Q66287: What _getvideoconfig() Returns for Non-Standard Adapters

Article: Q66287
Product(s): See article
Version(s): 6.00
Operating System(s): MS-DOS
Keyword(s): ENDUSER | s_quickc s_quickasm 2.50 2.51 | mspl13_c
Last Modified: 24-OCT-1990

The _getvideoconfig() run-time library function returns, among other
things, the type of the current display adapter. The possible return
values are documented. However, what if the adapter does not match any
of the cards represented by the nine manifest constants defined in
graph.h?

When the adapter is recognized as a "superset" of an adapter that is
supported, the value of the supported adapter is returned. For
example, if the adapter is a Super VGA card, the value _VGA is
returned.

When the active adapter is completely unrecognized, the
_getvideoconfig() function returns the least common denominator. If
the adapter supports color, _CGA is returned; otherwise the return
value is set to _MDPA.

A good programming strategy to reduce device dependencies is to use
_MAXRESMODE or _MAXCOLORMODE when calling _setvideomode, and using
_getvideoconfig to determine what mode was actually set. There is more
information on these topics in the Microsoft Advisor online help
system, which comes with your C compiler package.