Microsoft KB Archive/179897

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Memory Management Problems on Computers with Pentium Processors

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Q179897

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The information in this article applies to:


 * Microsoft Windows 95 OEM Service Release, versions 2, 2.1

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SYMPTOMS
When you run multiple programs (especially MS-DOS-based programs) on a Windows-based computer that has insufficient system memory (RAM) and contains an Intel Pentium Pro or Pentium II processor, information in memory may become unavailable or damaged, leading to unpredictable results. For example, copy and compare operations may not work consistently.

CAUSE
This behavior is an indirect result of certain performance optimizations in the Intel Pentium Pro and Pentium II processors. These optimizations affect how the Windows 95 Virtual Machine Manager (VMM) performs certain memory operations, such as determining which sections of memory are not in use and can be safely freed. As a result, the Virtual Machine Manager may free the wrong pages in memory, leading to the symptoms described earlier.

RESOLUTION
This issue is resolved by the following updated file for Windows 95 OEM Service Release 2 (OSR2):

  VMM.VXD version 4.00.1113, dated 9/24/97 11:13am  408,096 bytes

This issue is resolved by the following updated file for Windows 95 OEM Service Release 2.1:

  VMM.VXD version 4.03.1216, dated 9/23/97 12:16pm, 427,552 bytes

STATUS
Microsoft has confirmed this to be a problem in Microsoft Windows 95. An update to address this problem is now available, but is not fully regression tested and should be applied only to computers experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft does not recommend implementing this update at this time. Contact Microsoft Technical Support for additional information about the availability of this update.

This issue is resolved in Microsoft Windows 98.

MORE INFORMATION
For additional information about issues resolved by updates to this component, please see the following article in the Microsoft Knowledge Base:

"Q171284 Problems Enumerating CardBus Devices with No Free IRQs"

Additional query words:

Keywords : kbhw osr2 diskmem win95

Issue type : kbprb

Technology : kbWin95search kbOPKSearch kbWin95OPKOSR2 kbWin95OPKOSR210