it has 4 voices that have a limited but wide tuning range, and like the SN76489 and T6W28, the last voice is dedicated to playing noise.
the 3 pulse wave channels also have different octaves that they can play notes on:
- the first channel is the bass channel, and it can play notes from octave 1.
- the next is the 'mid/chord' channel, and it plays notes from octave 2.
- and rather obviously, the 3rd pulse channel is typically the lead channel, can play notes from octave 3.
these channels are not referred as "square" wave channels since a technique to play 15 additional pulse-like waveforms has been discovered long after the VIC-20's release.