SID chip
More info
- Creator
- Robert Yannes / MOS Technology
- Released
- 1982
- Type
- Sound chip
- Voices
- 3 oscillators + noise
- Successor
- MOS 8580
The sound chip in the Commodore 64 — three oscillators, ADSR, and an analog filter that sounded slightly different on every machine.
The Sound Interface Device, MOS 6581, was designed by Robert Yannes at MOS Technology and shipped inside the Commodore 64 from 1982. Three voices offered sawtooth, triangle, pulse and noise, each with an ADSR envelope, plus ring modulation, oscillator sync and a multimode filter. For its era it was close to a synthesizer on a chip, in a machine that cost a fraction of a real one.
The filter was analog and its manufacturing tolerances loose, so two C64s could sound audibly different — something the demoscene learned to exploit rather than curse. Yannes later left to co-found Ensoniq. The 8580 successor cleaned up the noise and gave a purer tone, which the purists never quite forgave.