First post, by jmk
I have been working on Covox Sound Master emulation... I am still trying to get to grips with the specs and how DMA sound works and so on, but I can play AY and samples with a few glitches and lock ups, depending on the game.
The only game I've found that supports the AY8930 properly (duty cycles and separate envelopes) is Where in Time is Carmen Sandiego? 😁 Nothing seems to use white noise though. 🙁 You'd think that people would've ported some of their Atari ST musical assets...
The Prince of Persia detection routine sets up a DMA 1 & 3 transfer and then reads port 08 (DMA status) to determine which one (if any) took place.
The routines reads the port and decides that if bit 7 is low then DMA 3 has occurred or if bit 5 is low then DMA 1 has occurred. Generally not what happens in the DMA emulation, where those bits are high or low depending on whether a callback routine has been attached. (For now I am rigging it).
If anyone has a Covox Sound Master+ and can reveal a bit of information on it (even just listing the chips on the board) then I would be grateful!
The CSM appears to use Base+0 to Base+4 for its AY, DAC and DMA (fine). The CSM2 seems to use Base+8 to Base+F for its DAC and DMA (fine, plus the usual Adlib ports for its OPL2 chip). The CSM+ is presumably similar to the CSM, but with an OPL2 chip added. The thing is, the CSM uses some of the AY registers to set up the DMA, so... does the CSM+ have the OPL2 and AY-3-8930?