Q38154: Graphic Routines Fail to Use Active Card when Two are Present

Article: Q38154
Product(s): See article
Version(s): 1.00 1.10
Operating System(s): MS-DOS
Keyword(s): ENDUSER | s_c | mspl13_c
Last Modified: 17-NOV-1988

On machines with two graphics cards, the graphics package shipped
with QuickC and the C Versions 5.00 and 5.10 optimizing compiler will
use only the higher-resolution card for graphic output, regardless of
which is the active card. The only solution is to remove the second
card. However, this is a particular problem with machines such as the
PS/2 model 30, which has a built-in MCGA card.

QuickC will recognize an add-on VGA card, which has higher resolution
than MCGA; however, it will not recognize an add-on EGA card, which,
although it provides lower resolution than the MCGA, is considered by
many to be a superior card for graphic output. If an attempt is made
to use _setvideomode to set the system into an EGA mode, _setvideomode
will return an error.

The graphics routines do not rely solely on the bios. Issuing a bios
call (Int 10, Function 0FH - Get Video Mode) to determine whether or
not the bios recognizes the EGA as the active card will return the
value for an EGA-only mode. However, the graphics routines will
continue to use the MCGA card.

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