Q41078: Failure to Set Video to Text Mode When Swapping to Environment

Article: Q41078
Product(s): See article
Version(s): 2.00
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist2.00 apnote buglist2.01 s_quickasm | mspl13_c
Last Modified: 11-OCT-1989

QuickC Version 2.00 and QuickAssembler 2.01 do not run properly
on some computers equipped with CGA and Olivetti graphics adapters.
When the display is in a graphics mode when QuickC swaps in the
integrated environment screen, the video is not set to color text
mode as it should be. The result is an unreadable graphics screen.
The QuickC environment is still operable, but movement through
the menus must be done by memory.

Microsoft has confirmed this to be a problem in Versions 2.00 and
2.01. There is a patch available that corrects the QC.EXE file in both
QuickC 2.00 and QuickAssembler so that they properly switch video
modes when swapping the QuickC screen and the program's output screen.

Please contact Microsoft Product Support Services at (800) 454 2030 to
obtain this patch.

This problem can be observed in the following three ways:

1. If the display is in a graphics mode when QuickC is invoked, QuickC
   remains in graphics mode. To work around this problem, use the DOS
   command MODE CO80 to set your display to text mode prior to invoking
   QuickC.

2. Use the following program:

      #include <graph.h>
      void main (void)
      { _setvideomode (_MRES4COLOR);
      }

   When the above program is executed within the QuickC environment
   (with F5) and a key is pressed to return back to QuickC, QuickC
   remains in graphics mode. The workaround is to add the following
   line:

      _setvideomode (_DEFAULTMODE);

3. Given the above program, press F8 twice to single step past the
   _setvideomode function. The video will remain in graphics mode
   when swapping back to the environment.

   This scenario is the most severe. This prohibits one from debugging
   a program that uses any graphics mode within the QuickC environment.

This problem has been observed on the following equipment:

   AT&T 6300 (8086, ROM-BIOS Version 1.43, MS-DOS Version 3.30)
   Compaq Portable (8088, MS-DOS Version 3.30)
   IBM PS/2 Model 80 (8514 Monitor, MS-DOS 3.30)

The following are videomodes with which this has been observed:

   _MRES4COLOR
   _HRESBW
   _ORESCOLOR

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