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【标准】计算机视频显示标准介绍(英文) - Extended Graphics Array (XGA)

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【标准】计算机视频显示标准介绍(英文)
MDA
HGC
CGA
EGA
PGC
8514
VGA
MCGA
SVGA
XGA
SXGA
QXGA
HXGA
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Extended Graphics Array (XGA)

IBM's XGA was introduced in 1990 and is generally considered to be a 1024x768 pixel display. It would be wrong, however, to consider XGA a successor to SVGA as the two were initially released about the same time. Indeed, the SVGA "definition" has expanded as seen above and one might consider XGA to have been folded under the SVGA umbrella.

Initially, XGA was an enhancement to VGA and added two modes to VGA...

  • 800x600 pixels at 16-bits/pixel for 65,536 colors.
  • 1024x768 pixels at 8-bits/pixel for 256 colors.

Graphic display processing offloading features from the 8514 system were incorporated into and expanded under XGA. The number and type of drawing primitives were increased over the 8514 and the 16-bit color mode added.

Later, and XGA-2 specification added 640x480 at true color, increased the 1024x768 mode to high color (16-bit/pixel for 65,536 colors) and improved the graphic accelerator performance.

Note: XGA was an IBM standard, the VESA released a similar standard called Extended Video Graphics Array (EVGA) in 1991. The two should not be confused. EVGA, as a standalone term, never really caught on.

XGA, over time developed into a family of different standards. The following entries summarize this family...

  • Wide Extended Graphic Array (WXGA). A widescreen standard that varied somewhat in the supported resolutions. The most common were 1280x720 pixels with an aspect ratio of 16:9, 1280x768 pixels with an aspect ratio of 5:3, 1280x800 pixels with an aspect ratio of 8:5, 1360x768 pixels with an aspect ratio of about 16:9, and 1366x768 pixels with an aspect ratio of about 16:9. The latter two are generally used for LCD Television; the first three of often found in notebook computers. The 1280x720 pixel mode is also called 720p when used with HDTV.