Put 2 YM2149 into the ST

[exxos]

Similar project was done here also viewtopic.php?f=29&t=4124

[dgw]

Should be quite possible to drive two YM2149 off printer port. I did something for Sinclair QL a few years ago when I wrote PT3 (& others) chip player for dual chips. (BUSY for Atari is pin11, AFAIK)

2PSG.png

[unseenmenace]

Another solution that would be easier to implement is actually to use a YM2203 which is YM2149 compatible. The pinout is different but basically with a small adapter it could act like a YM2149 replacement. Then by adding a small DAC you can add 3 FM channels.
The extra registers are addressed the same way than on YM2149.

This is exactly what I've been working on and as well as the thread Exxos linked there's this one over on AF:

https://www.atari-forum.com/viewtopic.p ... 0&start=75

I'm very close to getting a PCB ordered and it will look something like this:

PCB.gif