DOCUMENT:Q125759  08-AUG-2001  [winnt]
TITLE   :Windows NT3.5 Improves Performance with Intel Neptune PCI Chip
PRODUCT :Microsoft Windows NT
PROD/VER:
OPER/SYS:
KEYWORDS:

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The information in this article applies to:

 - Microsoft Windows NT Workstation version 3.5 
 - Microsoft Windows NT Server version 3.5 
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SUMMARY
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Microsoft has developed new Windows NT version 3.5 Hardware Abstraction Layer
(HAL) Dynamic-Link Libraries (DLLs) that take advantage of Intel's new A1
stepping of their Neptune 82434 PCI Cache Memory Controller (PCMC) chip. These
new DLLs allow your PCI-based computer with A1 or greater stepping to achieve
full operating performance.

MORE INFORMATION
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The A0 stepping of the Neptune 82434 PCMC chip had two routines, Read-
Around-Write Enable and PCI-to-Memory Posting Enable, that did not function
according to specification. This led to data corruption in random access files
and occasionally in memory.


Because BIOS updates to correct this problem were generally unavailable at the
time of its release, Windows NT version 3.5 avoided potential data corruption by
disabling these routines. However, this workaround resulted in a slight
performance degradation.

Intel has since introduced A1 stepping for their Neptune 82434 chip which
resolves the data corruption problem. Consequently, Microsoft has modified
Windows NT HAL to only disable these routines on A0 chips. Chips with A1 and
greater steppings will function normally and achieve full operating
performance.

The new HAL is available in the latest U.S. Service Pack for Windows NT version
3.5. 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

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Keywords          :  
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNT350search kbWinNTW350 kbWinNTW350search kbWinNTSsearch kbWinNTS350 kbWinNTS350search

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Copyright Microsoft Corporation 2001.