MicroChannel Architecture BUS

The Micro Channel Architecture (MCA) was IBM's attempt to improve the PC/XT bus and the AT bus (also known as the ISA bus). IBM had completed its design of the AT bus prior to 1987 when the AT standard was approved as the Industry Standard Architecture (ISA). So, in 1983, IBM started the work on a total redesign of system buses even before ISA was approved. The result was the MCA bus.

The MCA was actually a great improvement in its time, but it was developed under numerous concepts not shared outside IBM with the rest of the PC world. Consequently, over time, it did not gain the propularity of ISA and EISA.

Well, this is partly due to IBM's vision that PCs should be able to handle multiple jobs simultaneously, and as a platform to connect to mainframes. The MCA was technically superior to anything available, but not for the direction that PCs took. It had a substantial impact on all subsequent motherboard design throughout the industry. While millions of the MCA motherboards were sold, it was not marketed well, and its technologies could be used under duress of heavy licensing fees.

Needless to say, the rest of the industry manufacturers got together and went a different way. Please see the "EISA" discussion.

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