[fractallyte]

Actually, chiptunes (C64) and MODs (Amiga) used quite different playback technologies.

The C64 synthesized its sound via the MOS Technology 6581/8580 SID (Sound Interface Device). It was limited to 3 voices, so the only way to emulate chords on a single voice was to arpeggiate rapidly through a sequence of notes.

The Amiga used four PCM sample based sound channels (in stereo - two left, two right). So chords could easily be sampled and played back on one or more channels.

Chiptunes were limited to the distinctive '8 bit electronic' style - although it didn't stop groups like Maniacs of Noise pushing the technology to use primitive samples alongside the traditional sounds; one notable example was the 'Stormlord' soundtrack.

MODs, being sample-based, could be made to sound like quite respectable audio recordings. Even so, there were some musicians who tried to emulate the old C64 sound on the Amiga, hence the profusion of chiptune-sounding MODs.