IRQs and Windows XP : help?

[gary kleiger]

Hi:

I've just installed the digi 001 on my windows XP - based system. As instructed by users on the DUC, I placed the PCI card in slot 3 and set the IRQ to 9 in the BIOS. However, when I boot the machine to Windows and check the IRQ settings, it says that the digi 001 is assigned to IRQ 17. First, why is it not assigned to 9, as I instructed in the BIOS? Second, I thought there are only 16 IRQ settings total, why does my computer show up to 21?

Thanks, Gary

[QuikDraw]

Windows XP ignores BIOS IRQ assignments unless Windows was installed in "Standard PC" mode. The standard installation is "APIC mode" by default, and usually APIC is the best way to run it. Windows XP is very good at handling IRQs in APIC mode. The fact that your 001 is not showing up on the IRQ that you assigned in BIOS is probably not a bad thing.

If your computer is running fine, and PTLE is showing acceptable performance, I wouldn't worry at all about the IRQ that Windows chose to put the 001 on. It is usually best for the 001 to be alone on its own IRQ, but sometimes that doesn't even matter. Without setting up Windows in standard PC mode the only way to reassign IRQs is to swap cards in PCI slots. Like I said, if your system is working acceptably there is no reason to do that.

I actually had to play around a bit on my older P4 system to get things to work properly. Originally, my 001 was sharing with my Firewire card and everything worked except I would get errors reading/writing to the Firewire drive. Then I switched things around and the 001 was sharing with my USB2 card. Again everything seemed to work except that I got drive errors on my USB2 drive. I finally found a slot arrangement that put the 001 on its own IRQ (21 I think) and now it all works perfectly.

It can be a lengthy and confusing process to find the slot arrangement that ends up working the best, but usually it can be done. It's usually NOT recommended to install WinXP in Standard PC mode, but if you can't get it working correctly in APIC mode that may be the only solution. Usually though, WinXP will work just fine any old way you happen to throw it together.

Mike

[gary kleiger]

Thanks Mike, and also thanks for your building a PC page. Super helpful man.

Gary