Enhanced Graphics Adapter
| Release date | October 1984 |
|---|---|
| Architecture | Motorola 6845, Chips and Technologies |
| Cards | |
| Entry-level | IBM EGA card, Chips and Technologies, ATI EGA Wonder |
| Mid-range | ATI EGA Wonder 800 |
| High-end | ATI EGA Wonder 800+ |
| History | |
| Predecessor | Monochrome Display Adapter, Color Graphics Adapter |
| Successor | Video Graphics Array |
The Enhanced Graphics Adapter (EGA) is a historical IBM PC computer display standard from 1984 that superseded and exceeded the capabilities of the CGA standard introduced with the original IBM PC, and was itself superseded by the VGA standard in 1987.
EGA was introduced in October 1984 by IBM, shortly after (but not exclusively for) its new PC/AT.
The EGA standard was made obsolete by the introduction in 1987 of MCGA and VGA with the PS/2 computer line.
Shortly before the introduction of VGA, Genoa Systems introduced a half-size graphics card built around a proprietary chip set, which they called Super EGA (later cards supporting an extended version of the VGA were similarly named Super VGA).
EGA produces a display of sixteen simultaneous colors from a palette of sixty-four, at a resolution of up to 640×350 pixels. The EGA card includes a 16 KB ROM to extend the system BIOS for additional graphics functions, and includes a custom CRT controller that has a backward compatibility mode with the Motorola MC6845 chip used to generate video timing signals in earlier graphics controllers.
In the 640×350 high resolution mode, each of the sixteen colors can be selected from a palette comprising all possible combinations of two bits per pixel each for red, green and blue, allowing four levels of intensity for each primary color and sixty-four possible colors overall. EGA also includes full sixteen-color versions of the CGA 640×200 and 320×200 graphics modes; only the sixteen CGA/RGBI colors are available in these modes. EGA four-bit (sixteen colors) graphic modes are also notable for a sophisticated use of bit planes and mask registers together with CPU bitwise operations, which constitutes an early graphics accelerator inherited by VGA and numerous compatible hardware.
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