Extended Industry Standard Architecture

The Extended Industry Standard Architecture (in practice almost always shortened to EISA) is a bus standard for IBM compatible computers. It was announced in late 1988 by PC clone vendors as a counter to IBM's use of its proprietary MicroChannel Architecture (MCA) in its PS/2 series.

EISA extends the ISA bus architecture to 32 bits and allows more than one CPU to share the bus. The bus mastering support is also enhanced to provide access to 4 GB of memory. Unlike MCA, EISA can accept older XT and ISA boards — the lines and slots for EISA are a superset of ISA.

Although somewhat inferior to MCA, EISA was much favoured by manufacturers due to the proprietary nature of MCA, and even IBM produced some machines supporting it. But by the time there was a strong market need for a bus of these speeds and capabilities, the VESA Local Bus and later PCI filled this niche and EISA vanished into obscurity.

External links

• EISA bus technical summary

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This article was originally based on material from the Free On-line Dictionary of Computing and is used with permission under the GFDL.