Multi-Color Graphics Array: Difference between revisions
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Revision as of 02:39, 1 October 2014
Release date | 1987 |
---|---|
Cards | |
Entry-level | IBM PS/2 Model 30 & 25 motherboards |
History | |
Predecessor | Color Graphics Adapter |
Successor | Video Graphics Array |
The Multi-Color Graphics Array was a video subsystem built into the motherboard of the IBM PS/2 Model 30, introduced on April 2, 1987, and Model 25, introduced later on August 11; no standalone MCGA cards were ever made. The MCGA supported all CGA display modes plus 640×480 monochrome at a refresh rate of 60 Hz, and 320×200 with 256 colors (out of a palette of 262,144) at 70 Hz. The display adapter used a DE-15 connector. The MDA monochrome text mode was not supported.
MCGA was similar to VGA in that it had a 256-color mode (the 256-color mode in VGA was sometimes referred to as MCGA even though MCGA only existed on a small number of PS/2 models) and used 15-pin analog connectors, but the chipset's abilities were limited to that. MCGA lacked EGA compatibility, while VGA, on the other hand, was almost fully backwards-compatible with EGA. VGA also included other high-resolution display modes.
The 256-color mode proved most popular for gaming, but at the time the MCGA was introduced, many games lacking support for 256-color graphics were forced to fall back to four-color CGA mode (or not run at all) instead of using EGA video modes (320×200 16 colors). However, many other 16-color EGA games (such as older adventure games from Sierra On-line and Lucasfilm Games) specifically supported MCGA in its 320×200 256-color mode, picking the colors most resembling the 16-color RGB palette, while leaving the other available colors in that mode unused. 256-color VGA games ran fine on MCGA as long as they stuck to the basic 320×200 256-color mode and didn't attempt to use VGA-specific features such as multiple screen pages.
The tenure of MCGA was brief; the PS/2 Model 25 and Model 30 (which had an MCGA display adapter integrated into the motherboard) were discontinued by 1992, and no manufacturer produced a clone of this display adapter except for Epson Equity 1, since the VGA standard introduced at the same time was considered superior.[1] MCGA was also rendered redundant to VGA since almost all the capabilities of MCGA were also part of VGA.
Output capabilities
MCGA offered:
- 640x480 monochrome
- 320x200 in 256 colors (from a palette of 262,144)
CGA compatible modes:
- 320x200 in 4 colors from a 16 color hardware palette. Pixel aspect ratio of 1:1.2.
- 640×200 in 2 colors. Pixel aspect ratio of 1:2.4
- 160×100 16 color mode
- 40×25 text mode with 8×8 pixel font (effective resolution of 320×200)
- 80×25 text mode with 8×8 pixel font (effective resolution of 640×200)
See also
References
Scott Mueller Upgrading and Repairing PCs, Second Edition, Que Books, 1992, ISBN 0-88022-856-3