Microsoft KB Archive/137870

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New Emm386.exe Fixes Problem Receiving NMI in Protected Mode

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Q137870

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The information in this article applies to:


 * Microsoft Windows 95

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SYMPTOMS
A real-mode nonmaskable interrupt (NMI) handler does not receive an NMI if it is generated in protected mode. The real-mode NMI handler does receive the NMI if it is generated in real mode.

CAUSE
This problem occurs when Emm386.exe is loaded in protected mode, because the virtual machine (VM) flag does not get set during the process of creating the stack frame to go from protected mode to real mode.

RESOLUTION
This issue is resolved by the following updated file(s) for Windows 95, and later versions of these file(s):

  EMM386.EXE  version 4.00.950  dated 9/20/95  125,495 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 Windows 95 updates, please see the following article in the Microsoft Knowledge Base:

"Q161020 Implementing Windows 95 Updates" Keywords : win95

Issue type : kbprb

Technology : kbWin95search kbWin95