The Wurlitzer Sideman was the first electronic drum machine ever produced (if you don’t count tape loops), sold as a Wurlitzer organ accessory beginning in 1959. It’s got some fantastically great sounds and the ‘sequencer’ is actually a wheel covered in electronic contact points, with each point being a trigger.
Each row of contact points triggers a different drum sound, and each sound’s points are spread, in their own row, around the wheel in a pattern that generates a certain rhythm. The faster the wheel spins, the faster the pattern plays. Simple.
It’s completely tube based (even the sound generating circuits are tube), and has a great, crunchy sound. There is a slider that adjusts the wheel’s speed, and there are 10 preset rhythms. You can also individually trigger each sound via dedicated buttons and play the sounds yourself.
After the Sideman came out, the Musicians Association got pretty freaked out and put a lot of pressure on Wurlitzer to discontinue making the Sideman because they were worried about the unit putting drummers out of a job. I guess this was because it sounded so much like a real drummer…not.
http://www.synthgear.com/2009/audio-gear/wurlitzer-sideman/