M64 was written in 1997 to allow the Commodore 64 to function as a standalone synth module, producing sound in realtime driven by signals from a midi interface. M64 features a built in editor for programmable sounds and a virtual machine to execute the code that produce sound.
An extensive manual is available in the following formats.
A small change in the flowchart has been made from the original manual since Autoboy/Hack'n Trade pointed out it was wrong. localAlways is executed before globalAlways. This is reflected in all manuals except in the GEOWrite manual.