Peripheral Component Interconnect

"Conventional PCI" redirects here. For the related standard that supersedes PCI, see PCI Express.

PCI
PCI Local Bus
Three 5-volt 32-bit PCI expansion slots on a motherboard (PC bracket on left side)
Year createdJune 22, 1992; 32 years ago (1992-06-22)[1]
Created byIntel
SupersedesISA, EISA, MCA, VLB
Superseded byAGP for graphics (1997), PCI Express (2004)
Width in bits32 or 64
SpeedHalf-duplex:[2]
133 MB/s (32-bit at 33 MHz – the standard configuration)
266 MB/s (32-bit at 66 MHz)
266 MB/s (64-bit at 33 MHz)
533 MB/s (64-bit at 66 MHz)
StyleParallel
Hotplugging interfaceOptional
Websitewww.pcisig.com/home

Peripheral Component Interconnect (PCI)[3] is a local computer bus for attaching hardware devices in a computer and is part of the PCI Local Bus standard. The PCI bus supports the functions found on a processor bus but in a standardized format that is independent of any given processor's native bus. Devices connected to the PCI bus appear to a bus master to be connected directly to its own bus and are assigned addresses in the processor's address space.[4] It is a parallel bus, synchronous to a single bus clock. Attached devices can take either the form of an integrated circuit fitted onto the motherboard (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 several slow Industry Standard Architecture (ISA) slots and one fast VESA Local Bus (VLB) slot as the bus configuration. It has subsequently been adopted for other computer types. Typical PCI cards used in PCs include: network cards, sound cards, modems, extra ports such as Universal Serial Bus (USB) or serial, TV tuner cards and hard disk drive host adapters. PCI video cards replaced ISA and VLB cards until rising bandwidth needs outgrew the abilities of PCI. The preferred interface for video cards then became Accelerated Graphics Port (AGP), a superset of PCI, before giving way to PCI Express.[5]

The first version of PCI found in retail desktop computers was a 32-bit bus using a 33 MHz bus clock and 5 V signaling, although the PCI 1.0 standard provided for a 64-bit variant as well.[clarification needed] These have one locating notch in the card. Version 2.0 of the PCI standard introduced 3.3 V slots, physically distinguished by a flipped physical connector to prevent accidental insertion of 5 V cards. Universal cards, which can operate on either voltage, have two notches. Version 2.1 of the PCI standard introduced optional 66 MHz operation. A server-oriented variant of PCI, PCI Extended (PCI-X) operated at frequencies up to 133 MHz for PCI-X 1.0 and up to 533 MHz for PCI-X 2.0. An internal connector for laptop cards, called Mini PCI, was introduced in version 2.2 of the PCI specification. The PCI bus was also adopted for an external laptop connector standard – the CardBus.[6] The first PCI specification was developed by Intel, but subsequent development of the standard became the responsibility of the PCI Special Interest Group (PCI-SIG).[7]

PCI and PCI-X sometimes are referred to as either Parallel PCI or Conventional PCI[8] to distinguish them technologically from their more recent successor PCI Express, which adopted a serial, lane-based architecture.[9][10] PCI's heyday in the desktop computer market was approximately 1995 to 2005.[9] PCI and PCI-X have become obsolete for most purposes and has largely disappeared from many other modern motherboards since 2013; however they are still common on some modern desktops as of 2020 for the purposes of backward compatibility and the relative low cost to produce. Another common modern application of parallel PCI is in industrial PCs, where many specialized expansion cards, used here, never transitioned to PCI Express, just as with some ISA cards. Many kinds of devices formerly available on PCI expansion cards are now commonly integrated onto motherboards or available in USB and PCI Express versions.

  1. ^ PCI Local Bus Specification Revision 2.2. Hillsboro, Oregon: PCI Special Interest Group. December 18, 1998. page ii.
  2. ^ "PCIe (Peripheral Component Interconnect Express) | On the Motherboard | Pearson IT Certification". www.pearsonitcertification.com. Retrieved 2020-09-25.
  3. ^ "PCI". Web-o-pedia. September 1996..
  4. ^ Hamacher, V. Carl; Vranesic, Zvonko G.; Zaky, Safwat G. (2002). Computer Organization (5th ed.). McGraw-Hill. ISBN 9780071122184.
  5. ^ "PCI Edition AMD HD 4350 Graphic Card from HIS". Retrieved 2009-07-27.
  6. ^ Imdad-Haque, Faisal (1996). Inside PC Card: CardBus and PCMCIA Design: CardBus and PCMCIA Design. Newnes. p. 39. ISBN 978-0-08-053473-2.
  7. ^ Sumathi, S.; Surekha, P. (2007). LabVIEW based Advanced Instrumentation Systems. Springer. p. 305. ISBN 978-3-540-48501-8.
  8. ^ PCI Bus Variation
  9. ^ a b Williams, John (2008). Digital VLSI Design with Verilog: A Textbook from Silicon Valley Technical Institute. Springer. p. 67. ISBN 978-1-4020-8446-1.
  10. ^ Bachmutsky, Alexander (2011). System Design for Telecommunication Gateways. John Wiley & Sons. p. 81. ISBN 978-1-119-95642-6.