TheYM2203, a.k.a.OPN (FM Operator Type-N), is a six-channel (3 FM and 3 SSG)sound chip developed byYamaha. It was the progenitor of Yamaha's OPN family ofFM synthesis chips used in many video game and computer systems throughout the 1980s and early 1990s. It was used in a variety ofNEC computers, along with variousarcade game machines.
The YM2203 has the following features:
The YM2203 and the rest of the OPN synthesizer family generate sound viafrequency-modulated digital sine waves. It included 12 operator "cells", each generating a 13-bit sine wave at a programmable frequency, the volume of which is controlled by a programmableADSR envelope generator. The output of these cells could be either summed together by the mixer, or fed into the input of another cell, in 4-cell batches creating the final sound values or "channels". 4 operator cells per channel allowed a total of 8 different permutations of cell connections, known as "algorithms". The ADSR parameters, multiplier and detune settings for each operator, combined with the algorithm, make up what are known as instrument patches.
The resulting digital sound output of each channel through the mixer was then converted to analog sound via adigital-to-analog converter (DAC). The YM2203 is used with a YM3014 external DAC companion chip.
The SSG module implemented the YM2149F's three SSG channels, noise generator and dualGPIO ports.
The chip was also used in certain models of theFujitsu FM-7,NEC PC-8801, andNEC PC-9801 personal computers.
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