Introduction to reverse-engineering vintage synth firmware

#1

Post by jmillikin » Mon, Oct 20, 2025, 2:56 AM UTC

Introduction to reverse-engineering vintage synth firmware
ajxs.me

Re: Introduction to reverse-engineering vintage synth firmware

#2

Post by ajxs » Mon, Oct 20, 2025, 4:25 AM UTC

Author here, thank you for posting this! If anyone has any questions about the article, I'd be happy to answer them!

Re: Introduction to reverse-engineering vintage synth firmware

#3

Post by mutagen » Mon, Oct 20, 2025, 5:14 AM UTC

Seems like a good place to mention The Usual Suspects, a group that has built emulation of the Motorola DSP5630 and associated hardware to allow playable virtual instruments.

https://dsp56300.wordpress.com/

Re: Introduction to reverse-engineering vintage synth firmware

#4

Post by mrunkel » Mon, Oct 20, 2025, 5:33 AM UTC

ajxs wrote: post #2

Author here, thank you for posting this! If anyone has any questions about the article, I'd be happy to answer them!

I just wanted to say thank you. This is a great read.

Re: Introduction to reverse-engineering vintage synth firmware

#5

Post by jmillikin » Mon, Oct 20, 2025, 6:27 AM UTC

ajxs wrote: post #2

Author here, thank you for posting this! If anyone has any questions about the article, I'd be happy to answer them!

The https://github.com/blackjetrock/ghidra-6303 repository your post links to (containing a SLEIGH spec for the HD6303) is no longer available, did you happen to save a local clone that could be re-uploaded somewhere?

Re: Introduction to reverse-engineering vintage synth firmware

#6

Post by grawlinson » Mon, Oct 20, 2025, 6:50 AM UTC

mutagen wrote: post #3

Seems like a good place to mention The Usual Suspects, a group that has built emulation of the Motorola DSP5630 and associated hardware to allow playable virtual instruments. https://dsp56300.wordpress.com/

They've also been working on emulating the JP-8080, as per recent discord announcements.

The JP-8080 uses custom DSP chips designed by Roland, and Roland do not provide a Virtual Instrument (VST) for this much desired synth.

Re: Introduction to reverse-engineering vintage synth firmware

#7

Post by platevoltage » Mon, Oct 20, 2025, 7:14 AM UTC

ajxs wrote: post #2

Author here, thank you for posting this! If anyone has any questions about the article, I'd be happy to answer them!

Very cool! I have a DX7IIFD with an EEPROM in it. It will be cool to see what I can do with this!

Re: Introduction to reverse-engineering vintage synth firmware

#8

Post by throw_m239339 » Mon, Oct 20, 2025, 8:04 AM UTC

If someone could help me reverse engineer the Zoom ARQ96 firmware in order to fix the stupid LFO mod amount implementation (LFO is basically unusable), add velocity note control to the step sequencer, and why not, add basic USB MIDI Input recording support, and ideally, a chord mode, it would be great...

https://zoomcorp.com/en/us/digital-instruments/digital-instr...

For the LFO mod amounts I imagine the values are hardcoded somewhere, so it shouldn't be that hard. Adding a new UI for velocity levels or a chord mode would be more complex though. Even better if there was a Zoom engineer around here who could guide me a bit...

Re: Introduction to reverse-engineering vintage synth firmware

#9

Post by [deleted] » Mon, Oct 20, 2025, 8:06 AM UTC

mutagen wrote: post #3

Seems like a good place to mention The Usual Suspects, a group that has built emulation of the Motorola DSP5630 and associated hardware to allow playable virtual instruments. https://dsp56300.wordpress.com/

[deleted]

Re: Introduction to reverse-engineering vintage synth firmware

#10

Post by aa-jv » Mon, Oct 20, 2025, 8:11 AM UTC

Great work, ajxs, been following you for years.

I hope you get a chance to work on some other synths in the future .. would be fun to see you apply your skills to, for example, the UNO synths, or the Arturia *Freaks' .. would be hilarious to see custom firmwares for those modern synths, some day.