The abbreviation ISA stands for "Industry Standard Architecture." ISA is a form of interface used to introduce expansion devices to PCs. An ISA interface may be used to install a video card, network card, or additional serial port, for instance. The original 8-bit version of PCI employs a 62-pin connection and supports 8 and 33 MHz clock rates. 16-bit PCI supports the same clock rates and employs 98 connections.

The initial 8-bit version of ISA was introduced in 1981, but the technology was not extensively adopted until 1984, when the 16-bit version was introduced. During the majority of the 1980s and 1990s, ISA remained the most prevalent expansion bus despite the use of two competing technologies, MCA and VLB, by a few manufacturers. At the end of the 20th century, however, ISA terminals began to be supplanted by speedier PCI and AGP sockets. The majority of computers only support PCI and AGP expansion devices at present.