Windowed MS-DOS Apps Revert to Full Screen in Windows (71211)


The information in this article applies to:

  • Microsoft Windows 3.0
  • Microsoft Windows 3.0a
  • Microsoft Windows 3.1
  • Microsoft Windows 3.11
This article was previously published under Q71211

SUMMARY

While running an MS-DOS application in a window, Microsoft Windows may switch it to full screen if an MS-DOS critical error occurs. Typically, the critical error will be a disk error, but there are other causes as well.

The common critical MS-DOS errors are:

  • attempting to access a floppy drive with no disk
  • attempting to write a file to a write-protected floppy disk
  • attempting to access an unformatted floppy disk
When an MS-DOS critical error occurs, MS-DOS is unstable until the critical error is resolved. To maximize stability, Windows switches the application to full-screen text mode. This is by design and there is no workaround. Press ALT+ENTER, after the error is resolved, to switch the MS-DOS application back to the windowed display mode.

MORE INFORMATION

Switching Between Full Screen and Windowed Display Modes

The "windowed" display mode of MS-DOS applications is only available in 386 enhanced mode. There are three actions that can be performed to run an MS-DOS application in a window or full screen:

  1. Select the desired mode in the PIF Editor.
  2. Press ALT+ENTER to toggle between the two modes.
  3. Select the desired mode from the MS-DOS application's system menu:

    1. Start the MS-DOS application in question.
    2. Press ALT+SPACEBAR to display the system menu.
    3. Select Settings (press T).
    4. Select Windowed (press W).
    5. Press ENTER.

MS-DOS Int 24H Critical Errors

The critical error handler is a function of interrupt 24H. A complete listing of the MS-DOS Int 24H critical errors are listed below. 
Error Code
Hex     Dec  Description
---------------------------------------------

00H      0   Write-protect error
01H      1   Unknown unit (invalid drive number)
02H      2   Drive not ready (no disk or driver door open)
03H      3   Unknown command requested
04H      4   Data error (CRC)
05H      5   Bad request structure length
06H      6   Seek error; move to requested cylinder failed
07H      7   Unknown disk format
08H      8   Sector not found
09H      9   Printer out of paper
0AH     10   Write fault
0BH     11   Read fault
0CH     12   General, nonspecific error
0FH     15   Invalid disk change (MS-DOS version 3.0 or later)
Modification Type:MinorLast Reviewed:7/7/2005
Keywords:KB71211
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