Kahenraz wrote on 2022-03-28, 18:30:
On my board, there is no DMA support on the ISA bus. My guess is that the other reference is a mistake, unless he has some other board revision or a different bridge chip.
It's important to clarify that Adlib sound will always work, regardless of DMA, and this can be misleading. DMA is only needed for digital sound effects, not FM or MIDI.
Little bump: I have this board too now and blindly assumed your experience was definitive - but on a whim I decided to give it a try this evening and I think I have DMA working 🅾️
First off given your guess about revisions/bridge chips a run-down of what I have:
FIC KC19+ with sticker stating "REVC05"
Nat Semi PC87200VUL briedge chip, with "A3" indication on it, exactly as pictured here
I might have a different BIOS to the two listed on TheRetroweb, my string is "HY.91.03DU"
Sound hardware: Terratec EWS64 (hardly the simplest card, but I had a spare lying around...)
FWIW other hardware: P3-500 Katmai, 2x 128MB PC800 ECC RDRAM, Diamond Stealth3D 2000 (S3 Virge) 2MB, Quantum Fireball ST 1.6GB IDE HDD
So why do I think I have DMA working? Well, Doom2 with working sound effects makes me think so 😉
But I think I also understand why it didn't work for you:
- to get it to work at all I needed to disable onboard CS4280 audio
- I can only make it work with playback on DMA3
- If I try to set DMA to 0, I get typical no DMA symptoms: AdLib and MIDI on 330 work fine, but no SB sound effects
- if I try DMA 1, I get conflicts and the EWS64 can't initialize.
What I suspect is going on:
- the PC87200VUL supports DMA via PC/PCI, as stated in the datasheet
- the onboard CS4280 also supports PC/PCI
- somehow the two implementations conflict, either at BIOS or hardware level, resulting in DMA 0 and 1 being unavailable for ISA but DMA 3 is.
Having said this, I'll now try to dig up a simpler, less tempramental (preferably non-PnP) sound card to verify my findings.
Edit:
Re-tested with a very non-PnP Sound Blaster 16 CT1750 MCD (that urgently needs re-capping by the sound of it). Similar same story:
- did not need to disable onboard CS4280 to get things to work, in fact I didn't even need to reserve IRQ5
- DMA 0 no SB sound effects
- DMA 1 no SB sound effects (no noticeable conflicts either though)
- DMA 3 working SB sound effects