Multi-Color Graphics Array: Difference between revisions

Multi-Color Graphics Array

Release date	1987 (1987)
Cards
Entry-level	IBM PS/2 Model 30 & 25 motherboards; Epson Equity Ie motherboard
History
Predecessor	Color Graphics Adapter
Successor	Video Graphics Array

The Multi-Color Graphics Array or MCGA 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) and used 15-pin analog connectors. The PS/2 chipset's limited abilities prevented EGA compatibility and high-resolution VGA display modes.

The tenure of MCGA was brief; the PS/2 Model 25 and Model 30 were discontinued by 1992, and no manufacturer produced a clone of this display adapter except for Epson Equity Ie, 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 320×200 256-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 (320×200 16 colors). Some adventure games from Sierra On-line and Lucasfilm Games solved this problem by supporting MCGA in its 320×200 256-color mode and picking the colors most resembling the EGA 16-color RGB palette, while leaving the other available colors in that mode unused.

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

• List of defunct graphics chips and card companies

References

• Mueller, Scott (1992). Upgrading and Repairing PCs (Second ed.). Que Books. ISBN 0-88022-856-3.