ChristianHolzapfel
2025-01-10 14:42:45 UTC
Reply
PermalinkSystem (on-planar Crystal CS4231A) of my PC750 and installed a ChipChat.
After finding a game that would just_not_play on this very compatible
card, I decided to go on a very unorthodox adventure and re-enable the
on-board sound, because that seems to be better supported for digital
audio in this case.
Configuring the system this way leads to a resource conflict, because
both sound systems implement a Yamaha YMF262 OPL3 - the ChipChat by
emulation through FM-synthesis, and the planar with a discrete OPL3
chip.
To force things to my will, I edited the system planar's PFED0.ADF,
PFED1.ADF and PFED2.ADF on my refdisk, and cropped the lines for the
"Audio Port Address", reserving
io 0530h-0537h 0388h-038Bh, by removing the 0388h-038Bh part.
After reboot, the system lets me activate both sound cards.
Traveller beware - both OPL3 chips will now respond to 0x388h io
address!
I manually installed the Microsoft Windows Sound System driver with the
proper IO, IRQ and DMA.
Had to wire the PC750 _front_ audio out jack to the ChipChat's line-in
port to have it all come out of the CC's speaker port and have the
internal system speaker silenced, which would playback the MSS sounds
quite loud otherwise.
For my specific game, and aware of the 0x338h IO conflict, I choose
MPU-401 MIDI on port 330h, using the ChipChat's external wavetable which
sound better anyway, and the MSS on port 530h for digital playback.
As unholy this alliance seems, as seemless it just works.