SuperVGA Display Adapters (SVGA)
█▌Overview▐█
VESA is an acronym for Video Electronics Standards Association. In 1989,
this group saw that IBM was not taking up the reigns to define standards
for advanced SVGA or SuperVGA video systems that were evolving. Each
manufacturer had different video mode numbers and wildly-varying BIOS
support functions.
The VESA standard has not been adopted universally, and with the growing
popularity of Windows, emphasis has been placed on Windows video drivers.
However, OEMs that do implement VESA support enjoy some compatibility with
a wider range of non-Windows SuperVGA-aware applications. OEMs may
include VESA support in ROM or distribute a device driver or TSR that adds
the new support.
TECH Help! covers the following SVGA topics:
VESA/SVGA BIOS Functions··· includes VGA modes
VESA/SVGA Video Modes······ covers VGA services available via ROM-BIOS
All features of the VGA (and lesser systems) are supported on all SVGA
adaptors. In text modes, the SVGA's video memory begins at b800:0000 and
in hi-res graphics modes, video memory begins at a000:0.
█▌Testing for an SVGA▐█
Alas, there is NO certain way to know if you are running on a SuperVGA;
witness the chaos when you choose the wrong video driver with some
software!
However, you can check for VESA support via INT 10H 4f00H. If VESA/SVGA
BIOS is present, it returns with AX=004fH and lots of useful information
at ES:BX.
Although some SuperVGAs support some new text-mode capabilities (such as
132-column screen modes), SVGA-awareness is usually needed only by high-
end, non-Windows graphics applications.
See Also: CGA
EGA
MDA
VGA
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