I was looking around the Internet Archive for official Mega Drive development resources when I found this. It appears to be a much earlier revision of the development documents that we already have. What is notable about this version, however, is that its coverage of the console's sound hardware is much more extensive; so far, I have noticed that it documents the YM2612's F-Number and SSG-EG better than the current documentation does. This early documentation appears to contain an incomplete transcription of an official Yamaha document from 1988, which lacks figures and tables. According to Nemesis's website, the later version of the documentation claims that "FM sound generation and PSG are explained in another manual", and said manual has never been found. The PSG documentation is identical between the two versions, however, the additional FM documentation has me convinced that the Yamaha document is the fabled missing manual. The Internet Archive account that uploaded this is a goldmine of its own: the user appears to have access to internal resources of the development team(s) of RBI Baseball, Road Riot, and Road Blasters, including their source code. I figure that this may be useful to bring to people's attention, both to provide another means for people to learn about the Mega Drive's hardware, and for its historical significance: a large amount of the early manual is written by hand, with much, if not all, of these handmade additions being present in digital form in the later manual.
Hah, there's even a bit of extra documentation for PSG and stuff for Cinepak for Sega CD, too, and gives a very brief description of the format. Cool stuff.
The YM2612 document is a translation of the YM2612 Applications Manual that was included in the Japanese sound documentation that Hidden Palace scanned a few years ago, so you can look there for the tables and diagrams and stuff.
Now that is great to hear! So what we have is a proper translation that was endorsed by Sega themselves! That should save me the hassle of dealing with machine translation whenever I need to scour through the original Japanese document.
