The Commodore VIC-20 was an 8-bit home computer first released in 1980.  The "Video Interface Chip" (MOS Technology 6560/6561) was responsible for both the audio and visual graphics of the machine.  On the audio side, the VIC chip had 3 square wave channels and 1 white noise channel and a global volume control.  Each square wave had a range of 3 octaves, but were tuned an octave apart from each other.  This gives the chip a five octave range total.

'[#[Tools]
'[t[b3]baby-k'[/t]

A web based crossplatform tracker designed to target the unexpanded VIC20. Very simple interface. 128 patterns of 16 rows with a max song length of 128 patterns. Little to no effects, but there are programmable singular groove and volume loops.
'[l[http://b-knox.com/vixxen20/[try it here] '[l[https://langel.github.io/vixxen20/[manual] '[l[https://www.youtube.com/watch?v=BBclnLIG3aI[video tutorial]

'[t[b3]MOD2VIC'[/t]

A Python script made by cce that takes a FastTracker-compatible module and converts it to the .prg file to be used on the real VIC20 or its' emulator. The module and the executable, however, sound different to each other pitch-, speed- and tone-wise, so use it with caution.

MOD2VIC can be downloaded '[l[https://battleofthebits.com/academy/GroupThread/7606/mod2vic+-+VIC-20+tunes+for+the+masses/[here].

'[t[b3]VIC-Tracker 2.0'[/t]

The classic way of doing things. A real tracker running on real hardware (or in an emulator), made by Daniel Kahlin. Slightly unnerving because it does not use note names, and because it also requires you to know most of the hotkeys to get going.

VIC-Tracker 2.0 can be downloaded '[l[http://www.kahlin.net/daniel/victracker/[here]. And also a mod of this with note names and larger resolution can be download '[l[https://battleofthebits.com/academy/GroupThread/17861/VIC-Tracker+2.0%CF%80+%28finally+with+note+names%21%29/[here].

'[t[b3]VIC Duzz It'[/t]

Another tracker that runs on the actual machine, made by Glenn Rune Gallefoss. More complicated than VIC-Tracker, but also more advanced. Unlike VIC-Tracker, it requires full memory expansion.

'[#[Restrictions on submit]
Make sure to tell in the description if your track uses Expanded VIC20-RAM.

'[#[Playback (for voting)]
'[l[http://vice-emu.sourceforge.net[VICE] is a VIC20-Emulator and able to play prg-files. It might be necessary to expand the RAM to 16k to play larger files.

'[#[See also]
'[[VIC 20]
'[[Vic Tracker]
VIC Duzz It can be downloaded '[l[http://home.eunet.no/~ggallefo/tools/vdi1.zip[here].