Micro Channel Architecture (MCA) was a 32-bit bus developed by IBM that was used in some of their machines. It eliminated the need for adjusting DIP switches on expansion cards by using a unique ID on MCA cards. MCA had a data transfer rate of 20 to 80 MBytes/sec and supported 15 levels of bus mastering. However, IBM stopped using it in 1996 in favor of PCI. MCA, alongside other expansion card types like ISA, EISA, VL-bus, and AGP, are no longer supported by PCs, with PCI and PCI Express gaining popularity.
What is Micro Channel Architecture?
Micro Channel Architecture, which is also known as MCA, is a 32-bit bus introduced by IBM in the year 1987. It was primarily used in the PS/2, RS/6000, and a few ES/9370 machines. The main aim behind introducing MCA was to overcome the limitations of the traditional bus structures of the time that were used in PCs.
With the addition of Micro Channel architecture, IBM aimed to solve the problems that arose with the then-common peripheral expansion method, adjusting the DIP switches on ISA cards. MCA solved this issue with the inclusion of a unique ID on Micro Channel cards- making it much easier to configure the hardware devices plugged into the system.
Expansion Card Types
Apart from Micro Channel architecture, there were other expansion cards available such as ISA, EISA, VL-bus, and AGP. However, with the advancement in technology, these types of expansion cards have become outdated now. The buses that are widely used now include PCI (Peripheral Component Interconnect) and PCI Express.
In terms of data transfer rate, Micro Channel Architecture performed quite well with rates up to 20 to 80 MBytes/sec. Moreover, it also supported 15 levels of bus mastering. However, the popularity and demand of PCI forced IBM to abandon MCA and move on to a new type of bus structure.
Why was MCA Discontinued?
MCA had its fair share of technical limitations that eventually led to its discontinuation. The biggest reason was the emergence of other superior bus structures like PCI that were faster, cheaper, and more flexible compared to MCA. Other reasons that led to the discontinuation of MCA include the compatibility issues and considerably high cost of manufacturing Micro Channel-compatible devices.
The kernel
The introduction of Micro Channel architecture marked a significant advancement in the field of computer hardware. With the elimination of DIP switch configuration and faster data transfer rates, it added value to the traditional bus structures of the time. However, the emergence of more improved and efficient bus structures like PCI led to the discontinuation of Micro Channel Architecture, and today it is no longer used in PC hardware.
