This register map covers OPL3 specifically, and several OPL2 and OPL3 reference, and VGM.
VGM version should be above 1.51.
OPL3 IC is YMF262. clocked at 14318180
Hz. Command is 0x5Eaadd
OPL2 IC is YM3812. clocked at 3579545
Hz. Command is 0x5Aaadd