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Q28029: If ANSI.SYS Sets Background Color, BASIC Clears Line 25

Article: Q28029
Product(s): See article
Version(s): 4.00 4.00b
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist4.00 buglist4.00b fixlist4.50 B_BasicCom | mspl13_basic
Last Modified: 25-AUG-1989

If you have changed the background and foreground screen colors in
MS-DOS using ANSI control codes, then when a BASIC program using
screen input or output is run, the 25th line is incorrectly blackened
(cleared) when the program exits.

Microsoft has confirmed this to be a problem in QuickBASIC Versions
4.00 and 4.00b, and in the Microsoft BASIC Compiler Version 6.00 for
MS-DOS (buglist6.00). The problem is corrected in QuickBASIC Version
4.50 and in the Microsoft BASIC Compiler Version 6.00b for MS-DOS
(fixlist6.00b).

This problem does not occur in EXE programs compiled with QuickBASIC
Version 3.00.

The DOS ANSI.SYS driver can be used to change the background and
foreground colors. For example, place the following in a file:

   An ESC byte (ASCII 27) followed by [44;37m

Then use the DOS TYPE command to send the file to the screen. Typing
the file will change the background color to blue and the foreground
color to white. If a BASIC program using screen input or output is
then run, the 25th line is incorrectly blackened (cleared) when the
program exits.

Please note that the 25th line is not used by BASIC unless the
statement < VIEW PRINT 1 to 25 > is used or the KEY statement is used.
When the BASIC program ends, the 25th line automatically is cleared in
case the KEY statement has been used.

To use ANSI control codes, the ANSI.SYS driver must be installed at
boot time by placing the following statement in your DOS CONFIG.SYS
file on your root directory:

   DEVICE=ANSI.SYS

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