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Yamaha YM2151

Yamaha YM2151

The Yamaha YM2151, also known as OPM (FM Operator Type-M) is an eight-channel, four-operator sound chip developed by Yamaha. It was Yamaha's first single-chip FM synthesis implementation, being created originally for some of the Yamaha DX series of keyboards (DX21, DX27, and DX100[1]). Yamaha also used it in some of their budget-priced electric pianos, such as the YPR-7, -8, and -9.

Uses

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. It was also used in Sharp's X1 and X68000 home computers. The modern hobbyist Commander X16 8-bit computer also contains a YM2151 chip onboard for sound generation.[2][3]

The chip was used in the Yamaha SFG-01 and SFG-05 FM Sound Synthesizer units. These are expansion units for Yamaha MSX computers and were already built into some machines such as the Yamaha CX5M. Later SFG-05 modules contain the YM2164 (OPP), an almost identical chip with only minor changes to control registers.[4] The SFGs were followed by the Yamaha FB-01, a standalone version powered exclusively by the YM2164.

Technical details

Chart showing the 8 algorithms used in all of Yamaha's 4-operator FM synths, first implemented in the DX9 and later used in the YM2151 and other subsequent 4-operator FM chips

The YM2151 uses a form of sound synthesis known as FM synthesis, achieved by phase modulating the instantaneous frequency of each waveform via a modulator. 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. These operators can be rearranged into eight different connections (or "FM Algorithms" in Yamaha terminology) of the four operators for sound generation. The algorithms are based on that of the Yamaha DX9, which uses a set of algorithms based on the DX7's 32 FM algorithms but with four operators. The fourth operator on the eighth channel can also be swapped out for a variable-frequency noise channel for noise generation.

The YM2151 was paired with either a YM3012 stereo DAC or a YM3014 monophonic DAC so that the output of its FM tone generator could be supplied to speakers as analog audio.[5]

See also

References

  1. ^ "YAMAHA YM chips numerical classification". vorc.org. Retrieved 8 July 2014.
  2. ^ "Commander X16 - C64-Wiki". www.c64-wiki.com.
  3. ^ Murray, David (October 12, 2022). "The Commander X16 has finally arrived!". YouTube. Archived from the original on October 28, 2022. Retrieved October 28, 2022.
  4. ^ "Yamaha YM2164 OPP". map.grauw.nl.
  5. ^ "X68k FM Sound Source Register Map". www16.atwiki.jp. Retrieved 8 July 2014.