# 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]], [[EACA 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]
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.
For tips regarding the desoldering of ICs see this Wiki page: [[IC Repair]]
<br>
== Links ==
*[https://youtu.be/AhgUwqv2yAE Space Debris - Amstrad CPC Soundtrakker cover] [https://youtu.be/E_plcHyOC_8 RUN! - SID emulation on Amstrad CPC] by [[BSC]]
*[https://nguillaumin.github.io/ym-jukebox/ YM Jukebox] [https://ym.mmcm.ru/ AY Music Collection]
<br>
[[Category:Hardware]]
[[Category:Music and sound]]
[[Category:CPC Internal Components]]