Multi-Color 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.^[1]

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.^[2]

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. 

Computer display standards Video hardware MDA (1981) CGA (1981) Orchid Graphics Adapter (1982) Hercules (1982) Plantronics Colorplus (1982) Tandy (1984) PGC (1984) EGA (1984) MCGA (1987) VGA (1987) 8514 (1987) SVGA (1987) TIGA (1989) XGA (1990) Size comparison Display resolutions 160×120 240×160 320×200 320×240 480×320 640×200 640×350 640×400 640×480 720x348 800×600 1024×768 1280×800 1366×768 1152×864 1280×1024 1400×1050 1920×1080 2048×1152 1600×1200 1920×1200 2048×1536 2560×1600 2560×2048 3200×2400 4096×3072 5120×4096 6400×4096 6400×4800 7680×4800 Widescreen variants 432×240 800×480 854×480 1024×576 1280×720 1280×768 1366×900 1440×900 1600×900 1680×945 1680×1050 1920×1080 2560×1440 3200×2048 3840×2160 3200×2400 5120x2880 5120×3200 5760x3240 6400×4096 7680×4320 15360x8640