Hardware Reference
In-Depth Information
Video Display Adapters
A video display adapter (aka video card) provides the interface between your computer
and your monitor and transmits the signals that appear as images on the display.
ThroughoutthehistoryofthePC,therehasbeenasuccessionofstandardsforvideohard-
ware that represents a steady increase in screen resolution, color depth, and performance.
The following list of standards can serve as an abbreviated history of PC video-display
technology:
• MDA (Monochrome Display Adapter)
• HGC (Hercules Graphics Card)
• CGA (Color Graphics Adapter)
• EGA (Enhanced Graphics Adapter)
• VGA (Video Graphics Array)
• SVGA (Super VGA)
• XGA (Extended Graphics Array) and beyond
IBM pioneered most of these standards, but other manufacturers of compatible PCs adop-
ted and enhanced them as well. Today, IBM no longer sets standards for the PC business
(it sold its PC business to Lenovo in 2005), and most of these standards are obsolete.
Today's VGA and later video adapters can also handle most older software written for
CGA, EGA, and other obsolete graphics standards. This enables you to use many, if not
most, older graphics software (such as games and educational programs) on your current
system.
Video Adapter Types
A monitor requires a source of input. The signals that run to your monitor come from one
or more video display adapters in the system.
There are four basic types of video display adapters:
•
Discrete plug-in video cards
—These cards require the use of an expansion slot but
provide the highest possible level of features and performance.
•
Discrete video on the motherboard
—The same discrete circuitry that can be found
on a video card can also be directly built in or mounted on the motherboard. This is
how high-end video is installed in modern laptops and some older desktop systems;
however, modern desktops normally use either discrete video on a plug-in card or
motherboard chipset or processor integrated video.
