Книга: Enhanced Graphics Adapter: IBM Personal Computer, Computer display standard, Color Graphics Adapter, Video Graphics Array, IBM, IBM Personal Computer/ ... only memory, BIOS, Motorola, Motorola 6845

The Enhanced Graphics Adapter (EGA) is the IBM PC computer display standard specification located between CGA and VGA in terms of color and space resolution. Introduced in 1984 by IBM for its new PC-AT, EGA produces a display of 16 simultaneous colors from a palette of 64 at a resolution of up to 640?350 pixels. The EGA card includes a 16 kilobyte ROM to extend the system BIOS for additional graphics functions and includes the Motorola MC6845 video address generator as used in the CGA. Each of the 16 colors can be assigned a unique RGB color code via a palette mechanism in the 640?350 high-resolution mode the 64 palette colors are a balanced RGB color set comprised of all possible combinations of two bits per pixel for red, green and blue. EGA also includes full 16-color versions of the CGA 640?200 and 320?200 graphics modes only the 16 CGA/RGBI colors are available in these modes. The original CGA modes are also present, though EGA isn't 100% hardware compatible with CGA. EGA can drive an MDA monitor by a special setting of switches on the board only 640?350 high-res monochrome graphics and the standard MDA text mode are available in this mode.