The device rests on top of the C64 and uses carbon contacts that act as switches and connect directly on the keyboard inside the C64.
This design lets the C64 Music Maker work with ALL programs that use the C64 keys to play notes, allowing you to use a wide variety of music software for the C64.
This is the first part of a 2 video series. A song is played to demonstrate the C64 Music Maker in this episode. In part 2, MrCaliforniaD explains how the project was built.