yamaha_dx7_rom_disassembly VS MIDICtrl20_MegaCommand

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 like a DX7:

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 have forgotten to highlight, it's just that good. Oh the FAQ of course, what a great FAQ. Really I am being very wordy for someone that's lost for words.

BTW, I love retro computing too, this is my best attempt so far in the field https://github.com/billforsternz/retro-sargon. I aspire to similar standards to your good self, but I'm not there yet.

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:

https://github.com/ajxs/yamaha_dx7_rom_disassembly

Hey Cesare, fancy seeing you here ;)

As the other comment notes, I’m not sure if MAME can actually properly emulate any music hardware. There’s a skeleton Elektron Machinedrum/Monomachine in there for example but it can’t really do anything interesting (although this thread talks a bit about how some hackers used it to help reverse engineer and ultimately create their own firmware for the Machinedrum, see my other comment for more details: https://github.com/jmamma/MIDICtrl20_MegaCommand/issues/88)

Another project which may be of interest is this emulation of the Motorola DSP536xx DSP, which was used in a lot of classic late 90s hardware synths: https://dsp56300.wordpress.com. It can actually run Access Virus ROMs pretty much perfectly and apparently on an M1 the performance is pretty good, it’s usable but crackly on my i9 Mac. They’re hoping to be able to emulate many more synths which used the same DSP but for now the Virus is the focus.