yamaha_dx7_rom_disassembly

I've spent a lot of time reverse-engineering vintage synthesizer firmware (which is a bit simpler than modern games). I did complete end-to-end annotations of these two vintage synth ROMs: - https://github.com/ajxs/yamaha_dx7_rom_disassembly - https://github.com/ajxs/yamaha_dx9_rom_disassembly It started because I was just curious about how these devices actually worked. In the end I learned a lot of really invaluable skills that really broadened my horizons as an engineer. I got a chance to talk to a handful of incredibly smart people too. The actual work can be a lot of fun. It's like piecing together a really large and technical jigsaw puzzle. In my case, it also led to me being able to release a fun firmware mod: https://github.com/ajxs/yamaha_dx97 In case anyone is curious about how I worked, I wrote a bit of a tutorial article: http

I wrote the article mentioned by Ken: https://ajxs.me/blog/Yamaha_DX7_Technical_Analysis.html I've unwittingly become a bit of a Yamaha FM Synth historian! Here are some other contributions to reverse-engineering the DX7: A fully documented disassembly of the DX7 ROM: https://github.com/ajxs/yamaha_dx7_rom_disassembly A new firmware ROM that makes the DX9 function more like a DX7: https://github.com/ajxs/yamaha_dx97

I browsed through the repository as discovered by colejohnson66 downthread https://github.com/ajxs/yamaha_dx7_rom_disassembly. This is an example of superb, meticulous, lovingly documented work. The kind of thing you don't see every day, congratulations. The attention to detail is really just chef's kiss, starting with a really good repository name (a small thing, but still), continuing through clear and apparently comprehensive documentation of what you did and why, then on to beautifully formatted and commented assembly language (much better than the original source code I'd wager) with coherent and consistent paragraph commenting a particular delight, and finally (and very importantly) dedication to making sure others can reproduce your results and generate a matching binary too. There are likely to be other things of beauty in there I

Found it: https://github.com/ajxs/yamaha_dx7_rom_disassembly It’s extremely documented. More than I was expecting.

I'll mention this even though it isn't exactly the Motorola 6800: I've been doing a lot of work recently with the Hitachi 6303, which is a member of Hitachi's family of Motorola 680x alternatives. The Hitachi 6303 is featured in a lot of 80s Japanese synthesisers, particularly Yamaha's DX/TX range. The Motorola 680x series also features in the Ensoniq ESQ family of synthesisers, probably many more. I became acquainted with this architecture disassembling the Yamaha DX7 firmware: https://github.com/ajxs/yamaha_dx7_rom_disassembly It's a great instruction set to work with. It's my first experience with 8-bit programming, and I found it very intuitive.

Very cool! This is really great work! It's awesome that there's been so many synthesiser related topics on Hacker News lately. I did a similar project myself to disassemble, and fully annotate the firmware for the Yamaha DX7: https://github.com/ajxs/yamaha_dx7_rom_disassembly The biggest hint I could give anyone looking to disassemble a synthesiser operating system is to direct your attention towards the code processing individual MIDI messages. The code is invariably is huge mess, however you'll be able to very quickly identify the operating system's core functions, since the corresponding SysEx parameter numbers clearly identify what functionality you're looking at.

Anthony just released his annotated DX-7 ROM listing, aided by Ken's work: https://github.com/ajxs/yamaha_dx7_rom_disassembly