Freespin: A Demo Running on a Commodore 1541 Drive

Shared as a favorite example of retrocomputing hackery, a demo that runs entirely on a disk drive.

Freespin is a demo that runs on a Commodore 1541 floppy drive. It makes sound by vibrating the drive head and video by toggling the serial bus lines, and it keeps running after the C64 that booted it is disconnected.