I liked this barrel organ at St Fagans museum. Each tune is stored on a card that is fed into the organ. There are about 10 rows on holes that must be instructions for 10 parts of the musical accompaniment. It looked as though the whole thing was running through compressed air or something similar. Even the drums were on pressure valves. I'm not sure whether air went through the holes on the card or worked a device to blow air at those times. The first computers worked through cards like these.
