- VICMON is a machine language monitor released by Commodore in 1982 and is great for programming the VIC-20. Its interactive nature means that it can often be quicker to develop via this rather than using a fully fledged assembler because it’s easy to enter, alter and test code without having to wait for an assembler to load source code, assemble it, write a binary and then load the resulting binary separately. This also makes it good for debugging our programs and understanding other people’s better. Jeff Minter wrote in Compute! Gazette Issue 2, 1983 that he programmed all his games in the past with the VICMON cartridge before switching to a Commodore 64 assembler-editor.