Short answers, pulled from the story.
Léon Theremin built the Rhythmicon at Henry Cowell's request in 1930. This instrument could play sixteen different rhythms based on the overtone series and was a complex device that few musicians knew how to operate.
Harry Chamberlin created the Chamberlin Rhythmate in 1957 using fourteen tape loops of drum kits and percussion instruments inside the unit. About one hundred units were sold to families who wanted them for singalongs before Wurlitzer released the Side Man as a mechanical alternative in 1959.
Linn released the LM-1 Drum Computer in 1980 for $4,995. Only about five hundred units were ever manufactured before production stopped because this device became the first drum machine to use digital samples of real drums.
Roland launched the TR-808 Rhythm Composer in 1980 as a fully analog programmable unit that generated sounds non-digitally via hardware circuits. Roland built approximately twelve thousand units before discontinuing production due to semiconductor shortages despite mixed reviews from critics.
A cheaper version called the LinnDrum arrived in 1982 at $2,995 and included standard crash cymbals but removed individual tunability for some voices. The Cars' Heartbeat City and Giorgio Moroder's Scarface soundtrack utilized this updated model following the release of the original LM-1 in 1980.