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/* Technical information */
3 ports are used to control the OPL3 soundcard: &FEBC and &FEBE are register select ports, and &FEBD is the data port.
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=== OPL3 sound chip ===
OPL3 is register compatible with OPL2, with twice the number of signal sources, 4 new operator modes, 4 new selectable waveforms (including square wave) and stereo output.
* Both settings can be used at the same time, to obtain 6 FM 4-op chans + 3 FM 2-op chans + 5-chan FM percussion set
FM synthesis does a great job relative to its hardware requirements at reproducing melodic instruments but isn't especially useful for harsh percussion noises like drums. Yamaha provides separate drum noises for this purpose. The programmer has to forfeit three channels of regular FM synthesis, freeing up six operators for five rhythm instruments.
