Yamaha · 1984 · 1980s · 6 voices
The YM2203, or OPN, was the founding chip of Yamaha's OPN family: three FM channels plus three square-wave channels that gave Japanese home computers their distinctive layered sound throughout the 1980s.
The OPN (FM Operator Type-N) combined two synthesis methods on one chip. Its three FM channels used four-operator frequency modulation to produce the rich, metallic timbres Yamaha had pioneered, while three additional SSG channels — a built-in equivalent of the General Instrument AY-3-8910 — provided simple square waves and noise for basslines, arpeggios, and percussion. This hybrid gave composers a wider palette than either method alone, and it became the standard voice of NEC's PC-8801 and the sound boards of the PC-9801, along with the Fujitsu FM-7 and numerous arcade machines. A young Yuzo Koshiro cut his teeth writing for the YM2203 on Nihon Falcom's PC-8801 games, and its architecture directly seeded the more famous OPN descendants: the YM2612 that powered the Sega Genesis and the YM2608 (OPNA) that expanded the formula for the PC-9801. Understanding the YM2203 is understanding where the Genesis sound came from.