The term display mode refers to the characteristics of a computer display, in particular the maximum number of colors and the maximum image resolution (in pixels horizontally by pixels vertically). There are several display modes that can be found in personal computer (PC) systems today.
The earliest displays for personal computers were monochrome monitors that were used in word processors and text-based computer systems in the 1970s. In 1981, IBM introduced the Color Graphics Adapter (CGA). This display system was capable of rendering four colors, and had a maximum resolution of 320 pixels horizontally by 200 pixels vertically. While CGA was all right for simple computer games such as solitaire and checkers, it did not offer sufficient image resolution for extended sessions of word processing, desktop publishing, or sophisticated graphics applications.
In 1984, IBM introduced the Enhanced Graphics Adapter (EGA) display. It allowed up to 16 different colors and offered resolution of up to 640 x 350. This improved the appearance over earlier displays, and made it possible to read text easily. Nevertheless, EGA did not offer sufficient image resolution for high-level applications such as graphic design and desktop publishing. This mode has become essentially obsolete, although it is sometimes found in old word processors and PCs in private homes.
In 1987, IBM introduced the Video Graphics Array (VGA) display system. This has become the accepted minimum standard for PCs. Some VGA monitors are still in use today. The maximum resolution depends on the number of colors displayed. You can choose between 16 colors at 640 x 480, or 256 colors at 320 x 200. All IBM-compatible computers support the VGA standard.
In 1990, IBM intoduced the Extended Graphics Array (XGA) display as a successor to its 8514/A display. A later version, XGA-2 offers 800 x 600 pixel resolution in true color (16 million colors) and 1024 x 768 resolution in 65,536 colors. These two image resolution levels are perhaps the most popular in use today by individuals and small businesses.
The Video Electronics Standards Assocation (VESA) has established a standard programming interface for Super Video Graphics Array (SVGA) displays, called the VESA BIOS Extension. Typically, an SVGA display can support a palette of up to 16,000,000 colors, although the amount of video memory in a particular computer may limit the actual number of displayed colors to something less than that. Image-resolution specifications vary. In general, the larger the diagonal screen measure of an SVGA monitor, the more pixels it can display horizontally and vertically.
Recently, new specifications have arisen. These include Super Extended Graphics Array (SXGA) and Ultra Extended Graphics Array (UXGA). The SXGA specification is generally used in reference to screens with 1280 x 1024 resolution; UXGA refers to a resolution of 1600 by 1200. Nowadays, the older specifications (VGA and SVGA) are often used simply in reference to their typical resolution capabilities. The table shows display modes and the resolution levels (in pixels horizontally by pixels vertically) most commonly associated with each.
Display Mode Resolution (pixels)
VGA 640 x 480
SVGA 800 x 600
XGA 1024 x 768
SXGA 1280 x 1024
UXGA 1600 x 1200