Hi Freddy,

i guess you mean the PS/1 Audio Card? I'm not sure how the DAC part works, i imagine a FIFO buffer i don't think its DMA driven.

The music portion is a TI SN76496 3 voice, i guess there's emulation for that, NCR 8496 is a clone of that for the Tandy machines, and the TI chip on the PS/1 Audio Card is driven at a different frequency so PS/1 music sounds higher pitches compared to the Tandy 1000.

PS/1 Audio Card TI chip responds on port 0x205

PS/1 Audio card yes,

It is a 2KB FIFO, and send an interrupt when it is almost empty.
2KB FIFO (Port 200) 201: Control, 202 for the timer speed (Output rate) + 3 Channel tandy chip at port 205

Then, for a .MOD player for example, it is as simple as send in loop a buffer for 1/50th of second, wait for the IRQ to send another.

I don't think i can help you with this, but looking forward to it!

Owners of PS/1 with the Audio card will surely be interrested to have Mod Master XT supporting it 😀