a home computer with a synthesizer-grade sound chip of which people took decades to master. three oscillators with four selectable waveforms, ring modulation, oscillator sync, multi-mode filter and ADSR envelope.
very popular in Europe and mostly due to the demoscene, which stretched the machine's limbs to no end.
two versions of aforementioned chip exist - 6581 (original chip) and 8580 (improved version with working waveform mixing and somewhat more consistent filter curves).
10xx: change wave. the following values are accepted:00: nothing01: triangle02: saw03: triangle and saw04: pulse05: pulse and triangle06: pulse and saw07: pulse and triangle and saw08: noise11xx: set coarse cutoff. xx may be a value between 00 and 64.4xxx instead.12xx: set coarse duty cycle. xx may be a value between 00 and 64.3xxx instead.13xx: set resonance. xx may be a value between 00 and 0F.14xx: set filter mode. the following values are accepted:00: filter off01: low pass02: band pass03: low+band pass04: high pass05: band reject/stop/notch06: high+band pass07: all pass15xx: set envelope reset time.xx is 0 or higher than the song speed, the envelope will not reset.1Axx: disable envelope reset for this channel.1Bxy: reset cutoff:x is not 0: on new notey is not 0: now1Cxy: reset duty cycle:x is not 0: on new notey is not 0: now1Exy: change additional parameters.x may be one of the following:0: attack (y from 0 to F)1: decay (y from 0 to F)2: sustain (y from 0 to F)3: release (y from 0 to F)4: ring modulation (y is 0 or 1)5: oscillator sync (y is 0 or 1)6: disable channel 3 (y is 0 or 1)3xxx: set duty cycle. xxx range is 000 to FFF.4xxx: set cutoff. xxx range is 000 to 7FF.this chip uses the C64 instrument editor.