Q84943: Using HIMEM.EXE with Win 3.0 on COMPAQs with More Than 16 MB

Article: Q84943
Product(s): Microsoft Windows 95.x Retail Product
Version(s): WINDOWS:3.0,3.0a
Operating System(s): 
Keyword(s): 
Last Modified: 01-OCT-1999

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

- Microsoft Windows versions 3.0, 3.0a 
-------------------------------------------------------------------------------

SUMMARY
=======

Compaq Corporation has its own original equipment manufacturer (OEM) version of
the HIMEM.SYS extended memory manager called HIMEM.EXE, which is included on the
utilities disks that come with COMPAQ 80286-, 80386-, and 80486-based systems.
Some of these computers are capable of supporting more than 16 MB of RAM. These
systems are equipped with the Extended Industry Standard Architecture (EISA)
bus.

These computer models include the following:

  COMPAQ SYSTEMPRO
  COMPAQ DESKPRO 486/25
  COMPAQ DESKPRO 386/33L
  COMPAQ DESKPRO 486/33L

Compaq's HIMEM.EXE driver allows those systems to access extended memory using
the Extended Memory Specification (XMS). It also allows access to memory beyond
16 MB while allowing MS-DOS-based programs to use the 64K region of memory
located just above the 1 MB address.

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

HIMEM.EXE, which supports more than 16 MB of memory, is intended to replace
HIMEM.SYS. However, Microsoft Windows operating system version 3.0 does not
support more than 16 MB of RAM. If HIMEM.EXE is used with Windows 3.0 on a
system with more than 16 MB of RAM, data loss or corruption may occur.

To avoid problems on COMPAQ systems with more than 16 MB RAM, make sure to use
the Windows 3.0 HIMEM.SYS driver rather than the COMPAQ HIMEM.EXE driver.
However, the version of HIMEM.EXE dated 6-14-90 will work with Windows 3.0 and
is recommended by Compaq for use on COMPAQ machines with LESS than 16 MB of
memory.

The HIMEM.SYS driver included with Windows 3.0 supports only 16 MB of RAM. It
automatically detects COMPAQ memory above 16 MB and prevents access to that
memory.

The HIMEM.EXE driver is installed in the CONFIG.SYS file instead of the HIMEM.SYS
driver. The DEVICE= line should read:

       DEVICE=[drive:][path]HIMEM.EXE

If the computer has more than 16 MB of extended memory, the "/ISAONLY" switch
should be added to the DEVICE= line, as follows:

       DEVICE=[drive:][path]HIMEM.EXE /ISAONLY

KBCategory: kb3rdparty
KBSubcategory: win30 winmem

REFERENCES
==========

"COMPAQ User Programs Reference," COMPAQ Utilities.

Additional query words: 3.00 3.00a System Pro desk utility

======================================================================
Keywords          :  
Technology        : kbWin3xSearch kbZNotKeyword3 kbWin300 kbWin300a
Version           : 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.