How to Disable IRQ Sharing for 16-Bit PC Cards That Do Not Support ISA-to-PCI Routed Interrupts (279256)


The information in this article applies to:

  • Microsoft Windows XP Home Edition
  • Microsoft Windows XP Professional
This article was previously published under Q279256
Important This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

The R2 PC Card does not start, and you see the following error message in Device Manager:
This device is either not present, not working properly, or does not have all the drivers installed. (Code 10)
Try upgrading the device drivers for this device.

CAUSE

This behavior occurs because some R2 PC Cards do not support interrupt request (IRQ) resource sharing. In Windows XP, 16-bit PC Card (PCMCIA) PCI readers can use R2 PC Cards (the 16-bit ISA type) without requiring an ISA runner paddle to obtain ISA interrupts.

RESOLUTION

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To resolve this behavior, disable the ISA-to-PCI routing feature to allow these PC Cards to function in laptop computers:
  1. Start Registry Editor (Regedit.exe).
  2. Locate and click to select the following key in the registry:

    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\PCMCIA\Parameters

  3. On the Edit menu, click New, click DWORD Value, type DisableIsaToPciRouting in the NewValue box, and then press ENTER.
  4. Click to select DisableIsaToPciRouting, click Edit, and then click Modify.
  5. In the Value data box, type 1, and then click OK.
  6. Quit Registry Editor.
This procedure disables PCI routing for 16-bit PC Cards. With this feature, you can successfully install 16-bit PC Cards on computers that are low on ISA interrupts by using a shared-PCI interrupt.

Note: If you disable this feature, the device could potentially display an error code 12 (not enough free resources) in Device Manager if there is not a suitable free interrupt for the card to use. You may have to disable an unused device or port to make an IRQ available for the card.
Modification Type:MinorLast Reviewed:1/6/2005
Keywords:kbprb KB279256
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