Introduction to reverse-engineering vintage synth firmware (opens in new tab)

These guys do amazing work! I wish Korg hadn't beat them to the MicroKorg VST though. I've used the MicroKorg extensively in music over the years, and would have loved an accurate VST. Unfortunately the filter in Korg's VST doesn't quite match the original, and I can't recreate some of my patches. For understandable reasons these guys aren't going to step on Korg's toes and compete with an actual commercial product.

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.

These guys are awesome .. their interaction with Kemper&co, about their amazing emulation work, not so much.

There's a hard lesson for hardware manufacturers to be learned in this drama.

If Kemper were supportive, they'd have a very clear road to a next-gen Virus TI (a "Proton"?) on the horizon .. but the word on the street has it that they're hostile to the effort of emulating the Motorola DSP ...

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?

Amazing work. I briefly explored trying to RE a more modern piece of hardware, the Tascam Portastudio DP-24SD, in order to try to fix some well-known bugs and limitations. Your article inspired me to maybe give it another go.

Previously, I managed to decode a firmware update file for the unit, but quickly found out that it uses a special-purpose DSP chip, and I wasn't able to easily find public documentation for its instruction set. So I gave up. Do you have a gut feeling on if REing and hacking this firmware could be done by a dedicated amateur, or is this probably more like professional-level work and I should find something better to do?

Interesting work, thank you. May I ask what you are going to do with it? Do you want to emulate it on a PC, or redesign it to make a VST plugin?

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

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

Did you read the section about what made the DX7 hardware a good target for this project?

https://ajxs.me/blog/Introduction_to_Reverse-Engineering_Vin...

The ARQ96 is an incredibly niche product all things considered, but especially compared to the DX7. It's also ~10 years old rather than ~40 years old. It's a completely different beast.

Zoom released few firmware updates, but v1.x to v2.x was a very significant change. Are you using the latest version?

Thank you! I really appreciate your support!

Lately I've been working on the Casio CZ101. Hopefully in the next few weeks I'll publish a partially annotated disassembled firmware on my Github, along with article too talking about its interesting NEC μPD7810G CPU. Mostly because there's almost no other information about the CPU available online, despite featuring in some prominent 80s synths.

Following Pajen's awesome lead, I poked around inside the Korg Volcas, but I didn't accomplish enough to write about it. A 16KiB EPROM full of hand-crafted 8-bit assembly is a totally different animal to 256KiB of compiler optimised ARM! One modern synth whose firmware I loaded up in Ghidra is the Prophet X: After Espen Kraft's video complaining about it, I thought I'd have a peek inside it for myself. Sequential published the firmware without stripping out the debug symbols, so if anyone else is interested there's a real possibility of progress!