Floppy drives and stepper motors have been used to make music before, but for live playing I think the technology is underexplored.
This video features three separate Commodore 64 computers, colour coded for your convenience. I'm playing the melody on a dark grey C64C (custom case from Individual Computers) and chords on a brown "breadbin". These machines run Qwertuoso, my accordion-inspired C64 program for playing live chip music. An external potentiometer is hooked up as a volume control.
The chord progression was shaped by both musical and technical constraints: I wanted to pick chords that would fit the melody while playfully extending its harmonical structure—but I also had to avoid note combinations that would result in keyboard ghosting.
The third computer, a light grey C64C, doesn't use the SID chip to generate sound. Instead it controls the motors of a programmable floppy disk drive, providing bass and rhythmical noises. The lid of the drive has been removed in the video so you can see the moving parts.
A 1530 Datasette unit is also put to good use.