Hi there! Sorry to hear, that's a strange problem. I don't know what causes this, to be honest.

Hm. Only workaround I can think of is to make a backup and try out different memory managers (Emm386+Memmaker, 386Max, Qemm).

The reason is, that most of them use V86 and do provide features such as DPMI API.
Such memory managers are like little OSes and also virtualize i/o requests.

So they might indirectly fix things or cause trouble, depending on situation.
Alternatively, if a memory manage is already running, it's worth to remove it and try something else.

Himem.sys is usually harmless (no V86) can be kept.
Last but not least, instead of using something like EMM386 to get free UMBs and load driver up, it's also possible to use cloaked drivers that run past 1MB.

Helix Multimedia Fusion is such a package, for example.
It has a special memory manager w/ optional DPMI and comes with a few special drivers that run past 1MB.

These are just some ideas, of course. I hope some else knows how to help properly.
The FM+SFX issue is both interesting and annoying. It would make depressed, too.

Anyway, I think your CT1740 is okay. I do like that card, just like my PAS16.

Good luck! 🙂👍

Thanks Jo22. At this moment I'm ready to test anything. I've just tried the following:

* QEMM386 instead of EMM386 or nothing
* Running the games from within Windows 95 DOS box
* Swap SB16 with a SBPro2 CT1600
* Switch to a 256MB CF card instead of 4GB
* Win98 boot disk
* Physically disconnect the CD drive

Still, the issue persisted. I also found that Space Quest 5 is only able to play 1 digitized sound then no more SFX. But it doesn't freeze like other games. Only digitized sounds will disable. I'm starting to suspect a DMA issue. Problem is, in my mind this build was working flawlessly.. I already had all those games on the HDD, and I would have noticed at time of installing them if they had any issues, as I play each game a little bit after installing it. Something changed in the machine.

So this machine was stowed away for a few months after it was being used daily to play all sorts of games, and I pulled it recently to test a Pentium 90 processor. I installed the processor instead of my P233MMX, and the P90 worked fine. Then I put back the P233MMX... and now I have this stupid problem.

I don't suspect the sound card anymore since the issue is occurring with SB16 and SB AWE64 and the almighty SBPro2.

I tried to flash a different BIOS. The BIOS is Ami BIOS. I found a few ROMs here:
https://theretroweb.com/motherboards/s/pcchips-m571lmr-v1-x

But it seems I cannot flash it in DOS. When I run amiflash 8.95, it says my BIOS is write-protected. What parts do I need to flash an EEPROM and use it instead of the one in the machine currently? (programmer and chips)

Thanks all!

Hi,
try Uniflash 1.40.

But the chances are high, that something is wrong with you mainboard. Maybe even defective.

Thanks Demolition-Man, Uniflash was able to write the ROMs. I was able to try all ROMs from the RetroWeb... alas... no difference 🙁

So here are the things I tried this morning:

* Swap PSU with a different one
* Jump/Unjump J3 on the motherboard (enables/disables on-board sound chip)
* Reseat RAM
* Flash all 1Mbit BIOSes from The Retro Web using Uniflash

Still no luck... Visual inspection doesn't reveal any obvious defects like cracks, discolored components, liquids, bulgy caps.

Thinking about what could be going wrong... The only conversation going on with FM is via its standard port 388 or 220. I haven't tried changing the card's IO base port yet. Might be worth trying that next...

Also worth mentioning that using MT-32 instead of Adlib music will not cause any freezes. Only Adlib+digital is bad.

Heh.. so turned out I'm not the only with this nasty issue. This guy did a review of the board and faced the same problems as well, even though he was using the on-board sound chip.

https://youtu.be/6awMc5tHJAk?t=8m59s

He gets a hang with the exact characeterstics as me. FM+Digital freezes some games, but FM only is ok.

So we're against a design flaw here, and now I'm wondering if the on-board sound chip has anything to do with it. Though I'm jumpering it off in my case and I don't load its PCI drivers of course.

I will add also that I tried base address 260 instead of 220, and it didn't solve the problem. What a stubborn mobo 😅

wbahnassi wrote on 2024-05-30, 09:03:

He gets a hang with the exact characeterstics as me. FM+Digital freezes some games, but FM only is ok.

So we're against a design flaw here, and now I'm wondering if the on-board sound chip has anything to do with it. Though I'm jumpering it off in my case and I don't load its PCI drivers of course.

Hi, that reminds me of something.
The PAS16 uses the OPL3's address as its control port (port 388h).
There's a circuit on the card that makes sure both OPL3 and PAS16 are working without issues.

I noticed this when installing a secondary soundcard, an SB16 CT1740.
After booting, after mvsound.sys had initialized the PAS16, there was this high-pitched whine coming from the SB16's OPL3.
I had to run Creative's diagnose program to make it vanish.

So maybe there's a similar conflict with the ob-board soundcard here?
Some relationship between FM and DAC circuits?

Right, and now I'm more inclined to suspect that it really is the fault of this on-board SoundPro HT8738AM chip. It actually has very nice FM (almost indistinguishable from original OPL3), but weak SB digital support (PCI drivers are not very compatible, as usual with most PCI card DOS drivers). But yeah, I don't want it.

Now I double checked that all jumpers are set to disable access to this chip, and found that I had jumper JP8 left open. In this state, it means the on-board modem is enabled, and it is part of the sound chip as well. I closed the jumper and now I can see that the modem is not reported anymore in the PCI IRQ list. The only PCI devices mentioned are IDE0 and IDE1 and VGA IRQ, so pretty clean. Alas, this still didn't solve the freeze problem.

I'm seriously considering desoldering the SoundPro chip. But if people here advise against it, I wont. I don't have much skill extracting chips, so I'll need to train on something else first. But I do have a good hot-air station and good flux. I'll want to solder it back if removing it didn't fix the problem.

I was really loving this motherboard as it is very versatile and flexible.. allowing FSB and processor speed control all from within the BIOS screen (no jumpers/dip-switches). And its VGA solution plays great in DOS and has good Win3.1 and Win95 drivers (I use both). I guess like everything, it can't be just too perfect...

Ok. Desoldered the SoundPro, and that caused the mobo to not post any more. So returned it back. Looks like that chip is not wired just as a regular PCE device. Oh well... off to find a better board.