Microsoft KB Archive/72304

= OPTI 486 Memory Chips Require Special AWARD BIOS =

Article ID: 72304

Article Last Modified on 5/12/2003

-

APPLIES TO


 * Microsoft MS-DOS 3.1
 * Microsoft MS-DOS 3.2 Standard Edition
 * Microsoft MS-DOS 3.21 Standard Edition
 * Microsoft MS-DOS 3.3 Standard Edition
 * Microsoft MS-DOS 3.3a
 * Microsoft MS-DOS 4.0 Standard Edition
 * Microsoft MS-DOS 4.01 Standard Edition
 * Microsoft MS-DOS 5.0 Standard Edition
 * Microsoft MS-DOS 5.0a
 * Microsoft MS-DOS 6.0 Standard Edition
 * Microsoft MS-DOS 6.2 Standard Edition
 * Microsoft MS-DOS 6.21 Standard Edition
 * Microsoft MS-DOS 6.22 Standard Edition

-



This article was previously published under Q72304



SUMMARY
There are some Pioneer and other 80486 motherboards that come equipped with OPTI memory chips and an AWARD BIOS. Revisions A, B, and C of the OPTI memory chips have a conflict with HIMEM.SYS and may return the following error at bootup:

Cannot enable A20 handler

The following are the OPTI 486 Chip revisions and the necessary BIOS' for use with HIMEM.SYS:   If you have OPTI chip revision:      You need to: A              Call Award Software at (415) 968-4433 for more information. B              Obtain the OPTI Revision of AWARD BIOS 3.14. C              Obtain the OPTI Revision of AWARD BIOS 3.14. D              Your BIOS should be the correct revision.



MORE INFORMATION
Using alternate handlers with HIMEM.SYS will not work. The problem lies in a conflict between the memory chips and the AWARD BIOS. According to AWARD Software, there is a special revision of AWARD BIOS 3.14 that will correct this problem on the B and C releases of the OPTI memory chips. Revision A of the OPTI memory chips may not allow the A20 handler to be enabled regardless of BIOS version.

IMPORTANT: The AWARD BIOS revision offered to correct this problem is NOT the standard AWARD BIOS 3.14. The BIOS must be specified as the OPTI revision of the AWARD BIOS 3.14. If the OPTI revision is not specified, then the standard BIOS upgrade will be delivered and it WILL NOT correct the problem.

Revision D of the OPTI memory chips does not have this conflict and should function normally with HIMEM.SYS.

For more information, contact AWARD Software at (415) 968-4433.

The products included 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 3.30 3.30a 4.00 4.01 4.01a 5.00 5.00a 6.00 6.20 6.21 3rdparty

Keywords: KB72304

-

[mailto:TECHNET@MICROSOFT.COM Send feedback to Microsoft]

© Microsoft Corporation. All rights reserved.