PC Hardware in a Nutshell, 3rd Edition

I/O bus support

The chipset determines what I/O bus standards the motherboard can support. The chipset manages the I/O busses, arbitrating data transfer between them, the CPU, and system memory. The chipset features determine which I/O busses the system supports, the speed at which the busses operate, and what additional related system features are supported. Depending on how you count, half a dozen or more I/O bus standards have been in common use since the first PCs. In order of their appearance, they include:

Industry Standard Architecture (ISA)

Used in 8-bit form in the PC and XT and 16-bit form in the PC/AT. Obsolete, but most motherboards made through 2000 provided at least one ISA slot for legacy cards. By late 2000, many new motherboard models shipped without ISA slots. Good riddance, we say.

MicroChannel Architecture (MCA)

An IBM standard that never caught on. Obsolete.

Extended Industry Standard Architecture (EISA)

An open standard developed by Compaq and eight other PC makers (the so-called “Gang of Nine”) to compete with the proprietary MCA, but which achieved only limited acceptance, primarily in servers. Obsolete.

VESA Local Bus (VLB)

An open standard that was widely used in 486 systems, but whose technical shortcomings made it inappropriate for Pentium and later systems. Obsolete.

Peripheral Component Interconnect (PCI)

An open standard developed by Intel, used on late-model 486 systems and almost universally for Pentium and later systems. Older PCI systems use ...