3 ports are used to control the OPL3 soundcard: &FEBC and &FEBE are register select ports, and &FEBD is the data port.
OPL3 offers 18 FM 2-op chans. , that can be configured:* One setting converts 3 of the FM channels into a 5-channel percussion set. * Another setting pairs 12 of the FM channels into 6 FM 4-op channels* The base waveform of each chan can be chosen between 8 waveform types, including a square one. So the OPL3 can play square waves like the PSG.
== Compatible Serdaco soundcards ==