# set BC1/BDIR to Write Data
# and back to Inactive.
You must use 3 OUTs to send a value to an AY register, even if you don't change registers in the meantime. [https://www.cpcwiki.eu/forum/programming/interesting-walkthrough-video-coding-a-pet-to-play-samples-at-60khz/msg250874/#msg250874 Source]
So you have to enter the data on F4. Then on F6, select the type of data (bdir/bc1>>#10) and validate everything (bdir/bc1>>00). Otherwise, the data in other AY registers becomes corrupted quite quickly.
Consult this article for more information: [[How to access the PSG via PPI]]
=== Other Variants ===
The PSG chip family is composed of 3 variants: * the AY-3-8910 , with two 8-bit I/O ports, and a 40-pin package* the AY-3-8912 , with one 8-bit I/O port and a 28-pin package* the AY-3-8913 , with no I/O port. and a 24-pin packageIn addition to the CPC, these chips were also used in the [[KC Compact]], [[ZX Spectrum]], [[MSX]], [[Oric-1/Atmos|Oric]], [[EG2000 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]