Display standard
<hardware>
IBM and others have introduced a bewildering plethora of graphics and text display standards for IBM PCs.
The standards are mostly implemented by plugging in a video display board (or "
graphics adaptor") and connecting the appropriate monitor to it.
Each new standard subsumes its predecessors.
For example, an
EGA board can also do
CGA and MDA.
With the
PS/2, IBM introduced the
VGA standard and built it into the main system board
motherboard. VGA is also available as a plug-in board for PCs from third-party vendors. Also with the PS/2, IBM introduced the
8514 high-resolution graphics standard.
An 8514 adaptor board plugs into the PS/2, providing a dual-monitor capability.
Graphics software has to support the major IBM graphics standards and many non-IBM, proprietary standards for high-resolution displays.
Either software vendors provide display drivers, or display vendors provide drivers for the software package.
In either case, switching software or switching display systems is fraught with compatibility problems.
Display
Resolution Colours Sponsor Systems
MDA
720x350 T
2
IBM
PC CGA
320x200
4
IBM
PC EGA
640x350 16
IBM
PC PGA
640x480 256
IBM
PC
Hercules
729x348
2
non-IBM PC
MCGA
720x400 T 320x200 G 256 PS/2
VGA
720x400 T 640x480 G 16
SVGA
800x600 16 VESA
XVGA
1024x768 256 (IBM name: 8514)
T: text,
G: graphics.
More colours are available from third-party vendors for some display types.
See also MDA,
CGA,
EGA,
PGA, Hercules, MCGA,
VGA,
SVGA,
8514,
VESA.
