Wondering how filters such as the legendary Supersaw Oscillator works on sound keyboards?

This is an amazing story … It’s a story about breaking into DSPs ( digital signal processors), reverse engineering the algorithms, and finding out how functions are mapped onto silicon.

One of the findings is how the legendary Supersaw Oscillator works! Spoiler: No modulation, no phase shifting and no echo effects!

A team of engineers at The Usual Suspects has been pushing the boundaries of open-source music technology by reverse-engineering the custom silicon behind iconic synthesizers. Following their earlier work on Motorola-based devices, they took on the far more complex Roland/Toshiba TC170C140 ESP chip — the heart of the JP-8000 and its legendary SuperSaw oscillator. Using automated silicon analysis, clever microscopy, direct hardware probing, opcode statistics and fuzzing, they decoded an undocumented instruction set and built a bit-accurate, real-time emulator. Their work uncovers not only how the SuperSaw truly operates, but also demonstrates how modern tooling can transform the reverse engineering process.

Topics covered:

• Lessons learned from analysing more advanced chips
• Progress towards automating silicon reverse engineering
• Finding and exploiting hidden test modes
• Coaxing the chip into revealing its internal behaviour. How the ESP chip compares to known DSPs.
• What the SuperSaw oscillator actually does.

This amazing work was just presented by giulioz at the Chaos Computer Club (CCC) event 🔥

Talk: https://www.youtube.com/watch?v=XM_q5T7wTpQ

Github: https://github.com/giulioz/