Difference between revisions of "Enhanced Graphics Adapter"
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| Text || 640 × 200 || 80 × 25 (8 × 8 pixel font) || 16 || 1:2.4 || CGA backward compatibility. | | Text || 640 × 200 || 80 × 25 (8 × 8 pixel font) || 16 || 1:2.4 || CGA backward compatibility. | ||
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| − | | Text || 640 × 350 || 80 × 25 (8 × 14 pixel font) || 16 || 1:1.37 || New to EGA. | + | | Text || 640 × 350 || 80 × 25 (8 × 14 pixel font) || 16 (from a palette of 64) || 1:1.37 || New to EGA. |
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| − | | Text || 640 × 350 || 80 × 43 (8 × 8 pixel font) || 16 || 1:1.37 || New to EGA. | + | | Text || 640 × 350 || 80 × 43 (8 × 8 pixel font) || 16 (from a palette of 64) || 1:1.37 || New to EGA. |
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| − | | Graphics || 640 × 350 || || 16 || 1:1.37 || | + | | Graphics || 640 × 350 || || 16 (from a palette of 64) || 1:1.37 || |
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| Graphics || 640 × 350 || || 2 || 1:1.37 || | | Graphics || 640 × 350 || || 2 || 1:1.37 || | ||
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| Graphics || 320 × 200 || || 4 || 1:1.2 || CGA backward compatibility. | | Graphics || 320 × 200 || || 4 || 1:1.2 || CGA backward compatibility. | ||
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| − | | Graphics || 640 × 200 || || | + | | Graphics || 640 × 200 || || 2 || 1:2.4 || CGA backward compatibility. |
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Revision as of 14:05, 19 September 2023
The Enhanced Graphics Adapter (EGA) is a graphics card which gives IBM Personal Computers color graphics capabilities superior to those of the earlier Color Graphics Adapter. It was designed and developed by IBM and first sold in 1984, but competing companies quickly reverse-engineered it and sold clones. The display type was extremely popular for MS-DOS programs through the mid to late 1980s. IBM also sold a more advanced Professional Graphics Controller, but it was out of the price range for home users. The EGA was superseded in 1987 by the Video Graphics Array (VGA) which added superior color graphic capabilities, although software continued to support EGA for years to follow.
Contents
Personal
I spent a lot of my childhood acquainted with EGA graphics, not just because a lot of games I played used it, but because it was a very popular QuickBASIC screen (screen 7). Even though I haven't bothered with it in decades, I still have the default EGA color palette memorized.
Technical Specifications
Display Modes
EGA is backward-compatible with CGA, so it supports its text and graphic modes, but also adds higher resolution modes.
Its highest graphic resolution is 640x350 with 4-bit color (16 distinct colors at once, chosen from a palette of 64 colors), but most programs which supported EGA used its more primitive 320x200 resolution with 4-bit color and didn't modify the default color palette. One of the few game companies which frequently modified the EGA palette was Maxis.
| Mode | Pixel Resolution | Text Resolution | Colors | Pixel Aspect Ratio | Notes |
|---|---|---|---|---|---|
| Text | 320 × 200 | 40 × 25 (8 × 8 pixel font) | 16 | 1:1.2 | CGA backward compatibility. |
| Text | 640 × 200 | 80 × 25 (8 × 8 pixel font) | 16 | 1:2.4 | CGA backward compatibility. |
| Text | 640 × 350 | 80 × 25 (8 × 14 pixel font) | 16 (from a palette of 64) | 1:1.37 | New to EGA. |
| Text | 640 × 350 | 80 × 43 (8 × 8 pixel font) | 16 (from a palette of 64) | 1:1.37 | New to EGA. |
| Graphics | 640 × 350 | 16 (from a palette of 64) | 1:1.37 | ||
| Graphics | 640 × 350 | 2 | 1:1.37 | ||
| Graphics | 640 × 200 | 16 | 1:2.4 | ||
| Graphics | 320 × 200 | 16 | 1:1.2 | ||
| Graphics | 320 × 200 | 4 | 1:1.2 | CGA backward compatibility. | |
| Graphics | 640 × 200 | 2 | 1:2.4 | CGA backward compatibility. |
Examples
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Color Palette
In QuickBASIC, screens 0 and 9 supported customizing the default 16 colors of the EGA palette with the command PALETTE index, color, where index was one of the 0-15 colors and color was one of the 64 possible colors.
Although any game designed for EGA could technically modify the default palette, very few developers ever took advantage of this feature, which is a real shame since the default palette isn't conducive to attractive art. However, the following software does modify the palette.
To see an example for how much improvement is possible when using a custom palette, I made this mock up. The image on the left is a screenshot from Hoyle: Official Book of Games - Volume 1. In the image to the right, I modified the colors and a little bit of the graphics to better fit human skin tones and less contrasting colors. The could be made even more attractive if the artist started drawing with a custom palette in mind.
| 320px |
320px |
Software
- All software that used 4-bit Color
These are programs that I think made good use of EGA graphics:
Commander Keen IV: Secret of the Oracle
Large attractive graphics.
King's Quest IV: The Perils of Rosella
Good use of dithering to simulate additional colors.
Lemmings
Hi-res with a custom palette.
Loom
Great use of dithering to create gradients.
The Secret of Monkey Island
More advanced use of dithering.
SimAnt
Hi-res with a custom palette. Uses red (36), blue (9), and yellow (54).
Documentation
Technical manual.
Links
