Have you ever wondered how the chips and algorithms that made all those electronic music hits work? Us too!
At The Usual Suspects we create open source emulations of famous music hardware, synthesizers and effect units. After releasing some emulations of devices around the Motorola 563xx DSP chip, we made further steps into reverse engineering custom silicon chips to achieve what no one has done before: a real low-level emulation of the JP-8000. This famous synthesizer featured a special "SuperSaw" oscillator algorithm, which defined an entire generation of electronic and trance music. The main obstacle was emulating the 4 custom DSP chips the device used, which ran software written with a completely undocumented instruction set. In this talk I will go through the story of how we overcame that obstacle, using a mixture of automated silicon reverse engineering, probing the chip with an Arduino, statistical analysis of the opcodes and fuzzing. Finally, I will talk about how we made the emulator run in real-time using JIT, and what we found by looking at the SuperSaw code.