Expansion Buses

Computers need to communicate with any of a number of peripherals, some of which reside inside the computer's case. The primary link to these internal components is the expansion bus.

As the name implies, the expansion bus of a computer allows you to expand its capabilities by sliding in accessory boards (cleverly termed expansion boards). For this to work, the expansion bus sets up an internal communication channel inside your computer. Expansion slots are spaces inside the computer that provide special sockets or connectors to plug in the capabilities and functions locked in the circuitry of the expansion boards.

In a desktop computer, the expansion bus usually is a row of three or more long connectors on the main circuit board near the back of the computer's case. Depending on the overall design of the computer, one or more of these slots will be filled with expansion boards in the basic factory configuration. In a notebook computer, expansion slots are different, meant to accept modules the size of credit cards that deliver the same functions as expansion boards.