I've got this option for atclk in the bios. Any idea if this might relate to isa bus speed or what I'd write in it? I have the option to change the 55h value, but I'd need to type something in manually, there's no selection of choices.

I have managed to fix this, but not in a good way!

What fixed the audio drop outs was changing a setting in my bios to run the CPU "slow" rather than "fast" (fast is the default, so this option is kinda like a turbo button I guess).

So running the CPU slow fixed the audio, but since we're talking about running a 386 in slow mode, the games that had the issues such as Jazz Jackrabbit and OMF 2097 play like molasses... This does still suggest to me that the issue is related to the ISA bus as it makes sense to me that the speed of the isa is related to the cpu speed. Just wish the bios here had independent settings for that, don't see any dip switches on the board either. Is there a TSR somewhere that could do it? Oh well, at least this provides some more clarity around things.

Is there any way to use a different BIOS with this board?

Hmm I don't know. I have no documentation for this board and haven't been able to find it on the retroweb. In any case, the current bios doesn't say anything about flashing or upgrading within the GUI.

Looking for the chipset might give some clues

Looking at your first thread, and going with the 386 board there.
It seems to be an opti 82c381/2 chipset

This leads to https://theretroweb.com/chipsets/366#docs which has a pdf for download which on page 7 and beyond,
lists some register information which could correspond to the bios display photo you posted in this thread.

edit: it also seems that your 386 board is not listed on the retroweb. If you could take the board out of the case and supply the retroweb with clear photos of frond & back it would be helpful to document it further.

weedeewee wrote on 2024-08-09, 18:47:

Looking for the chipset might give some clues […]
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Looking for the chipset might give some clues

Looking at your first thread, and going with the 386 board there.
It seems to be an opti 82c381/2 chipset

This leads to https://theretroweb.com/chipsets/366#docs which has a pdf for download which on page 7 and beyond,
lists some register information which could correspond to the bios display photo you posted in this thread.

Why so it is, good find! I can see the Opti 82c382 chip in one of the pictures I previously took of the board. The time period and specs match too.

So I'm looking at the documentation, and it says very clearly in several places that AT bus speed can be adjusted and the multiplier can be adjusted, which sounds great... but I'm not getting a good picture of how this is done, or how it might translate into the hexadecimal input I see in the bios for ATCLK, default value of which is 55h. I plugged 54h into there earlier to see if I would get any different performance and could not tell a difference.

edit: it also seems that your 386 board is not listed on the retroweb. If you could take the board out of the case and supply the retroweb with clear photos of frond & back it would be helpful to document it further.

I'd love to. I went to do this previously but ran into some issues with removing the power supply and some of the case chassis components (I unscrewed the visible screws but for the life of me could not remove some of the chassis components that are blocking removal of the board). I'll have to revisit this in the future.

Well if I read the pdf correctly then 55 would be clkin/2
53 would be clkin/3 and 51 would be clkin/4

weedeewee wrote on 2024-08-09, 19:54:

Well if I read the pdf correctly then 55 would be clkin/2
53 would be clkin/3 and 51 would be clkin/4

I gave each of these a shot but there was no improvement to the audio drop out issue. Thanks though.

I added an opti pnp soundblaster card to the machine so I can at least get non-skipping music in the epic games and otherwise have an alternative to the GUS and SBOS when I want that. The good news is that I correctly set things up and things were working just how I wanted with the opti being a nice backup card when I just wanted the sound to work right... but I was doing this by setting variables realtime at the dos prompt rather than saving stuff in my autoexec, and now that its a week or so later, I'm not remembering exactly what I did... so now when I try to duplicate things, the opti will play OPL, but it is silent if I want it to play pcm such as the Jazz Jackrabbit or OMF tracker music.

I've set the GUS and Blaster variables to be at different baseports, irqs and dmas. For instance, I've tried different combinations, but currently the ultrasnd is at 220,i7, d3 and the opti is at 240, i5, d1.

I'm also using unisound to initiate the PNP card, which has worked for me fine with this card before. I don't think its an issue with games being hardcoded to look for a soundblaster at base 220, as I'm testing it with Jazz and OMF which allow for identifying base 240 or others for soundblaster in the sound setup.

I am using unisound to initiate the opti card and it displays all the correct info when initializing it. Other stuff like virtual mixer volume levels, and physical connection from the opti to the speakers is good... But I'm not getting any sound from the opti other than OPL/adlib sound.

Any thoughts what I might be overlooking?

I seem to have fixed this issue by simply switching the irqs of the cards, so the GUS is now 5 and the opti is 7 instead of vice versa.

dukeofurl wrote on 2024-08-22, 01:05:

I seem to have fixed this issue by simply switching the irqs of the cards, so the GUS is now 5 and the opti is 7 instead of vice versa.

Do you mean to say you had another soundcard with an OPTi chip in the system besides the GUS MAX? I did not see that mentioned anywhere before in your post...

CHiLL72 wrote on 2024-08-23, 13:43:

dukeofurl wrote on 2024-08-22, 01:05:

I seem to have fixed this issue by simply switching the irqs of the cards, so the GUS is now 5 and the opti is 7 instead of vice versa.

Do you mean to say you had another soundcard with an OPTi chip in the system besides the GUS MAX? I did not see that mentioned anywhere before in your post...

The opti is a new card I just added in to the system recently, it has not been in the system since the start of this thread and it is not the cause of the GUS music skipping, as that occurred before I added the opti card just very recently. Adding the opti card is just me doing a kludge so I can have an option to play the games that have skippy tracker music without the skipping.

Is there an LPT port configured to use IRQ7 ?

Maybe the GUS is more sensitive to this than the your other sound card.

I had this memory that when everything worked 30 years ago, it was actually with the gus Max v1.8 rather than the v 2.1 I was currently using. The curiosity got to me, so I splurged and bought the earlier version of the gus Max just to rule out that there might be an issue with the 2nd revision gus Max, or something the matter with the particular 2.1 card I had.

In any case, my testing has the v1.8 giving the same performance as the 2.1 (works ok for games that use the gus samples like Doom, but glitches out when playing games that load their own samples for tracker music, like Jazz jackrabbit) so there is definitely an incompatibility with my system or settings.

Are the drivers different between the gus Max 2.1 and 1.8? I was testing out the v1.8 with the installation software I have from the v2.1, but I noticed when I tried using sbos 3.84 with the rev 1.8, my system locks up immediately after a PCM sample plays, such as opening a door or shooting a gun in Wolfenstein 3d. Whereas this does not happen with the rev 2.1. I know I have an older version of sbos somewhere... Will give that a shot.

EDIT - I fixed this issue with sbos and freezing. I don't know why but it seems (at least on my machine) that the playback and recording irqs must be different for sbos to work correctly and not freeze upon PCM sample playback when in sb emu mode. I haven't seen this identified anywhere because it doesn't seem like anyone else regularly uses sbos these days, and in fact most install guides tell you that it does not matter if the playback and recording irqs are the same, and suggest ultrasnd variables with them being the same, which seems ok for regular gus mode use.