Multi-Color Graphics Array
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The Multi-Color Graphics Array or MCGA is a video subsystem built into the
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of the
IBM PS/2 Model 30 The Personal System/2 Model 30 and Personal System/2 Model 30 286 are IBM's entry-level desktop computers in their IBM PS/2, Personal System/2 (PS/2) family of personal computers. As opposed to higher-end entries in the PS/2 line which use Micro ...
, introduced in April 1987, and Model 25, introduced later in August 1987; no standalone MCGA cards were ever made. The MCGA supports all CGA display modes plus monochrome at a refresh rate of 60  Hz, and with 256 colors (out of an 18-bit RGB palette of 262,144) at 70 Hz. The display adapter uses a DE-15 connector, sometimes referred to as HD-15. MCGA is similar to
VGA Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the IBM PS/2 line of computers in 1987, which became ubiquitous in the IBM PC compatible industry within three years. T ...
in that it had a 256-color mode (the 256-color mode in VGA was sometimes referred to as MCGA) and uses 15-pin analog connectors. The PS/2 chipset's limited abilities prevent EGA compatibility and high-resolution multi-color VGA display modes. The tenure of MCGA was brief; the PS/2 Model 25 and Model 30 were discontinued by 1992, and the only manufacturer to produce a clone of this display adapter was
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, in the Equity Ie and PSE-30, since the VGA standard introduced at the same time was considered superior.


Software support

The 256-color mode proved most popular for gaming. 256-color VGA games ran fine on MCGA as long as they stuck to the basic 256-color mode and didn't attempt to use VGA-specific features such as multiple screen pages. Games lacking support for 256-color graphics were forced to fall back to four-color CGA mode (or not run at all) due to the incompatibility with EGA video modes (, , or , all in 16 colors). Some games, including point-and-click adventures from
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and
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, as well as simulation and strategy titles from
Microprose MicroProse is an American video game publisher and video game developer, developer founded by Bill Stealey, Sid Meier, and Andy Hollis in 1982. It developed and published numerous games, including starting the ''Civilization (series), Civilizat ...
, solved this problem for low-resolution titles by supporting the MCGA's 256-color mode and picking the colors most resembling the EGA 16-color RGB palette, while leaving the other available colors in that mode unused. Higher resolution titles were often unsupported unless graphics could be converted into either MCGA low or high ( monochrome, which would also support and with some letterboxing) resolution mode in an acceptable fashion. An alternative approach used by a small number of (generally earlier) games was to use four-color CGA assets but make use of the adaptor's ability to freely change the palette for a slightly enhanced appearance.


Output capabilities

MCGA offered: * monochrome (mode 11h) * in 256 colors (from a palette of 262,144; mode 13h) CGA compatible modes: * text mode with 8×8 pixel font (effective resolution of ; mode 0/1h) * text mode with 8×8 pixel font (effective resolution of ; mode 2/3h) * in four colors from a 16 color hardware palette with a pixel aspect ratio of 1:1.2. (mode 4/5h) * in two colors with a pixel aspect ratio of 1:2.4 (mode 6h)


See also

* List of defunct graphics chips and card companies


References

* {{IBM personal computers Computer display standards IBM PS/2 Multi-Color Graphics Adapter Computer-related introductions in 1987