An IRQ Holder for PCI Steering may be displayed when you view the System Devices branch of Device Manager. An IRQ Holder for PCI Steering indicates that an IRQ has been programmed to PCI mode and is unavailable for ISA devices, even if no PCI devices are currently using the IRQ. To view IRQs that are programmed for PCI-mode, follow these steps:

Click Start, point to Settings, click Control Panel, and then double-click System.

Click the Device Manager tab.

Double-click the System Devices branch.

Double-click the IRQ Holder for PCI Steering you want to view, and then click the Resources tab.

HOW TO DETERMINE IF YOUR COMPUTER IS USING IRQ STEERING
To determine if your computer is using IRQ Steering, follow these steps:


Click Start, point to Settings, click Control Panel, and then double-click System.

Click the Device Manager tab.

Double-click the System Devices branch.

Double-click PCI Bus, and then click the IRQ Steering tab. You should see one of the following settings:


- IRQ Steering Enabled



- IRQ Steering Disabled


NOTE: PCI bus IRQ steering is disabled by default in OSR2. If you are using OSR2, and IRQ steering is disabled, verify that the Use IRQ Steering check box is selected on the IRQ Steering tab.
IRQ Steering may be displayed as disabled in Device Manager for any of the following reasons:

The IRQ routing table that must be provided by the BIOS to the operating system may be missing or contain errors. The IRQ routing table provides information on how the motherboard is configured for PCI IRQ's.
The Use IRQ Steering check box is not selected.
The "Get IRQ table from Protected Mode PCIBIOS 2.1 call" check box is not selected.
Your computers BIOS may not support PCI bus IRQ steering. For more information, contact the manufacturer of your BIOS.




Author: Eric C. Vogel
Source: Microsoft TechNet
Posted: 3/8/99
Updated: 11/22/2000


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