Bypass or step through Config.sys and Autoexec.bat

MS DOS 6.0 introduced the ability to bypass the Config.sys and Autoexec.bat, and only load the Himem.sys, or single step through the Config.sys and Autoexec.bat. This can be useful if having problems with diagnosing what device driver or other terminate and stay resident (TSR) that is causing problems.

These options can be activated by pressing the keyboard key F8 during startup, when it displays "Starting MS-DOS ..." (Shown for two seconds). If pressing F5 instead of F8 then it will bypass the startup files without showing any options. MS DOS 7.1 (Win98) also reacts to CTRL being held down (same as F8), instead of waiting for the right moment to press F5 or F8.

Note it is possible to remove the 2 seconds delay (ex. if using Multiple configurations), by adding the following switch to Config.sys:


Note it is possible to disable the F5 and F8 entirely by adding the following switch to Config.sys:


More Info MS KB93602
More Info MS KB96332


  1. Don Speight says:

    I am not interested in any of the DOS's included with any version of Windows. I am referring to the last publish version of MS DOS 4.2, standing alone.

    • Ole M says:

      The last stand alone version of MS-DOS is actually 6.22, but what is your actual reason for leaving a comment here?

  2. Marc says:

    Thank god this just saved me. (Still running DOS here and I f^$%&^%$&d up the config.sys.


  3. Louis says:

    Hallo There.

    I am trying to print to pdf from a Dos program.
    Can you perhaps suggest a program that might be able to do so?
    DosPrint; Printfill; PdfCreator; etc does not work.

    At first my program did not find any printer at all.
    Juggling with config.sys and autoexec.bat got me to the point where the program starts to print to LPT1 but then reports "print error".

    Any suggestions please?

    Best regards.


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