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Tyan S1854 - Problem controlling IRQ assignment

D

Dethoff

Member
I have a Micron Millennia PIII 667, Win 98 SE, with an OEM Tyan 1854 MB with onboard audio. Other items include, GeForce classic AGP video card, bus mouse, PCI modem, PCI network card, and Studio DV PCI firewire card.


I have recently tried to install a Studio PCTV PCI card which the manufacturer says should not share an IRQ. I went ahead and disabled my two unused com ports and parallel port in my BIOS as well as disabling legacy soundblaster support, all in the hopes that by freeing up more interrupts, I could grab one soley for the Studio PCTV card.

I found the following advice posted concerniong how this MB assigns IRQs:

> The following PCI slots use these IRQ's on S1854 Via board.
> AGP slot, PCI slot 2 and 6 share same IRQ
> PCI slots 1 and 3 share same IRQ
> PCI slot 4 does not share IRQ with others
> PCI slot 5 and USB share same IRQ
> PCI slot 1 is the nearest to the AGP slot.
> I strogly advise to put system critical cards (ie, network cards,
> etc) in slot 4


Experience has shown that the above scheme is not always true on my board. --e.g. when a board is put in slot 4, the onboard audio shares the same IRQ, yet when nothing is in slot 4, the audio is successfully shared elsewhere. Furthermore, despite some people's advice, I have never had any problems when the network card or video card shares its IRQ.

I have spent over an hour experimenting with rearranging the order of my boards without the desired result.

I have tried switching off PNP OS in BIOS as well as turning off AUTO assignment, with no change in effect.

No matter what I've tried, IRQ 9 ,which appears not to be used, is never assigned. Isn't IRQ 9 a valid assignable resource?

Is there any rhyme or reason to getting the desired result or is this puerly hit and miss?

I am still running the origonal Micron BIOS ver. 1.07. Would upgrading help? I kind of hate to flash since everything else has always worked perfectly! If I were to reflash, I assume I'd be safer sticking with the Micron BIOS rather than one from the Tyan site.

Thanks,
Please remove the "spamnot" before my e-mail address.
 
Forgive me but I not quite sure if you are having an IRQ conflict(WIN Exclamation in device manager,crashes,etc.)or just looking for a "combo" that has your tv card on it's own irq? Also have you ever had the tv card installed and working in a shared irq?
 
I am not having a true conflict in the sense of an exclamation mark, but am just looking for a way to control the assignments so the PCTV card has its very own (non shared) IRQ.
 
Best you can do is see to it that there are four system IRQs available to the PCI bus. Only then can the chipset route each of the four PCI INTs to separate system IRQs. Otherwise you'd get more sharing than what's implied by the limit of four INT lines.

And for the 2394598457104537715305th time: PCI devices sharing interrupts is not a problem. PCI was specifically designed to allow that.

Regards, Peter
 
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