Super GP-16 Rosetta OS (JSW ROSETTA OS WIP)
A new OS for the Roland GP-16 guitar processor: the rack becomes one pedal with real knobs, a pedal + amp rig, or a 12-slot pedalboard, played from the front panel with no patch list in the way.
- Custom firmware
- Alpha
- Medium brick risk
- Reversible
This project hasn't been claimed by its maintainer yet, so its details come from the community. Is it yours? Claim it
JSW ROSETTA OS v2.3 beta: the final beta of the non-DSP line. Every sound runs on the GP-16's stock DSP algorithms, re-voiced and driven by the new OS. The next line changes the DSP code itself.
What's in it
- 59 pedals, 12 amps across PEDAL, RIG and BOARD modes.
- Real knobs. Macro knobs move several settings at once, like the original circuits. There's a 6-knob screen, plus switches and mode buttons (Dimension C).
- Voiced in real units. Every sound is written in Hz, dB and Q from the firmware's own EQ tables, and the levels are matched.
- Signature tones, each with a matching RIG amp:
- DETROIT (Ace Frehley, Detroit Rock City solo) with SUPER LEAD
- FLOOD 1 and FLOOD 2 (Dimebag) with RANDALL
- HOLYWAR (Mustaine) with JCM800 RIP
- Boards: 8 board memories, the expression pedal assigned per pedal, per-pedal chain order (FUNERAL), and an A/B/Y output box.
- GP Tone Zone (
tonezone/): a PC app that turns NAM captures and cab IRs into GP-16 sounds. You can audition them over MIDI and add them to the OS build.
Install
No ROM data or images are attached. Read your own IC11, build with re/build_all.py, and burn the _sst512k file to an SST39SF040 / A29040. Full steps are in the README.
Made by JunkSmithWizard (JSW) together with Claude (Anthropic's AI). MIT.
Before you start
- How hard is it?
- ExpertMeans opening the device, soldering or special hardware.
- What you need
- A USB or MIDI cable
- Comfort with the command line
- A computer
- Tools to open the case
- Can it break my device?
- Small chance of trouble, with a way to recover.
- Can I undo it?
- Yes. You can go back to the official software.
Did it work for you?
Did Super GP-16 Rosetta OS (JSW ROSETTA OS WIP) v2.3-beta work on your Roland GP-16?
No reports yet for v2.3-beta.
One-tap reports from owners. Bricked reports are checked before they count.
Compatibility
Devices: Roland GP-16.
No compatibility information yet.
Getting started
From the project's README ("Build and burn"):
You must supply your own IC11 dump. It is Roland's copyrighted code and is not in this repo. The tools refuse anything other than the "Super GP Ver 1.0" ROM (MD5 ac5f56bcb3d8c30ddf3f1ffe88b13556).
Read IC11 (128 KB, 32-pin DIP mask ROM) on a programmer such as a T48 and keep the original chip: minipro -p AM27C010@DIP32 -y -r ic11.bin
Build (Python 3.11, pip install capstone, NASM 2.16): cd re py -3.11 buildall.py ../ic11.bin This writes re/build/gp16modv28.bin (128 KB) and re/build/gp16modv28sst512k.bin (the same image 4x).
Burn the sst512k file to a 512 KB flash (SST39SF040, or AMIC A29040 for chips that ID as 0x3786), read it back and compare: minipro -p SST39SF040 -w gp16modv28sst512k.bin
Fit it in IC11 (notch the same way). The GP-16 board already ties pin 31 high, so the flash drops straight in: no wires, no cuts. Put the original chip back any time.
- No factory reset on the unit any more: v2.7 removes the stock power-on menus (factory preset load, system data init, test mode, demos, credits) and the stock Edit menu. Your patches and settings stay as they are; MIDI, SysEx (bulk dump / data load) and the stock System menu are untouched.
- Settings across versions: knob positions and board memories reset only when the pedal list or the number of knobs changes; voicing and knob retunes keep them.
- Please don't share patched .bin files: share this repo.
Test in emulation first (optional) …
Risk and recovery
- Brick risk
- Medium
- Reversible
- Yes
- Requires opening the device
- Yes
From the project's README ("REVERSE DLY: the edges"):
This runs on real hardware and sounds like a reverse delay, but it lives at the edge of what a 1989 rack DSP and an 8 MHz CPU were built to do, and the rough edges are real:
- It is a CPU trick, not a native effect. The GP-16's DSP has no reverse mode. The CPU walks the delay tap backwards one step every two DSP frames (~16 kHz) from a timer interrupt. That rate is the hard ceiling, and it is where the digital crackle comes from: reversing at half sample rate folds a mirror image in at 16 kHz minus the note, loudest on high notes and at high volume. Lowering the input tone and the level tames it; a low-pass placed after the delay would mostly kill it, and is not built yet.
- The CPU and the DSP share one set of latches. If the engine's write and the OS's own DSP write overlap, the interface jams and the unit hangs. The engine now stands down for the whole time the menu is doing anything, which fixed the hang on select/exit, but this is the single most fragile part and the reason this is unstable testing, not a release. Writing DSP levels from inside the engine interrupt hangs it outright and scrambles battery RAM; that path is walled off.
- Memory is ~2 s. Borrowing the rest of the delay chip's RAM gets 2.05 s; the DRAM clock sets that wall. Long chunks auto-halve to fit, so very slow tempos shorten the reversed grain.
- Still open: click-free chunk edges (fades must never touch the DSP from the engine interrupt), the post-delay …
Releases
| Version | Name | Released |
|---|---|---|
| v2.3-beta | v2.3 beta: final non-DSP betaPre-release | 13 October 2026 |
Credits, license and support
- License
- MIT