Step sequencer
A sequencer that divides the bar into a fixed number of slots and plays whatever is in each one, in turn, on a loop.
The idea predates MIDI. Buchla and Moog modular systems in the 1960s had sequencers where each step was a knob producing a voltage; the Moog 960 had three rows of eight and drove oscillators over CV/gate. A clock pulse advanced the steps and the melody was wherever the knobs happened to be pointing. The result was the repetitive, hypnotic style that Tangerine Dream and Kraftwerk built careers on.
Drum machines turned the format into an interface: sixteen buttons per bar, one per sixteenth note, and a light marching along the row. The TR-808 set the template. You don't play notes in time, you switch squares on. Elektron extended the idea in 2001 with parameter locks, letting each step carry its own filter and sound settings. A DAW gives you a piano roll instead, but the step grid survives in most drum editors.