Win 98 installation problem .Error : Unable to control A20 line ??

Posted on 2000-04-03
Last Modified: 2008-02-20

I had my pc running Windows NT 4.0. I had the pc formatted as I wanted to install Windows 98 and therefore the PC had to be formatted in FAT thus overwriting the NTFS format. Though the formatting did take place smoothly, Windows 98 managed to run the setup program almost 80 % installing all the necessary files and also showed the startup screen at first attempt, however it gave an error saying

"ERROR: Unable to control A20 line ! XMS Driver not installed.... and furthur Himem,sys is missing.Windows has stopped."

Though himem.sys is in place, I feel the problem is somewhere else. I formatted the 8 GB hard disk twice to confirm but .. still the same problem.

Please help... this matter is urgent


Question by:explorer007
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions

Expert Comment

ID: 2679932
     Whose BIOS is it? Can you describe exactly the procedure used to format it and which version of fdisk and format were used?

Expert Comment

ID: 2679949
I have seen this problem once before, but I cannot recall the exact problem.

Some older BIOSes have an option to control the A20 line. Try changing that setting to see if it will help.

Also, do you simply have a corrupt copy of himem.sys?

LVL 10

Expert Comment

ID: 2681785
I have seen this problem on older compaq computers. Usually the errors disappeared when we switched the computer off and let it sit there for a while. I did try to mingle with the control A20 line in the compaq bios, but was not successfull.
Did some research at the time and the Himem.sys error is directly linked to the A20 error. Solve the A20 error and you automatically solves the Himem.sys error.
Some more exact information and maybe the answer here:
Good luck
Free learning courses: Active Directory Deep Dive

Get a firm grasp on your IT environment when you learn Active Directory best practices with Veeam! Watch all, or choose any amount, of this three-part webinar series to improve your skills. From the basics to virtualization and backup, we got you covered.


Expert Comment

ID: 2689294
From Microsoft Knowledge Base -

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) option.
   For more information, query on the following words in the Microsoft Knowledge Base:
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 site:
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.


I hope this helps!

David Johnson
LVL 10

Expert Comment

ID: 2689345
You can't post other experts comments as your answer. Look at the comment right above your answer. It points to the same file that you have posted.
Kindly withdraw your answer.

Expert Comment

ID: 2689356
My apologies.
LVL 63

Expert Comment

ID: 2690237
Unless this computer is really old, you may have a hardware problem or RAM problem. In anycase please provide details on the hardware you are using. Computer type, motherboard, BIOS, Hard drive, and VGA card.
In any case I would make sure you have the newest BIOS installed.
Also clean the CD-ROM drive. Maybe a corrupted himem,sys is being transferred due to a bad CD-ROM.
Have you tried copying the win98 dir to the hard disk and then installing ?
I hope this helps.

Expert Comment

ID: 2713096
What does FDISK tell you?  Sounds like there might be remnants of the NTFS affecting the install.
You did not mention whether you used FDISK first before the format.  So my advice would be to start over and FDISK first.
LVL 10

Expert Comment

ID: 2724941
I refer to my previous comment.
I submit this as an answer, because you have not respondet in 15 days.
You should reject this answer, if you didn't use my comment to solve your problem.

LVL 10

Accepted Solution

tonnybrandt earned 70 total points
ID: 2742429
                    I refer to my previous comment.
                    I submit this as an answer, because you have not respondet in 15 days.
                    You should reject this answer, if you didn't use my comment to solve your problem.


Featured Post

Simple, centralized multimedia control

Watch and learn to see how ATEN provided an easy and effective way for three jointly-owned pubs to control the 60 televisions located across their three venues utilizing the ATEN Control System, Modular Matrix Switch and HDBaseT extenders.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

#Citrix #Citrix Netscaler #HTTP Compression #Load Balance
Data center, now-a-days, is referred as the home of all the advanced technologies. In-fact, most of the businesses are now establishing their entire organizational structure around the IT capabilities.
After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

726 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question