There is a segment of the computer art culture which works on creating “demos”: short bits of combined computer animation and music which play on computers. They are often praised for being clever and short. They seemed to start back during the time of the Commodore 64 and other 8 bit computers. But check out this demo to see what’s possible using an 8 bit computer today, without any dedicated sound or video chips at all.

Addendum: Dan pointed me at the full write up on the project, which includes a fairly basic schematic.