Yamaha YM2608

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

The YM2608 consists of four internal modules:

• FM Sound Source, a six-channel, four operator FM synthesis sound system based on the YM2203
• SSG Sound Source, a complete internal implementation of the Yamaha YM2149/SSG, a variant of the popular AY-3-8910/PSG for producing three channels of square wave synthesis or noise.
• ADPCM Sound Source, a single channel for samples in 4-bit ADPCM format at a sampling rate between 2–55 kHz
• Rhythm Sound Source, a six-channel ADPCM system, enabling playback of six percussion "rhythm tones" from a built-in ROM

The FM Sound Source includes six concurrent FM synthesis channels and four operators per channel, with eight possible operator interconnections (or algorithms) for producing different types of instrument sounds. The SSG (or Software-controlled Sound Generator) Sound Source is Yamaha's YM2149 programmable sound generator. It includes the SSG's three sound channels, noise generator and dual 8-bit GPIO ports. The chip also includes dual interrupt timers, as well as the addition of a single sine-wave low frequency oscillator (LFO). The YM2608 is used with a YM3016 stereo DAC.

The YMF288,^[1] a.k.a. OPN3, is a later development of the YM2608, used in later NEC PC-9801 computer sound cards. It removes the YM2608's GPIO ports, CSM (composite sinusoidal modeling) and the ADPCM Sound Source. It also reduces the wait times on register access, and adds a low-power standby mode. The YMF288 also came in much smaller physical 28-pin SOP and 64-pin QFP packages.

El YM2608 se convirtió en la base de otros dos chips de sonido de la familia OPN, el YM2610 y el YM2612 . El primero se utilizó principalmente en la máquina recreativa y consola doméstica Neo-Geo de SNK , mientras que el segundo se utilizó principalmente en la consola Mega Drive (Genesis) de Sega y en los ordenadores FM Towns de Fujitsu . El YM2610 está directamente relacionado con el YM2608, utilizando especificaciones casi idénticas, mientras que el YM2612 es una versión simplificada del YM2608, que carece de muchas características como los canales ADPCM y SSG. Ambos chips se basaron en el bloque FM del YM2608 (que a su vez se basó en el YM2203). ^{[ 2 ]}

• VGM : un formato de archivo de audio para múltiples plataformas de videojuegos, incluyendo NEC PC-8801/PC-9801.
• Yamaha YM2149
• Yamaha YM2203
• Yamaha YM2610
• Yamaha YM2612
• Chip de sonido

• Manual de aplicación YM2608 (traducido)