Re: How XP assigns IRQ?

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From: Michael Solomon \(MS-MVP\) (user_at_#notme.com)
Date: 10/13/04 

Date: Wed, 13 Oct 2004 14:45:52 -0700

Why the assignments I cannot tell you and that would probably be a better
question for the windowsxp.configuration_manage or windowsxp.hardware
newsgroups. You really can't assign IRQs within XP unless you turn off ACPI
and I can almost guarantee the system will run like crap and become rather
prone to crashing.

The only way to get IRQs reassigned by the system is to shut down, pull the
cards from their slots and move the cards to different slots. The will
force the system to reassign IRQs but you don't have a lot of control so you
likely would want to pull card that currently has the IRQ you need for a
different device and try and get that IRQ assigned to that device then
reinstall the card, probably in a different slot. 

-- 
Michael Solomon MS-MVP
Windows Shell/User
Backup is a PC User's Best Friend
DTS-L.Org: http://www.dts-l.org/
"Raj" <Raj@discussions.microsoft.com> wrote in message 
news:910F00F4-A93B-49F9-9FBE-B18F4F722DFA@microsoft.com...
> Hello,
>
> I would like to know how XP assigns IRQ for each devices that are on the
> ACPI enabled system.
>
> Let me explain my problem,  I have a system where IRQ 7 & 11 are
> free/available.  When I plug 2 16-bit PCMCIA cards in its slots, OS finds 
> it
> and assigns 11 for one card and either irq 3 or 4 for another card that
> conflicts with COM ports. why OS assigns irq 3/4 even though IRQ 7 is
> available.
>
> I could get rid of this conflicts if I do the following steps,
> 1. Assign IRQ 7 for COM port and boot the system.  Insert one PCMCIA card.
> 2. Assign IRQ 4 back to COM port and boot the system.  Insert the second 
> card.
>
> Now XP assigns IRQ 7 for the second one and no conflicts.  Why its so?  Is
> it a BIOS issue or OS issue? Any soln?
>
> I tried with different types of 16-bit PCMCIA card from different vendors.
> Still the same problem.  When I tried to reinstall the OS with two PCMCIA
> card inserted, I get blue screen.
>
> Thanks in advance.

Relevant Pages

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