IBM MCGA Gate Array Reverse Engineering

IBM MCGA Gate Array Reverse Engineering IBM's MCGA (Multi-Color Graphics Array) is a low-cost video chipset introduced with the PS/2 models 25 and 30. The Epson Equity 1e uses MCGA compatible video but does not use the same chips. The IBM chipset consists of the memory controller gate array and the video formatter gate array. Some examples of these were fabricated on an internal IBM gate array process, while others used an external gate array part by Seiko. Memory Controller Gate Array (72X8300) This gate array contains an implementation of the MC6845 sync generator IC, manages the video RAM interface to the ISA bus, manages the character RAM interface, and a few other miscellaneous functions including clock selection and monitor ID readback.

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Excerpt limited to ~120 words for fair-use compliance. The full article is at GitHub.