Microsoft KB Archive/164391

= WinNT 4.0 SP2 Atapi Claims IRQ for Unused IDE Channel =

Article ID: 164391

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q164391





SYMPTOMS
After you install Windows NT 4.0 Service Pack 2, you find that you no longer have available a previously unused IRQ normally reserved for the secondary IDE controller, which is usually IRQ 15.

Another side effect may include IRQ conflicts between Atapi and another previously working adapter that was using the same IRQ prior to loading Service Pack 2.

Use Event Viewer and Microsoft Diagnostics to verify which devices are conflicting and which IRQ each adapter is claiming.



CAUSE
The device driver Atapi.sys erroneously claims the IRQ for the empty IDE secondary controller.



STATUS
Microsoft has confirmed this to be a problem in Windows NT version 4.0. This problem was corrected in the latest Microsoft Windows NT 4.0 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

Additional query words: prodnt sp2

Keywords: kbbug kbsetup KB164391

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