This might help:

Doom 95 and Dark Forces sounds missing

The native PPC-Mac Version has Hires-Support und looks fantastic!

The joys of battling with a mixed Windows / DOS system 🤣

Some things you can try:

- Disable serial and parallel ports in the BIOS
- In the BIOS under PnP, try reserving IRQ5 or IRQ7 for an ISA card
- Disable / Enable PnP int the BIOS to see if that helps
- Format C: and just install MS-DOS 6.22 🤣

If that doesn't get you anywhere, create yourself a Start-up Floppy disk and load bare minimal drivers + sound drivers.

AaronAsh wrote:

Recently I have been trying to play Dark Forces using my Roland MT-32 for music

Man, Dark Forces was probably the game that consumed more hours than any other game combined prior to Half-Life.

I know this doesn't help with the IRQ issue, but I think Dark Forces might be looking for a Roland SC-55, and not a MT-32? Could be wrong on that.

I have a PnP sound card as well in my setup, and I try to have the card configured for the same IRQ (7) whether in Windows or in DOS. Unfortunately my knowledge of Yamaha is extremely limited so I am not sure why the Yamaha configuration utility is not able to set the IRQ you want, unless perhaps you have another PnP card that configured itself at IRQ 5 when booting into DOS.... maybe the Ethernet card? They usually get IRQ 9 or 11, but I've seen 5 as well.

I would make sure the BIOS setting for "Plug-and-Play OS" is set to "no" and perhaps try setting it to IRQ 7. Maybe disable the parallel port as Phil suggests, as that can/will use IRQ 7, and mark IRQ 5 and 7 as reserved for "Legacy ISA" in the BIOS PnP settings.

The Network-Card produces this issue. It uses IRQ5 in Dos right?

AaronAsh wrote:

One thing I've noticed about my setup which I've found strange is that my soundcard changes IRQ dependent on whether I am running in DOS or Windows mode; In Windows it sits at 5, which the standard for the card, whereas when I restart into DOS the Yamaha SETUPSA.EXE application that configures the card picks either IRQ 9 or 11 for it - and attempting to manually set the IRQ to the standard 5 (or 7 or 10) simply returns an error that it couldn't initialise the device.

Where are you checking the IRQ in WIndows? In theory, Windows 98 provides its own emulated Sound Blaster device to DOS programs.

Do you have a program that will check occupied IRQs in DOS? The first thing that comes to mind is msd.exe.

Disabling your onboard serial and parallel ports to free up IRQs is often worth a try.

Thanks for all the replies!

So it was the network card, or something else, taking up the 5 and 7 IRQ slots (my parallel ports etc... are already disabled) - I assigned them as reserved for legacy ISA in the bios and sure enough they are now free to use by the soundcard and the Yamaha SETUPSA application is able to assign them correctly etc... This means my sound configuration between Windows and DOS are now (mostly?) identical.

Unfortunately this has not resolved my problem with Dark Forces freezing whenever it tries to play music via the "Roland" setting with my MT-32. It can still play music via "General MIDI" just fine - in fact if the Roland is switched on when using general MIDI it will kick into its midi translation playback mode and handle rendering the music itself, complete with screen readout on the MT-32. It is also still happy to play music while in Windows when using the "Roland" option, but it is too unpleasantly distorted to be usable.

The above suggests to me that there is still some lingering difference between the way my soundcard is configured in DOS vs the way the emulated DOS soundblaster system under Windows is working, and if I can find the difference and port it into my DOS configuration I might fix the issue.

A specific question about the "SET BLASTER" environment variable - am I right in thinking this is only necessary under Windows? I presume it controls the emulated sound system mentioned above.

AaronAsh wrote:

A specific question about the "SET BLASTER" environment variable - am I right in thinking this is only necessary under Windows?

It is entirely necessary in DOS; it was around long before Windows. I would think a game with its own independent setup utility for configuring the IRQ and such forth would operate independently of the BLASTER environment variable – but practically every game installation/troubleshooting guide I've ever seen places significant emphasis on making sure it is correct.

I presume it controls the emulated sound system mentioned above.

The sound system ought to set the environment variable and not the other way around. I'm a little fuzzy on the details, but it's definitely a thing; see for instance https://msdn.microsoft.com/windows/hardware/d … udio-components .