VOGONS


First post, by dukeofurl

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I have a p233 PC with a vibra 16. I've noticed I have some audio issues with a small group of early 90s dos games like Street Rod 2, Xargon, Solar Winds, Traffic Department 2192, such as:

-game does not recognize the system has a sound card, does not let me choose one in an options menu, or
-game plays some pcm sfx but not all, or
-game produces a loud distorted buzz instead of the sound blaster audio, or
-game is silent, no soundblaster audio is played

I used to have a slower CPU in this system, and I did not have these errors. So I used Setmul to disable the l1 cache on the p233, greatly slowing things down, and lo and behold, it seems like that fixes my audio issues.

But what's going on? I tried to look for people having similar errors and didn't come across much. Just wondering if this is a common thing when using a fast CPU, or an eclectic issue with my system.

Reply 1 of 7, by wbahnassi

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You'll need to adjust the clock divider for your 233 CPU. Looks like right now you're overclocking the ISA bus. Check the BIOS options to find the proper option. It should read something like CLK or SCLK

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Reply 2 of 7, by danieljm

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I don't necessarily have an answer for you, but I know this was definitely a problem with at least some versions of the Sounds Blaster Pro.

Do you know if your FSB and more specifically the ISA bus are running at standard speeds? I could potentially see that being a problem.

Reply 3 of 7, by dukeofurl

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wbahnassi wrote on 2025-01-23, 23:40:

You'll need to adjust the clock divider for your 233 CPU. Looks like right now you're overclocking the ISA bus. Check the BIOS options to find the proper option. It should read something like CLK or SCLK

Oh that makes total sense. I'll check the bios, but in any case, looking at a manual for my board, it looks like there is a dipswitch related to that, and I think the way it might currently be set (the default) would have it running at 11mhz with this faster CPU. Whoops

Reply 4 of 7, by dukeofurl

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Ok now that I've checked things, the dipswitch was set to the correct setting for having the isa bus speed be slower with a faster processor. The bios does not appear to have any settings for adjusting the CLK or ISA bus speed, so I guess I have to live with this. Full disclosure, this is a socket 5 motherboard that was never intended to support a p233, so I guess I should expect some glitches.

At least there is the Setmul work around to get things to work, and in any event, this issue seems to only effect a very small fraction of the software I'm running so not the biggest issue in the world.

Reply 5 of 7, by jakethompson1

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I've heard of games trying to autodetect the sound card, and using a delay that isn't independent of the processor speed (eb 00 for example), so as the CPU gets faster, they eventually stop waiting long enough for the card to answer, and miss that it's there.

Reply 6 of 7, by megatron-uk

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Speed sensitivity in DOS games when detecting sound cards is a very real, and very common issue.

As two common examples; almost all of the early Sierra adventure games will refuse to detect a Soundblaster if you have too fast a system (meaning fast 486+), and Indiana Jones and the Last Crusade is the same with its Adlib detection.

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Reply 7 of 7, by dukeofurl

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Oh yeah for sure, in this case though, it was like, there was no problem with these games on a fairly fast system such as a p166, but switching to the p233 introduced the problems.