Micro Channel architecture (in practice almost always shortened to MCA) was a proprietary 16 or 32-bit parallel computer bus created by IBM in the 1980s for use on their new PS/2 computers.
Micro-Channel architecture was designed by IBM engineer, Chet Heath and first introduced on the PS/2 series of machines in 1987; it slowly spread to IBM's entire computer line. For a time, MCA could be found in the PS/2, RS/6000, AS/400, and even some of the System/370 mainframes. However, most of these systems later were redesigned to incorporate PCI. MCA is no longer used in new designs.
MCA was primarily a 32-bit bus, but the system also supported a 16-bit mode designed to lower the cost of connectors and logic in Intel-based machines like the IBM PS/2.
The situation was never that simple, however, as both the 32-bit and 16-bit versions initially had a number of additional optional connectors for memory cards which resulted in a huge number of physically incompatible cards for bus attached memory. In time, memory moved to the CPU's local bus, thereby eliminating the problem. On the upside, signal quality was greatly improved as MCA added ground and power pins and arranged the pins to minimize interference, a ground or a supply was thereby located within 3 pins of every signal.
Comments