Conventional PCI

Conventional PCI (PCI is an initialism formed from Peripheral Component Interconnect, part of the PCI Local Bus standard and often shortened to PCI) is a local computer bus for attaching hardware devices in a computer. The PCI bus supports the functions found on a processor bus, but in a standardized format that is independent of any particular processor. Devices connected to the bus appear to the processor to be connected directly to the processor bus, and are assigned addresses in the processor's address space.

Attached devices can take either the form of an integrated circuit fitted onto the motherboard itself, called a planar device in the PCI specification, or an expansion card that fits into a slot. The PCI Local Bus was first implemented in IBM PC compatibles, where it displaced the combination of ISA plus one VESA Local Bus as the bus configuration. It has subsequently been adopted for other computer types. PCI is being replaced by PCI-X and PCI Express, but as of 2011, most motherboards are still made with one or more PCI slots, which are sufficient for many uses.

The PCI specification covers the physical size of the bus (including the size and spacing of the circuit board edge electrical contacts), electrical characteristics, bus timing, and protocols. The specification can be purchased from the PCI Special Interest Group (PCI-SIG).

Typical PCI cards used in PCs include: network cards, sound cards, modems, extra ports such as USB or serial, TV tuner cards and disk controllers. PCI video cards replaced ISA and VESA cards, until growing bandwidth requirements outgrew the capabilities of PCI; the preferred interface for video cards became AGP, and then PCI Express. PCI video cards remain available for use with old PCs without AGP or PCI Express slots.

Many devices previously provided on PCI expansion cards are now commonly integrated onto motherboards or available in universal serial bus and PCI Express versions.