The Extended Industry Standard Architecture is a bus standard for IBM well-matched computers. It was announced in late 1988 by PC clone vendors as a counter to IBM's use of its proprietary Micro Channel Architecture 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 improved 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.