MS-DOS 5.0 Setup Doesn't Always Copy HIMEM.SYS (74825)

The information in this article applies to:
    Microsoft MS-DOS operating system 5.0

This article was previously published under Q74825


The Microsoft MS-DOS 5 Upgrade includes version 2.77 of the Microsoft XMS driver HIMEM.SYS. If SETUP.EXE detects an earlier version of the Microsoft HIMEM.SYS driver in use, Setup replaces it. If Setup detects any other XMS 2.0 driver, however, Setup does not copy HIMEM.SYS 2.77 to your hard drive to avoid any possible conflicts with your present XMS driver.

To use HIMEM.SYS, you must expand it and copy it to the hard drive separately.


The compressed file HIMEM.SY_ is located on Disk 1 of the 720K MS-DOS disk set and Disk 2 of the 360K disk set. If you want to expand and copy it from the MS-DOS disk in drive A to your C:\DOS directory, use the following command:

C:\>expand a:\himem.sy_ c:\dos\himem.sys

If you were using MS-DOS version 4.0x and another XMS driver, it is possible that you will still have HIMEM.SYS version 2.04, which was part of MS-DOS 4.0x, in your DOS directory. It is possible to load MS-DOS 5.0 high using HIMEM.SYS 2.04, but not recommended.

If EMM386.EXE is loaded after HIMEM.SYS 2.04, it will display the following and may not work properly with HIMEM.SYS 2.04:

Warning : This version of HIMEM.SYS may cause conflicts with EMM386.
HIMEM.SYS version 2.77 should be used with MS-DOS 5.0.

Modification Type: Major Last Reviewed: 11/26/1999
Keywords: KB74825