This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Modern motherboard with isa slot help to improve this article by introducing more precise citations. AT and similar computers based on the Intel 80286 and its immediate successors during the 1980s. XT as well as IBM PC compatibles.
The ISA concept was coined by competing PC-clone manufacturers in the late 1980s or early 1990s as a reaction to IBM attempts to replace the AT-bus with its new and incompatible Micro Channel architecture. The 16-bit ISA bus was also used with 32-bit processors for several years. Later buses such as VESA Local Bus and PCI were used instead, often along with ISA slots on the same mainboard.
The ISA bus was developed by a team led by Mark Dean at IBM as part of the IBM PC project in 1981. It originated as an 8-bit system.
The newer 16-bit standard, the IBM AT bus, was introduced in 1984. XT, and the 16-bit version as an upgrade for the external bus of the Intel 80286 CPU used in the IBM AT.
Therefore, the ISA bus was synchronous with the CPU clock, until sophisticated buffering methods were developed and implemented by chipsets to interface ISA to much faster CPUs. Designed to connect peripheral cards to the motherboard, ISA allows for bus mastering although only the first 16 MB of main memory are available for direct access.