Expansion Card or Add-in Cards

A printed circuit board that plugs into an expansion slot in a computer to provides some extra facility. The sockets normally connect to a bus, and the type of connector and the use to which each contact is put are strictly defined to ensure compatibility between the card and the computer. Cards are available that provides extra memory, communications interfaces, sound I/O capabilities, device interface to extra disks or tape backup devices for instance, or perhaps extra processors in multiprocessor systems.