DOCUMENT:Q72304  17-DEC-2000  [msdos]
TITLE   :OPTI 486 Memory Chips Require Special AWARD BIOS
PRODUCT :Microsoft Disk Operating System
PROD/VER:MS-DOS:3.x,4.x,5.x,6.0,6.2,6.21,6.22
OPER/SYS:
KEYWORDS:

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft MS-DOS operating system versions 3.1, 3.2, 3.21, 3.3, 3.3a, 4.0, 4.01, 5.0, 5.0a, 6.0, 6.2, 6.21, 6.22 
-------------------------------------------------------------------------------

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          :  
Technology        : kbMSDOSSearch kbMSDOS321 kbMSDOS400 kbMSDOS320 kbMSDOS330a kbMSDOS621 kbMSDOS622 kbMSDOS620 kbMSDOS600 kbMSDOS310 kbMSDOS500 kbMSDOS330 kbMSDOS401 kbMSDOS500a
Version           : MS-DOS:3.x,4.x,5.x,6.0,6.2,6.21,6.22

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2000.