Multi-Color Graphics Array

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The Multi-Color Graphics Array or MCGA is a video subsystem built into the motherboard of the IBM PS/2 Model 30, 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 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 Epson, 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 Sierra On-line and Lucasfilm Games, as well as simulation and strategy titles from Microprose, 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: CGA compatible modes:

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