Sammich FM synthesizer Un-assemble DIY kit Yamaha YMF262 OPL3 sound chip

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You can find some videos featuring the YMF262 in the archives.

"The Yamaha YMF262, also known as the OPL3 (OPL is an Acronym for FM Operator Type-L), is an Frequency modulation synthesis Sound chip released by Yamaha Corporation in 1988. It is an improved version of the Yamaha YM3812 (OPL2). It was used in a number IBM PC soundcards including Sound Blaster 16 and Pro AudioSpectrum (16bit). It adds the following features:

The YMF262 improved upon the feature-set of the YM3812, adding the following features:[1]

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)
subtle differences in the sine-wave lookup table and envelope generator to YM3812 (e.g. the modulator waveform on YM3812 is delayed by one sample, whereas both carrier and modulator waveforms on OPL3 are properly synchronized)[2]
YMF262 also removed support for the little-used CSM mode, featured on YM3812 and YM3526.[2]

The YMF262's FM synthesis mode is configurable in different ways:[1]

Its basic mode provides 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 six 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."