OPL3 offers 18 FM 2-op chans in its standard mode, but that can be configured:
* One setting converts 3 of the FM channels chans into a 5-channel chan FM percussion set (Bass Drum, Snare Drum, Tom-Tom, Top-Cymbal, Hi-Hat)* Another setting pairs 12 of the FM channels chans into 6 FM 4-op channelschans* 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
Also, a square waveform can now be selected on each chan. So the OPL3 can play square waves like the PSG.