Q74851: Different Default Modes for EMM386.EXE and EMM386.SYS

Article: Q74851
Product(s): Microsoft Disk Operating System
Version(s): MS-DOS:5.0,5.0a,6.0,6.2,6.21,6.22; WINDOWS:3.0,3.0a
Operating System(s): 
Keyword(s): 
Last Modified: 03-DEC-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft MS-DOS operating system versions 5.0, 5.0a, 6.0, 6.2, 6.21, 6.22 
- Microsoft Windows versions 3.0, 3.0a 
-------------------------------------------------------------------------------

SUMMARY
=======

Microsoft Windows version 3.0's EMM386.SYS always defaults to OFF mode, whereas
MS-DOS version 5.0, 6.0, or 6.2's EMM386.EXE defaults to ON mode. If you want to
compare the behavior of these two versions, either specify ON in the EMM386.SYS
command line or specify OFF in the EMM386.EXE command line. The command line
arguments ON and OFF activate and suspend the operation of the EMM386.EXE device
driver.

MORE INFORMATION
================

Certain non-VCPI aware applications may fail when attempting to enter protected
mode with EMM386 enabled. These programs cannot sense that EMM386 has already
placed the CPU in protected mode and, thus, cause an "EMM386 Privileged
operation error" when they attempt to switch into protected mode.

Applications that function properly with EMM386.SYS but encounter problems with
EMM386.EXE may function properly if EMM386.EXE is loaded with the mode specified
as OFF.

Additional query words: 6.22 5.00 5.00a 6.00 6.20 3.00 3.00a win

======================================================================
Keywords          :  
Technology        : kbWin3xSearch kbZNotKeyword3 kbWin300 kbWin300a kbMSDOSSearch kbMSDOS621 kbMSDOS622 kbMSDOS620 kbMSDOS600 kbMSDOS500 kbMSDOS500a
Version           : MS-DOS:5.0,5.0a,6.0,6.2,6.21,6.22; WINDOWS:3.0,3.0a

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.