Drum machine
An electronic instrument that plays programmed drum patterns — first meant to replace drummers, later a genre in its own right.
The earliest rhythm boxes, like Wurlitzer's Sideman of 1959, played preset patterns such as bossa nova and waltz for home organists. Programmability arrived in the 1970s, and 1980 brought two things: Roger Linn's LM-1 played back digital samples of real drums, and Roland's TR-808 synthesised analogue sounds that didn't resemble drums at all. The former was the professional product. The latter flopped, sold cheaply second-hand, and became the foundation of hip-hop, electro and techno.
Patterns are typically written in a step sequencer with 16 steps per bar, one button per sixteenth note. Syncing with other gear was handled first by pulse signals, then by MIDI clock. Most drum machines today are software, but the row of buttons survived.