furnace/papers/doc/7-systems/vic20.md

Commodore VIC-20

the Commodore VIC-20 was Commodore's major attempt at making a personal home computer, and is the percursor to the Commodore 64.

it was also known as the VC-20 in Germany, and the VIC-1001 in Japan.

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.

effect commands

• 10xx Switch waveform (xx from 00 to 0F)