The Yamaha YMF262, also known as the OPL3 (OPL is an acronym for FM Operator Type-L), is an FM synthesis sound chip. It is an improved version of the Yamaha YM3812 (OPL2), adding the following features:
- twice as many channels (18 instead of 9)
- simple stereo (hard left, center or hard right)
- 4 channel sound output
- 4 new waveforms (alternating-sine, "camel"-sine, square and logarithmic sawtooth)
- 4 oscillator mode, pairing 2 channels together to create up to six 4 oscillator FM voices
- reduced latency for host-register access (the OPL2 had much longer I/O access delays)
The YMF262's FM synthesis mode was configurable in different ways.
- Its basic mode provided 18 two-operator FM channels.
- One setting, common to the OPL line, converts 3 of the FM channels into a 5-channel percussion set.
- Another setting, introduced with this chip, causes 12 of the channels to be paired up into 6 four-operator channels. This trades in polyphony for more complex sound formation.
- The two settings can be used separately or in conjunction, resulting in four total modes:
- 18 2-operator channels
- 15 2-operator channels + 5 drum channels (drum setting on)
- 6 2-operator channels + 6 4-operator channels (4-op setting on)
- 3 2-operator channels + 6 4-operator channels + 5 drum channels (both settings on)
Like its predecessor, the OPL3 outputs audio in digital-I/O form, requiring an external DAC chip like the YAC512. Competing sound chip vendors (such as ESS, OPTi, Crystal and others) designed their own OPL3-compatible audiochips, with varying degrees of faithfulness to the original OPL3. Yamaha also produced a low-power variant of the OPL3 called the YMF289. Yamaha's later PC audio controllers, including the YMF278 (OPL4), the single-chip Yamaha YMF718/719S, and the PCI YMF724/74x family, included the YMF262's FM synthesis block for backward compatibility with legacy software. See YMF7xx for more information.
- MIDIbox FM, a YMF262-based DIY synthesizer
- AdlibTracker.net Adlib Tracker II (YMF262-Tracker)
- An YMF262 emulator with an online player for OPL3 music.
- OPLx decapsulated (a reverse engineering report)