Micro Channel Architecture
The Micro Channel Architecture ( MCA , German microchannel ) is a proprietary bus system from IBM with a bus width of up to 32 bits and a bus rate of 10 MHz . From 1987 it was found in PS / 2 personal computers , but also in RS / 6000 workstations, AS / 400 mini-computers and even some System / 370 mainframes. Some early ThinkPads also used MCA.
The MCA bus tried to solve the problems of the first IBM AT bus, now known as the ISA bus:
- higher data throughput (theoretically 66 Mbytes / s)
- shared interrupt lines
- Support of several bus masters with DMA
- Configuration register
- Processor independence
- automatic card recognition
- improved electrical properties
MCA is incompatible with all other bus systems.
One of the motivations for IBM to develop its own bus system was to regain the expansion card market.
However, the MCA bus was unable to establish itself over the other bus systems on the market, as only a few and very expensive cards were available and older ISA cards could no longer be used. Manufacturers of MCA cards also had to purchase an expensive license from IBM . With the PCI bus, MCA almost completely disappeared from the market.
