What was done
Claude analysed the vendor driver and USB captures to document the protocol of a 2008 USB box holding real C64 sound chips, now played from macOS and Linux.
Per Thulin owns a HardSID 4U, a 2008 USB box that holds up to four real Commodore 64 SID sound chips. It shipped with a Windows-only driver and no published protocol. He had Claude reverse engineer the protocol, and the repo now plays the chips from macOS and Linux, including as a MIDI instrument.
How it was done
Thulin supplied the device, the vendor files and USB captures. By his account Claude did the binary analysis, formed and discarded hypotheses, wrote the probe scripts, and wrote the library and docs. Static analysis of the packed driver got the wire format right but the state machine wrong several times. What broke the deadlock was capturing the real driver on the wire. One finding is that 0xFFFF, long treated as padding, is an escape prefix that can stall the device.
Results
A Python library over libusb plays a note on a power-cycled device, with a virtual MIDI destination for Ableton or Cubase. A note-on is one bulk write at 0.8 ms median. It was endurance tested for six hours. The author records each wrong theory in the docs.