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xms driver error

Posted on 1999-12-31
Medium Priority
Last Modified: 2013-12-28
when i boot up my screen says

  Windows xms driver ver 3.5
          xms version 3.0

 ERROR-unable to control A20 line
       xms driver not installed
       HIMEM.sys is missing
       check windows directory.
and goes to c: prompt.
I have checked the dir and himem is there.
it will boot in safe mode or in step by step.but when i power down it alwaws goes back to the error.
I have even reloaded windows to no avail..
I followed there help function to no avail..
please help..........ken

Question by:cen12676
  • 2

Expert Comment

ID: 2316957
do you have a bootable floppy disk?

Accepted Solution

sgenther earned 600 total points
ID: 2316965
See if this helps:
PSS ID Number: Q73713
Article last modified on 06-07-1999

The information in this article applies to:
 - Microsoft MS-DOS operating system versions 5.x, 6.0, 6.2, 6.21, 6.22
 - Microsoft Windows 95
 - Microsoft Windows 98
The following error message is generated when the device driver HIMEM.SYS is
being loaded and doesn't have a machine handler chosen:
   ERROR: Unable to control A20 Line
There are two workarounds for this problem:
 - Add the "/M:x" switch to the HIMEM.SYS line in the CONFIG.SYS file, where x
   is number from the valid range of 1-14 and 16, shut down and then restart
   your computer. For example:
   NOTE: In Windows 95/98, The Himem.sys file is located in the Windows folder,
   not the DOS folder.
   NOTE: An incorrect handler may lock or hang the system at boot up. You should
   have an MS-DOS version 5.0 bootable floppy disk available to boot from before
   you experiment with different machine switches.
 - Upgrade your machine's BIOS or contact your machine vendor for assistance in
   modifying your CMOS settings. You may need to disable a FastGate (or similar)
   For more information, query on the following words in the Microsoft Knowledge
The A20 line is the start of the first 64K of extended memory, known as the high
memory area (HMA). The HIMEM.SYS device driver must control the A20 line to
provide management of extended memory. The error message is reported by
HIMEM.SYS if it incorrectly identifies the extended memory handling mechanism of
the computer or if the handling method of the machine's BIOS is unknown.
For more information concerning HIMEM.SYS, please refer to the Microsoft MS-DOS
version 5.0 "User's Guide and Reference" and to the README.TXT file.
If you are using MS-DOS 6.x, type "help himem.sys" at the MS-DOS command prompt,
and then press ENTER.
Norton Utilities or Norton AntiVirus Installed
This behavior may also occur if you have Norton Utilities or Norton AntiVirus
installed. For additional information, please see the following Symantec Web
The third-party contact information included in this article is provided to help
you find the technical support you need. This contact information is subject to
change without notice. Microsoft in no way guarantees the accuracy of this
third-party contact information.
The third-party products discussed here are manufactured by vendors independent
of Microsoft; we make no warranty, implied or otherwise, regarding these
products' performance or reliability.
Additional query words: 6.22 5.00 5.00a 6.00 6.20
Keywords          : kbenv kberrmsg msdos win95 win98
Version           : WINDOWS:95
Platform          : WINDOWS
Issue type        : kbinfo
Copyright Microsoft Corporation 1999.


Author Comment

ID: 2323025
no solution yet but now checking into bios settings  as soon as daughter arrives back at college with it..should be sometime late tonight or tomarrow and will inform you as soon as possible..thanks..

Author Comment

ID: 2334573
finally ended up reloading default bios setup and it cleared the problem.........thanks...

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