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Microsoft KB Archive/105071

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Microsoft Knowledge Base

FastTips: MS-DOS 6.2 Configuration Questions and Answers

Last reviewed: November 23, 1994
Article ID: Q105071

The information in this article applies to:

  • Microsoft MS-DOS operating system versions 6.2, 6.22
1. Q. I receive the message "ERROR: Unable to control A20 line" during
      the startup (boot) process. How can I correct this problem?

   A. The A20 line is a hardware component of 80286 and higher
      processors that allows programs to access the first 64 kilobytes
      (K) of extended memory. HIMEM.SYS must be able to control the
      A20 line to manage the extended memory on your computer. Since
      different computers use different techniques for controlling the
      A20 line, HIMEM.SYS cannot always determine the correct
      technique to use. If HIMEM.SYS cannot identify the correct
      technique for controlling the A20 line on your computer, you may
      need to use the /machine switch with the DEVICE=C:\DOS\HIMEM.SYS
      command in your CONFIG.SYS file. For further instructions,
      see your MS-DOS 6.2 printed documentation. You can also type
      "help himem.sys" (without the quotation marks) at the MS-DOS
      command prompt and press ENTER for information on HIMEM.SYS and
      the /machine switch.

2. Q. I made a change to my CONFIG.SYS or AUTOEXEC.BAT file and now my
      computer stops responding (hangs) when I turn it on. What should
      I do?

   A. MS-DOS 6.2 contains two functions that can help you correct this
      problem. The first function lets you bypass the CONFIG.SYS and
      AUTOEXEC.BAT files when booting. The second function lets you
      step through and confirm each startup command in your CONFIG.SYS
      and AUTOEXEC.BAT files.

      To completely bypass the CONFIG.SYS and AUTOEXEC.BAT files,
      restart your computer and press and release the F5 key when
      you see the "Starting MS-DOS..." message. To step through
      CONFIG.SYS and AUTOEXEC.BAT, press and release the F8 key when
      you see the "Starting MS-DOS..." message.

      NOTE: If you bypass your configuration files, some devices
      (such as the mouse) may not function. If you use a third-party
      disk-compression program, you should use the F8 key during startup
      and load any required device drivers. This is not necessary if you
      use Microsoft DoubleSpace.

3. Q. How do I add the Windows-based utilities after I install MS-DOS
      6.2?

   A. The MS-DOS 6.2 Upgrade includes Windows-based versions of
      Microsoft Backup, Microsoft Anti-Virus, and Microsoft Undelete.
      To install these programs after you have installed MS-DOS 6.2,
      insert Setup Disk 1 in your floppy disk drive and run Setup
      with the /E switch. For example:

         a:setup /e

      If you are using MS-DOS 6.2 Step-Up, see the "Installing
      Microsoft Backup, Undelete and Anti-Virus" section of the
      README.NOW file on your original MS-DOS 6.2 Step-Up disk.

4. Q. Now that I have upgraded to MS-DOS 6.2, my CD-ROM drive no
      longer works correctly. Why is this occurring and how can I
      correct the problem?

   A. If MS-DOS 6.2 Setup finds the Microsoft Compact Disc Extensions
      (MSCDEX) in your AUTOEXEC.BAT file, it updates MSCDEX.EXE to
      version 2.23. This version may be incompatible with your CD-ROM
      drive's device driver. Contact the manufacturer of your CD-ROM
      drive to determine whether your drive's device driver is
      compatible with MSCDEX version 2.23.

      If you didn't experience incompatibility problems with your
      earlier version of MS-DOS, you can avoid problems by replacing
      version 2.23 with your previous version. If you do so, you must
      also add the following command to your CONFIG.SYS file and then
      reboot your computer:

         device=c:\dos\setver.exe

      This problem may also be caused by a memory conflict involving
      MSCDEX. If you load MSCDEX in the upper memory area (UMA) and
      encounter CD-ROM problems, try loading it in conventional
      memory.

5. Q. Why do I receive the message "Out of memory" when I use the
      Microsoft Defragmenter, Microsoft Anti-Virus, or Microsoft
      Undelete?

   A. The message "Out of memory" means that the program cannot access
      enough conventional memory. Use MemMaker to optimize your system
      and make more memory available.

      If you are receiving insufficient memory error messages from
      Microsoft Undelete for Windows or Microsoft Anti-Virus for
      Windows, close a few Windows-based applications and try again.
      If the problem persists, exit Windows, restart Windows, and then
      run the application.

      If you are receiving out of memory errors when you are running
      Microsoft Defragmenter, make sure you have at least 384K of extended
      memory available.

6. Q. After I compressed my drive, some of my MS-DOS-based games don't
      work any more. What can I do to correct this situation?

   A. Some MS-DOS-based games may not run correctly with the
      DoubleSpace component (DBLSPACE.BIN) loaded. Problems can occur
      due to lack of conventional memory, problems with application
      use of nonreadable video memory, or timing problems with sound
      files.

      To work around this problem, install your MS-DOS-based games on
      your uncompressed host drive and then start your computer
      without loading DBLSPACE.BIN by pressing CTRL+F5 or CTRL+F8 when
      the "Starting MS-DOS" prompt appears.

      If you need specific CONFIG.SYS and AUTOEXEC.BAT files to run
      your games, put these files on the host drive for drive C. To
      process these files, press CTRL+F8 when the "Starting MS-DOS"
      prompt appears and then press the ESC key.

      To determine which drive is your host drive, type "dblspace
      /list" (without the quotation marks) at the MS-DOS command
      prompt and then press ENTER.

   NOTE: If you have MS-DOS 6.22, substitute DRVSPACE /LIST for the
   DBLSPACE /LIST command.

KBCategory: kbtool kbdisplay kbsound kbfasttip

KBSubcategory: msdos
Additional reference words: msbackup MWAV defrag 6.20 stepup


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Last reviewed: November 23, 1994
©1997 Microsoft Corporation. All rights reserved. Legal Notices.