Chiptune
Music made with — or in the style of — home computer sound chips, where three channels and a noise generator are the whole orchestra.
The origin is purely technical: a 1980s computer had no room for recorded audio, so music had to be described as instructions to a sound chip. The Commodore 64's SID, the ZX Spectrum's and MSX's AY-3-8910, Atari's POKEY and the NES 2A03 each had a character, and composers like Rob Hubbard and Martin Galway wrung effects out of them the chips were never designed for — arpeggios faking chords, drums built out of noise.
When the constraint disappeared it became a genre. Chiptune is written today both on original hardware and in modern tools, with the Game Boy and the program LSDJ as the scene's favourite instrument, and the aesthetic has travelled on into indie games and electronic pop.