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Forum nameThe Computer Forum
Topic subjectIRQ Question
Topic URLhttp://www.pcqanda.com/dc/dcboard.php?az=show_topic&forum=2&topic_id=206432
206432, IRQ Question
Posted by _Chewy_, Thu May-22-03 01:49 AM
I have a problem with Windows 2000 automatically assigning IRQs to some of my devices. In the screenshot provided, you'll see several devices all assigned to IRQ 9. I would like to change the assignment but Windows 2000 will not let me. I thus thought about going into the system BIOS menu and changing the settings. Dell 4100 system. It has been a long time since i've looked but as I recall there was an option in my BIOS where it said something like PnP OS? Yes/No.

If i set that option to No, then will I be able to manually re-assign them or not? Will it totally screw up my system? If IRQ 10 and 11 are supposed to be available, then why aren't they being used?????

I have been having a long-time modem issue with my setup and am just absolutely at my wits end trying to figure out what is wrong. Right now i suspect that is because it is on IRQ 9 (in the screenshot provided) and I know that internal modems are typically assigned to IRQ 3. Regardless, it's supposed to be IRQ 3 or 4 as dictated by the order of assignments on COM ports.

I have a winmodem (Dell provided) that connects ok upon boot up but if i get knocked off or disconnect, then it refused to re-connect. Always gives me some excuse about line being busy or password is not valid, etc. I have even tried new access numbers provided by my ISP (MSN). So I have to warm boot the system in order for the modem to connect again on the first try. My question is the paragraph in italics. And yes I have updated my drivers for the modem.

I would appreciate any suggestions.
206433, RE: IRQ Question
Posted by Shelly, Wed Mar-19-03 08:23 AM
This is normal in W2K and XP. It is a result of the ACPI specification. http://www.acpi.info/index.html

ACPI is, among other things, a solution for the limited number of IRQ addresses available in the original PC design. It works by switching a single IRQ among a number of devices as needed transparently. I would not try to outsmart ACPI, it is a valuable fix that allows PC's to meet modern computing needs. It can be turned off in the BIOS, if there is a problem with your system, but if it is working you should leave it alone.
206434, RE: IRQ Question
Posted by _Chewy_, Wed Mar-19-03 08:43 AM
Thank you Shelly. Quick question... this is as i have memorized them: IRQ 3 for COM 2 & 4; IRQ 4 for COM 1 & 3. If an internal modem is supposed to be on COM 3 or 4... then how is it possible for my modem to be assigned IRQ 9 and still connect? And do you think that perhaps my modem issue (as described in my original post) has in anyway related to this IRQ assingment?