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PSG
,/* Chip Variants */
== Chip Variants ==
The PSG chip family is composed of 3 variants: the AY-3-8910 with two 8-bit I/O ports, the AY-3-8912 with one 8-bit I/O port and the AY-3-8913 with no I/O port. In addition to the CPC, these chips were also used in the [[KC Compact]], [[ZX Spectrum]], [[MSX]], [[Oric]], [[Vectrex]], [[Intellivision]] and in the Mockingboard expansion for the [[Apple II]]. There are also PSG clones: Toshiba T7766A, Winbond WF19054, JFC 95101, and File KC89C72. [https://wiki.agiri.ninja/sound_chip_clones:index Source]
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.
