This CD-ROM is a collection of interviews, information, and more about Nintendo consoles and games from 1997-1998, including the 64DD! This CD-ROM is by the same developers who created the Nintendo Encyclopedia which I've previously shared. There's some nice goodies in here, including screenshots and descriptions for games that would go on to be unreleased, such as Mother 3 and SimCity for the 64DD.
I had difficulties running it on a modern Windows Operating System, but it works fine in a Virtual Machine running Windows XP. Just make sure your locale settings are set to Japanese, or else you could get some broken symbols and letters, especially in the Database section of the ROM.