Some other 8-bit systems used more sophisticated soundchips such as the [https://youtu.be/7pONRbIHT_w C64 SID], the [https://youtu.be/BANwL2sQ0DM NES APU] and the [https://youtu.be/-mdjiWBYIqU Gameboy soundchip].
== PSG Part numbers used in the CPC during its lifetime ==
* GI AY-3-8912 [https://www.cpcwiki.eu/imgs/c/cc/CPC464_PCB_Top_%28Z70378_MC0046A%29.jpg Source]
* GI AY-3-8912A [https://www.cpcwiki.eu/imgs/f/f1/CPC6128_PCB_Top_%28Z70290_MC0020B%29.jpg Source]
* Microchip AY-3-8912 [https://www.cpcwiki.eu/imgs/c/cf/AmstradCPC464_Z70375_MC0044D_GA40010_PCB_Top.jpg Source]
* Microchip AY38912/P [https://www.cpcwiki.eu/imgs/5/5e/CPC464Plus_MC0122B_2700-016P-3_PCB_Top.jpg Source]
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== I/O Access ==
== Chip Variants ==
=== IC models used in CPC ===
These are the ones known to be used in the CPC by looking at pictures of CPC mainboards. All should operate almost identically.
* GI AY-3-8912 [https://www.cpcwiki.eu/imgs/c/cc/CPC464_PCB_Top_%28Z70378_MC0046A%29.jpg Source]
* GI AY-3-8912A [https://www.cpcwiki.eu/imgs/f/f1/CPC6128_PCB_Top_%28Z70290_MC0020B%29.jpg Source]
* Microchip AY-3-8912 [https://www.cpcwiki.eu/imgs/c/cf/AmstradCPC464_Z70375_MC0044D_GA40010_PCB_Top.jpg Source]
* Microchip AY38912/P [https://www.cpcwiki.eu/imgs/5/5e/CPC464Plus_MC0122B_2700-016P-3_PCB_Top.jpg Source]
=== Other 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]], [[EACA Colour Genie]], [[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]
The chip is clocked differently depending on the computer: ZX Spectrum: 1773400 Hz ; Pentagon: 1750000 Hz ; MSX: 1789772 Hz ; CPC: 1000000 Hz ; Oric: 1000000 Hz ; Atari ST: 2000000 Hz.
The PSG chip competed with the DCSG (Digital Complex Sound Generator) chip family (SN76489, SN94624, TMS9919) by Texas Instruments. The DCSG has similar sounding features except that it does not have any envelope control and that its noise generator has its own dedicated channel.
The EPSG (AY-3-8930), used in the Covox Sound Master soundcard on PCs, is a register-compatible evolution of the AY-3-8910:
* The noise period setting is more accurate (8-bit instead of 5-bit)
* The noise tone can be changed by applying an AND and OR mask to the output
=== Competitors ===
The PSG chip competed with the DCSG (Digital Complex Sound Generator) chip family (SN76489, SN94624, TMS9919) by Texas Instruments.
The DCSG has similar sounding features except that it does not have any envelope control and that its noise generator has its own dedicated channel.
=== Replacing the AY-3-8912 in the CPC with an AY-3-8910(A) ===