DOCUMENT:Q73293 19-NOV-1999 [msdos] TITLE :When MS-DOS Fails to Load in the HMA PRODUCT :Microsoft Disk Operating System PROD/VER:MS-DOS:5.0,5.0a,6.0,6.2,6.21,6.22 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft MS-DOS operating system versions 5.0, 5.0a, 6.0, 6.2, 6.21, 6.22 ------------------------------------------------------------------------------- SUMMARY ======= MS-DOS version 5.0 and 6.0 can save memory by loading itself into the first 64K of extended memory, the high memory area (HMA). To check whether MS-DOS has loaded itself in the HMA, issue the MEM command and look at the output. If the last line of output reads MS-DOS is resident in High Memory Area then MS-DOS has loaded itself into the HMA. However, if MS-DOS has failed to load into the HMA, you will get one of two messages: 64Kb High Memory Area is Available -or- High Memory Area is in Use MORE INFORMATION ================ The first message, "64Kb High Memory Area is Available," is usually caused by not having the following line in the CONFIG.SYS file: DOS=HIGH To correct this problem, add the "DOS=HIGH" (without the quotation marks) line to CONFIG.SYS. The second message, "High Memory Area is in Use," has two possible causes: - Something else is being loaded into the HMA, such as a network driver or some other application. If you want to run MS-DOS in the HMA instead of the program that is currently using it, you must disable the ability of the other program to use the HMA. Consult that program's documentation for the disable procedure. Then, you will need to add the line "DOS=HIGH" (without the quotation marks) to your CONFIG.SYS file and ensure that you are loading HIMEM.SYS. - HIMEM.SYS is using the incorrect A20 handler. Upon installation, HIMEM.SYS usually selects one of 16 different A20 handlers, depending upon the hardware it detects. HIMEM's automatic detection can be overridden by the /MACHINE: or /M: switch. If HIMEM.SYS is installing the wrong A20 handler on its own, you must force it to install the correct handler with the /MACHINE: switch. However, if HIMEM.SYS is being forced to install an incorrect A20 handler by the /MACHINE: switch, you may be able to solve the problem by removing the /MACHINE: switch and allowing HIMEM to select which A20 it uses. For more information on MS-DOS 5.0's HIMEM.SYS and the /MACHINE: switch, see pages 610-613 of the version 5.0 "Microsoft MS-DOS User's Guide and Reference," or query on the following words: " HIMEM and /M and MS-DOS " (without the quotation marks) If you are using MS-DOS 6.x, type "help himem.sys" (without the quotation marks) at the MS-DOS command prompt, and then press ENTER. Additional query words: 6.22 5.00 5.00a 6.00 6.20 ====================================================================== Keywords : Technology : kbMSDOSSearch kbMSDOS621 kbMSDOS622 kbMSDOS620 kbMSDOS600 kbMSDOS500 kbMSDOS500a Version : MS-DOS:5.0,5.0a,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 1999.