whether this was an oversight I
don’t know.

On a similar, and possibly equally trivial
point, spelling such as ‘gasses’ and dis-
olves’ also had one wondering about the
speed of production of these programs.
Moreover, again in Elements , the answer
did not appear when you followed the
escape routine, which was most
frustrating.

The range of tests often seemed inad-
equate, especially on the higher levels of
Elements, since when one is dealing with
the full breadth of the Periodic Table,
elements that are close to each other are
necessarily similar in properties. It was at
this point that the range of tests seemed to
fail - particularly when dealing with metals.
The same comment in general terms could
be applied to all three programs to a
greater or lesser extent.

Another disturbing point was that there
was no ‘descending’ of the numbers in
formulae.

As a revision aid this program would
probably be quite useful and constant use
would enhance the student’s basic know-
ledge of these three areas. However, as a
classroom aid it is limited and seems over-
priced for what it is.

Nick Evans

Beyond Basic

6502 Assembly Language Programming for the
Br»tish Broadcasting Corporation Microcomputer

Richard Freeman

ZX GRAPHICS

Firehawks, Postern, BBC model B, £6.95

DOES the world really need more space
invaders? Well, whether we need them or
not, Postern had given us them. This isn’t
quite the standard invaders though, the
Firehawks appear singly and in groups
from the top of the screen and have to
negotiate various fixed patterns of shields.

After each wave of Firehawks, a new
shield pattern is drawn. At first, they come
in slowly - they seem to hover waiting to be
shot and get caught behind the shields -
later, they come in more quickly but never
show signs of intelligence. The last Fire-
hawk on each sheet is very much faster,
and so difficult to hit. In later sheets you’re
left feeling that the program has cheated.

The tape loaded successfully every time
with three programs - a title and fanfare,
some terse instructions and the game
itself. The cassette cannot easily be copied
to disc as it contains several protection
mechanisms; however, a disc version is
available.

The graphics of the game are disap-
pointing - they make the BBC look like a
Spectrum. One 12-year-old’s reaction was
‘what’s that - a flying Haggis?’.

The controls are difficult: ‘Z’ and ‘X’ move
your base left and right at such speed that
we had no fine control even after practising
for several days. There is no joystick op-
tion. You get a choice of the starting sheet
and the speed of the Firehawks. The
sheets count backwards from 15 but we
never reached zero, so I can’t tell you what
happens.

Personally, I prefer Swoop or Arcadians
but, if you’re looking for a new challenge,
Firehawks is an interesting version of an
old favourite.

Peter Balch

EXCELLENT BOOK
ON ASSEMBLER

Beyond Basic: 6502 Assembly Language
Programming for the BBC micro, by Richard
Freeman, BBC/NEC, price £7.25 (cassette
£11.50)

THIS package consists of a book - 256
pages (could this be significant?) and a
cassette of the programs which are used
as examples within the book - 81 pro-
grams in all plus a Title program which is
similar to. but even less inspiring than, the
Intro program which comes on the Wel-
come cassette. Having said that, however,
the contents of the actual book are really
excellent.

The book is in the same series and uses
the same techniques as the NEC book 30
Hour Basic. It aims to lead you into the
world of assembly language programming
by getting you to do practical exercises,
with the emphasis strongly on 'hands on’
and brain engaged’. Each chapter con-
tains self assessment questions with an-
swers, carefully stated objectives, and an
assignment.

The book is spiral bound like the User
Guide which makes it easy to use. It is well
set out and makes good use of green and
black printing and different typefaces,
though some of the diagrams contain hand
written titles which make it a little untidy in
places.

The programs are well presented, using
lower case for variables names and labels,
and using lots of comments.

Ten chapters cover: number representa-
tion - hex and binary notation; addition and
subtraction; jumps, loops and branches;
addressing modes; multiplication and divi-
sion; lists and tables; the stack, CALL, USR
and masking; operating system calls;
tough stuff - 16 bit multiplication and
division, plus sorting a Basic array; round-
up - a useful final section on hints and tips,
and errors to avoid.

Two complaints come to mind. First, in
an exhortation to follow the text methodi-
cally at the beginning of the book, the
author says that if you don’t the only way to
find points you miss is through the index -
but there isn’t one! (Mind you, I suppose
that just emphasises his point.) Second,
since the BBC has such a powerful operat-
ing system it seems a shame more use is
not made of it in teaching the basics of
assembly language programming. I find
that students are more excited by writing a
machine code program to draw lines on
the screen and change colours, than to
add and subtract hexadecimal numbers.

Despite the complaints, I think it is an
excellent book and have already recom-
mended it to a number of people, and will
continue to do so.

Paul Beverley

ACORN USER JANUARY 1984

155

BBC BASIC

R.B. Coats

o A carefully designed text that can be used
either to teach oneself or with help from
an instructor.

o Adopts a practical approach.

o The text is divided into short units :
reading material followed by practical
exercises and questions to reinforce the
aspect of BASIC being studied in the unit.
This enables users to pace progress
according to their needs.

o Good programming practice and style are
emphasized throughout the book.

£5 . 95 paper 256 pages

(D

Edward Arnold

41 Bedford Square, London WC1 3DQ

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156

ACORN USER JANUARY 1984

ELECTRONIC MONOPOLY FOR THE WHOLE FAMILY

Jeremy’s marker lands on one of the less-pleasant delights of Pass Go

Pass Go by Kay Dee Software, BBC 32k, £12.

THIS delightful program is similar to the
famous Waddington game of Monopoly (a
picture of a Monopoly-type board appears
on the box) but has some interesting
refinements.

Up to nine players can participate and
the object is to drive the opposition into
bankruptcy. Each in turn moves round a
board’ on the screen this is represented
as a car with the player’s name on it
cruising past various buildings while a jolly
jingle emerges from the loudspeaker. What
happens next depends on which building
you come to halt in front of. . .

Each player starts with £15,000 cash
and as in Monopoly, the art of survival
depends on steering a fine course be-
tween maintaining enough cash to pay
your debts and buying enough property to
ensure an adequate income. If you stop in
front of an hotel or store you can buy it (if
it’s for sale and you have the cash avail-
able) If it’s already yours you can sell it or
improve it (which increases its rental val-
ue). Of course, if someone else owns it you
have to pay out rent.

Sometimes you land on Chance, when
more or less anything can happen jail
(which you can buy your way out of) or,
more agreeably, Salary, which gives you a
cash sum based loosely on the amount of
property you own. There are also banks
which will sometimes lend you money,
depending on your assets.

Another feature is the Market, where you
can buy and sell commodities in the form
of shares, land and gold The price of
these varies considerably during the game
and there are real killings to be made, as
well as shirts to be lost.

At the end of a turn, each player’s
personal balance sheet of cash and other
assets is shown Light-fingered Monopoly
players in the habit of snitching a few
hundred quid from the bank when no one’s
looking will get no joy from this all-electron-
ic version!

I tested the game en famine one Sunday
and it lasted for several hours. It is a
measure of the careful thought which has
gone into it that, though one can dispense
with the graphics and sound, no one grew
tired of them. The participants were: yours
truly, a left-wing sister (who took to this
most capitalist of games with alarming
enthusiasm), a plutocratic brother to the
right of Genghis Khan, and a disobedient
but decorative dalmatian puppy called
Pimms, whose main talent is her ability to
recognise the rustle of a packet of crisps at
several hundred yards and to take ap-
propriate action. We jointly took the deci-
sions for Pimms during her absences on
crisp-hunting forays. . .

The first two hours produced little of
incident but were totally absorbing. My left-

wing sister concentrated steadily on ac-
quiring property (despite her claim that all
property is theft), while the capitalist broth-
er, after an initial disastrous attempt to
corner the gold market and ruin another
player (something the program doesn't
cater for) also prospered. Alas! I began to
find it cheaper to sit in jail and collect my
rents than to move around the board. It
became clear that the more property you
own the more revenue you receive, but the
more lolly you have to fork out for things
like gas, electricity and telephone.

If you’re faced with a bill you don’t have
the cash to pay, a debt collector steps in
and forcibly sells some of your assets, first
deducting his own 15 per cent of course.

My sister became incensed when she
received a Chance message saying: ‘Ex-
wife sues, pay £2,500’. Typical sexist non-
sense,’ was her comment. Meanwhile my
brother was more annoyed that you can’t
buy a bank in this game as he had some
‘interesting’ economic theories he wished
to try out on his fellow players. His other
complaint was that the car you drive
around in looks more like my own battered
Renault 5 than the Mercedes he felt he
deserved.

I have three main criticisms of the pro-
gram. First of all, it needs a printed rule-
book. The rules are on the tape, so you
can’t refer to them during a game. Next,
there should be a facility to save a game to
return to it later: most adventure games
allow this.

Finally, when a game ends you should
have the chance to start again without
having to reload the program (a lengthy
process).

These comments apart, this is one of the
more impressive games I have seen for the
Beeb; it should appeal to families who
enjoy playing games together and who
would like to sit around a computer or
introduce someone else to the joys of a
computer.

The outcome of our game? Pimms won,
of course. It’s a dog’s life.

Simon Dally

ACORN USER JANUARY 1984

157

DOUBLE ACTS

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unlimited motion in space! MISSION ALPHA 3D
High speed action, hall of fame & music!

SPY, SPY:

KREMLIN Escape through the endless 3D corridors
of the Kremlin, aided by map & compass, but watch
for the Gremlins!

BONDSKI Lethal action as James skies down the
slope & parachutes into the void!

WORD PROCESSOR:

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Full facility 40/80 column word processor, wrap
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Only £15.95 Disc only.

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Only £8.95 inc. VAT & PP (Disc £11.95)

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REVIEWS

WHITE KNIGHT SPEED TELLS OVER CRAFTY ACORNSOFT

White Knight Mkll by Martin Bryant,
BBCSoft, model B (OS 1.0 onwards), £11.50
Chess by Arthur Norman and Nick Pelting,
Acornsoft, model B (OS 1.0 onwards), £9.95

IN THE March issue, the three chess pro-
grams then available for the BBC micro
were reviewed. Since then two others have
been released, one from Acornsoft (at last
this was expected nearly a year ago) and
one from BBCSoft. The original article
gives details of the tests which were done
However, in case you haven’t read it, the
six positions with which the programs were
tested are shown again
The Acornsoft program, simply called
Chess, comes in the familiar, well-pack-
aged style and the BBCSoft box is almost
identical Documentation in both cases is
very good, a six-page and a twelve-page
booklet respectively Unlike some of the
arcade-type games, the picture on the
front of the Acornsoft box is a true repre-
sentation of the screen display. The
BBCSoft program is White Knight 1 1
Chess has a main menu and an editor
menu which makes it easy to use and after
a while the booklet becomes superfluous.
White Knight has less helpful information
on screen, so reference to the booklet is
needed, especially on returning to the
game after using another program. Both
have all the facilities needed for normal
play and for setting up problem positions,
clocks, and the ability to save and recall
games. The displays of the board and
pieces are good, particularly the Acornsoft
version, and compare well with the three
older programs As well as showing the
last few moves, White Knight also gives the
current best line found, the ply being
searched to and, at the end, displays the
number of positions examined. This latter
information disappears rather quickly.

Chess and White Knight allow moves to
be entered either by keying in the from and
to board positions in normal algebraic
notation or by using the cursor keys to
select the positions on the board. Chess
can also use joysticks, but in both games
setting up a position is very easy
Levels of play are set differently. Chess
has ten levels from 0 (easy) to 9 (very
difficult), while White Knight levels are
based on time - average move time may
be set up to 59 minutes 59 seconds. It can
be set to play at the same speed as its
human opponent. Both programs have a
special mode for chess problems to reach
mate in so many moves. Mate in five
moves, is allowed ie, nine-ply - potentially
very powerful, but see iater None of the
earlier programs had this feature
Like the earlier programs neither of these
have an opening 'book They seem to
prefer knight openings and are soon away
from the standard lines. However, their
ooening moves are usually quite sound.

As explained in the earlier article, set

Screen shot from White Knight

problems as published in chess books are
a good test of how well chess programs
play. I have used the same set of problem
benchmarks as before with a few
additions.

Mate in two moves (three-ply) Each
program was given nine problems. The
best of the earlier programs (Program
Power) solved all nine correctly in times
from ten seconds to eight minutes. Acorn-

Amazing speed

soft solved all nine in problem mode in four
seconds to just over one minute - consid-
erably faster than Program Power. White
Knight solved them all in problem mode in
less than one second each! Figures 1 and
2 are two of these problems. Solutions are:
A4-E4 check, B7xE4; D3xE4 mate; and
D5-A8 check, C8-C7; A8-B7 mate

respectively

Mate in three moves (five-ply) Program

ACORNSSFT GAMES

Chess

for the BBC Microcomputer Model B

Better at tricky problems

ACORN USER JANUARY 1984

159

■■IIS

TOOLSTAR - an

ESSENTIAL UTILITY FOR THE BBC MICRO

This exciting new toolkit ROM offers many extra facilities and will significantly reduce program
development time. The new commands offered by Toolstar are:

★ FIND

Search a BASIC program for all
occurances of the specified string
(mixed tokens/ASCII), and list all lines
with string highlighted.

★ OPEN

Smart renumber parts of a BASIC
program.

★ FKEY

Display what is behind function keys in a
format suitable for on-screen editing.

★ RESET

An unforgettable new!

★ DFORMAT

Format a disc to the Acorn standard with
any number of tracks within the
capabilities of the Drive.

★ REPLACE

Selective replacement of one string by
another in a BASIC program, including
wild card options.

★ FUST

List a Bad Program' with suspicious
areas highlighted.

★ FIX

Repair a Bad Program' then list it.

★ CONV

Convert between Decimal, Hexadecimal

and Binary in any combination.

★ DVERIFY Verify a disc.

★ DLOAD

Load the data from the specified sector
on a disc to memory.

★ EXTEND

Expands the Toolstar to encompas RAM
based utilities which then automatically
appear under the ★ HELP command.
This feature ensures that Toolstar is
capable of future expansion.

★ DSAVE

Save the data from memory to a
specified area on the disc.

The following commands are
directed at the whole machine
memory and complement the
BBC micro's assembler:

★MROM

All the M (Memory) commands can be
directed at the specified paged ROM. eg.
BASIC, DFS, TOOLSTAR. WORDWISE,
etc.

★ MDUMP

Hexadecimal/ASCII dump of memory
with on-screen editing.

★ MSEED

Fill the specified memory area with any
value.

★ MCOMP

Compare memory areas and list those
where memory contents are not the
same.

★ MBRK

Installs a serial BRK handler giving CPU
register and stack displays together with
program counter and paged ROM value
when BRK occurred — can be used in
machine code or BASIC.

★ MDIS

Full feature disassembler with parallel
ASCII display. Features include
automatic labelling of Acorn O S. calls
and vectors, and on-screen editing.

★ MFIND

Search memory for all occurances of
specified machine code/ASCII string.

★ MCOPY

Smart memory copy from one area to
another.

★ MCRC

Calculate a Cyclic Redundancy Check for
the specified memory area.

Any or all of the above commands can be used from within a BASIC program. This allows the
user to develop many powerful utilities (ie. disc doctor etc.)

Also included are ★HELP menus with a list of the above commands and their correct syntax.
Toolstar comes complete with a most comprehensive manual including many program
examples.

j/

ONLY £34.00 inc. VAT.

COMMSTAR - ROM BASED

INTELLIGENT COMMUNICATIONS FACILITY

Commstar is a unique intelligent communications facility, developed by Andy Hood, for the
BBC micro. It will allow communication with other computer users and allow access to Prestel
and other large data bases throughout the world via a suitable modem.

Commstar is extremely flexible, allowing full configuration of the RS 423 (RS 232) part of the
BBC micro, full XON/XOFF protocol, and 'safe' file transfer by the use of enhanced
'Christiensen' protocols.

All commands are easily accessed from a main menu from which it is a simple matter to toggle
into 'chat' mode (and vice-versa).

Menu options available are:

mode 7, 80 columns available in mode 3,

B — Copy to buffer on/off: All input from
the host may be copied into a memory
buffer which is approx, 23K in mode 7

L — Load buffer from current filing
system file for transmission to modem.

S — Save buffer to current filing system
file for 'browsing' later.

V — View current buffer contents on
screen — display speed may be varied,
or paused with optional dumping to
printer.

T — Toggle screen mode : normally

Commstar also contains its own software clock in memory which is useful in displaying length
of log-on time etc.

Details of the above products can be obtained from your nearest BBC dealer or direct from:

O — Output buffer to modem — speed
may be varied to suit particular modem
speeds.

M — Issue any MOS command from
within COMMSTAR eg. *FX8,3 (ie set
RS423 baud rate).

C — Exit menu to 'chat' mode to allow
conversational access to bulletin boards.

W — Wipe buffer prior to use of other
buffer commands if necessary.

E — Echo on/off — set echo on when
using host terminals which do not
provide an echo.

X — Toggle XON/XOFF protocol
R — Reset buffer pointers

I — Initialise RS423 port for word length,
parity and stop bits.

F — File transfer using XMODEM
protocols High integrity via use of
enhanced 'Christiensen' protocols.

PACE

92 NEW CROSS STREET,
BRADFORD BD5 8BS.

Tel: (0274) 729306 Telex: 51564

160

ACORN USER JANUARY 1984

REVIEWS

Power was the only one of the earlier
programs considered good enough to
tackle these. Its times were 49 minutes for
one problem (figure 3) and nearly three
hours for another, both solved correctly.
Acornsoft did the first one in 35 minutes.
White Knight - this is the amazing thing -
did this one in 15 seconds! It did other
mate-in-three problems in six seconds, 13
seconds and 19 seconds. The solution to
figure 3 is: E8-H8 check, H7xH8; E3-H6
check, H8-G8; H6xG7 mate.

White Knight was so good that it was
given three mate-in-four (seven-ply) prob-
lems. It solved these in four minutes, eight
minutes and 10 minutes. Any of the other
programs would have taken hours.

Both the new programs were faster solv-
ing problems in problem mode than play-
ing normally. For instance, for one of the
mate-in-two problems Acornsoft took 24
seconds in problem mode and needed
level four to get the correct answer in over
two minutes. White Knight took one second
and four seconds respectively.

Now for the special problems in figures
4, 5 and 6. Both Acornsoft and White
Knight failed to solve figure 4. The answer
is to let black promote the pawn, exchange
it with the queen, then easily win with the
four-to-nil pawn advantage. The answer to
figure 5 is to promote to a knight rather
than the usual queen, thereby forking the
king and queen. Acornsoft was correct,
White Knight was not, presumably be-
cause it is programmed only to promote to
a queen.

Figure 6 shows an endgame pawn-king
race situation. In this case the king cannot
catch the A-pawn before it promotes but
can catch the B-pawn. So the answer is to
advance the A-pawn. White Knight could
not solve this even at its highest level.
Acornsoft solved it at level six in 30 sec-
onds. Bug Byte was the best of the earlier
programs, solving it in 24 seconds.

On this occasion I had no access to a
chess machine so could not try actual
games. Playing them myself would have
been too variable - 1 am a very inconsistent
player!

To summarise, there still isn't a perfect
chess program for the BBC micro. White
Knight is fast, particularly in problem
mode. The display shows it to be examin-
ing positions at over 50,000 per minute! It
has its limitations as mentioned above, but
I would still rate it as the best buy. I would
rate Acornsoft and Program Power about
the same as second choice.

The problems were taken from How to
Get the Most from Your Chess Computer
by Julio Kaplan; The Computer Chess
Book by T Harding and Rate Your Own
Chess by F Donald Bloss.

John Vaux

n

A.

u

s

A

#

A

w

A

A

a

A

*

Figure 1 . White to move

*

1

A

A

A

A

,A

Figure 4. White to move

A

H

A

$

#

A

Figure 5. Black to move

#

z

A

A

A

m

m

A

A

A

A

A.

A

A|

4

&

Figure 2. White to move

,

s

□n

A

A

#

A

s

m

A

A

A 1

*

Figure 3. White to move

#

A

A

A

A

A

&

Figure 6. White to move

ACORN USER JANUARY 1984

161

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JUST AVAILABLE!

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External dimensions only

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Please supply the following items

(Enter items required All prices include VAT'

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BBC Programmers Kit

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each item,

Name

Address

Tel No.

1 enclose cash/cheaue to the value of £

(or) please debit my Access A/isa card

No

Signature

Allow 28 days for delivery

162

ACORN USER JANUARY 1984

Official Acorn and BBC dealers

Dealers have been appointed by Acorn to stock and service the BBC micro, Atom computer, Acorn systems and Acornsoft software.

LONDON

■ Home A Continental

■ National Mic'o Centre

ESSEX

■ Compote' Plus

■ Oakleaf Computers

OXFORDSHIRE

YORKSHIRE

■ Edinburgh Compute'

■ Design Council

Computer Services Ltd

(Stockport Micro Centre)

■ Akhter Inshuments Ltd

47 Queens Road

Grantham

■ Compute' Cabin

■ Corn-Tec

Centre

28Haymarket

22 Market Squa-e

4 Brown St'eet

Unit 19

Watto'O WOI 2LW

0476 76994

24 The Parade

6 Eastgate

55 Lothian Road

$W1

Biggleswade SG18 BAS

Stockport SKI 1RF

Artingnide Estate

0923 33927

MANCHESTER

Silverdale

Ba'nsley

Edinburgh

01-8398000

0767 317300

061 480 0539

South Road

■ Q-Tek Systems Ltd

■ NSC Compute' Shops

Newcastle ST56LQ

022646972

03'?29 4416

■ Civomasonic

■ 3D Computers

■ National Micro Centre

Templefietos

2 Daltry Close

29 Hanging Ditch

0782628785

■ Customised Elechomcs

■ Silicon Cenhe

Electronics

Manor Road

(Wilmslow Micro Centre)

Harlow CM20

Old Town

Manchester M4 3ES

Ltd

7 Aniigua Street

48Juncn>n fioao

Cadcington, Luton

62 Gwe Sheet

0279412639

Stevenage SGI 4BW

061032 2269

SUFFOLK

Winke' Green Mills

Edinburgh

Archway N19 5RO

01-2639493

05827667104

Wilmslow SK9 IDS
0625530891

■ Computers to- All

72 North Street

043865383
■ Spechum UK

MERSEYSIDE

■ Mic'o Management

32 Pnnces Street

Stanmngley Road

A-mley

031 557 4546

■ Oeansol Kensington

BERKSHIRE

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Rom tore

Burrowfietd

■ Data Exchange

Ipswich IPl 10G

Leeds LSI 2 38B

Tayskte

191 Kensington High Street

■ Computer Penpherai

Churchtietd Road

0708-752862

Welwyn Garden City

Exchange House

047359181

0532 792332

■ Gale Microsystems

W8

Supplies

Frodsnam

■ Di'ect Data Marketing

■ 3D Compute's

1 64 New Chester Road

■ Midwich Computer Co

■ Datron Mic'o Cenhe

The Nethergate Centre

01-937 7896

Unit 20. Stadium Way

Nr Warrington

22 Wartey Hill

Greystone Works

Birkennead 141 9BG

Rckmghatl House

2 Aobeydale Road

36 Yeaman Sho'e

■ tVeet Data Marketing

Battle Farm Trading Estate

WA66RO

Brentwood CM f 4 5HA

The G-een

051 6479185

Rickmghall IP22 1HH

Sheffield S7 1FD

Dundee D0 1 4BU

0M7 Wilton Road SW1V1DN

Reading RG3

0928 35110

0277 229370/2 1 4 1 68230480

Croxley Green

0379896751

0742-585490

038228194

■ Group 70

0734 418383

■ 3SL System Support

■ heatey Management

Rtckmanswo'fn

MIDDLESEX

■ Suffolk Computer Cenhe

■ Datron Compute's A

206 Mayoanx Road

■ ME Elechonns

Services

l4Hemmels

■ Ba'cac Consuttan's

■ Mc'oage Electronics

1 Gartarxl Street

Supplies

Strathclyde

ScuthWoodfO’oEiS

5 Hatheriey Road

B-oc* House

Lainaon North Trade Cenhe

Radiett

135 Hate Lane

Bury St Edmunds

109 191 Glossop Road

■ Allot Uo

01-505 7724

Reading RGl 5QA

513 Crewer Road

Basildon

092765897

Edgware

IP331EZ

Sheffield S102GW

Workshop 13

I Dh Vino Computers

0734 669480

Wheetock. Sandbacn

0268 416155

01 959 7119-906 3666

0284 705503

0742 756105

6 Harmony Row

H2 Brent Sheet

■ Micmsiyte

08367 3842-61249

■ Mic'oco'e Llo

HUMBERSIDE

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Glasgow

HBndon NW4 JOT

47 Cheap Sheet

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5 Broomfield Road

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236 Imperial Drive

SURREY

217Mamingham lane

041 445 5130

012022272

Newbu-y

IHead Office)

Chelmsford SMI iSY

Services

Rayners Lane

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Bradford BOB 7HH

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0616 41929

061-45610001

0245264230

1 7 Westgate

Harrow HA2 7HJ

29a Brigstock Road

0274 491371

321 Blythswood Court

Unit 5

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Partington

01-4294991

Thornton Heath

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Anderslon Centre

Tiong Sheet E2 8HN

14 Wood End

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Hull HU1 1 0NA

■ Twickenham Compute'

CR4 7JJ

2 RoscCoun

Glasgow G2

01-7393232

C-owtho'ne

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30 Hornsby Square

0964 30225

Centre

01-6891280

Garforth

041221 0310

■ ugntmng Reco-ds A

0344 772361

Ltd

Southfield Industrial Park

■ Mic'oserve Ltd

72 Heafn Road

■ (kxlotord Computer Cenhe

Leeds LS25 INS

■ Lome Compute* Services

Videos

■ Fe”an’i A Craig

155 Marion Roao

Basiloon

39 Oswald Road

Twickenham

1 The Quadrant

0532865 H8

12 High Street

841 Ha'row Road

(Reading Compuer Centre)

Middlesbrough

0268418414

Scunthorpe DN15 7PN

01-891 4991

Bnage Street

■ Mrc'o Powe'

Oban PA38 90G

HartesdenNWIO

48 Tne Buns Cenhe

0642 247727

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8 8a Regent Street

063165635

01-9695255

Reading

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17 Regina Road

0483578848

Chapel Allerton

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26 Anlaby Road

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Kingston upon T names

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1 78 West Street

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■ Microtest Ltd

7 Hare Lane

Cleetho'pes DN35 7 AO

Systems

■ J S Simneti Computers Ua

0742 755005

Glasgow

72 Rochester Row

Winoso-

18 Normandy Way

Gtouceste* GL1 2 BA

047258561

462 Coventry Roao

1 06 Villiers Avenue

■ Yorkshire Computers

041 221 7409

SW1P1JU

07535-58077

Bodmin PL31 1EX

0452411010

Small Heath

Kingston upon Thames

28 Ramshili Road

■ vero' Moms Lta

01828 74679

■ Fe"anti A C-a»g

0208 3171

KENT

Birmingham B 10 0UG

01-3999201

Scarborough YO1 1 2QF

340 Argyle Street

■ REW West End Vioeo

(Wok.ngham Computer

HAMPSHIRE

■ Kent Mrc'o Systems

021 771 3636

■ 3D Compute's

0723352378

Glasgow G2 81. Y

Centre

Centre)

DERBYSHIRE

■ Ameeco Ltd

Conquest House

■ Coventry Micro Centre

230 Tolwonh Rise South

■ Eltec Compute's

041 221 8958

2X Tottenham Court Road

62 Peach Street

■ Dahon Mic'o Cenhe

2 North Way

1 7 Palace Sheet

33 Far Gosrord Street

Tolworth

29 Negate

W1

Wokmgnam

Duckworth Square

Wallworth industnal Estate

Canterbury CT1 4PT

Coventry CVi SOW

Surbiton KT5 9NB

Bradford BDi ISO

WALES

01 -500 1785

0734 789381

De-by DEI 1J2

Andover SP10 5AZ

022750200/50366

020358942

01-3374317

0274 722512

Ctwyd

■ RFW Wes( End Video

0332 380065

0264 58744

■ Medway Compute'S Ltd

■ Walters Computer Systems ■ 3D Compute' Cenhe

■ Mic'o Powe'

■ Clwyd Technics Uo

Owe

BUCKINGHAMSHIRE

■ Business Etect'onics

Ml New Road

1 2 Hagley Road

30 Staton Road

Northwood House

Unit 4b

1 1 4 • 1 1 6 Channg Doss Road

■ Cittern Elechonicf.

DEVON

Rownhams House

Chatham

Stourbndge DY8 IPS

Belmont Sutton

North Street

Antelope Industnal Estate

WC2

C r 24033867

High Street

Chaltont St Giles

■ A A D Compute's
Computeriand

Rowrmams Lane

Soutnampton SOI 8AH

ME4 4PT

0634 826080/681547

03043 70811/2/3

01-6422534

Leeds LS7 2AA

0532 458800

Rhydymwyn nr Mold
CH75JH

■ Tecn-omaiic lid

02407 71234

6 City Centre

0703 738248

NORFOLK

SUSSEX

■ Ronnie Rae Marketing

035283 766

i5- 17 Burnley Road

■ 3D Compute'S

Fore Street

■ Elec'onequip

LANCASHIRE

■ Anglia Computer Skye

■ Capital Cameras

157 Kings Road

NWiOIED

Unit t

Exeter

36 38 West Street

■ Blackpool Compute'

88 St Benedicts Street

24-26 The Boulevard

Ha'rogate

Dyfad

0i-4521500'450 6687

Heathtieid

0392 77117

Fa'eham

Centre

Norwich NR2 4AB

Crawley RH101EF

042368851

■ Cardigan Electronics

■ "ecviomahc Llo

Stacey Bushes

■ Bi’s A Bytes

0329230670

i79Chuxh Sheet

060329652

0293 543555

■ Ronnie Rae Marketing

Chancery Lane

305 Edgware Road W2

Milton Keynes

44 Fore Street

■ Fe"anli A Craig

Blackpool

■ Castle Electronics

209 North Street

Cardigan

017230233

MK126HP

Mf-acombe EX34 9DJ

Ferranti House

02532709120239

NORTHAMPTONSHIRE

4-7 Castle Street

Leeos 7

0239614483

■ Tne Byte Shop

324 Euston Road W2

0908317807

03271-62801

■ JAD integrated Services

G-ahon Way

Basingstoke

■ Menl Compute's Lta

Unit 4

■ Data Leaf Ltd

41-42 High Street

Hastings TN34 3DY

0424 437875

0532451508

■ Highlands Computer
Systems

01-3870505

CAMBRIDGESHIRE

3? Western Approach

025669966

Ca-oline Sheet

Wellingborough

■ Game'

GUERNSEY

2 Cowell Sheet

■ Video Palace

■ Cambridge Computer

City Cent’e

■ D«gita' Sendees Ltd

Wigan

NN84HI

24 Gloucester Road

■ Be"y s Office A Compute'

Llanelli SA 15

lOOOxtord Street WIN 9FB

Store

Plymouth

Fitzherbert Road

09424958?!

093322896F

Brighton

Supplies

05542 70517

01-63703667

t Emmanual Sheet

07526261629038

Fa'lmgton

■ Microrose LtO

■ Da vent ry Computer Centre 0273698424

Cha-rotene Mills

■ 30 Compute’s

CamondgeCBl 1NE

■ JAD integrated Services

Portsmouth P06 1 RU

Mam Street

67 High Street

■ Michael Business Systems

St Peter s Port

Glamorgan

1 14 Gumerstxsy Avenue

0223-65134358264

21 Market Avenue

0706 324934

Bentham LA2 7HJ

Daventry

7 Franklands Way

048i 28797

■ Cardiff Microcomputers

Ealing W5

■ Control Universal

Plymouth PL1 IPG

■ Byte Snop Xitan Systems

046862100

03272 78058

Bu-gess Hill

IRELAND

Belfast

46 Charles Street

01992 5855

Unit 2

0752669462

23 Cumberland Place

■ Sweetens Computer

■ Fuhon Computers

044464144’

Ca'Ottf

26 Tottenham Court Hoad W1
01 5801328

■ Wei Deck Vioeo
XWetoeck Street W1M 7HF
01 486 3783

AVON

■ Avon Compute' Rentals
16 West Street
OloMa-Vet

Bristol BS2 OEY
0272550600

■ Microsfyie
29 Belvedere
Lansdown
Bath BA 1 SHR
0225334659

BEDFORDSHIRE

■ B'oaaway Etect'orncs
1 The Broadway

Ande'tsons Court
Newnham Road
Cambnoge
CB39EZ
0223 358757

CHESHIRE

■ Diskwtse Compute’ Centre
68-70 lower Hill Gate
Stockpon SKI 3AI

061 477 5931

■ Ma'pie Compute' Centre
30-32 Market Square
Marple Stockport

SK6 7AD
061-4499933

■ National Micro Centre
(Europress)

Norbury House
Norbury Crescent
Stockport SK7 7NY
061 456 9548

DORSET

■ Lansdown Compute'
Centre

5 Hoioennu’st Road
lansdown
Boumemoutn
020220165

■ lansdown Compute’
Centre

1 lansdown C'escent
Bournemouth BH8 3EH
020220165

CO DURHAM

■ Darlington Compute' Shop
75 Bondgate

Darlington

0325487478

Soutnampton
0703 334711

■ R0S Electncai
157-161 Kingston Road
Portsmouth
0706012470

■ Baytree Computer Centre
1 3 The Precinct
Waterkxville

07014 3084

■ Ferranti & C'aig
(T A Microchips;

46-48 Si Geo-ges Street
Winchester

■ Ferranti & Craig
27 Bedtord Place
Southampton
070338899

HERTFORDSHIRE

■

14 Station Road
New Barnet ENS iQW
01-441 2922

Services
48 Fisnergate
Preston PR 1 BAT
046862180

■ Whiteheads Lta
48Grassmere Road
Blackpool
025367253

LEICESTERSHIRE

■ Mays ol larceste’
27 Churchgate

l eiceste' Lf 1
0533 58662

■ D A Computers
104 London Road
Leicesle* l£2 1ND
0533 549407

LINCOLNSHIRE

■ mpute’S
63 Wide Bar gale
Boston

0206 543321

Compel erwortd'
19Ablngton Square
Northampton NNl 5AA
0604 3166’

NOTTINGHAMSHIRE

■ Leasalnk Viewdata Ltd
Scientific House
Bncge Street
Sandiacre NG10 5BA
0602 394000 '396976
(a'so Homedata' dealers)

■ Byte Snop

92a Upper Parliament Street

Nottingham

060240576

■ Jentech Services Ltd
Rosemary Cottage
Nordley

Bndgnonh WV164SU
0746261458

I Lion Microcomputers
Burgess Hill
0444641441

TYNE AND WEAR

■ HCCS Associates
531 Durham Road
Low Fell Gateshead
0632821924

WARWICKSHIRE

■ Leamington Hobby Cenhe
121 Regent Street
Leamington Spa
0926292H

WILTS

■ Fe rantr & Craig
(Salisbury Computer Centre)
20 Winchester Sheet
Saksoury

■ CEM Mrcrocompute-
Services

1 1 7 University Sheet
Beflast BT7 1HP

SCOTLAND
Dumfrlee A Galloway

■ Cntfel Mien B-.-
Systems
Glasgow Road
Dumtnes DG2 0NY
0387 8915l>2

Lothian

■ Andrew Whyte A Sons Lid
Constable House
Hopetoun Sheet
Edinburgh EH7
0315560191

■ Anqrew Wnyte A Sons Lid
(Microworld)

i2 Leven Sheet
TollCfOSS

Edmbu’ghEH39LG

0222373072

■ Vioeocam
tZCowbridgeRoad
Pontyclun

Mid Glamorgan CE 7 9ED
0443 225482225332

■ Vioeocare

1 46 Hotton Road
Bar-y

South Glamorgan
CF66HL
0446 747647

■ Videoca’e
The Square
DeWinlon Sheet
Tonypandy
Mid Glamorgan
0443430510

GWENT

■ Gwent Computers
151 Chepstow Road
Newpo-t
0633215008

Leasalink Viewdata dealers— L easalink is Acorn’s UK distributor and has appointed a chain of dealers which it supports

AVON

■ Software Plus
Bath

0225 61676

BUCKINGHAMSHIRE

■ A l Wheete'

G’eat Missenden
024-06 2560

CHESHIRE

■ Computer City Design
A Display

Widnes
051 424 9999
H C lech Son ware
Hyde

061 366 8223

DERBYSHIRE

■ FBC Systems
Derby

963 65280

■ Graves

■ Home A Business

LINCOLNSHIRE

MANCHESTER

■ ManstieW Computers

SUFFOLK

WORCESTERSHIRE

SCOTLAND

1 70 Bate Street

Computers

■ Greens of

■ Bladen Computer

A Electronics

■ C- E Matthews A Co

■ Phoenix Data Systems

■ Graham Begg

Ilkeston.

Oldham

Gainsborough

Systems

Mansfield

Ipswich

25 Worcester Ftoad

Wick

Derby DE7 8FH

061633 1607

Gainsborough

Greater Manchester

0623 31202

0473 215666

Great Malvern

0955 4777

■ J Lambert (Radio)

0427 5101

0204 705 310

■ PR Hartley

■ S J Emery A Co

WR14 4QY

■ Commtsccii

ESSEX

Burnley

■ Cakleat Computers

■ Lomax

Nottingham

Bungay

Glasgow

■ ACL Radio Services

0282 71459

Grantham

Manchester

0602 213493

0271 62503

YORKSHIRE

041 226 4878

Grays

0375 79034

■ T tie Almaine Company
Colne

0476 76994

061 B32 6167

■ S P Electronics
Nottingham

SURREY

■ Greens Telecom
Barnsley

■ W M Coupar
Blairgowrie

0282 863 520

LONDON

MIDLANDS

0602 640377

■ Statcom

12262

0250 2436

HEREFORDSHIRE

■ Wildings Photography

■ Canonbury Ftadio

■ A E Chapman A Co

Sutton

(Acorn Atom only)

■ j H Donald

■ BP Kemp son

Wigan

N1

(Old Hill)

SHROPSHIRE

01 661 2266

■ Arthur Yates

HurlfofU

Hereford

0942 44382

01 226 939?

West Midlands

■ Vermillion

Ripon

0563 26477

0432 3480

LEICESTERSHIRE

(Acorn Atom only)

■ Cavendish Sates

0384 66497

■ DF Gibbs

Telford

0952 582995

SUSSEX

■ Microcentre

0765 2737

■ 1 he Service Centre
Greenock

KENT

■ Percy Lord A Son

El

Coventry

Bognor Regis

WALES

0475 20228

■ Kent Microcomputers
Maidsione

Wtgston

0533 785033

01 247 3453
(Acorn Atom only)

0203 87432

STAFFORDSHIRE

■ Computers ma

0243 827779

■ Bucon

Swansea

ISLE OF WIGHT

0622 52704

■ Praff Bros (Leicester)

■ Electro Leisure

NOTTINGHAMSHIRE

Stafford

WARWICKSHIRE

0792 467980

■ f xceil of Bombndge

Bfaby

W11

■

0785 41899

■ Carveii <:! Rugby

■ SIR Computers

Bembndge

LANCASHIRE

■ Finquick

Foulndge Cotne

0533 773020
■ R H Murcotl
Loughborough

01 727 0511

(Huthwaite)

Sutton m Ashfield

91 553434

■ JohnWBagnall
Stafford

0785 3420

3 9 Bank Street

Rugby

CV21 2QE

Cardiff

0222 759015

098 387 2578

Acorn overseas distributors — Companies have been appointed to set up dealer networks in these countries

AUSTRALIA

■

Melbourne
Tel 419 3033

BELGIUM A
LUXEMBOURG

■ Sooete
Luxembourgecxse
D'mtormatique
Luxembourg
Ter 207637066?

DENMARK

BHL Electronic
I shoe;

Tel 730073

FRANCE

■ jCS Composants
Paris

Tel 355 962?

GREECE

■

Athens

Tel 010 30 1

3615483/3633377

HOLLAND

■ Compact Acoustical

Kortenhoel

Tel 61614

HONG KONG

■ Kong King
Kowloon

Tel 3 450212

ICELAND

■ B Skaptason
Reykjavik

Tel 91 2907?

IRELAND

■ Lendac Data Systpms
Dublin

Tet 7 1 0226/70 1 796

ISRAEL

■ A dcxla Ltd
l el -Aviv

Tel 219111

■ Aschpia Ltd
TelAviv

Tel 03 455 467

NEW ZEALAND

■ Barson Computers
Auckland

Tel (9) 541 030

■ Access Data
Auckland

Tel 68657B

NORWAY

■ Micronor As
Oslo

Tel 785065

SINGAPORE

MALAYSIA

■

Singapore

Tel 29662207966221

SOUTH AFRICA

■ Psion Computers

Durban

Tet 322351

SRI LANKA

■ Dataserve Ltd
Colombo

Tei 98488 D3674

UNITED ARAB
EMIRATES
SAUDI ARABIA
BAHRAIN

■ Key information
Technology
Dubai Tel 474489

WEST GERMANY

■ Acorn Overseas
Deutschland
Munich

Tei 41671

USA

■ Acorn Inc
Woburn Mass

Tel 0101 617 935 1190
’ '91 2.1797463

ACORN USER JANUARY 1984

163

SPECIAL OFFERS

PHONE FOR DETAILS

Electronequip is an authorised Acorn service centre and has
been an Acorn dealer since the introduction of the Acorn.
Our demonstration facilities include 20 station Econet and
Torchnet systems.

NORDMENDE

14" TV/Monitor £21 7.00 + VAT

Ref.

Monitors

Ex VAT

Inc VAT

MNB1401

BMC 1401 Colour Monitor

225.00

258.75

MNCE370A

Cable CE 370A Colour RGB Monitor

199.00

228.85

MNKVIS2

Kaga 1 2" RGB Monitor Vision II (Medium)

285.00

327.75

MNKVIS3

Kaga 1 2" RGB Monitor Vision III (Hi)

399.00

458.85

MNM1431

Microvitec 1 43 1 1 4" Colour Monitor (BBC)

215.00

247.25

MNM1441

Microvitec 1 441 High Res 1 4" BBC Monitor

440.00

506.00

MNM1451

Microvitec 1451 Medium Res 14" BBC Monitor

325.00

373.75

MNN1534

Nordmende 14" TV/Monitor

217.00

249.55

MNN3534

Nordmende 14" TV/Monitor with remote control

234.00

269.10

MNN4430

Nordmende 20" Prestige TV/Monitor remote

417.00

479.55

MNN4432

Nordmende 22" Prestige TV/Monitor remote

458.00

526.70

MNN4437

Nordmende 27" Prestige TV/Monitor remote

512.00

588.80

M

BBC Micros

Ex VAT

Inc VAT

ANB01

BBC Model B Micro Computer

348.26

39900

anbo;

BBC Model B with Econet Interface

389.14

446.00

ANB03

BBC Model B with Oise Interface

409.14

469.00

ANB04

BBC Model B with Oise & Econet Interface

450.01

516.00

EPSON

RX-80 £263.12 + VAT
FX-80 £365.09 + VAT

Printer price includes cable for BBC and screen
dump rom.

TRADE ENQUIRIES WELCOME
Access & Barclaycard Accepted
Large Stocks - 24 Hour Despatch
Carriage 50p to £3.50

Wacom

cotof

SIDEWISE SIDEWISE FITTED

“SIDEWAYS” rom board for BBC Micro.
No soldering required £38.00 + VAT

TORCH *

COMPUTERS -ik-'

Perfectly Made in Britain

Ref.

Torch Computers

Ex VAT

Inc VAT

TC301

Torch Work Station (No monitor) (301 )

1244.00

1430.60

TC303

Torch Work Station with T0SCA (No monitor)

1449.00

1666.35

TC401

Torch Computer twin 400K (new style)

2250.00

2587.50

TC403

Torch Computer twin 400K & T0SCA (grey)

2455.00

2823.25

TC68000

Torch Computer twin 400K Floppy & 68000

3550.00

4082.50

TC68020

Torch Computer 20Mb Hard Disc & 68000

5900.00

6785.00

TCF500

Torch Computer twin floppies (CF500)

2950.00

3392.50

TCFS500

Torch Computer twin 400K & T0SCA (CH500)

3150.00

3622.50

TCH520

Torch Computer 20Mb Winchester CH520

5650.00

6497.50

TCHS520

Torch Computer 20Mb Hard Disc & T0SCA

5850.00

6727.50

TMC240

Torch Computer Monitor (MC240)

575.00

661.25

3" Micro Disc £129.95

(inc. VAT)

Disc Interface & Drive
£198.95 (inc. VAT)

Micro Disc Drive for the BBC Micro
The Micro disc drive offers a method of low cost quick access to
programs. The drive is essentially a small version of a 5i" disc
drive and offers similar features to the larger drive.

The data is stored on a 3" disc, this is enclosed in a protective
hard plastic cassette which features a write protect switch.

The micro drive requires the standard Acorn disc interface, but a
new disc filing system rom. Acorn DFS may be exchanged for the
micro DFS for £12.00. The new micro disc filing system allows 60
files per disc surface and it can read and write to Acorn DFS discs.
Thus if a 5i inch and a micro floppy were connected on the same
cable files could be transfered between them.

Capacity: 80.64 K bytes Transfer Rate: 125kbit/s

164

ACORN USER JANUARY 1984

THE BEST THING
TO HAPPEN TO
THE BBC MICRO

MICRO DISC DRIVE

£129.95 (inc. VAT)

(Available ex-stock now)

. 4 .'.

BBC US

ACORN USER JANUARY 1984

165

MINIMUM POSSIBLE

Sir, May I congratulate you and Stan Froco
on drawing attention to the existence of the
so-called NP-complete problems, such as
the travelling salesman and knapsack prob-
lems, which are fairly easy to specify and to
program straightforwardly but whose naive
solution would be practically impossible
because of the computing time required.

Your readers may be interested to know
that such problems are of great practical
importance, for example in the placement
of circuits on chips and in their wiring,
particularly in a large mainframe computer
where one might wish to keep connections
short (to reduce signal transmission time)
yet not too densely packed. A radically
new, powerful yet simple procedure for the
resolution of such problems has recently
been proposed and demonstrated, based
on a computer model analogy with the
physical process of annealing that a metal-
lurgist uses to produce a relatively defect-
free alloy.

The object of the exercise is to minimise
something - the distance travelled by the
salesman, the space unoccupied in the
knapsack; we call this the cost function.
The quantity we change is called the con-
figuration; for example, the order of the
cities visited by the salesman. It would be
prohibitive in computer time to calculate the
cost function for every value of the configu-
ration. We must find the minimum without
such a calculation.

It is easy to minimise the cost functions of
problems for which from any starting con-
figuration we can make small changes so
that we reduce the cost function each time,
eventually reaching the unique minimum.
NP-complete problems do not have this
property - rather, if one imagines a graphi-
cal representation with the cost function as
the height, one has something more like a
mountain range with many peaks, valleys
and cols of various heights.

From an arbitrary starting point one can-
not reach the lowest valley by only going
downwards; one must go over intermediate
cols. In fact, there are usually many ‘lowest’
valleys of similar height, any one of which
would be acceptable, but all have secon-
dary valleys and cols of different sizes on
the valley sides, inhibiting a systematic
descent to the floor.

How can one find one of the lowest
valleys without knowing anything about the
overall terrain and in a reasonable (not NP-

complete) computing time?

The key idea was provided last year by
three IBM scientists. It employs a Monte
Carlo technique in which the system tests
random changes in its parameters, accept-
ing downward changes but also upward
ones with a reduced probability. Initially,
upward changes are allowed fairly readily
so that the system can get over some of the
higher cols, but this probability is gradually
reduced until finally the system is in a low
valley. More precisely, upward changes are
allowed with probability given by exp
(-C/T) where C is the change of cost
function and T determines the ease of such
changes.

This is precisely the procedure nature
uses in changing the microscopic state of &
solid (or liquid or gas) where now C is the
change in internal energy and T is the
absolute temperature (except for a multipli-
cative constant). When a metallurgist an-
neals an alloy he starts at high temperature
and gradually cools it. So here one per-
forms an annealing simulation, starting at
fairly high T and gradually reducing it. As a
rough rule of thumb, at temperature’ T one
can overcome barriers of height C=T.

This procedure is currently being evalu-
ated and applied at many laboratories and
appears to have great potential, particularly
for complicated and large problems. It has
already proven itself on problems such as
the travelling salesman, bi-partitioning of
the IBM 370 microprocessor and repack-
age of the chips of the IBM 3081 processor.
More details of background and applica-
tions can be found in the very readable
article by its inventors S Kirkpatrick, C D
Gelatt Jr, and M P Vecchi in Science vol
220, page 671 (1983).

Professor David Sherrington
Imperial College of Science
and Technology
London

OFF TUNE

Sir, I use my BBC model B with a Grundig
domestic television set. I have reserved a
channel for the microcomputer, but when I
first switch on the picture is not satisfactory.

The set has an automatic picture-search
facility. When I use this facility, it is not able
to find the optimum output from the comput-
er. I am, however, able to adjust the picture
manually and therefore I can usually obtain
a reasonable picture.

Can you explain why the television set is
unable to find’ the best output from the
computer? Is the output from the computer
different in any way to television pro-
grammes broadcast over the air-waves and
fed to the TV from an aerial? The television
is always able to find the best TV picture on
any channel.

Nigel Webley

W Yorkshire

Generally, microcomputers do not pro-
duce a VHF output of nearly as good
quality as broadcast television. The set
is adjusted to lock on to only very good
signals, and that from the computer is
simply not good enough. When you tune
normally, you choose what picture is
good enough, so the problem doesn’t
occur.

IN THE PICTURE

Sir, I am loyal subscriber to Acorn User and
admire the presentation of the magazine.
However, please note the points below.

Your review of the Hobbit micro-cassette
filing system (September issue) was regret-
tably superficial. I have been told by a
Nascom user of the same drive unit of its
incredible reliability. 1 in 1 0 9 bit error rate
(cf, floppy disc 1 in 10 6 ), yet your review
suggested otherwise.

Could future reviews be more compre-
hensive both in technical detail and discus-
sions of user applications environments?

Your discussion of the Beeb Teletext
adaptor was interesting reading and gave
much useful information, as do also your
news items. However, photographs would
have been worth many extra pages of print:
an open-top view of the board, connections
etc, alongside Beeb view.

Similarly, in your news section, more
photographs of the items being discussed
are longed for.

What does the Beeb ROM socket look
like? A view of the board with the Speech
chips in place, pictures of the second
processor, a picture of the SWR extension
boards on sale and possibly in situ - and so
on. Perhaps small points, but a feast for the
Acorn user’s eye and mind. More encour-
agements to go and buy?

Keep up your high standards.

M Davies

Wirral

166

ACORN USER JANUARY 1984

LETTERS

COLOUR SCHEME

Sir, I find your magazine excellent value, as
a beginner. The ‘Painting by texture' article
of McGregor & Watt (September issue) was
particularly fine and I have dared to make a
small addition, enclosed, which might be of
interest. The two extra procedures are
added between lines 40 and 50 of program
1, page 32 (as amended in program 2,
page 35).

The effect, if you will excuse my amateur-
ish programming, is to permit you to choose
the three basic colours, in PROCchoose
colour, then print a small palette’ showing
the 15 combinations which can then be
used in the painting.

Since adopting this, I have had many
hours of pleasure.

Secondly, an annoying problem. With my
first experience with the Commodore Pet,
where the printer is specially made for it,
dumps were easy, so I bought an Epson
FX80, which has no dump for my BBC
micro. Programs for the Epson MX80, giv-
en in earlier Acorn Users , did not work. An
Epson technical writer finally kindly con-
verted one of them for me, so I have a basic
dump for Mode 1 .

But why was it necessary? Coming from
an older age, as you might suppose, I am
staggered that the modern computer age
can make such a mess of a seemingly
simple procedure!

D Fry

Kent

You have to remember that the Commo-
dore Pet was sold as a complete system
with VDU, drives and printer included.
The concept of the BBC micro, however,
is one of total expandability, which al-

lows you to choose from a much wider
range of add-ons. Remember, too, how
much the Pet cost.

As far as printer dumps go, the pro-
gram in the December Acorn User is
designed to print all the BBC’s modes
on any Epson bit image printer, and so
should work on both MX80 and FX80.

XREF BLOCKED

Sir, I have a model B micro with 1 .2 OS and
have just keyed in the XREF program in the
November issue of Acorn User.

I have used INPUT# and PRINT# in
other programs, together with LOAD and
SAVE, and have never experienced any
problems with cassette file handling - hav-
ing the volume level on my Smith’s
CCR800 set at 1J-2.

However, running XREF against pro-
gram files on cassette, I found that
BLOCK? errors kept occurring for the
BGET# command at line 550. Turning up
the volume control helped get past one
such error, only to encounter a repeat
further bn. Trying to find an optimum setting
resulted in either BLOCK? or DATA?

As written, the program doesn’t allow
recovery from such an error, so it became
quite frustrating having to start again. I
amended the *OPT command at line 100 to
*OPT2,1 which then gave the option of a
rewind back to the beginning of the block
without having to restart the entire run.
Additionally, it should be possible to incor-
porate error handling to cater automatically
for such occurrences.

I am interested to know if anyone else
has experienced this problem on byte
handling and whether there is a remedy.

Simon Holland
_ Hastings

1 1 30VDU 1 9
1 1 40CLS
1 1 50ENDPR0C

121UREST0RE I S00

--

1260RESTORE 1600
1270F0R N-l TO ig
1280READ e,, !l10VF
1290NEXT E !m ix=NlPROC

1330£Np PROC
1500DATA

" ue"

’ 1 , col our 1 , 0, 1 9 , l" co l' our2M-,’ 1 our 1 . ■ col

-,r> # • f 1 3,tolour3:

curtT 2 ’" 10 ^ 3

^awpal lette
500
TO 10

& PPaint (e,f >

;|E«;Sr

SSK

156odata*4o’ j 1 , 000 ’

161 ODATA i 1

ssasSF^^'’

^ ^

XREF STOP-GAP

XREF users (November) will find there is a
problem with certain tape recorders. When
a program is saved, the operating system
uses a 0.6second inter-block gap. XREF
can only read files if the tape recorder in
use is capable of stopping and restarting
the tape within this gap. Unfortunately, the
inter-block gap cannot be altered for save;
however, the attached program Copy will
save a program (which can be loaded or
chained in the normal way) using a 2.5
second inter-block gap.

Copy is used as follows:

Load or enter the program to be copied.

Type PAGE = HIMEM-&200

Load or enter Copy.

Run.

Enter the file name for the copied

program.

Start the tape recorder.

When the copy is finished reset PAGE to

&E00.

XREF can then be used on this copy of the
program.

Ian Graham

n User , November
•p “ -g" -

r- Z'Zzxr than stand *

svsL» EM ”‘ th BBC tin,

50 r*/.=?,E 00
60 *0PT1 , l

, 70 tNPUT"Progr am name », fl

80 F7.=OPENOUT(A$)

*0 REPEAT

_ ? {® 0 »PUT#F •/..?, X . I*-x* +llEX
THE i\r 0 UT * F% ' Ey - IF «-*FF

-u"i£JS 1,8PUT " rx, ‘ 7 n,Iy -

L%sBPUT * n

140 UNTIL E7.=^FF
150 CLOSE #F 7.

160 END

Jan Graham bridges the inter-block gap

XREF TRUE

Sir, Thank you for the very useful utility
XREF in the November issue.

Unfortunately there are still some bugs
left in it. PROCassembler is not working
correctly, ass% is not reset, and if the
assembly code delimiter is the first charac-
ter, it will be missed

My suggestion is:

640 ass%- TRUE : IF B%-93 GOTO
660

660 IF B%= 93 THEN ass%=

FALSE:PROCread

J Rye

Ipswich

ACORN USER JANUARY 1984

167

TRAIN SPOTTERS

& GRICERS

2 POWERFUL PROGRAMS FOR THE MODEL B AND O.S.1

(Electron Versions Available Later)

PROGRAM 1

A Menu-Driven facility for maintaining a file of loco and
stock spots, with capacity for an incredible 5000 numbers.

Handles all number formats.

58001 86003 M59006 253004.

Save/ load database to tape.

Full Search /sort /edit functions.

Can print sorted database.

PROGRAM 2

For the spotter who is nearly clear' a Menu -Driven
facility for maintaining a wants list of locos and
home sheds.

Designed for locos/ EMU s/ DMU s.

Prints /displays wants by shed.

Prints wants lists.

Produces visit/trip reports.

Allows changes of shed .

To order, send £6.99 or £13.00 for two Plus 50p P&P
Payable to Novelty. 7day despatch. State which program.

P.0. Box 85 LUTON LU4 OTD

POWER DISK

12 powerful machine code a^a
utility programs for only LlU

inc. manual
and P&P

These high quality utility programs have been
written to extend the power and simplify the
use of your BBC MICRO disk system.

POWER DISK is supplied on a 40 track disk with
an introduction program and a comprehensive
manual explaining each program in detail.

POWER DISK utilities include;

-FORM59

-DIS PLAY
-DIREDIT
-KEYEDIT

-PRINT

-LOCK

-FORMAT

-TAB

a disk reformatter that allows up to
59 files on each disk instead of the
normal 31 ; a real money saver!
a fast, flexible memory display/editor,
a disk directory editor,
allows easy viewing, editing, loading
and saving of function key definitions,
a high quality background printer-
spooler that lets you use your micro
while listings and documents are
printed; why wait for your printer?
a time-saving disk access editor,
a 35,40 and 80 track disk formatter,
a TAB key activator.

Set and clear tab stops with ease;
make your space bar live longer!

also ARRSAVE, VARSAVE, ZERO and CHANGE.

For your POWER DISK
send £10 to STEIN-SOFT,

8 West View, Hatfield, Herts ALIO OPJ

CGP-115. Creates beautiful graphics in red, blue,
green and black. Text mode prints 40 or 80
characters per line at 12 characters per second.
Includes serial and parallel interfaces and easily
replaceable ink cartridges and standard 4 V 2 ” paper

rolls 26-1192 £149.00

BBC Cable. 26-7203 £39.95

The Biggest
Name in Little
Computers

See Our Extensive Range of Microcomputer Accessories
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SOFTWARE

f BBC POOL (32K) - £7.95*

SUPERB VALUE FOR MONEY PACKAGE

Classic representation ot the real thing using high resolution super smooth
colour graphics for accuracy and detaiL A real pleasure to play

BBC HORSERACE (32K) - £6.95*

An exciting and colourtul multi-player game complete In every detail
with tumbling jockeys, realistic horses. TV van. tote and leader
boards, stewards enquiries, sharp bookies and much more
Don’t lose your money at the track, try HORSERACE instead.

MULTI- AID (32 K)

A powerful 3 program utility incorporating many useful features not

ChaSclen A^wTyou to define and edit MULTICOLOURED
characters in blocks of up to 8 x 3 (max. 128) using up to 4
chosen colours Characters previously loaded into memory can also
be recalled and examined/edited in any mode. VDU23 statements
are automatically generated and can be saved for later use. Simple
to use and probably the best of its kind available.

Soundlab - Experiment with up to 7 envelope and 9 sound commands
simultaneously. All parameters clearly displayed and easily altered EVEN
when envelopes are in use allowing the effect of changes to be heard as
you make them Envelopes already defined by another program can also be
read out of RAM and fine tuned to your own requirements
Graph 7 - Any possible mode 7 display can be created and edited on the screen
with minimal effort. Store up to 24 screens and recall at will for viewing or editing.
Ideal for animated sequences, visual aids for lectures/presentations, slide prepara-
tions etc Screens can also be saved and used In your own programs.

Complete with full documentation. ONLY C7.95

BRAIN TEASERS (32 K) - Only £5.95

Six thought provoking games of mental agility including Reversi, 3D noughts and crosses, mastermind etc
Superb fun for all the family

^ All programs available NOW! s.ae for catalogue

"ELECTRON OWNERS-

Special versions now available for the Electron

r

Orders to:

Dynabyte Software

31 Topcliffe Mews,

Wide Lane, Morley,

Leeds, LS27 8UL

r \

Dealer and Distributer
Enquiries Welcome

Call (0532) 535401

v y

Please add 50p p & p to all orders

J

168

ACORN USER JANUARY 1984

TAB TASK

Sir. For some time I have been using a
technique which performs virtually the
same task as George Hill’s item The key to
tab' (page 65, October Acorn User). Al-
though my method does not produce the
same number of spaces as set by @% or
move to the next column, it only requires
two simple commands rather than using up
memory and altering the OSRDCH vector. I
list the method below:

*KEYO" "<cr>; (required spaces)
*FX219,128<cr>

Osbyte call 219 sets the TAB key to pro-
duce the code passed in X (128 in this
case). The function keys produce codes in
the range 128-137, so to use key 4, for
example, X would be 132. Thus the TAB
key can simulate any function key.

I keep this as a IBOOT file on my disc
used for machine code programming and I
have found no need for producing the set
number of spaces.

Many thanks for a most informative
magazine.

Julian Blythe

Cornwall

George Hill replies :

Your neat suggestion is useful, but does
not do the same as my TAB program.

TAB should advance the cursor to the
next pre-defined column, independent of
the present position of the cursor. Your
suggestion accomplishes the function SPC,
ie, to insert a fixed number of spaces
between the end of the last item and the
beginning of the next.

To illustrate the difference, look at the
output from program 1. My program pro-
duces output like the TABbed line, yours
like the SPCed line, but with a constant
number of spaces

You say that you use your program to
write assembly language programs. If they
are to finish up in neat columns for label,
instruction and comment fields you must
have to use the delete key a lot - or always
use labels of the same length, and avoid
comments.

Incidentally, there were two reasons for
writing the TAB program. One was to
accomplish the TABbing function to lay
assembly language programs out properly,
the other was to illustrate the method of
intercepting the vectored calls - a fairly
advanced idea, which bears further study.

D

Mr-, H;jJL.

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Me.

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iBREM Using TAB and SPC
IM2M0DE3

T3PR I NT ' ” Usi ng TAB f ur c
40PPINT TAB (S3) : "A”; TABU
“BC M : TAB ( 20) ; "CDE" ; TAB ( 30)
"FGHI " ; TAB (40) ; " JPLMNOPD
RSTLVWXYZ " ; TAB (60 ; ’ END. "
50PRINT ' "Usi ng SPC tunc
P0PR I NT SPC ( 0 ) ; " A" ; SPC ( 1
"SC":SPC C20> ; M CDE-;SPC 32)
FGHI"; SPC ( 40 > ; " JKLMNOPQ
R5TUVWXYZ" ; SPC 160) ; "END. "
70END

1 1 on "
0 : ;

t i on 1
0 ) ;

>RUN

Us; ng

TAB

functi on

A

BC CDE

FGHI

Using

SPC

functi on

A

BC

CDE

JKLMNDPQRSTUVWXYZ END.

J KLMNOPQRSTUVW X Y Z
END.

FGHI

Program 1 and output

ACORN USER JANUARY 1984

169

BEEBUG ™ BBC MICRO

DEVOTED EXCLUSIVELY TO THE BBC MICRO

MEMBERSHIP NOW EXCEEDS 20,000 MEMBERS
BRITAIN'S LARGEST COMPUTER USER GROUP

20,000 members can't be wrong — BEEBUG provides the best support for the BBC Micro.
BEEBUG Magazine — NOW 64 PAGES devoted exclusively to the BBC Micro.

Programs — Hints 8- Tips— Major Articles — News — Reviews — Commentary.

PLUS members discount scheme with National Retailers. PLUS members Software Library.

10 Magazines a year. First issue April 1982. Reprints of all issues available to members.

SCREEN SHOTS FROM PROGRAMS
IN BEEBUG

ILLUSIONS
October 1983

MUNCHMAN
October 1983

3D SURFACES
October 1983

SPIDERS WEB
Aug/Sept 1983

COMPUTER AIDED DESIGN

PROGRAMME
Dec 1983

CHEQUERB0ARD
Dec 1983

8-6-2 Looonotiw*

Hurt tlbthn

Magazine programs now available on cassette at
£3.50 inc: VAT 8- p8p — see BEEBUG magazine for
details.

Aug/Sep Issue: Games: Space Lords (32k) a two-player space battle. Build
yourself a light pen — a simple explanation for the beginner, together with a
sample program. Use our “Contact Points for the Beeb" to discover who to
contact when in need . We show how to put those 'awkward' cassette programs
onto disc. Final instalment of our popular 5-part series on “Using Files"
REVIEWS of-MICRONET, Watfords Electronic's Disc Filing System, two
EPROM programmers, and the tax advisory package “Microtax". This month's
visual programs include Spider's Web, Super Large Screen Characters, Bounce
and Swing. We also show how to hold two complete screen pictures at once,
and switch rapidly between them in “Dual Screens on the Beeb". A Crossword,
Brain Teaser and our 4th Software Competition provide a competitive edge to
this month's magazine. We also have our very popular scattering of Hints and
Tips.

October Issue: Games. Munch-man, a Snapper type game with super
graphics, Illusions graphics and sound you won't believe. A versatile Renum-
ber program for Basic, Fabric Patterns, an invisible Alarm Clock, Disc
Sector String Search and a program for drawing 3D Surfaces. Articles on the
T eletext Mode for beginners, Compilers and Interpreters, using Joysticks,
using the Speech Synthesizer and more. Reviews of two Cassette Recon
ders (Marantz Superscope C190 and Acorn Data Recorder), three Printers
(NEC pc-8023B, STAR DP840 and CP-80), and lots of new games software
(and we've arranged SPECIAL OFFERS for members). Plus a review of the new
Acorn Electron and news of our new magazine for Electron users called
ORBIT. Plus all our usual features like Hints and Tips, Postbag, and a new
Brainteaser.

November Issue: Program Features: Reversi, a challenging board game,
Lunar Escape, an addictive arcade type game, SNARFER, a very useful disc
recovery program, SHAPER for defining multiple character shapes, RAPIDS,
another short game, DEMOLITION, a sizzling display with matching sound
effects. Plus articles on a Clock Display, theTeletext Mode (part2 of a series),
an Introduction to Interrupt Programming, a new Mode 8 and The Beeb in
Slow Motion. Plus Extension ROM Board Reviews, Games Reviews, Book
Reviews, M-TEC Torch Basic Review. Plus News, Hints and a new
Competition.

December issue: Program Features: Killer Dice game, Galactic Invasion,
a fast moving space invasion game, LINK, a very useful disc utility for program
development, ASTAAD, a really excellent program for Computer Aided
Design, the Percussion Machine, moving Chequer Board display, Screen
Freezer, a routine to freeze your favourite game in mid-play, and a musical
rendering of the Twelve Days of Christmas to add a seasonal flavour. Plus
articles on theTeletext Mode (part3) and Fitting an External Speaker. Plus
Disc Drive Reviews. Book Reviews, Hints and Tips.

BEEBUGSOFT: BEEBUG SOFTWARE LIBRARY

offers members a growing range of software from
£3.50 per cassette.

BEEBUG NEW OPERATING SYSTEM OFFER

BEEBUG members can now obtain the new 1 -2 OPERATING SYSTEM
ROM at around HALF PRICE

As a result of BEEBUG negotiations with Acorn the ROM now may also be
offered by other user groups to their members.

1. Starfire (32K). 2. Moonlander (16K). 3D Noughts and Crosses (32K). 3.
Shape Match (16K). Mindbender (16K). 4. Magic Eel (32K). 5. Cylon Attack
(32K). 6. Astro-Tracker (32K).

Utilities: 1. Disassembler (16K). Redefine (16K). Mini Text Ed (32K).
Applications: 1. Superplot (32K). 2. Masterfile (32K).

13% DISCOUNTTO MEMBERS ON THE EXCELLENT WORDWISE
WORD PROCESSING PACKAGE — THIS REPRESENTS A SAVING OF
OVER £5.00.

Send £1 .00 8 SAE for Sample
Membership: UK £5.40 for six months, £9.90 for one year.

Overseas one year only: Europe £16.00, Middle East £19.00, Americas 8 Africa £21.00, Other Countries £23.00
Make cheque to BEEBUG and send to: BEEBUG Dept 13, PO Box 109 Baker St, High Wycombd, Bucks HP11 2TD
Send editorial material to: The Editor, BEEBUG, PO BOX 50, St. Albans, Herts AL1 2AR

170

ACORN USER JANUARY 1984

LETTERS

40/80 QUERIES

Sir, I have been using the 40-track to 80-
track copier from the August issue of Acorn
User to copy a couple of 40-track discs.
Please could you explain the following
points?

What does OSWORD with A set to &7E
do?

I have been able to work out most of the
disc commands through FND, except for
the one called in PROCset I can find no
mention of command &7A in my 8271 data
sheet, although I suspefct that it is the
command to write to a special register with
R% determing the current track’ for the
surface in use. My data sheet gives this
command as &3A

I suspect that line 610 has been omitted
from the listing and should read

610 = X% ? T%

I think it would be very helpful if you could
produce an article describing these new
OSWORD calls, and any other details of
the DFS which people, like me, who do not
have Acorn discs and therefore an Acorn
manual are unaware of.

William Smith

Sheffield

OSWORD &7E returns the size of the
current disc. This facility is provided by
the DFS ROM, not the MOS.

Command &7A is synonymous with
command &3A but with the select 0 bit
set, which selects the required drive
surface. The command sets the current
track, as you suggest.

Line 610 has indeed been omitted.

POWER SHARING

Sir, An increasing amount of software is
becoming available in ROM or EPROM and
there is only limited space in the Beeb to fit
them. As the system can support up to 16
sideways ROMs several firms are now
producing add-on sideways ROM boards to
allow for all 16 ROMs to be fitted at once.

I am a little concerned about whether the
power supply can take the extra load of all
16 ROMs in addition to my disc drive, which
is already powered from the power outlet of
the micro. Presumably, if I converted my
single drive to a double drive this would
further increase the load.

A dealer I have spoken to thought that it
should be alright, but didn’t seem to be very
sure. Could you please let me know if 16
ROMs and dual disc drives (modern slim-
line type) are likely to overload the PSU of
the BBC micro?

Michael Lowe

Loughton, Essex

We would not recommend that 16
sideways ROMs are added to a BBC
micro with discs because the power

consumption of this amount of memory
is far greater than that available. The
solution is to buy a separate power
supply unit for the ROM board or disc
drives.

COPY PROBLEM

Sir, I have a Beeb with a single-sided 40-
track disc drive. I have been giving a lot of
thought to the subject of backups. Backing
up to another disc with only one drive is
tedious, to say the least.

I have come to the conclusion that the
best solution is to have a program to enable
backing up a whole disc to tape one file at a
time, with no operator intervention required.
This method is full of problems, as I have
discovered. For a start, all files need to be
‘LOADED and ‘SAVED to take into ac-
count the different types of files.

I think a combination of your automatic
menu program (September Hints & Tips) to
get the file information from sectors 0 and
1, and tape to disc transfer (April Beeb
forum) in reverse would provide some of
the answers.

I would be very grateful if one of your
readers could give me the answer.

Malcolm Andrews

Trowbridge, Wilts

COUNTER CRASH

Sir, I am writing to inform you of what could
be a bug in the BBC computer. When using
AUTONUMBER in any mode other than
mode 7 I found that the machine will count
away quite happily for so long and then for
no apparent reason will suddenly begin
counting from line 10 again.

Unless this resetting of the counter is
noticed it is possible to unknowingly begin
to erase the very program that you are
typing in.

Is this a bug, or do I have a faulty
machine?

J Revis

Leeds

It seems you have a faulty machine. The
problem has not arisen in tests carried
out by Acorn.

UNWANTED DIN

Sir, Your readers may be interested in a
possible cause of tape load/save errors.

One particular brand of tape recorders,
being sold under several different names
specifically for computer use, has a DIN
connector which the handbook recom-
mends is used. The problem is that the
microphone is not cut out of circuit by the
DIN plug, so any noise nearby comes out
as an overlay on the computer recording.

This can easily be checked by talking into
the tape recorder while recording a pro-
gram, and then listening to the playback.
The remedy is to insert a dummy jack plug
into the microphone input socket.

Dealers could help potential buyers by
checking their stock for this feature and
warning purchasers of such offending
items.

D Stiles

Bristol

DISC DISPATCH

Sir, I am sure that I am speaking for the
people who own an Acorn Atom machine
when I say that we must seem to be like
long-forgotten, second-class customers!

My local computer dealer, Electroniquip
of Fareham, placed an order on my behalf
for an Acorn Atom disc-pack: this was done
at the beginning of March this year. Despite
the many assurances of prompt dispatch of
this expensive item by Acorn, still nothing
has happened, and I am writing to you as a
last resort, having made several telephone
calls to the customer service department.

If the likes of Dr R Flinn, who works for
the University of Birmingham (June Acorn
User) are having problems with delivery
dates where does it leave individual Atom
users?

D Bourner

Fareham, Hants

COLOUR QUEST

Sir, I understand that I should be able to
use my 14in television set (Panasonic mo-
del TC 431 GR) as a colour monitor for the
BBC model B, connecting the video outlet
socket of the computer to the video in
socket of the television set.

When I have tried this, the picture is clear
in black and white but I cannot get colour.
However, I can get a colour picture by
connecting the aerial out of the computer to
aerial in of the television set, but the
definition is not so good.

How can I get colour on the video input?
(The television set has three input sockets:
the aerial, the video in and the audio in.)

T James
Chippenham

If your micro has an issue 1, 2 or 3 board
fit a 470pF ceramic capacitor between
the emitter of Q9 and the base of Q7.
Both Q9 and Q7 are transistors near the
modulator. The emitter is marked with
an e’ on the PCB in white/yellow letter-
ing; the base is the central leg.

With boards of issue 4 and onwards,
fit an insulated wire link between the two
holes of S39, found next to the video out
socket.

ACORN USER JANUARY 1984

171

VORTEX!

4iii5& i n ! i i i Ti I • r « ' V i

‘. '• :: ' '-A ^ &/■• ; _ • *? & • "j.

’ >£ » > - tTLo* r. JL^V' t mk \ ■■

•***#* , ;v.

,;4f,

"• v '*. V

the graphics are excellent and
the whole thing well designed."

. . . "a game for the family —
simple, but enjoyable"

. THE MICRO USER

"This is a very addictive game and
is good value for money"

BEEBUG

"The game features some of the
best and most unusual graphics
yet for the BBC micro"

BEEBUG

\js 1

9

Send a S.A.E. for details or ask your local dealer for a demonstration.

Our software is available from more than 500 retail outlets in the UK, including
W.H. Smith, HMV, all Spectrum Group shops and most good dealers.

We also offer a rapid mail-order service by writing to:

^ Software Invasion, 50 Elborough St., Southfields, London SW18 5DN.

Other programs available for the BBC Micro Model B:- Cassette £7.95 me. Disc £1 1.95 me.

GUNSMOKE

3D BOMB ALLEY

ATTACK ON ALPHA
CENTAURI

172

ACORN USER JANUARY 1984

SECRET DOOR

Sir, I recently purchased a model B with a
Wordwise chip for use as a word processor
and added it to an ordinary black and white
television and a cassette recorder. I
couldn't afford a printer but a friend prom-
ised to let me use his any time I liked.

However, I then purchased from W H
Smith a Silver Reed EX42 portable elec-
tronic typewriter. I wondered if this might be
converted into a printer but was told by
Silver Reed, which does an interface (the
I/F44) for its EX44 machine (which is nearly
twice the price of my EX42), that this was
impossible. But I noticed in the front of my
machine a little trapdoor. On opening this, I
found a connector. I bought the I/F44
interface and - lo and behold - 1 now have a
printer at a considerably reduced price.

I have checked all the EX42s I can find in
local shops: they all have the connector.

When I contacted Silver Reed about this,
they claimed I was doing the impossible
and implied that I was not telling the truth.
When my computer shop manager phoned
them, there was a pregnant pause.

Now, I’m a writer, not a computer buff - I
don't know a Centronics compatible inter-
face from a 36-pin connector (receptacle),
but I do know I’ve got both and they
efficaciously operate my good but com-
paratively inexpensive typewriter. So
someone, somewhere, has made a Big
Mistake and if any readers want a cheap,
but effective, daisywheel printer, the above
tells them how to do it.

Martin Booth

Somerset

SPLIT THE ATOM

Sir, Barry Pickles suggests there are some
40,000 Atom users.

I bought an Atom two years ago but have
hardly used it, mainly because I have little
spare time to type in long programs copied
from magazines which do not specify
whether they are suitable for Atoms and
what size memory is required, and I have
little money to spend on cassettes from
advertisers who do not bother to state what
machine the cassettes are for (BBC A or B,
Electron or Atom), let alone what size
memory is required.

I flip through your magazine and despair.
In 95 pages of magazine there are two
pages relevant to the Atom and they are
beyond me. Can you not cater for idiots
such as myself?

I am looking at issue No 11 (June ’83),
pages 14 and 16. Will that bubble sort
program run on my Atom? Why can’t you
use a REM to say, for instance, ‘Suitable for
Acorn Atom 2k’ to help people like myself?
And your general articles on interrupts,
graphics, etc - which machines are they

relevant to? Why can’t you keep the maga-
zine in sections: BBC, Electron and Atom?

I see adverts like ‘Practical programs for
the BBC & Atom’, a book advertised for
£5.95. Does this imply that BBC programs
will run on an Atom? I cannot for the life of
me understand that a person with an Atom
would want BBC programs and vice-versa.
Who can afford two machines; let alone
master them?

I see that Garland Computing is advertis-
ing some superb educational programs for
the BBC, eg, Seed Germination, Blood
Circulation etc. Is there no similar, simpler
type of program available for the Atom? Is
the Atom incapable of handling such pro-
grams, or is it that programmers just don’t
write for the Atom any more? Can some-
body please help me?

Mrs P Gough

PS. Perhaps it is true that computers and
women were not meant for each other, and
that I should sell my Atom in your personal
ad column. Would I be any better off if I
bought an Electron?

FORMAT FAILURE

Sir, Having read the erudite questions and
answers appearing in your column during
the last months, I have hesitated to pose
my mundane problem. However, I wonder if
you or your readers would help.

An OS 1.2 ROM was fitted by my local
Acorn dealer to my BBC model B micro,
which originally had OS 0.1 .

I have failed miserably to obtain a screen
display which uses the right-hand column
and, say, 23 rows. Ordinarily, when a
character is printed in the 40th column the
cursor moves to the next line and receipt of
a ‘new line’ character results in double-
spacing. The obvious solution should be to
add a semi-colon (see line 70 in TEST
program). It is this semi-colon which is
giving trouble.

As the simple program and the resulting
printout show, the screen displays the first
six lines as expected. Then the computer
inserts six spurious spaces after 260 char-
acters and 250 characters alternately.

To my mind there seems to be an associ-
ation with blocks of 256 bytes. Have I
discovered my own private bug, peculiar to
my OS 1.2 ROM (unlikely), or is it shared
with all those who use a 1 .2 ROM?

Les Fountain
Ferndown, Dorset

The problem you are encountering is
based on the fact that the pseudo-vari-
able COUNT is only one byte long, so if
more than 256 characters are output
without a carriage return the counter
overflows, causing mis-formatting - as
in your example.

To avoid this, ensure that you print a
carriage return before 255 characters
have been printed.

QW TO AZ?

Sir, Last year I bought a BBC model B for
my personal use, which I would like to start
using as a word processor for my company.

The typing will be done by my secretary,
who is used to an Azerty keyboard and the
Qwerty from the BBC gives her many
difficulties.

How can I change the Qwerty keyboard
to an Azerty one? Changing the keys is no
problem, for they can easily be lifted off and
put on another location, but is it possible to
redefine the hexadecimal ASCII codes, or
should any chip be changed on the
keyboard?

T Marres

Belgium

The keyboard layout can be changed
permanently only by modifying the MOS
chip - which clearly cannot be done by
an average user - or by major hardware
modifications. Keys can be redefined by
means of software, as Simon Berry dem-
onstrates in his article this month on
creating a ‘numeric keypad’, but con-
verting the keyboard is not really a
practical proposition when you are
using a commercial software package,
as the word processor is liable to be
overwritten by your conversion
program.

10

REM TEST

20

A= 1 0

30

B=20

40

C=30

50

D=40

60

FOR J =0 TO

70

PRINT A , B

80

NEXT

90

END

Les Fountain’s program to test

the screen display

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

io

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

10

20

30

40

IO

20

30

40

10

20

30

40

IO

20

30

40

10

20

30

40

, .

. and the printout that shows a

failure in formatting

ACORN USER JANUARY 1984

173

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P.LGRAPHICS SVSTEfTl

WILL UNCHAIN THE GRAPHICS POWER OF YOUR BBC MODEL B MICROCOMPUTER

An easy to operate, complex
graphics system with new and
very advanced software giving a
versatile CAD system. Complex
pictures and diagrams, or origi-
nal designs can be quickly, easily
and accurately reproduced. The
system consists of the GRAPHIC
DIGITISER' incorporating a 256mm
x 205mm tracing pad. the
'Control Program (tape or disc),
instruction manual, key card and
quick reference card

WIDE RANGE OF INSTRUCTION
BLOCKS

Instruction blocks enable
boxes and circles to be con-
structed from two probe posi-
tions filling area with chosen
colour, painting area with colour
or shading, drawing of irregular
shapes, outlining in different
colour and varying line thick-
ness. creating lines in horizontal,
vertical or angled modes with
parallel lines in repeat or mul-
tiple repeat styles in selected
thickness. Special routines for
plotting circular arc’s and for
the animation and multiple plot-
ting of text.

USER-DEFINED CHARACTER
PROGRAM

Freedom of character design
means shapes and symbols can
be created in very fine detail.
Characters may be plotted many
times over, clustered, mixed
with normal text characters,
used in animation effects/ turtle"
control.

COMPLETE EDITING FACILITIES
PROVIDE A CAD SYSTEM

Mistakes can instantly be
erased and rectified with random
and sequential access to stored
picture data which may be easily
revised, corrected and modified.

IMAGE MANIPULATION

Images may be reflected, ro-
tated. moved, scaled, duplicated,
compressed and extended.

STORAGE DISPLAY PROGRAM

Pictures may be saved on The main control program
cassette or disc file or dumped to contains a Display' program
printer. The Control Program which enables the user to freely
contains a range of printer mix visuals in their own
dumps. programs.

FULL COLOUR/RESOLUTION
The range of colour facilities
offered by the BBC Micro in
Modes 4 and 5 are easily han-
dled by the PL GRAPHICS
SYSTEM, in high and medium
resolution.

CURSOR UTILITY CALLS
The probe positions displayed
on screen can be justified verti-
cally and horizontally to aid
rapid joining of lines. Addition-
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pective guide lines can be con-
structed.

ACCURACY/SPEED
Probe position is continuously
displayed on the screen and
fidelity of image to original
drawing is excellent. Completed
images can be recalled from file
and dumped to the screen in
seconds.

NO KNOWLEDGE OF BASIC
REQUIRED

Users can very easily and
quickly familiarise themselves
with the PL GRAPHICS SYSTEM.

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174

ACORN USER JANUARY 1984

-

DIM SPACE

Sir, In the October Acorn User , Michael
Johnson posed the problem of redimen-
sioning arrays in BBC Basic. This is a tricky
little problem if the storage space used in
the previous array declaration is to be re-
used.

The approach to this problem is to clear
the variables back to those which were
defined at a previously specified point in the
program. This part-clearance can then not
only be used for redimensioning arrays, but
also for recovering variable storage space
after the temporary use of variables. The
temporary’ variables are all the new vari-
able names (except A% to Z%) used after
vartop is saved with a DIM V 1 statement.

See, for example, line 30 of the test
program below, when OLD— VARTOP is set
to the value of vartop immediately prior to
dimensioning the array A. PROC-CLEAR
in line 60 then clears all the variables which
have been first named between lines 30-60
inclusive, that is array A and J in the
program as written. Lines 40 and 50 print
array A to show it exists and lines 70 and 80
permit you to check whether it exists after
PROC— CLEAR. Enter “A(0) M to confirm
that array A has gone or RETURN to
redimension A.

To follow the workings of PROG-
CLEAR, a knowledge of variable storage
between LOMEM and vartop is needed
(see Acorn User , July, page 39). However

briefly, the variables are held in chains
identified by the first letter of the name, with
each stored variable starting with a two-
byte address pointing to the next variable in
the chain.

The chains are started using initial ad-
dresses stored at locations &40CK2*ASC
(first character of name), and terminated
with a zero address vector.

Lines 120 to 140 set A% in turn, to
address each variable chain. Lines 150 and
160 update A% to point to each variable in
the chain until the chain ends or uses RAM
above the procedure parameter V%. B%
then contains the address of the required
last member of the chain and its address
"hi” is set to zero to fix it as the last member
in line 170. Finally, in line 180 vartop is
reset to V%.

There are two situations when PROC—
CLEAR could misbehave. First, I am un-
clear as to the effect of PROC-CLEAR if
used with a second processor across the
Tube: perhaps someone would like to com-
ment on this. Second, if existing string
variables are lengthened between setting
vartop and PROC_CLEAR, they might be-
come corrupted after PROC-CLEAR The
way to avoid this (and to save space) is to
set the permanent’ string variables to their
maximum length when they are first used.
Any new string variables named between
setting vartop and PROC-CLEAR are de-
leted along with the other variables by
PROC-CLEAR.

ECONET SOFTWARE

Sir, Woolwich College ordered, in good
faith, 20 BBC micros for use on two Econ-
ets. These were delivered at various times
over the past year and have been set up
ready to test at the start of this term, in early
September.

We took the precaution of ordering the
Econet software early, in June 1983. there
was then no mention from Acorn of any
delay in getting the software. We fondly
hoped, in our ignorance, to have the sys-
tem up and running in September for use
throughout the current academic year.

It is now November and no sign of
software. Are our Econets white elephants?

I feel, as so many people have in the
past, conned by over-hopeful advertising.
Nowhere in their literature lauding the
Econet did it say that it would not be usable
until 1984 (and then only in very limited
form, without such important things as file
handling from the stations).

I would be grateful for a response from
Acorn to this complaint. I am sure that
Woolwich cannot be the only college or
school in this unenviable position.

George Hill
London

DRIVE JUMP

Sir, I would like to bring to your attention a
fault in the dual-catalogue program in the
October edition.

If it is executed on a newly formatted disc
in drive 0 of a double disc drive system,
have caution when using it in drive 1 . I had
a very important disk in drive 0 completely
ruined. I inserted my dual-catalogue disc
into drive 1, logged on to the drive, and
typed ‘ALT. The computer jumped to drive
0 and erased my catalogue!

Colin Millerchip
Cheltenham

See December s issue, page 157 , on this
point.

FRED-LESS

Sir, I read the letter from Tom Boyd in your
October edition about FRED, the memory-
mapped input/output area, and his associ-
ated spaces.

I too had this problem and started dab-
bling with character codes. I found that I
could redefine code 32 to be anything, a
block of white being best. It is then imposs-
ible to copy spaces.

However, to activate the new character, I
found it necessary to run the program first
(the redefiniton is done using VDU 23).

H Hollingworth

University of Essex

Jack Pike

Bedfordshire

10REM Partial clearance of variables
15REM by Jack Pike
20 INPUT "Array size", I
30DIM QLD_VARTOP -1,A(I>

40PR I NT ' SPC ( 9 ) "I"SPC(S) "A(I)"'

50FGR J =0TO 1 : PR I NT J , A < J ) ; NEXT
60PROC_CLEAR (OLD_VARTQP)

70INPUT"Pri nt variable named”, AT-
30 IF LENA* PRINTEVAL (AT) : GOTO70
90GOTO20

100DEFPROC_CLEAR (V/.)

1 1 0LOCAL I 7. , A7. , B7.

120FOR I %=2-;482 TO ?<4FB STEP2
130 IF I7=&4B6 I7.= I7.+8
140A7.=I7.

1 50REPEAT : B7.=A7. : A7.=?A7.+256*A7.7 1
160UNTIL A7.< LOMEM OR A7.>=V7.

170B7.? 1=0: NEXT

180?2=V7. MOD 256:?3=V7. DIV 256
190ENDPROC

Jack Pike’s test program clears variables back for redimensioning arrays and
recovering variable storage space

ACORN USER JANUARY 1984

175

BACK ISSUES

BINDERS

July' August The first issue Arti-
cles on drawing techniques the
BBC Computer Programme
machine code graphics, ques-
tions and answers, hints and
tips, sound, interfacing scientific
instruments dumb terminals for
0 1 machines, disc drives,
econet in schools

September Ceefax tele-
software. Beeb in business,
mailing list, simple files, 30-hour
Basic course, art on a micro,
music BBC micro as a key-
board. extra Atom commands.
BBC Basic board. ULA design,
teletext graphics, machine code
graphics. analogue input,
schools training, 0 1 cassette
bug patch

October Electron details, BBC
TV series— confessions, two Ep-
son graphics dumps, Seikosha
GP 100 dump, worldwide
networking for BBC micro, gar-
bage handling, voice ROMs,
sound pitch envelope, moving
graphics. ZX printer for Atom,
RGB colour separations for
Atom, biofeedback. book
reviews

BACK ISSUES of magazines are available
(except July, February, March and April) for
£1.25 each from BKT (address below),
which includes postage. Please make
cheques payable to Addison-Wesley Pub-
lishers Ltd. For issues which have sold out
we offer a photocopy service (right).

November Teletext, second
BBC TV series, machine code
series 1. programming forum,
Trek III, speeding up graphics.
Bomber game listing. 7-tone Ep-
son graphics dump, Mom
graphics manipulation, dumb
terminal for 0 1 machine, fire-
work graphics, editing tips

December BBC TV in schools,
machine code 2- registers, pro-
gramming forum, program gen-
erators, carols, hints and tips.
Logo and turtle graphics in
schools, introduction to proce-
dures. software review Atom
word processing, toolbox re-
view, 16-colour graphics on mo-
del A, sorting, sound envelope
design

January MEP school launch.

*FX commands tor sound, sec-
ond BBC TV series, machine
code 3 — two pass assembly,
disc drives for the Beeb pro-
gramming forum, program pro-
tection. micros in schools — new
series. Commodore Pet printer
used with Beeb, BBC programs
written on an Atom, extra Atom
memory

ENQUIRIES about subscriptions and back
issues should be sent to BKT. The company
will also accept credit card subscriptions by
phone: 0732 351216.

Overseas enquiries for bulkordersshould
be made to the publisher’s marketing man-
ager at Bedford Square.

WE CAN now offer binders which will easily
hold a dozen issues of Acorn User at the
special price of £4.25 each (includes post-
age). These quality binders have been
specially commissioned in a maroon, simu-
lated leather finish with ‘Acorn User’ over-
printed in gold lettering. Please make
cheques payable to Addison-Wesley Pub-
lishers, and send the order to BKT (ad-
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(rest of the world). The binders will be
despatched by air mail.

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PHOTOCOPIES of articles in early issues
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3DZ.

Please note this service is subject to a.
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176

ACORN USER JANUARY 1984

YOUR BBC MICRO FOR £4.95.

H &H

SOFTWARE

PRESENTS 3 IMEW TAPES

for the

BBC 32K COMPUTER

to add to their existing range of games
and educational software.

LOONEY LIFT

A new action packed arcade game with hi-res
graphics, full colour and sound. Keep your guests
jumping, operate the lift and watch out for the
luggage. The alternative is the sack!

£7.50

CHEMIPLANT

Another first? A chemical plant simulation. Avoid
explosions, spills and other disasters on your way to
your first million. Plant manual included. Hi-res
graphics.

£7.50

STORY

Electronic storytelling!

First make up some scenes using pictures from the
computer bank or use your own drawing skills. Then
write your story. Up to 7 screens can be displayed,
saved and printed.

£6.50

To get more information about our new and
existing software, ask for a catalogue. Please send
a s.a.e.

*** Disc versions available: please add £1.50 ***
Please send orders and cheques/PO to:

H & H Software, Dept B, 53 Holloway,
Runcorn, Cheshire WA7 4TJ. Tel: 09285
65566

PUTTING YOUR BBC MICRO TO WORK

□ Chris Callender £4.95.

Yes, it's true. A complete word processor
program is just one of 1 5 major programs in
this new, 1 20- page book. You can keep your
accounts in order with the HOME
ACCOUNTS program, organise your life
with planner and keep your numbers under
control with TELEPHONE DIRECTORY.

You can even gain experience with spread-
sheet calculations with SPREADCALC
THE BBC

MICRO COMPENDIUM

□ Jeremy Ruston £14.95.

More than 500 pages in this massive work, the
most important ever published for serious
BBC Micro programmers Major topics
covered include: assembly language
programming; floating point algorithms;
recursive programming, increasing the
vertical screen resolution to 5 1 2 with
software; and an intelligent disassembler.
From the author of THE BBC MICRO
REVEALED.

36 CHALLENGING
GAMES FOR THE BBC MICRO

□ Tim D Rogers and Chris Callender £5.95
From graphic adventure programs, to fast
moving arcade action, this 270-page book
gives you a whole library of software-
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with detailed program notes, and screen
printouts. Games include 3D INVADERS,

RAT ATTACK, DOWNHILL SKIING
and SHARK. LET YOUR BBC

MICRO TEACH _

YOU TO PROGRAM *

□ Tim Hartnell £6.45
This book, by best-selling
author Tim Hartnell, is the ideal companion for
you if the BBC Micro is your first computer.

It takes you, step by simple step, through
programming in BBC BASIC, with a number
of worthwhile programs (including a
complete REVERSI/OTHELLO game, and
another to play CHECKERS). Computer
and Video games said: "... takes you
further into the cloudy areas of the BBC

Microcomputer than anything else I've
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CREATING ADVENTURE PROGRAMS
ON YOUR COMPUTER

□ Andrew Nelson £4.95

A major work (complete with three complete
ADVENTURE programs) to show you how to
devise, program and solve Adventures
on your BBC Micro.

Interface Publications, Dept. A A,

44-46 Earls Court Road, London W8 6EJ

rr

Please send me the books indicated I enclose £

Name:

Address:

MTERFdCE

PUBLICATIONS

All Interlace books are available Irom computer and book stores, including W H Smiths.
Menzies. and Dixons Trade supplied by The Computer Bookshop, 30 Lincoln Road.
Olton, Birmingham B27 6PA (021 707 7544. telex 33436 i )

ACORN USER JANUARY 1964

177

USER GROUPS

□ Belfast Computer Club, described by
hon sec Patrick Roddie as ‘Beeb orientat-
ed’, is being set up and new members are
asked to take a computer if possible
Meetings are on the first Monday of the
month at 7-1 Opm at the Ashby Institute,
Stranmillis Road, Belfast 9. Contact Mr
Roddie on Holywood 3212.

□ A new club has been formed in Surbi-
ton for Atom users. It meets on alternate
Monday evenings at Charrington Bowl,
Kingston Road, Tolworth, Surbiton, Surrey

(contact Andy Nicholls on 01-337 2696
during working hours).

□ The Southampton Amateur Computer
Club has its main meetings at the Medical
Sciences Building. Basset Crescent East,
on the second Wednesday of the month at
7.30-1 0.30pm, but it also has a very active'
BBC group which gathers at the
Crestwood Centre. Meetings take place on
the last Friday of the month, also between
7.30 and 10.30pm.

On the following day each month the

SACC holds junior group meetings at the
Baptist Church, Bitterne Park, which both
members and non-members can attend
between 9am and noon.

Membership enquiries should be ad-
dressed to the club at the Crestwood
Centre, Shakespeare Road, Eastleigh,
Southampton.

□ Another Beeb group has been formed in
Belgium (see Acorn User, September),
this one specialising in model B Club “B”,
as it is called, is at Micro-informatique,
Chemin de Weyler, 2, 6700 Arlon, Belgium

• Rupert Steele

Amateur Computer Club

St John’s College
Oxford OX1 3JP

• Beebug

374 Wandsworth Road
London SW8 4TE

• J Smith, Secretary

Brighton, Hove & District
Computer Club

30 Leicester Villas
Hove

E Sussex BN3 5SQ

• Dr Leo McLaughlin
North London BBC
Micro Users Group

Dept ot Chemistry
Westfield College
University of London
Kidderpore Avenue
London NW3 7ST
Tel 01-435 0109

• West Midlands
Computer Group

1 2 Apsley Road
Oldbury

West Midlands B68 0QZ

• Mr J Price
Bedford House

27-28 St George's Road

Brighton

Sussex

• Mr P Beverley

Norwich Area Acorn User
Group

Room 12a, Norwich City
College
Ipswich Road
Norwich NR2 2LJ

• Keith Mitchell

Edinburgh ZX Computer Club

1 9 Meadowplace Road

Edinburgh

Tel 031-334 8483

• Steve White

Atonrv BBC User Group

c/o Superior Systems Ltd
1 78 West Street
Sheffield

Tel: (0742) 755005

• Robin Bradbeer

Association of London
Computer Clubs

Polytechnic ot North London

Holloway

London N7 8DB

• Nik Kelly

Liverpool BBC & Atom Group

56 Queens Drive
Liverpool L4 6SH
Tel 051-525 2934

• Andy Purkiss
Namebug

12 Palm Close
Witham, Essex
Tel 0376 515609

• i Beng

• Oivind Grenness

BBC Micro Club

BBC Norway

PO Box 1297

O-Inform

Santa Cruz de Tenerife

PO Box 716

Tenerife

N3191 Horten

• Lindsay Thachuk

Beebnet

Norway

• R V Souter

PO Box 262

TRS 80 Beeb Users Group

Kmgswood

25 Carr Lane

South Australia 5062

Willerby

• Richard Sterry

Hull HU10 6JP

Tel 0482 654117

BBC Micro User Group

1 Waved Garth

• E R Piper

Sandal Wakefield

Bognor Computer Group

West Yorkshire WF2 6JP

(BUG)

Tel Wakefield 255515

2 Ely Gardens

• Colin Price

Aldwick Park

Bognor Regis

Keighley Computer Club

Sussex P021 3RY

Red Holt

Hamsworth Wood

• Andrew Pike

Keighley

Peterborough Personal

W Yorks

Computer Club

Tel Keighley 603133

920 Bourges Boulevard

• Jennifer Woeller

Peterborough PEI 2AN

Tel 0733 44342 (after 5pm)

Sutton Library

Computer Club

• Dave Clare

Sutton Central Library

Mid-Cheshire Computer Club

St Nicholas Way

Providence House

Sutton. Surrey

222 Townfields Road

Tel 01 -661 5031

Wmsford

• Mr C Rutter

Medway Atom Users Club

St John Fisher School

Cheshire CW7 4 AX

Tel Wmsford 51374

I

• Liverpool BBC

Ordnance Street

Microgroup

Chatham

c/o Fred Shaw

Kent

14 Albany Avenue

• Mr J Ashurst

Eccleston Park

Prescot

Merseyside L34 2QW

Acorn Computer

Users Group

Abraham Moss Centre

• John Harris

Crescent Road

Bottisham Acorn User Group

Manchester 8

1 Rowan Close i

• Mr D L Evans

Bottisham i

Cambridge CB5 9BN i

Tel (0223)811487

23 Hitchin Road

Henlow Camp

Bedfordshire

• Peter Smith

• N P (Bazyle) Butcher

Fareham and Portchester

Amateur Computer Club

23 Sandy Ciose

Harrow Computer Group

Petersfieid

1 6 St Peter's Close

Hants

Bushey Heath

Watford WD2 3LG

1

• Paul Barbour

• R Welch

Laserbug

1 0 Dawley Ride ,

Harpenden

Colnbrook

Microcomputer Group

Slough |

7 Tylers

Berks SL3 0QH

Harpenden

Tel 02812 3064

Herts AL5 5RT

• Mr P Frost

• Brian Pain 1

Colour Micro Users Group

Atom Users Group

40a High Street 1

3 Leyland Road

Stony Stratford

Bulkington

Milton Keynes

Warks CV12 9LW

Tel (0908)564271

• Mr D Coulter

Preston BBC User Group

8 Briar Grove
Ingol

Preston PR2 3UR

• Acorn Users Group of Sweden

c/o Janne Soderberg
Frihetsvagen 32
S-175 33 Jarfalla
Sweden

• Peter Wilson

Universal Micro Club

26 North Cape Walk
Corby

Northants NN18 9DQ
Te' Great Oakley 742622

• John Haigh

Iver Computer Society (IC’s)

141 Leas Drive
Iver

Bucks SL0 9RP

• John Eary

Kinder Peak Computer Club

36 Parkway
New Mills

Tel New Mills 43870

• C Verrier

Wandsworth Computer Club

Earlsfieid Library
Magdalen Road
London SW18

• Mr J Craig

National BBC User Group

40 Mount Pleasant Avenue
Wells

Somerset BA5 2JQ

• Mr R Luff

Kingbee

54 Arlington Close
Kingwinford
West Midlands

• Computer Club

Caterham Leisure Centre

Godstone Road

Caterham

Surrey CR3 6RE

Tel Caterham 48304/43316

• Ted Ryan

Eastwood Town
Microcomputer Club

1 5 Queens Square
Eastwood

Nottingham NG16 3BJ

• Mr T A Kayani

SOBAT Computer Club
(East London)

1 2 Calderon Road
London Ell 4EU
Tel 01 -556 5423

• Mr M G Forster

Potbug BBC Users Group

8 St George’s Avenue
High Lane
Tunstall
Stoke-on-Trent
Tel 818499

• Muse (for teachers)

Freepost

Bromsgrove

Worcs B62 7BR

• Mr B Carroll
The Cottage
42 Manor Road
Aldershot GU1 1 3DG

• Steve McLeod

BBC Users Group of Canberra

5 Hatfield Street
Evatt A C.T 2617
Australia

Tel: (062) 58 7719

• AH Fowler

Tonbridge School Computer
Society

44 Birling Road
Tunbridge Wells
Kent TN2 5LY

• J Assies, Secretary

Big Ben Club

POBox 177

4670 AD Zevenbergen

The Netherlands

• H W H Fisher

Sunningdale BBC User Group

82 Cedar Drive
Sunningdale
Berks SL5 0UB
Tel Ascot 25030

• Peter Hughes
Format 40 80 Club

BBC Disc User Group
5 March Street
Bristol BS1 4AA

• Dave Davies
229 Manley Road
Chorlton-cum-Hardy
Manchester M2 1 1RB
Tel 061-881 0382

• Tony Latham

Computer Users Club

69 Hadlow Road
Welling, Kent DAI 6 1AX

• Tony Pickard

Newcastle & Washington BBC
User Group (NEWBUG)

c/o Washington Town Centre
Library
The Galleries
Washington. Tyne & Wear
Tel 091 -41 7 3992 after 7pm

• John Fryer, Treasurer

ABUG

1 7 Edgedaie Road
Sheffield S7 2BQ

• Chris Parry. Secretary

Stratford Computer Club

1 6 Sackville Close
Stratford-on-Avon
Tel 0789 68080

• Robert Watt

Inverclyde BBC Micro Users' Club

9 St John's Road
Gourock

Renfrewshire PA 19 1PL
Tel Gourock 39967

178

ACORN USER JANUARY 1984

FREE ADS

BBC model B with 1 2 ROM, disk inter-
face. Wordwise. extn speaker socket.
Immaculate condition. £450 ono. Acorn
Teletext adaptor, brand new. £200.
Acorn DFS chip (0 9A), £20 (with man-
ual) Deliver in Kent 0227-750600

FOR SALE: BBC model B Arcade
games: Kansas City. Galactic Firebird;
andSecta Software: Space Invaders. £6
each. Original packaging. Will sell sepa-
rately. Scott Basham. Upmmster 23147.

BBC model B, Basic and Pascal. Four
games, tape recorder and lead. Only 2\
months old Worth over £500 My bar-
gain price of only £387. Ask for Ramin.
01-452 38 78 (Dollis Hill, London), after
630pm

ATOM 12K + 13K. FP ROM, colour via
Ross toolkit ROM, Creed teleprinter.
12ch music synthesizer, joystick, 5A
power supply, all Atom books Software:
Chess, 747, music, Galaxians, plus
many other games. £200 01-743 7523
(anytime).

ATOM 12K + 12K FPROM, via Atom text
editor. Programmer's toolbox, PSU, four
software books, manual and 1 3 issues of
Acorn User' Ring Atherton 878590
(Manchester).

COLOUR Atom, 2 PSUs, manuals inc
Getting Acquainted, Atom newsletters
and software on paper Software in-
cludes GPs. 3. 4, +9, 747 and many
others £170 ono Phone Westerham
64060 after 6pm. Ask for Jason.

ATOM 12 x 16 Ross ROM Atom Calc
and BBC Basic teletype printer with
interface Separate regulated power
unit ROM selector board. All for £150
plus carriage or collect. S. Browning. 54
Helmdon Close, Ramsgate, Kent CT12
6TT. Tel: Thanet (0843) 582719

ACORN Atom 8K + 6K including all
leads, manuals, PSU. etc. Ideal starter,
£78 ono Reading 29157 after 4pm.

ATOM 12K + 12K FP ROM. Wordpack.
toolbox, expansion board 6522 via PSU,
manual, leads, Getting Acquainted.
Business Book, complete set Newsletter
Software covering business applica-
tions, filing systems. Offers near £150.
Copthorne 7 1 3096 evenings.

SUPER Atom includes: BBC Basic, 5
EPROMS (eg, Wordpack, Disatom), 8-
channel A/D. D/A, joysticks, EPROM pro-
grammer, 3-channel sound, colour, C/W
cassette (all in wood carry-case). Plus
Software Library. £140 Tel: Melton Mow-
bray 691 19.

1 2K ATOM with disk drive, colour board,
Atom word chip, games, Peeko-comput-
er, manuals, printer interface, and Atom
Business book and tape. £225. R.
Haines. Westbourne Schools, Penarth.
Tel: (0222) 705705 (day).

ATOM 12K RAM 8K ROM plus program
books, £95 Tel: Chertsey (093 28)
63889

ATOM 38k + 16k FP. toolkit 6522, printer
connector, long leads, PSU 4amp max.
will power two Atoms. Software, Acorn-
soft and others worth £350, will accept
offers region of £250. Tel: South Benfleet
(03745) 50654

ATOM 12k -f-1 2k, VIA, new colour board,
timedata ROAM expander board Word-
pack and graphics dump, ROMS. Printer
interface. Also disk pack. Software Forth
Galaxians, dozens more. Bargain £320,
may split. Tel: Bradford (0274) 612529.

ATOM 12k+12k FP ROM. £100. Acorn-
soft cassettes, introductory package
and others, all leads and manuals, as
new, £140. Tel 0480 76397 Huntingdon

ATOM 12k+12k FP ROM, £80. Software.
Space Invaders, Cylon Attack, Chess
and more. All leads and manuals just
£110. Tel: Aldershot 319286 afternoons
please

ATOM 12k -Hi 2k and software, manual
and books. About £120 for quick sale.
Richard. Tel 01-278 9441 (work). 01-263
0510 (home).

TANGERINE system, Microtan 65,
Tanex, 40K Tanram, high resolution
board, sound board, system mother-
board, system rack, switch-mode PSU.
full ASCII Keyboard, Basic, Xbug, hi-res
toolkit. 9in rack, EPROMS. £220. Split/
exchange. Ben. 01-328 1800 evenings.

TANGERINE Micron, cased, MPSI. 8k
RAM, 15k ROM. Tanbug, Xbug, Basic,
toolkit, ASCII keyboard. Hex keypad,
Invasion keypad, chunky graphics
Much software, 4 manuals. Microtan
Companion book, £240 ono Tel: 01-668
3326.

SHARP MZ80k in excellent condition,
hardly used, over 150programs. games,
educational and utilities, suitable begin-
ner or small business, £265 ono Tel:
Bexleyheath 01-303 4173 anytime.

UK101, cased, Cegmon monitor. 20k
RAM, 18k ROM, New Basics 1-4, Basic
5, Basic X, toolkit, encoder, screen ex-
pansion, superb sound, quality expan-
sion keyboard, 20+ programs, manuals
and books, £125 ono Tel: Emsworth
(02434) 5548 Hampshire

ATARI 800 computer, 810 disk drive,
Basic cartridge, full 48k, DOS Master,
immaculate condition, only one month
old, used once, boxed, all leads, man-
uals etc, £495 ono. Tel! Paignton (0803)
553799 after 5pm

ATARI 800, 48k, Basic, 410 cassette
recorder, Joystick, Zaxxon Game, man-
uals, books — Mapping the Atari, and
Atari Programming, with 55 Programs,
numerous programs and magazines,
boxed, five year guarantee, £370. Tel
(09277) 65845.

ATARI VCS with Combat, Adventure.
Haunted House. Missile Command.
Yar’s Revenge, Berzerk, Defender, ex-
cellent condition, boxed Tel: 01-995
3420 after 5pm.

MATTEL Intellivision, only 10 months
old, 3 tapes including Lock ‘n‘ Chase,
Advanced D&D and Auto Racing. Only
£75. Tel: (0276) 20284

COMMODORE VIC20 + 16k + C2N
cassette unit, 8 games, inc Centipede,
Defender, Krazy Kong (joystick includ-
ed). £180 ono. Robert Pa ton, 26 Ray-
mond Ave, South Woodford, London
El 8. Tel: 989 2330 between 5-6pm

ZX81 with 64k Memopak and Fuller
FD42 full size keyboard, £60 Buyer
collects. Also various books and soft-
ware Tel: 061-439 9665 after 6pm and
weekends.

ZX81 + 16k RAM with many games,
tapes, £45 Excellent condition. Books
also available. Tel: Amersham (02403)
3857.

ZX81 16k includes leads, power pack,
tapes, magazines, also ZX81 books, ex-
cellent condition, £60 worth of software.
Will accept £70 ono. Tel: Dewsbury
452514 (West Yorks).

16k ZX81 + approximately 20 games,
tapes, various books, eg, Mastering Ma-
chine Code + first 14 issues of Sinclair
User magazine + all leads, £40 ono Tel:
Slough 43805 evenings.

TANRAM board unused, issue 2 with
16k, offers or swap for Acornsoft Forth
and Lisp. Contact George Seaton, Briar
House Lodge. 184 Fulford Road, York
YOI 4DA.

100K disc drive and complete Dfile sys-
tem, all chips All for only £190 For BBC
Will separate if required. Tel: 0452
503119

BBC 1 00k disc drive complete with man-
ual, utility disc and leads. Superb condi-
tion. Only £190. Acorn DFS ROM, £25.
Complete Bigears speech recognition
system, immaculate condition, £30. Da-
vid. Tel: 01-854 9028 after 6pm.

COLOUR board Acorn Atom. £16 BBC
converter for Atom. £25. 8k extra mem-
ory Techtroniks board with toolkit, £10.
Tel: 0753 654666, ext 208 (office).

BBC 100k disk drive, utilities disk, all
leads included, £140. Official Acorn
BBC disk interface, £60. Richard. Tel:
021-783 8651 evenings.

DISK drives. TEAC with power supply,
£150. Cannon powered from BBC, £120.
Both 100K, cased, with leads, at two
thirds new price Will help with installa-
tion if required Tel: (0734) 470588
Reading

ACOUSTIC modem plus terminal soft-
ware for BBC B. Access Prestel and
Micronet Only £40 Sell (£3 each) or
swap original games, Acornsoft, Pro-
gram Power etc. Tel: 0543 76993 even-
ings/weekends only. Hurry!

PRINTER Tandy DMP 100 with BBC
cable. £170 ono Send sae for sample
print. Duncan Winstone. 41 Wordsworth
Road, Radford, Nottingham. Tel: 0602
705650.

BBC official 100k disk drive + leads +
BBC utilities disk and BBC manual. Up-
grading to bigger drive Still under guar-
antee, £200. Street. Tel: 0458 45707
after 6pm

PACE-AMCOM DFS. Operates in Acorn
and extended modes, latter gives many
new features. ROM, manual and utilities
disc, £27 Tel: Aldershot 22539 evenings
after 7.30pm.

FREE PERSONAL AD SERVICE

Sell your old hardware or software for cash. Fill in the form below to a maximum of 32
words (one in each box) and send it to Acorn User Free Ads, 53 Bedford Square,
London WC1. Use capital letters, and remember your name, address or telephone
number. This is a free service to readers — no companies please. One entry per form
only, and we cannot guarantee any issue.

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ACORN USER JANUARY 1984

179

BBC ROM

EXPANSION

BOARD

the ROM board for the BBC micro

★ Easy to install, no soldering, full
instructions provided.

★ 12 extra sockets allow up to 256 K ROM
space.

★ Fully buffered.

★ Fits easily inside BBC case.

★ Price (Model 1): £35 + VAT

We also stock a complete range of BBC Micro peripherals and software, many at
unbeatable prices! The following are just a small sample:

PRINTERS
Dot Matrix:

Epson FX-80 £399.00

Epson RX-80 £275.00

RX-80F/T £299.00

Shinwa CP-80 263.35

Daisywheel:

Juki 6 100 £399.00

BBC MICROCOMPUTER

BBC Model B

£399.00

BBC Model BD

£469.00

MONITORS

Sanyo B/G

. £85.00

Microvitec RGB

£249.00

DISC DRIVES

Single 100K . .

£199.00

Dual 100K . . .

£349.00

Dual 400K . . .

£669.00

TORCH Z80

DISC PACK:

(Now with FREE £1000 worth

of software!) . .

£839.50

SIR BBC ROM BOARD
MODEL 2
NOW WITH RAM!!

The SIR ROM Board Model 2 is an upgraded
version of the highly successful Model 1
design. The new Model 2 includes facilities
for the use of up to 16 K Static RAM allowing
you to write your own firmware!

BBC ROM Board (Model 2)

Price: £40 + VAT

iso

ACORN USER JANUARY 1984

SIR
COMPUTERS
FIRST FOR

electron

SUPPORT!

r

SIR RESEARCH PRESENTS:

OUR RANGE OF PERIPHERALS FOR THE NEW ACORN ELECTRON

SIR ELECTRON 8-ROM BOARD

★ Provides for up to 128K of ROM space.

★ Fully buffered design.

★ Easy to install, just plugs in, no soldering
necessary.

★ Allows further expansion via rear edge-
connector.

★ Permits use of most BBC ROM- based soft-
ware (such as VIEW, PASCAL, FORTH,
etc).

★ Price: £40.00 + VAT.

SIR ELECTRON PRINTER
& JOYSTICKS INTERFACE

★ CENTRONICS printer interface

★ Analogue-to- Digital Converter (ADC)
allows use of any BBC- compatible joysticks.

★ Full firmware support.

★ No soldering, plug-in design.

★ Built-in, versatile edge-connector provides
for further expansion.

★ Price: £45.00 + VAT.

AVAILABLE SOON: INPUT/OUTPUT PORT, RS423 INTERFACE, and more!

Please write or telephone for further details on any of the above.

All our prices are inclusive of VAT unless stated otherwise.

Postage & Packaging: Small items ( ROM Boards, etc) please add £ 1 .00 Large items ( Printers, etc)
please add £10.00 ACCESS/BARCLAYCARD TELEPHONE ORDERS WELCOME.

SIR COMPUTERS Ltd.

91 WHITCHURCH ROAD, CARDIFF CF4 3 JP
Telephone: CARDIFF (0222) 621813

ACORN USER JANUARY 1984

181

BBC disc drive. Twin 100k TEAC drives
with power supply, utilities disc, cable,
manual and ten discs, some with pro-
grams, £300 ono Tel: (061) 682 5901
after 6pm.

TEAC disc drives, s/s 80 track, ideal for
use with BBC. One drive + 5 Datalife,
£110. Two available. Tel: 01-373 5545
night.

TERMIPRINTER 7075 complete with
desk paper tape reader and punch plus
workshop manual. £80 ono. ARR 33
teletype TTL interface VGC, £50 ono.
Faller Tel: 01-449 1808 after 6pm

DISC drives, two single sided 40 track
drives with box and power supply for
BBC or other micros. £280 Tel: Colches-
ter (0206) 863960 after 7pm

LVL dual 200k disc drives, £320 BBC
disc interface. £70. Microvitec colour
monitor. £260. All new. Various Acorn-
soft cassettes, £4. Micropower games
including Moonraider, Croaker, Killer
Gorilla. £3.50. Daventry 3792.

SEIKOSHA GP100A printer good condi-
tion, buyer collects. Tel: 01-940 9361
Richmond

BBC B software swap Colossal Adven-
ture, Rocket Raid, Galactic Firebird. Me-
teors. Golf, for Great Britain. 747, Danger
UXB, Bug Blaster, Super Invaders, or
other such games. Tel: Linlithgow
843854 after 5pm

BBC games to swap/sell. Space Warp +
book. Atlantis. Beebmunch. Hyperdrive
all 0.1 OS only, £4 each Adventure and
Laser command. £5 each (both Program
Power) Acornsoft Countdown to Doom
also £5. Tel: (051) 520 2012 after 4pm

ACORNSOFT cassettes for sale. Star-
ship Command. Rocket Raid, Count-
down to Doom, Snapper. Missile Base.
Hopper, Arcadians, all as new in original
packing. £7 each. Tel: Leeds (0532)
688479 after 6pm Ask for Mark

SOFTWARE for BBC B Multifile. Golf
and Chess by Bug-Byte and Planetoid
and Desk Diary by Acornsoft, £6 each or
£25 the lot Tel: 01 -864 5019 evenings

BBC games: Meteors, Snapper, Defend-
er, Rocket Raid, Gorilla. Monsters. Arca-
dians, Starship Command, Chess,
Regression/Correlation Program and
others (please ask), £5 each. David
Wellham. Brunei University, Uxbridge.
Middlesex. Clifton Hall, Room S3.

SWOP or sell Originals programs, Gun-
smoke, Pharaoh’s Tomb, Space Adven-
ture, Escape from Pulsar 7, Feasibility
Experiment, El Dorado Gold, The Wiz-
ard, £30 or £6 each. Gavin Stephenson
Tel: Chesham (0494) 782993 after 6pm

BBC software. All originals 747 Right
Simulator, Castle of Riddles. Q'Bert. Kill-
er Gorilla. Road Runner. Alien Dropout,
Perseus and Andromeda, all £4 each or
swap all for original Wordwise. Tel: 021-
382 3106

BBC Acornsoft software new: Super In-
vaders, Arcadians. Meteors, Desk Diary,
Algebraic Manipulation and Cosma’s
Time Traveller Worth £60. will sell for
£4.50 each or all for £24. Tel Nottm.
(0602)619169

SWAP BBC Rocket Raid and Snapper
for Missile Command, Starship Com-
mand, Countdown to Doom. AMS disc
utility ROM and System User Guide, £6
Tel: Basingstoke 67574.

SOFTWARE for BBC/B Acornsoft: Mete-
ors*, Rocket-Raid*. Planetoid*, Star-
corn*. Snapper*, Invaders* also Killer
Gorilla*, K.C Frogger*. Swoop*, UXB,
Hunchback. Q*Bert. Colossal, Mon-
sters*. Felix, Arcadians*. Will swap for a
compiler or progs. (*On disc only.) A.
Bailin Tel: Brighton 562810 .

SWAP BBC games including Starship
Command. Countdown to Doom, El Dor-
ado Gold, Felix in the Factory and Killer
Gorilla. For Road Runner. F for Freddie,
Q Bert and other originals. Tel: Steynmg
815411 (Sussex).

BBC software to sell or swap (large
selection). Tel: (0274) 687249 after 7pm
or weekends anytime.

SOFTWARE Acornsoft games, Sphinx,
Castle of Riddles, Drawing, Record
Keeper, Swap or sell half price Dave
Tel: 061 430 2060 Stockport

ORIGINAL programs package Three
games: Rog-vaders. Lewin-maze-

munch, R L-Driver Synthesizer key-
board, £2.25 Roger Lewin 5 Welshmill
Road, Frome, Somerset BA1 1 2LA.

BBC B games, many popular titles to
swap or sell on tape and disc (about 100
games to swap). Contact Robert Tim-
mins, 204 Sefton Road. Stevenage,
Herts. Tel Stevenage 722975 after 6pm

ACORNSOFT games Monsters, Plan-
etoids. Meteors. £5 each or £10 the lot
Cylon Attack, Centipede, Galactic Fire-
birds, Dracula Island, all for £3 each
Contact Saleem Chowdhery, 25 Colwick
Road, Sneinton, Nottingham, NG2 4AL

SWAP or sell, for BBC, Starship Com-
mand. Snooker, Music Processor. £4
each Killer Gorilla. Alpha Centauri,
Bomb Alley. Hunchback, Space Adven-
ture, Painter. £3 each. All originals in
good condition Tel Kings Langley
65116

SWAP large range of Acornsoft, Pro-
gram Power. Bugbite. Superior Software,
etc, including 747 Flight Simulator Also
a range of graphics and utility programs
Tel Bromsgrove 77031 (after 6pm) and
ask for Nigel

£200 WORTH of software, swap for
Acorn Disc interface or Watford or Pace
(Software includes Acornsoft, A + F, Su-
perior, Doctor Soft, Program Power etc.)
Contact Steve Corcoran (evenings). 01-
299 1980

BBC SOFTWARE Moonraider. £5. Kill-
er Gorilla. £5. Planetoid, £5, Superior
Software Centipede. £5, also Pimania,
£3 all as new Tel 051 355 9325

SWAP magazine program cassettes. I
have micro user Nol Deathwatch. No2
King Kong. No3 Air Strike, Beebug Vol 2
Nol, Vol 2 No2 Tel: Kings Langley
651 16 evenings/weekends.

EXCHANGE Acornsoft Philosophers
Quest or Doctor Soft 747 Flight Simulator
for Pimania or Sphinx Adventure (original
copies) Telephone 041 946 9110 Gor-
don Keenan. 61 Glenfinnan Road, Flat
13D, Glasgow G20 8JG

GEMINI Home Accounts Package for
sale Unwanted gift Will accept £10
John. Tel: Marshalls Cross (0744)
81 9453 evenings

RUSTON instant machine code Basic
compiler + manual (original), £20 ono.
Write to Wain Lancaster 164 Goscote
House, Moon Walk, Leicester.

ATOM software to swap (or sell), De-
fender. Cylon Attack, 3D Asteroids, Lu-
nar Lander, £10 the lot. Paul King. Tel:
Stoke-on-Trent (0782) 632600 evenings.

FORTH ROM Watford A5, new plus
manual, £25. J. Rees, Caerleon, Picton
Road. Tenby, Dyfed SA70 7DP

WORDWISE ROM as new, complete
with manual, keyboard strip, fitting
instructions and demonstration cassette,
£27. David Tel 01-854 9028 after 6pm

FOR SALE Wordwise’ word processing
package and 1.2 OS upgrade. £30 Tel
Hemel Hempstead 49395 (after
5.30pm).

UNWANTED Wordwise ROM with user
guide and fitting instructions. £25. Paint-
box by Oakleaf on cassette for BBC B.
£5 Tel: 01-864 5019 evenings

BBC Wordwise ROM. demo tape and
manual Unsuitable for owner’s appli-
cation. £26 Tel: 01-428 8455 (Middx).

FOR SALE or swop complete set of
OMNI science fiction magazines. 61 in-
cluding recent issue Wants BBC
games, Hobbit, Roms etc. Any reason-
able offer Bob Tel 041 332 7666
(Glasgow)

MATTEL software for Intellivision Ar-
mour Battle, Triple Action B17, Space
Spartans + others £10 each ordinary.
£15 talking. Also voice synthesis mod-
ule, £30 or £100 the lot Mike Tel 051
933 8387 after 5pm or at weekends

WANTED Acorn User February. March,
April issues. Oakley 16 Pitton Close,
Wigston, Leicester LE8 2RP

WANTED Acorn Users have you got any
old copies in reasonable condition, be-
tween July '82 and July *83 inclusive 9
Tel: 01-958 81 15

WANTED Micronet modem and driving
software for Beeb Also wanted, software
to swap (prefer to swap discs). Tel:
Harpenden 69152

WANTED 12k Atom working, no extras,
will pay £60 Tel Rochdale 31686

MUSIC files (Muproc). will pay up to £1
Eprom programmer (all Eproms) circuit
diagrams, Beeb model B wanted. Pro-
grams and joysticks for sale Tel Pipe
Gate (063081) 312 (Stoke-on-Trent
area).

LIGHT pen and graphics tablet (like the
Apple’s) wanted For sale Graphics digi-
tiser with control program only, £12 +
nearly 100 software titles. Swap or sell.
Everything for BBC B Full details, tel
(0524) 68100 4-9pm

WANTED 1 2in green screen monitor Hi-
res Under two years old Excellent con-
dition, preferably under £50 Michael
Tel: 01-670 2745 (London).

GOOD price paid for Atom Wordpac
ROM with instructions Simon Tel. Luton
(0582) 32334.

WANTED database for Acorn Atom. Tel
Belfast (0232) 692495 after 5pm

WANTED A B Designs Drawing Pro-
gramme or EDG disc if possible Offer
Program Power Munchyman, Alien De-
stroyer, World Geography, Physics.
Quicksilva Music Processor, BBC Star-
trek. Voltmace Driver Tel: 0353 89438
evenings or weekends.

WANTED please Morse-Reading pro-
gram for Atom or other 6502 computer
Anderson. 44 The Spring, Market Lav-
mgton, Devizes, Wilts SN10 4EB

WANTED BBC model B Up to £250
cash. Preferably without software or re-
corder. Tel: Faulkand 499 (Somerset)
after 6pm

ANYONE interested in forming a Torch
User Group in the North-West? Contact
Leslie Klein Tel: 061 980 4056 evenings
or 061 881 7233. ext 202, business
hours.

WANTED Wordpack ROM for Atom, also
issues 1 .2,3, and 6 of The Atom’ (Bug-
Byte Magazine) Offers at half-price
Giles, Officers Mess. RAF Bruggen
BFP0 25

WANTED printer for BBC Tel Maldon
869398

WANTED Atomcalc 4k ROM, via RDM,
toolbox ROM, ROM selector board and
software games, educational and busi-
ness for use with Acorn Atom Tel: 0247
63266.

WANTED BBC model B. consider model
A, will pay up to £200 John Finlayson.
16 Manitoba Close, Corby. Northants
Tel: Great Oakley (0536) 745367 even-
ings only

WANTED Bug-Byte Atom, 747 Flight
Simulator Tel I Ikley (0943) 609571 after
5pm, weekdays only Ask for Duncan.

182

ACORN USER JANUARY 1984

■ BBC RS423 cable kits with instruc-
tions £3.95 (2 metres) + 50p/extra metre
(cheque with order) Send sae for details
of Cheapo-net system for fast program/
data transfer Datathorn. 50 Spring
Grove, Loughton, Essex IG10 4QD.

A service for enterprising readers and small companies. For
£10, you get up to 32 words, one insertion only. Appearance
in a particular issue cannot be guaranteed. To advertise,
simply complete the form below in capitals with one word per
square. Remember your name and address or phone num-
ber! £10 is the standard fee up to 32 words (no more!).

■ Killa the upgrade For owners of BBC
game killer Gorilla Provides - 15 levels
Climb/jump with hammer Extra lives
Practice mode Pause Disc compatible
tape £2 95 Bit Twiddlers, 158 Church
End, Harlow. Essex CM 19 5PF

■ Magicwand Lightpen paint on tele-
vision screen for Christmas with BBC B
Magicwand Lightpen, eight colours
Software cassette and user guide in-
cluded £22 50 CWO Magicwand, 3
Queensbridge Park, Isleworth Middx
TW7 7LV Further details Tel 01-890
5093

■ Atom extensions CMOS RAMS static
RAM #9800-#9FFF Eprom boards
EPROM programmer power supplies
etc Keep the Atom alive Further details
from Clare Computer Components,
Freepost (GR1271), Stroud, Glos, GL5
3JL

■ Sideways ROM module for BBC each
plug-in module supports 4 switch selec-
table ROMS, may include 2 x8k
EPROMS le 16k SAE for details to S R
Electronics 9 Haddom Drive, Balderton.
Newark, Notts NG24 3HN

■ Control mains appliances using
opto-isolated solid state relays activated
from computer Obtain comprehensive
details of interface components and re-
lays at fraction of normal price from D.
Johnston, 12 Balgillo Road, Dundee
DD53LU

■ Speech synthesiser (BBC) Fits in-
side case, no soldering, unlimited vo-
cabulary Ready to build and tested
module and instructions £25 J Larsen,
21 Queen Anne’s Close, Stotfold, Hit-
chin, Herts SG5 4LP

■ Micro equipment Discount prices for
quality peripherals, printers, disc drives,
cases, power supplies, monitors, work-
stations, 12 months guarantee. Free
demonstration 30 mile radius. Phone for
quotation. Calancratt Ltd Tel Woking
68139 or 4866.

■ Special offer for one month only Cl 5
blank computer cassettes 34p each
Sold in packs of 10. Post and packing
£1 Cheques to Micro Media Supplies,
Freepost, Roydon, Diss, Norfolk IP22
3BR

■ BBC Dust Covers Acorn approved,
fabric colour exactly matches computer
case, finished with neat brown taped
edge, cable access slits. £3 50 inc
Cotswold Covers. 6 Middle Row, Chip-
ping Norton. Oxfordshire. Tel: (0608)
41232.

■ Printing on FX-80 listings from tapes
or 40/80 discs (including Wordwise).
lOp per block (mm £1). Send full details,
payment and return sae. Confidentiality
guaranteed Soft-Ex (A), 18 Trelawney
Road. Falmouth. Cornwall.

■ Machine code data recording se-
quence To record your machine code
programs from your BBC computer. Very
easy to use £1 M.C. Data Sequence, 24
St Mary’s Way. Chigwell, Essex. Only
mail order

■ Super sort program. Ultra-fast recur-
sive technique, ten times as fast as
bubble. Full instructions for incorporat-
ing into your own programs. On cassette
£3. Scorby Soft, Main Street, Flixton,
Scarborough, YO1 1 3UB

■ Graphics toolkit model B OS 1 .2 draw
freely, no coordinates needed. MC paint
routine fills any shape. 28 functions.
Card included, demonstrations, instruc-
tions. Tape £7.50. Disc (40/80) £9.50
Micralsoft (Av), 35 Hartley St. Rochdale,
Lancs OL12 7NF

■ Misar (BBC 32k) monthly index data
processor graphs, histograms, com-
parisons. Use with earnings index, share
indices etc. Supplied with retail price
index £13.50 Prosoft, 10 Begonia Close.
Hinckley, Leics, LE10 2SS

■ Pools Predictor program for BBC mi-
cro. A very powerful forecasting pro-
gram combining six different techniques
of prediction based on statistical
analysis of current form £4.99 Mayday
Software, 181 Portland Crescent, Stan-
more, Middx.

■ AC linear circuit analysis program for
BBC model B Analyses circuits with up
to 16 nodes and 60 components. Cas-
sette £35. Disc £45 Tel: Number One
Systems, St Ives (0480) 61778 Access
or Visa.

■ Nutcracker: Unlocks locked' files as
in Star-command. Snooker, Chess etc
£5. Note: this is not a copy program as
output file is completely unlocked and
accessible. K. Rutgers. 22 Marriotts
Close, Felmersham MK43 7HD Tel
(0234) 781730

■ Ruston Basic compiler users Add
while-wend control structure, use all
’commands and multi-statement lines.
Listing of modifications with documenta-
tion £2 inclusive. JSOFT, 19. Mayfield
Road, Southam, Warks CV33 0JX.

■ Enhanced Accounts now with data
sorting, standing orders etc. Disc only
£12 95. R. C. Bean, 81 Hinley Green,
Leighton Buzzard, Beds LU7 7QA. Stan-
dard Program also available on Prestel,
or cassette £6 50.

■ Autocopy produces backup copies
of complete tapes. Instant transfer of
even C90’s in one operation! Includes
special lead, m/code program and full
instructions. £7 25 from D&D Electron-
ics, 11, Smeaton Av, Torrance, Glasgow
G64 4BG

■ Tape-Disc-Tape copier for BBC mi-
cro. Automatic copying of tape files to
disc and vice versa £10. Sutton Comput-
er Support, 12 Auckery Avenue, Great
Sutton, South Wirral L66 2ST.

■ Linacap electronic circuit analysis
program (BBC B). Calculates magni-
tude, phase, delay, Zin, Zout. A must for
schools, colleges, industry, hobbyists.
£20.45 including manual Waveney Soft-
ware, 30 Margill Close. Middlesbrough
TS7 8QG. Sae for details

■ Magic grotto (BBC 32k): A multi-
player adventure game providing fun for
all the family Full colour and sound,
every game different £5 95 Prosoft, 10
Begonia Close, Hinckley. Leics, LE10
2SS.

■ What makes you tick — personality
profile test. Also Horoscopes, accurate,
based on Zodiac characteristics. Great
at parties! £5 95 each, BBC or Electron
Send cheques to Third Program, 189,
Cheddon Road. Taunton TA2 7 AH

■ Primary school software for the BBC
We offer eleven programs developed in
close consultation with primary school
teachers Write for details to Bagust and
Pellmg, 9 Paulet Close. Townhill Park.
Southampton SQ2 2EY

■ Can you help Bertie Bear work out
the similes before Simon Snake? Instruc-
tive and highly entertaining educational
software. Cassette £4 95, disc £6 50.
Alma Systems, 20 Wykeham Road. Lon-
don NW4 2SU Tel 202 4240

■ Game! BBC B 1.2. “Wonderworm”, a
wondergame with wondersound. won-
dergraphics for wonderfun at a wonder
price. Cassette: £4.99 The Software
Sensorium, Lime Tree Cottage, St
Mary’s Lane, Binbrook, Lincoln LN3 6DL.

■ Earn £££s with your micro and print-
er. Full details for only £2. Money back
guarantee D. North, Plot 18, Highlands
Park. Seal, Nr. Sevenoaks, Kent.

r £10 SMALL AD SERVICE “I

■ Please include your cheque for £1 0 made payable to Addison-Wesley Publishers Ltd. ■
This is the standard fee. Don’t forget your name, address or phone number. Send
| cheque plus form to Acorn User Small Ads, 53 Bedford Square, London WC1 B 3DZ. |

i

l

u

J

ACORN USER JANUARY 1984

183

jurEEnpLaq ^

1 34 St. Vincent Street, Glasgow G2 5JU. Telephone 04 1 -248 248 1

SCREENPLAY products for the BBC MICRO include EDUCATIONAL PROGRAMS, GAMES
AND UTILITIES.

In EDUCATION we have 2 word recognition games which allow parents to participate in the
development of their childrens’ vocabulary.

CHICKAROO: Designed to improve hand eye co-ordination this
game involves shooting at moving targets which reveal letters that
may complete a word shown on the screen. PRICE £7.95

PIRATES: Identify the concealed word before you reach the end of
the plank or face the perils of the deep! You will be surprised at the
result if you succeed. PRICE £7.95

UTILITIES

BOTH PIRATES AND CHICKAROO ARE SUPPLIED WITH A
VOCABULARY OF 100 WORDS AND PARENTS HAVE THE OPTION
OF CREATING THEIR OWN FILES

THE ILLUSTRATOR: Turn your tv screen into an electronic canvas. This program allows
complex images to be drawn using simple commands. Text can also be mixed with the
graphics and the resulting image stored on tape. PRICE £9.95

GAMES

MAD MONTY: A fast and furious version of the well known snake in the garden game
featuring MONTY THE MAD PYTHON. PRICE £7.95

Aardvaark Software 99

A B Designs 117

Acorn Computers 154

Advanced Memory Systems 120

A J Vision 142

Alien 148

Applied Real Time Systems 42

Beebug 170

British Micro 100

B S Dollamore 174

Cambridge Computer Consultants 115

Cambridge Microcomputer Centre 11

Cambridge Processor Services 138

Cambridge Systems Technology 90

Cambridge University Press 60

Cases Computer Simulations 60

Chalksoft 90

Chase Data 78

C J E Microcomputers 102

Clares Micro Supplies 22

Computer Concepts 34, 64

Computer Marketplace 117

Computer Operated Motion 88

Computer Room 156

Computer Town 1 28/1 29

Comtec 54

Control Universal 134

Cumana 14

DACC 82

Datapen 42

Datastore 38

Dataware 38

Diamondsoft 38

Dial Software 38

Disco Technology 44

Display Distribution 28

Doctor Soft 158

Dynabyte Software 168

ECCE 138

Economatics 25

Educare 144

Edward Arnold 156

INDEX TO ADVERTISERS

Elbug 76

Electronequip 164/165

Flipstrip 138

Golem 144

Golden Challenge Software 50

Guildford Computer Centre 134

Harris McCutcheon Systems 126

Hessel, S 118

H & H Software 177

I J K Software 74

Ikon 66

Intastore 162

Interface Publications 177

Kansas 86

Kosmos Software 62

Leasalink Viewdata i.f.c.

Level 9 36

Lothlorien 52

Loynes Computer Consultancy 146

Mayfair Micros 52

M D A 126

Micro Advent 70

Michael Business Systems 146

Micro Aid 142

MicroAge Electronics 112/113

Microgame Simulations 156

Micro Power o.b.c., 21, 111

Micro Resources 40

Microvitec 94

Microware 96

Microworld 108

Midwich 56/57

Minor Miracles 152

Mirrorsoft 6

Molimerx 124

Muse 50

M W Systems 106

National Extension College 146

National Magazine Co 85

Newark Video Centre 146

Novelty 168

Oakleaf 154

Off Records 144

O I C 152

Opus 32, 46

Orion Software 62

Pace 160

Postern 104

Ricksoft 154

Salamander Software 140

Screenplay 184

Shards Software 52

Shumwari Associates 42

Silent Computers 154

Silverlind 44

Sir Computers 180/181

Soft Shop 156

Software Invasion 1 72

Solidisk 136

Steinsoft 168

Superior Software i.b.c., 150

Synergy Software 88

System Software 132

System Support Services 50

3 D Computers 174

Tandy 168

Technomatic 26/27

Tim Tom Micros 42

Torch 4/5

Twillstar 1

Video Palace 162

Viglen 30, 48

Virgin Games 12

Voltmace 150

Watford Electronics 16/17/18/19, 122

West Coast Personal Computers 148

Windsor Computer Centre 9, 148

Wise Owl 148

184

ACORN USER JANUARY 1984

THE BEST BBC MICRO SOFTWARE

PRODUCED BY AN INDEPENDENT SOFTWARE HOUSE KK l .

* TOP QUALITY MACHINE-CODE PROGRAMS *

10>o M,CM «3S8**

HUNCHBACK (32K) £7.95

Beautifully detailed animation (the best we’ve yet
seen!) as Quasimodo leaps over the ramparts
dodging rocks and arrows, swinging on ropes, and
avoiding the guards's spears as he attempts to
rescue Esmeralda. Twelve different screens of
action! This program is sold under licence from
Century Electronics Ltd; we have exclusive rights to
its sale for use on the BBC micro.

(For use with KEYBOARD or JOYSTICKS).

■ft is an extremely good version of the arcade game
thoroughly recommended " ... BEEBUC
MAGAZINE

FAIRGROUND (32K) £7.95

An exciting target-shooting game! Bonuses are scored for
spelling out the word FAIRGROUND by hitting the
appropriate target letters, and for shooting all the targets
Extra bullets are obtained by shooting the numercial
targets, but watch out for the "smileys” who are intent on
stealing your bullets. Music, sound effects, hi-score, and
ranhngs.

•M NEW RELEASE —

£7.95

Incredible arcade-style game featuring mushrooms,
snails. Dies, spiders, and the centipedes of course
Excellent graphics and sound. 6 skill levels, hi-score,
rankings, bonuses, and increasing difficulty as the spiders
become more lively and the number of mushrooms
increases.

(For use with KEYBOARD or JOYSTICKS).

“Visually this game compares well with the arcade
version, being colourful and dear . "

YOUR COMPUTER

ROAD RUNNER (32K) £7.95

The only full feature machine-code version available
for the BBC micro. Features include: scrolling
screen, radar display, 3 pursuing cars, checkpoint
flags, fuel gauge, smoke screens, 6 skill levels,
rankings, increasing difficulty, and sound effects.
(For use with KEYBOARD or JOYSTICKS).

7 enjoyed the game very much . . the graphics are
excellent . . . movement is smooth and fast as only
machine code can produce. " . HOME
COMPUTING WEEKLY

£7.95

Not just another version of Frogger ... this is the arcade-
action version that you've been waiting to see Graphically
brilliant with gaping-mouthed crocodiles, diving turtles,
Dies, and frogs that Dex their legs as they jump along.
Increasing difficulty, and responsive controls
(For use with KEYBOARD or JOYSTICKS).

". . . very good indeed . fast flicker free graphics and a
frog that really hops!". . BEEBUC MAGAZINE

ALSO AVAILABLE

SPACE FIGHTER (32K) ....

... £7.95

GALAXIANS (32K)

.£7.95

INVADERS (32K)

... £7.95

FRUIT MACHINE f32K) ...

... £7.95

CRIBBAGE (32K)

£6.95

PONTOON (32K)

... £6.95

DEALERS . . . DEALERS . . . DEALERS . . .

Our software is now available at all good dealers including:-
W.H. SMITH - Selected branches.

JOHN MENZIES - Selected branches.

BOOTS - Selected branches.

ELTEC COMPUTERS, 29 Ivegate, Bradford
MICRO MANAGEMENT, 32 Princes Street, Ipswich
WEST COAST PERSONAL COMPUTERS, 47 Kyle Street, Ayr
MICROSTYLE, 29 Belvedere, Lansdown Road, Bath.
ELECTRONEQUIP, 36-38 West Street, Fare ham, Hants.

3D COMPUTERS, 230 Tolworth Rise South, Tolworth, Surrey.

GTM COMPUTERS, 864 York Road, Leeds.

+ MORE THAN 300 OTHER DEALERS THROUGHOUT THE U K AND
OVERSEAS.

ADVENTURE GAMES

COLDITZ ADVENTURE (32K)

£7.95

STAR TREK ADVENTURE (32K)

£7.95

LOST CITY (32K) £7.95

GIDEON’S GAMBLE (32K) .£7.95

£7.95

A space docking simulator using 3D graphics to model
the motions and responses of the ORION 4 spacecraft.
Your mission is to pilot the shuttle to a "soft dock" with the
space station PITCH, YAW, ROLL, FORWARD.
LATERAL and VERTICAL engines are provided together
with orbit manoeuvenng booster engines 6 skill levels
provide for the completely inexpenenced pilot as well as
the fully-fledged commander
••• NEW RELEASE —

ALIEN DROPOUT (32K) £7.95

A novel ana unusual program. Arcade-action with
this enthralling multi-stage shooting game . You have
to shoot the aliens out of their "boxes” before the
"boxes" fill up. Once full, the aliens fly down
relentlessly, exploding as they hit the ground. Hi-
score, rankings, and sound effects.

(For use with KEYBOARD or JOYSTICKS)

"...this game is as good as any on the marker". . .
HOME COMPUTING WEEKL Y.

CRAZY PAINTER (32K) £7.9S

The only full-feature version available for the BBC micro.
On the first screen, you take the pari of a monkey being
chased by African tribesmen. If you manage to survive by
painting-in all the squares, the bonus screen features the
monkey trying to reach his bunch of bananas. After that,
you take control of a paint-roller and each square painted-
in adds to your score. But beware the teddy-bears are
now in hot pursuit. Superb animation and sound-effects.
(For use with KEYBOARD OR JOYSTICKS)

••• NEW RELEASE —

WE PAY UP TO 20% ROYALTIES FOR HIGH QUALITY BBC MICRO, ELECTRON AND ORIC- 1 PROGRAMS

f SUPERIOR SOFTWARE LTD.

Dept. AU1,

69 Leeds Road, Bramhope, Leeds

Tel: 0532 842385

ALL OUR PRICES ARE INCLUSIVE OF VAT. AND P & P.

DISC SOFTWARE AVAILABLE NOW

All our programs are ready for despatch on 5 V discs at £ 1 1 .95 each.

OUR GUARANTEE

(1) All our software is available before we advertise.

(2) All our software is despatched within 48 hours by first-class post.

(3) In the unlikely event that any of our software fails to load, return your cassette or disc
to us and we will immediately send a replacement.

The following titles are available for both the
BBC Micro and Electron Killer Gorilla £7.95/
Moonraider £7.95/Bandita at 3 o'Clock £6.95/
Croaker £7. 95/Felix in the Factory £7.95/

Felix and the Fruit Moneter* £7.95/Chess £7.95/
Escape from Moonbase Alpha £7.95/Dr*w £9.96/
Swoop £7.95/Cybertron Mission £7.95.
iB.B.C. only (at present) Labyrinths of LaCoshe £7.95/
[Martian Attack £7 95/Demon Decorator £6 95/
[Asteroid Storm £7. 96/Laser Command £7.95/

Galactic Commander £7. 95/Cowboy Shootout £0 95/
Danger! UXB £7.96/Timetrek £7. 95/Filer £9 95/ .

Adventure £7.95/Beebmon £7. 95/Barrage £7 .95/
Alien Swirl £6. 95/Caveman Adventure £6.95/
Chemistry £6. 95/World Geography £6.95/

Where? £6. 95/Junior Maths Pack £6.95/y^|ffi^J^f
Constellation £6.95/Physics £6.96. ^

WE STOCK THE BBC MICRO, ELECTRON, DRAGON 3Z

COMMODORE 64, ORIC AND SPECTRUM

All cassettes are fully guaranteed and
contain two recordings.

jJTbt — All prices inclusive of VAT.

Mail Order Please add 55p per order

BflCZiXdaSlM to cover P & P

WE’RE EXPANDING! P

oom: Mail order:

vood House Dept.

Street 8/8a Regent Street

Chapel Allerton
Leeds LS7 4PE
Tel: (0532) 683186/696343

WRITTEN ANY
PROGRAMS? WE
PAY 20% ROYALTIES

Tel: (0532) 458800

Another

the stranded