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PSG
,/* Chip Variants */
Yamaha produced the SSG (Software-controlled Sound Generator) chip family (YM2149F, YM3439, YMZ294, YMZ284, YMZ285) which is a quasi-clone of the PSG. The main difference is that the envelope counter on the PSG has 16 steps. On the SSG it has twice the steps, happening twice as fast. This chip equips the [[Atari ST]], [[Aleste 520EX]] and [https://www.msx.org/wiki/Yamaha_YM2149 some MSX computers]. It is also used in the [[PlayCity]] expansion.
The SSG has also been integrated as a component inside some of the arcade soundchips of the Yamaha OPN family. That's why you can find it in the [[Neo-Geo]] as a component inside the YM2610 soundchip. And the same is true for the OPN3 soundchip of the [[Play2CPC]] expansion.
The EPSG (AY-3-8930), used in the Covox Sound Master soundcard on PCs, is a register-compatible evolution of the AY-3-8910:
