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CMI8738 DOS drivers like to assign IRQ A

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Reply 20 of 42, by aVd

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Hi, @itzCrassio,
This problem with C-Media CMI8738 sound cards driver/initializer is well known. "IRQ=A" (in hexadecimal) is same as "IRQ=10" (in decimal) and this is not correct setting for SB emulation. In order to make working CMI8738 sound card SB emulation, first you need to be sure that the motherboard's chipset supports DDMA, and second - you have to set "legacy mode" with manually set IRQ in the BIOS for the PCI slot with the installed sound card. It seems like the "reserved" setting in your BIOS will be same as "legacy mode".

Good luck!

SvarDOS fan :: artificial "intelligence" bots - not a fan at all :: say NO to systemd :: is freeware a lie, when human freedom is a fundamental lie? :: f00ck €u!

Reply 21 of 42, by itzCrassio

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NeoG_ wrote on Yesterday, 10:18:
itzCrassio wrote on Yesterday, 09:59:
NeoG_ wrote on Yesterday, 09:12:

My 98 box doesn't have IRQ10 free but I just tested it on dosbox and it worked fine after manually editing the CFG file

How can I be sure that for this driver whether IRQ A means IRQ 10 or INTA#?

PCI INTA# is not something that sound blaster games can access, so it doesn't make sense for it to mean that. Also everything else is in hex.

Doom just does this

The attachment setup_000.png is no longer available

Reply 22 of 42, by itzCrassio

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aVd wrote on Yesterday, 10:37:

Hi, @itzCrassio,
This problem with C-Media CMI8738 sound cards driver/initializer is well known. "IRQ=A" (in hexadecimal) is same as "IRQ=10" (in decimal) and this is not correct setting for SB emulation. In order to make working CMI8738 sound card SB emulation, first you need to be sure that the motherboard's chipset supports DDMA, and second - you have to set "legacy mode" with manually set IRQ in the BIOS for the PCI slot with the installed sound card. It seems like the "reserved" setting in your BIOS will be same as "legacy mode".

Good luck!

Soltek SL-K8AV2-RL with VIA K8T800 chipset and VT8237 southbridge. I don't know for sure whether that chipset supports DDMA.

Reply 23 of 42, by NeoG_

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itzCrassio wrote on Yesterday, 11:12:

Doom just does this

I chose 7 in the setup and modified default.cfg in the game directory to 10 after closing the setup, then launch the game with doom.exe

Last edited by NeoG_ on 2026-07-04, 11:22. Edited 1 time in total.

98/DOS Rig: BabyAT AladdinV, K6-2+/550, V3 2000, 128MB PC100, 20GB HDD, 128GB SD2IDE, SB Live!, SB16-SCSI, PicoGUS, WP32 McCake, iNFRA CD, ZIP100
XP Rig: Lian Li PC-10 ATX, Gigabyte X38-DQ6, Core2Duo E6850, ATi HD5870, 2GB DDR2, 2TB HDD, X-Fi XtremeGamer

Reply 24 of 42, by Ydee

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aVd wrote on Yesterday, 10:37:

Hi, @itzCrassio,
This problem with C-Media CMI8738 sound cards driver/initializer is well known. "IRQ=A" (in hexadecimal) is same as "IRQ=10" (in decimal) and this is not correct setting for SB emulation.

Weird, I have same message at boot and IRQ is correct 5...

Reply 26 of 42, by itzCrassio

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Ydee wrote on Yesterday, 11:22:
aVd wrote on Yesterday, 10:37:

Hi, @itzCrassio,
This problem with C-Media CMI8738 sound cards driver/initializer is well known. "IRQ=A" (in hexadecimal) is same as "IRQ=10" (in decimal) and this is not correct setting for SB emulation.

Weird, I have same message at boot and IRQ is correct 5...

Just checked, I have PCI audio V1.98, should I try V1.97 instead, or would that not make a difference? Does V1.98 even have any known issues?

Reply 27 of 42, by NeoG_

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itzCrassio wrote on Yesterday, 11:27:
NeoG_ wrote on Yesterday, 11:19:
itzCrassio wrote on Yesterday, 11:12:

Doom just does this

I chose 7 in the setup and modified default.cfg in the game directory to 10 after closing the setup, then launch the game with doom.exe

And it actually played SFX by setting it in the default.cfg?

Yes but after further testing, it seems that the sound works with any IRQ, even the wrong one selected. As long as the address and DMA are correct sound seems to work. Someone just reported the same behaviour in the PicoGUS thread so it seems not to be limited to happening in Dosbox, maybe on launch the game is reading the BLASTER variable and the setup.exe values are only used as a backup. Not really sure what that means but maybe the IRQ for you isn't working at all as per aVd post and the card should have the same PCI and SB IRQ if DDMA is active.

98/DOS Rig: BabyAT AladdinV, K6-2+/550, V3 2000, 128MB PC100, 20GB HDD, 128GB SD2IDE, SB Live!, SB16-SCSI, PicoGUS, WP32 McCake, iNFRA CD, ZIP100
XP Rig: Lian Li PC-10 ATX, Gigabyte X38-DQ6, Core2Duo E6850, ATi HD5870, 2GB DDR2, 2TB HDD, X-Fi XtremeGamer

Reply 28 of 42, by itzCrassio

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NeoG_ wrote on Yesterday, 11:40:
itzCrassio wrote on Yesterday, 11:27:
NeoG_ wrote on Yesterday, 11:19:

I chose 7 in the setup and modified default.cfg in the game directory to 10 after closing the setup, then launch the game with doom.exe

And it actually played SFX by setting it in the default.cfg?

Yes but after further testing, it seems that the sound works with any IRQ, even the wrong one selected. As long as the address and DMA are correct sound seems to work. Someone just reported the same behaviour in the PicoGUS thread so it seems not to be limited to happening in Dosbox, maybe on launch the game is reading the BLASTER variable and the setup.exe values are only used as a backup. Not really sure what that means but maybe the IRQ for you isn't working at all as per aVd post and the card should have the same PCI and SB IRQ if DDMA is active.

Just tried it out in DOSBox, it somehow actually works, the setup actually limits you to IRQ 9.

Reply 29 of 42, by Ydee

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itzCrassio wrote on Yesterday, 11:31:
Ydee wrote on Yesterday, 11:22:
aVd wrote on Yesterday, 10:37:

Hi, @itzCrassio,
This problem with C-Media CMI8738 sound cards driver/initializer is well known. "IRQ=A" (in hexadecimal) is same as "IRQ=10" (in decimal) and this is not correct setting for SB emulation.

Weird, I have same message at boot and IRQ is correct 5...

Just checked, I have PCI audio V1.98, should I try V1.97 instead, or would that not make a difference? Does V1.98 even have any known issues?

I dont think, it is only initializer. Have you set all in Autoexec.bat?:

C:\PCIAUD\SETAUDIO
SET BLASTER=A220 I5 D1 H5 T4
C:\PCIAUD\C3DMIX /M77000 /F77000 /W77000 /L44144 /EFF1FF /A00100 /C00170 /P10000 /410200 /R1f0ff /D040ff

I have COM and LPT ports disabled in BIOS, so I have more free resources and even I can reserve IRQ for every single PCI slot, so it is simple here..

Reply 30 of 42, by aVd

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itzCrassio wrote on Yesterday, 11:14:

Soltek SL-K8AV2-RL with VIA K8T800 chipset and VT8237 southbridge. I don't know for sure whether that chipset supports DDMA.

Here is one thread in which VT8237 and DDMA support is mentioned: Socket 754/939 and Win9x/DOS

Seems like it is still unclear if this southbridge chip supports DDMA. Rather no.

EDIT: Ok, I found the right thread. According to the first post:

kodi wrote on 2019-11-17, 15:29:

* Note: VT8231/VT8233/VT8235/VT8237 and VT8251 DO NOT have DDMA support, no matter of rumors spreading, everyone claiming the contrary is welcomed to share independently reproducible technical proof.

Unfortunately, you have no luck with SB emulation support for CMI8738 sound card on your motherboard.

SvarDOS fan :: artificial "intelligence" bots - not a fan at all :: say NO to systemd :: is freeware a lie, when human freedom is a fundamental lie? :: f00ck €u!

Reply 31 of 42, by itzCrassio

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Ydee wrote on Yesterday, 13:21:
I dont think, it is only initializer. Have you set all in Autoexec.bat?: […]
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itzCrassio wrote on Yesterday, 11:31:
Ydee wrote on Yesterday, 11:22:

Weird, I have same message at boot and IRQ is correct 5...

Just checked, I have PCI audio V1.98, should I try V1.97 instead, or would that not make a difference? Does V1.98 even have any known issues?

I dont think, it is only initializer. Have you set all in Autoexec.bat?:

C:\PCIAUD\SETAUDIO
SET BLASTER=A220 I5 D1 H5 T4
C:\PCIAUD\C3DMIX /M77000 /F77000 /W77000 /L44144 /EFF1FF /A00100 /C00170 /P10000 /410200 /R1f0ff /D040ff

I have COM and LPT ports disabled in BIOS, so I have more free resources and even I can reserve IRQ for every single PCI slot, so it is simple here..

this is my full autoexec (don't mind the line seperation, that was just to get the entire command in frame)

The attachment 20260704_154634.jpg is no longer available

Reply 32 of 42, by itzCrassio

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this is also what doom does when setaudio actually assigns irq 5 to sb instead of running the autoexec which supposedly assigns irq a

worth mentioning that for some reason, dosplay (the sound card's own player) works without initializing the driver, however loading it causes it to freeze up with the hdd activity light on as soon as i play music

Last edited by itzCrassio on 2026-07-04, 13:53. Edited 1 time in total.

Reply 33 of 42, by NeoG_

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Seems like aVd has found the smoking gun so to speak, this motherboard will not work correctly with any PCI sound card which relies on DDMA to function (like the CMI8738)

98/DOS Rig: BabyAT AladdinV, K6-2+/550, V3 2000, 128MB PC100, 20GB HDD, 128GB SD2IDE, SB Live!, SB16-SCSI, PicoGUS, WP32 McCake, iNFRA CD, ZIP100
XP Rig: Lian Li PC-10 ATX, Gigabyte X38-DQ6, Core2Duo E6850, ATi HD5870, 2GB DDR2, 2TB HDD, X-Fi XtremeGamer

Reply 34 of 42, by itzCrassio

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NeoG_ wrote on Yesterday, 13:52:

Seems like aVd has found the smoking gun so to speak, this motherboard will not work correctly with any PCI sound card which relies on DDMA to function (like the CMI8738)

damn, i thought i could get some type of sfx inside doom. the only other computer i have has pci hardlocked to irq 11 and the only way to fix it is soldering a 0 ohm resistor, so that pc also doesn't work for doom sfx

Reply 35 of 42, by itzCrassio

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I installed Windows 3.1 on this PC once, and the sound effects played normally. How come that worked?

Reply 36 of 42, by Ydee

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NeoG_ wrote on Yesterday, 13:52:

Seems like aVd has found the smoking gun so to speak, this motherboard will not work correctly with any PCI sound card which relies on DDMA to function (like the CMI8738)

Give me one day and I can try it on VT8237A, which I have laying here - I had PCI ALS300 in it and the sound and music in DOS worked smoothly on it , so I will test even CMI 8738 and we will see, how is it.

Reply 37 of 42, by itzCrassio

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Ydee wrote on Yesterday, 14:54:
NeoG_ wrote on Yesterday, 13:52:

Seems like aVd has found the smoking gun so to speak, this motherboard will not work correctly with any PCI sound card which relies on DDMA to function (like the CMI8738)

Give me one day and I can try it on VT8237A, which I have laying here - I had PCI ALS300 in it and the sound and music in DOS worked smoothly on it , so I will test even CMI 8738 and we will see, how is it.

Thank you. Also what is the difference between VT8237 and V8237A?

Reply 38 of 42, by Ydee

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itzCrassio wrote on Yesterday, 15:07:
Ydee wrote on Yesterday, 14:54:
NeoG_ wrote on Yesterday, 13:52:

Seems like aVd has found the smoking gun so to speak, this motherboard will not work correctly with any PCI sound card which relies on DDMA to function (like the CMI8738)

Give me one day and I can try it on VT8237A, which I have laying here - I had PCI ALS300 in it and the sound and music in DOS worked smoothly on it , so I will test even CMI 8738 and we will see, how is it.

Thank you. Also what is the difference between VT8237 and V8237A?

VT8237A is a bit improved, for example has better sound (HDA instead AC´97) or compatibility with SATA HDDs.