DOCUMENT:Q164391  10-AUG-2001  [winnt]
TITLE   :WinNT 4.0 SP2 Atapi Claims IRQ for Unused IDE Channel
PRODUCT :Microsoft Windows NT
PROD/VER:4.0
OPER/SYS:
KEYWORDS:kbsetupkbbuglist kbfixlist

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The information in this article applies to:

 - Microsoft Windows NT Workstation version 4.0 
 - Microsoft Windows NT Server version 4.0 
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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

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Keywords          : kbsetup kbbuglist kbfixlist
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400
Version           : 4.0
Issue type        : kbbug

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