Wurlitzer SideMan, the worlds first drum machine?

The Wurlitzer SideMan is a 1950's tube drum machine and it was arguably the world's first drum machine. obviously It depends on whether you count the Chamberlin Rhythmate, which was apparently introduced some years earlier, but featured tape loops instead of electronically generated drum sounds, the SideMan is definitely the first "beat box." this was picked up for $50. It's got all its guts exposed so you can see how it works...