Stupid IRQ's

[Helevitia]

I can't enable my serial port without it screwing up my ATA100 BIOS. It tells me it can't find the BIOS and therefore I can't boot. So i disable the serial port and it works great. I'm assuming it's an IRQ problem since I tried to manually assign IRQ's to different PCI slots and I have the same problem. Anyone have any ideas? Thanks and much appreciated.

Dave

[The PIT]

Just go into the bios and try different irq settings and memory settings for the com ports. It sounds more like memory being mapped to the wrong place to me though.
Also make sure the pnp bios is set to yes and then reset resource configuration if you have that option.
It may also be worth seeing if theres bios upgrades for both the controler card and the motherboard bios.

[Jon P. Inghram]

If you've got a recent motherboard and WinXP, you might be able to turn APIC mode on in the BIOS. That'll give you 24 IRQ's instead of 16.

[RichL]

I've experienced the joys of shuffling PCI cards to get the right IRQs many a time. Win2k/XP seems pretty okay with having multiple cards on the same IRQ, 95/98 doesnt.
About all I've ever found you can do is shuffle the cards in the slots or alter the BIOS allocation (but it frequently isnt clear what slot it relates to in BIOS and slots seem to share an IRQ between 2 or 3.)
Or you could get a motherboard with Compaq BIOS, as my old Prolinia P51xx and Deskpro 2000 systems seems to setup IRQs automatically far better than anything else I've owned.

[The PIT]

If you move cards around you should still reset the resource configuration data in the bios.
Other things you can do is also load up the bios defaults as this can also sort out the problem.

[Helevitia]

Thanks for the help guys. Wha I did was tell the BIOS that IRQ 3 & 4 were reserved for ISA devices(even though I don't have any ISA slots) and that worked! I can probably un-reserve IRQ 3 since all I need is IRQ 4 for one serial. Thanks again.

Dave

[Helevitia]

Originally posted by Jon P. Inghram
If you've got a recent motherboard and WinXP, you might be able to turn APIC mode on in the BIOS. That'll give you 24 IRQ's instead of 16.

I'm not familiar with this. Sounds interesting. How does it give you 24 IRQs?

Dave

[Rags]

Originally posted by Helevitia


I'm not familiar with this. Sounds interesting. How does it give you 24 IRQs?

Dave

http://www.microsoft.com/hwdev/platform/proc/IO-APIC.asp

HTH

Rags

[Jon P. Inghram]

I found out about this over at www.asusboards.com when I was checking up on the new motherboard I bought (TUSL2-C). I was getting wierd scratchy sound on with my SBLive! in Everquest in certain situations, and figured the problem was due to IRQ sharing that was virtually unavoidable due to the two onboard USB controllers and SMBus eating up three IRQ's. Since I run Win98 I ended up having to rearrange my NIC and soundcard and force the NIC to IRQ 12, but it still didn't fix the problem. Turns out it was actually caused by the memory system getting saturated by AGP 4x texturing out of system RAM. Just switched to 2x and everything was fine. I wanna Parhelia, this G400 MAX is beginning to get rather tired.

[Kosh Naranek]

Originally posted by The PIT
Also make sure the pnp bios is set to yes

Microsoft recommends that you set this to no / disabled.

http://support.microsoft.com/default.aspx?scid=kb;en-us;Q314068

(Valid for W2K as well)


Does anyone know why Microsoft recommends that ?

Some BIOS sites like http://www.rojakpot.com/ and like http://www.lostcircuits.com/advice/bios2/1.shtml
both recommend to enable it.

a quote from lostcircuts :

Most of us have some experience with IRQ conflicts, which, in fully loaded systems, can become a constant source of grief and the desire for more IRQs can be found on basically all bulletin boards throughout the web. One alternative solution is to implement a hardware IRQ distributor or IRQ expansion chip / arbiter. ASUS is doing exactly this with their proprietary ASIC found on most of their boards. Keep in mind though, that, in order to enable this function, it is necessary to enable PnP OS Installed in the BIOS which effectively eliminates the IRQ sharing from the main level of the chipset and assigns it to the ASIC chip.

[The PIT]

Originally posted by Kosh Naranek

Mmm you post didn't get quoted.
If you're using acpi Microshaft say set to no. I did see a reason somewhere but I've never notice it make much differance.