Yamaha YM2608

Yamaha YM2608

YM2608, aka OPNA, is a sixteen-channel sound chip developed by Yamaha. It's a member of Yamaha's OPN family of FM synthesis chips, and the successor to the YM2203. It was notably used in NEC's PC-8801/PC-9801 series computers.

The YM2608 comprises four internal modules:

• FM Sound Source, an FM synthesis sound system, based around the YM2203
• SSG Sound Source, a complete internal SSG implementation
• ADPCM Sound Source, a single 8-bit ADPCM channel, 2-16kHz sampling rate
• Rhythm Sound Source, a six-channel ADPCM system, with six percussion "rhythm tones" on a built-in ROM

The FM Sound Source module includes six concurrent FM channels (voices, twice as many as the Yamaha YM2203), four operators per channel, with dual interrupt timers and an LFO. It also includes eight possible operator interconnections, or algorithms, for producing different types of instrument sounds.

The SSG, or Software-controlled Sound Generator, is Yamaha's YM2149 programmable sound generator. The YM2608 includes the SSG's 3 sound channels and dual 8-bit GPIO ports.

The YM2608 is used with a YM3016 stereo DAC.

The YMF288, aka OPN3, is a development of the YM2608, used in later NEC PC-9801 computer soundcards. It removes the YM2608's GPIO ports and various deprecated FM functions, and replaces the ADPCM Sound Source with a controllable noise channel. It also reduces the wait times on registry access, and adds a low-power standby mode. The YMF288 also came in a much smaller physical package.

See also

• Yamaha YM2203
• Yamaha YM2610
• Yamaha YM2612
• Sound chip

References

• Yamaha YM2608 Application Manual
• Yamaha YM2149 Datasheet

External Links

• YM2608 Application Manual (Translated)