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The Yamaha YMF262, also known as the OPL3 (OPL is an acronym for ''FM Operator Type-L''), is an FM synthesis sound chip. It is an improved version of the Yamaha YM3812 (OPL2). ==Overview== The YMF262 improves upon the feature-set of the YM3812, adding the following features:〔http://web.archive.org/web/20030520163334/http://www.fit.vutbr.cz/~arnost/opl/lost+found/ymf262.pdf〕 *twice as many channels (18 instead of 9) *simple stereo (hard left, center or hard right) *4 channel sound output *4 new waveforms (alternating-sine, "camel"-sine, square and logarithmic sawtooth) *4 oscillator mode, pairing 2 channels together to create up to six 4 oscillator FM voices *reduced latency for host-register access (the OPL2 had much longer I/O access delays) *subtle differences in the sine-wave lookup table and envelope generator from YM3812 (e.g. the modulator waveform on YM3812 is delayed by one sample, whereas both carrier and modulator waveforms on OPL3 are properly synchronized)〔http://dev.kewl.org/misc/ymf262/ymf262.c〕 YMF262 also removed support for the little-used CSM mode, featured on YM3812 and YM3526. The YMF262's FM synthesis mode was configurable in different ways. * Its basic mode provided 18 two-operator FM channels. * One setting, common to the OPL line, converts 3 of the FM channels into a 5-channel percussion set. * Another setting, introduced with this chip, causes 12 of the channels to be paired up into 6 four-operator channels. This trades in polyphony for more complex sound formation. * The two settings can be used separately or in conjunction, resulting in four total modes: * * 18 2-operator channels * * 15 2-operator channels + 5 drum channels (drum setting on) * * 6 2-operator channels + 6 4-operator channels (4-op setting on) * * 3 2-operator channels + 6 4-operator channels + 5 drum channels (both settings on) The YMF262 was used in many sound cards, including the popular Sound Blaster Pro 2.0, Sound Blaster 16 ASP and AWE family. Like its predecessor, the OPL3 outputs audio in digital-I/O form, requiring an external DAC chip like the YAC512. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Yamaha YMF262」の詳細全文を読む スポンサード リンク
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