# 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).
Consult this article for more information: [[How to access the PSG via PPI]]