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【标准】计算机视频显示标准介绍(英文) - Enhanced Graphics Adapter (EGA)

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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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Enhanced Graphics Adapter (EGA)

The Enhanced Graphics Adapter was introduced by IBM in 1984 as the primary display for the new PC-AT Intel 286-based computer. EGA increased resolution to 640x350 pixels in 16 colors. The card itself contained 16 KB of ROM to extend the system BIOS to add graphics functions. The card started with 64 KB of video memory but later cards and clone cards came with 256KB of video memory to allow full implementation of all EGA modes which included...

  • High-resolution mode with 640x350 pixel resolution. On any given screen display a total of 16 colors could be displayed; however, these could be selected from a palette of 64 colors.
  • CGA mode included full 16-color versions of the CGA 640x200 and 320x200 graphics modes. The original CGA modes were present in the card but EGA is not 100% hardware-compatible with CGA.
  • MDA could be supported to some degree. By setting switches on the card an MDA monitor could be driven by an EGA card however only the 640x350 display could be supported.

Some EGA clones extended the EGA features to include 640x400, 640x480, and 720x540 along with hardware detection of the attached monitor and a special 400-line interlace mode to use with older CGA monitors. None of these became standard however.

EGA's life was fairly short as VGA was introduced by IBM in April of 1987 and quickly took over the market. In the meantime, IBM had a brief go with a specialized graphics system called PGC and the 8514 Display Standard...