Yamaha YMF278

The FM part is essentially a YMF262 (OPL3) block; thus, it is also backward-compatible with the YM3526 (OPL) and the YM3812 (OPL2).

Like the OPL3, it can operate in one of four ways: Four-operator FM allows more complex sounds but reduces polyphony.

The sample synthesis part is based on pulse-code modulation (PCM).

It features: The PCM synthesizer part accepts: For ROM wave data access, the Yamaha YRW801 2MB ROM chip can be connected to the OPL4.

Like its predecessors, the OPL4 outputs audio in digital-I/O form, thus requiring an external DAC chip.