Yamaha YM2151

The YM2151 was used in many arcade game system boards, starting with Atari's Marble Madness in 1984, then Sega arcade system boards from 1985, and then arcade games from Konami, Capcom, Data East, Irem, and Namco, as well as Williams pinball machines, with its heaviest use in the mid-to-late 1980s.

The modern hobbyist Commander X16 8-bit computer also contains a YM2151 chip onboard for sound generation.

Later SFG-05 modules contain the YM2164 (OPP), an almost identical chip with only minor changes to control registers.

The chip contains eight concurrent FM synthesis channels, and each channel contains a number of operators that can be connected in a variety of ways, using a modified ADSR envelope along with rate scaling, frequency multiplication, and detuning settings.

There are four operators per channel, each of them containing a sine wave oscillator and an envelope generator.