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Computer Display Standards

The display systems used by today's computers follow several standards that dictate key aspects of their signals, including the onscreen resolution, the number of colors on the screen, and the signals used to connect monitors to your computer.

The starting point in a modern computer display is called VGA, named after IBM's pioneering Video Graphics Array, which was introduced in 1987. This little bit of history remains the default mode of nearly every computer video system. Switch on your computer, and it begins life as a VGA system. Only after your operating system loads its video drivers does it switch to the resolution you set. The first screen you see, usually the Windows splash screen announcing your investment in making Bill Gates' fortune, pops on your monitor courtesy of VGA. When you can't get anything to work and your Windows-based computer snarls into service in safe mode, VGA is what you see. Much as you might want, you can't get away from VGA.

But VGA is still just for starters. Except for the lowliest of notebook systems, every computer today strives higher. The best display systems put more than six times as much detail on your screen in more colors than you can name (or even distinguish). At one time, standards were important for properly displaying these higher resolution modes. But because the use of driver software has removed the need for hardware to exactly match any set configuration, most of the older standards survive only as names that identify onscreen resolutions or operating modes. Table 24.1 lists the most popular display standards for personal computers.

Table 24.1. Computer Video Standards
Designation Name Resolution Maximum Colors
MDA Monochrome Display Adapter 720 by 350 3
CGA Color Graphics Adapter 640 by 200 16
EGA Enhanced Graphics Adapter 640 by 350 256
VGA Video Graphics Array 640 by 480 256/65,536
SVGA SuperVGA 800 by 600 16.7 million
XGA Extended Graphics Array 1024 by 768 16.7 million
SXGA SuperXGA 1280 by 1024 16.7 million

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