ID Number: Q43587
5.00 5.10 6.00 6.00a 6.00ax
MS-DOS
Summary:
The following are possible reasons that _setvideomode() might fail
when attempting to set a video mode:
1. Some of the older IBM EGA (enhanced graphics adapter) cards only
have 64K of video memory. As such, they cannot display the
640 x 350, 16 (_ERES16COLOR) color EGA mode. However,
lower-resolution modes may work correctly because they don't
require that much memory.
2. There are EGA cards that have DIP-switch settings to set the card
into high- or low-resolution modes. Some BIOS ignore these DIP
switches and set the mode to high resolution. However, the
_setvideomode() function does its own checking and may honor the
DIP-switch settings depending on the particular card. Setting the
DIP switches properly for the high-resolution modes should resolve
the problem.
3. The video card may not support the requested mode. If the card does
not support the mode, then _setvideomode() cannot set it into that
mode.
4. Many VGA cards have non-standard extended modes that are unique to
those cards. _setvideomode() supports only standard video modes,
and thus does not recognize the extended modes.
Additional reference words: 6.0 6.00 6.0a 6.00a 6.0ax 6.00ax quickc
setvideomode _setvideomode 2.0 2.00 2.01 2.5 2.50 2.51