Modifying a Sound Blaster to use only the OPL hardware? \ VOGONS

Modifying a Sound Blaster to use only the OPL hardware?

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First post, by Kahenraz

Posted on 2022-06-14, 18:00

Kahenraz Offline

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Is it possible to modify a Sound Blaster so that the OPL chip will still function on port 0x388, but all connections for IRQ and DMA are severed? I'm interested in using a card exclusively as an OPL3 device and pair it with a PCI card that does not have Yamaha FM. I want to make certain that there won't be any conflicts with other hardware devices, as this motherboard does not support DMA anyways.

Reply 1 of 8, by maxtherabbit

Posted on 2022-06-14, 18:09

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If you use a jumperless SB without initializing it with DIAGNOSE /S it will not respond on any IRQ or DMA channels

Reply 2 of 8, by Kahenraz

Posted on 2022-06-14, 18:20

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Does it need to be jumperless or just supporting PnP?

Reply 3 of 8, by maxtherabbit

Posted on 2022-06-14, 19:48

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I have never owned a PnP soundblaster so I don't know. It definitely works with the jumperless cards though I have a system set up that way using the SB16 as an "adlib"

Reply 4 of 8, by Kahenraz

Posted on 2022-06-14, 20:01

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I wasn't able to get this to work with DIAGNOSE.EXE, but I think it's working as disabled if I use Unisound with IRQ 0 and DMA 4.

What does DIAGNOSE need to disable digital sound? I am testing with a jumperless CT2950.

Reply 5 of 8, by Gmlb256

Posted on 2022-06-14, 20:46

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maxtherabbit's statement about DIAGNOSE would only work with Sound Blaster cards that still uses jumpers to configure the SB and MPU-401 addresses, but the IRQ and DMA are configured in software.

Reply 6 of 8, by maxtherabbit

Posted on 2022-06-14, 20:48

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Kahenraz wrote on 2022-06-14, 20:01:

I wasn't able to get this to work with DIAGNOSE.EXE, but I think it's working as disabled if I use Unisound with IRQ 0 and DMA 4.

What does DIAGNOSE need to disable digital sound? I am testing with a jumperless CT2950.

It needs to not be run at all. The card doesn't use and IRQ or DMA resources until it's initialized. Simply don't initialize it. Adlib will still work

Reply 7 of 8, by Gmlb256

Posted on 2022-06-14, 20:57

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maxtherabbit wrote on 2022-06-14, 20:48:

Kahenraz wrote on 2022-06-14, 20:01:

I wasn't able to get this to work with DIAGNOSE.EXE, but I think it's working as disabled if I use Unisound with IRQ 0 and DMA 4.

What does DIAGNOSE need to disable digital sound? I am testing with a jumperless CT2950.

It needs to not be run at all. The card doesn't use and IRQ or DMA resources until it's initialized. Simply don't initialize it. Adlib will still work

If the motherboard BIOS is PnP capable, it could set the ISA PnP sound card resources during POST.

Reply 8 of 8, by Kahenraz

Posted on 2022-06-14, 21:04

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Gmlb256 is right. I tried a jumperless PnP card and the resources were set every time the system booted, even if I disabled them explicitly with Unisound.

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