Editing Micro Channel architecture (section)

== Background ==
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The development of Micro Channel was driven by both technical and business pressures.

=== Technology ===
The [[IBM AT]] bus, which later became known as the [[Industry Standard Architecture]] (ISA) bus, had a number of technical design limitations, including:
* A slow bus speed.
* A limited number of [[interrupt]]s, fixed in hardware.
* A limited number of [[I/O device]] addresses, also fixed in hardware.
* Hardwired and complex configuration with no conflict resolution.
* Deep links to the architecture of the [[80x86]] chip family<ref group='NB'>Use of the ISA bus outside of machines employing the 80x86 CPU family was rare.  Notable non-x86 hardware that used the ISA bus include the [[IBM RT PC]], [[BeBox]], some [[Apollo/Domain]] workstations, and some members of the [[Digital Equipment Corporation|Digital Equipment]] [[AlphaServer]] line.</ref>
In addition, it suffered from other problems:
* Poor [[Ground (electricity)|grounding]] and power distribution.
* Undocumented bus interface standards that varied between systems and manufacturers.

These limitations became more serious as the range of tasks and peripherals, and the number of manufacturers for [[IBM PC compatible|IBM PC-compatibles]], grew. IBM was already investigating the use of [[RISC]] processors in desktop machines, and could, in theory, save considerable money if a single well-documented bus could be used across their entire computer lineup.

=== Market share ===
It was thought that by creating a new standard, IBM would regain control of standards via the required licensing. As patents can take three years or more to be granted, however, only those relating to ISA could be licensed when Micro Channel was announced. Patents on important Micro Channel features, such as [[Plug and Play]] automatic configuration, were not granted to IBM until after PCI had replaced Micro Channel in the marketplace. The overall reception was tepid and the impact of Micro Channel in the worldwide PC market was minor.