From: Max : Subject: [PCBUILD] Two devices take on one interrupt -- the
sequel; first round failed


> Hello Yui and others, thanks for responding to my post;
> the problem is not yet solved hence the follow-up.
>
> A few days ago, I wrote:
>
> YS> ----- Original Message -----
> >>   I've got a problem. On friend's PC, his Sound Blaster Live! and
> >>   Rockwell PCI WinModem both take IRQ 12 and I can't change it (the
> >>   Settings window shows Can't change this resource).
>
> And was replied with:
> YS> Hi, I just had a similar issue this morning involving a
> YS> STB display adapter and a 3Com NIC. They were
> YS> both sharing IRQ 11 and did not allow maual configuring
> YS> of the settings in Device Manager. These cards also lacked
> YS> jumpers for on-board settings.
>
> YS> My fix was as follows:
> YS>      1.) I disabled(not removed) the STB in device manager,
> YS>           ( by disabling your device you can still save the settings.)
> YS>      2.) I removed the 3Com from device manager to be
> YS>           redetected.
> YS>      3.) After rebooting, I enabled plug & play in BIOS
> YS>           and reserved IRQ11 to get Windows to place
> YS>           the 3Com elsewhere.
> YS>      4.)Plug and Play placed the 3Com on IRQ10
> YS>      5.)I re-enabled the STB on its current settings
> YS>          which was IRQ11
> YS>      6.)One more reboot completed it.
>
> That did not work. Here are more details:
>
> * Modem is a DynaMode, Rockwell-based 56k WinModem, sitting in PCI slot 3
> * Sound is a Creative Live! Value sitting in PCI slot 5
> * all of this is on some not-widely-known 440bx-based mobo, with
>       * Pentium-II 450 and
>       * 64M of RAM;
> * the video is VooDoo 3000 AGP, if that's of any help.
>
> When we tried to do the steps you described, [disable the sb, kill the
> modem, close IRQ12, reinstall the modem] it jumped on IRQ5. No dice :
> irq5 is a standard SoundBlaster 16 setting. Didn't try to change it to
> 7, but I'd like to see a better solution : I really don't want to
> fiddle with a few dozen of his old games tweaking the sound settings
> [although it might eventually boil down to that].
>
> The next step: blocked IRQ5 as well. All is great : modem IRQ 10, SB
> IRQ 12. On next reboot, both are on IRQ 10. Of course, no DOS sound.
>
> Try 3: Removed the "Isa Legacy" blocks, tried again - both back on 12.
>
> Try 4: Disabled USB interrupt in BIOS [he doesn't have any USB
> devices] - both jumped to 9...
>
> Why can't I manually assign IRQ's?!?     :-(
>
> att. Mary Wolden : the SB Legacy driver settings are OK : port 220/
> dma low 1/irq 5/dma high 5, midi 330 and adlib on 388.
>
> The next steps I can try:
> 1) to change the card to different slot...  and I don't want
>    the friend to get into the PC if possible...
> 2) Try and squeeze the SB16 emulation to non-standard settings, for
>    example to IRQ7 [if free]. Many games won't take anything other
>    than 5 or 7.
>
> If you have are any other ideas, please share them -
>
> +=-.
> | Max Timchenko [MaxVT]

In Windows 95 I remember being able to change IRQ's in Device Manager.  The
PCI  bus is part of the Plug and Play standard.  The PCI chipset circuitry
handles the identification of cards and works with the operating system and
BIOS to automatically set resources for compatible peripheral cards. Windows
98 is supposed to be a Plug and Play system so we do not have the same
control over selecting IRQ's, and have to use the BIOS or just plain moving
cards around to try and resolve conflicts.  The Original Bios for the Abit
BH6 did not allow you to set the IRQ's for the PCI slots it only let you
select whether an IRQ should be reserved for an ISA legacy device or not.
This was changed with a Bios upgrade which then allowed setting the IRQ for
PCI slots.

Since both of the cards keep selecting the same IRQ it appears that on this
motherboard that PCI slot 3 and PCI slot 5 are sharing an IRQ.  Your only
solution may be moving one of the cards to a different slot so you can
select separate IRQ's.  If the manual doesn't have information on which PCI
slots are sharing IRQ's it will be trial and error to find slots that won't
force the cards to use the same IRQ.

Mary Wolden

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