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

Last reviewed: April 26, 1996
Article ID: Q84943

The information in this article applies to:

Microsoft Windows operating system 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

Reference(s):"COMPAQ User Programs Reference," COMPAQ Utilities.

KBCategory: kb3rdparty
KBSubcategory: win30 winmem
Additional reference words: 3.00 3.00a System Pro desk utility

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Last reviewed: April 26, 1996
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