Editing Peripheral Component Interconnect (section)

{{Short description|Local computer bus for attaching hardware devices}}
{{redirect|Conventional PCI|the related standard that supersedes PCI|PCI Express}}
{{Use American English|date=May 2023}}

{{Infobox computer hardware bus
| name        = PCI 
| fullname    = PCI Local Bus 
| logo = PCI Local Bus logo.svg
| image       = PCI Slots Digon3.JPG
| caption     = Three 5-volt [[32-bit computing|32-bit]] PCI expansion slots on a [[motherboard]] (PC bracket on left side)
| invent-date = {{Start date and age|1992|06|22}}<ref name="PCI-Spec-2.2pii">{{cite book |title=PCI Local Bus Specification Revision 2.2|date=December 18, 1998 |author=<!--Staff writer(s); no by-line.-->|publisher=[[PCI-SIG|PCI Special Interest Group]]|location=[[Hillsboro, Oregon]]|at=page ii}}</ref>
| invent-name = [[Intel]]
| replaces    = [[Industry Standard Architecture|ISA]], [[Extended Industry Standard Architecture|EISA]], [[Micro Channel architecture|MCA]], [[VESA Local Bus|VLB]]
| super-date  = 2004
| super-name  = [[Accelerated Graphics Port|AGP]] for graphics (1997), [[PCI Express]]
| width       = 32 or 64
| pin count   = 124 [[32-bit computing|32-bit]]
| numdev      =
| speed       = [[Half-duplex]]:<ref>{{Cite web|title=PCIe (Peripheral Component Interconnect Express) {{!}} On the Motherboard {{!}} Pearson IT Certification|url=https://www.pearsonitcertification.com/articles/article.aspx?p=2731934&seqNum=24|access-date=2020-09-25|website=www.pearsonitcertification.com}}</ref>
<br />133&nbsp;[[Megabyte|MB]]/s (32-bit at 33&nbsp;MHz{{snd}} the standard configuration)<br />266&nbsp;MB/s (32-bit at 66&nbsp;MHz)<br />266 MB/s (64-bit at 33&nbsp;MHz)<br />533&nbsp;MB/s (64-bit at 66&nbsp;MHz)
| style       = p
| hotplug     = Optional
}}

'''Peripheral Component Interconnect''' ('''PCI''')<ref>{{Cite web |url=http://www.webopedia.com/TERM/P/PCI.html |title=PCI |date=September 1996 |publisher=Web-o-pedia}}.</ref> is a [[local bus|local]] computer [[Computer bus|bus]] for attaching [[Computer hardware|hardware]] devices in a [[computer]] and is part of the '''PCI Local Bus''' standard. The PCI bus supports the functions found on a [[System bus|processor bus]] but in a standardized format that is independent of any given [[Processor (computing)|processor]]'s native bus. Devices connected to the PCI bus appear to a [[bus mastering|bus master]] to be connected directly to its own bus and are assigned addresses in the processor's [[address space]].<ref>{{cite book |last1=Hamacher |first1=V. Carl |last2=Vranesic |first2=Zvonko G. |last3=Zaky |first3=Safwat G. |date=2002 |title=Computer Organization |edition=5th |publisher=McGraw-Hill |isbn=9780071122184}}</ref> It is a [[parallel communication|parallel]] bus, [[synchronous circuit|synchronous]] to a single [[clock signal|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 compatible]]s, 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 card]]s, [[sound card]]s, [[modem]]s, extra ports such as Universal Serial Bus ([[USB]]) or [[serial port|serial]], [[TV tuner card]]s and [[hard disk drive]] [[host adapter]]s. PCI [[video card]]s replaced ISA and VLB cards until rising [[Bandwidth (computing)|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.<ref>{{Cite web |title=PCI Edition AMD HD 4350 Graphic Card from HIS |url=http://www.hisdigital.com/un/product2-444.shtml |access-date=2009-07-27}}</ref>

The first version of PCI found in retail desktop computers was a [[32-bit computing|32-bit]] bus using a {{val|33|ul=MHz}} bus clock and {{val|5|ul=V}} signaling, although the PCI 1.0 standard provided for a [[64-bit computing|64-bit]] variant as well.<ref name="pci-bus-demystified">{{Cite book |last=Abbott |first=Doug |title=PCI bus demystified |date=2004 |publisher=Newnes |isbn=978-0-7506-7739-4 |edition=2nd |series=Demystifying technology series |location=Amsterdam Boston |pages=xi, 7-10}}</ref> These have one locating notch in the card. Version 2.0 of the PCI standard introduced 3.3&nbsp;V slots, physically distinguished by a flipped physical connector to prevent accidental insertion of 5&nbsp;V cards. Universal cards, which can operate on either voltage, have two notches. Version 2.1 of the PCI standard introduced optional 66&nbsp;MHz operation. A server-oriented variant of PCI, PCI Extended ([[PCI-X]]) operated at frequencies up to 133&nbsp;MHz for PCI-X 1.0 and up to 533&nbsp;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{{snd}} the [[CardBus]].<ref name="Haque1996">{{cite book|last=Imdad-Haque|first=Faisal|year=1996|title=Inside PC Card: CardBus and PCMCIA Design: CardBus and PCMCIA Design|url=https://books.google.com/books?id=Mr8xEbnHYngC&pg=PA39|publisher=Newnes|isbn=978-0-08-053473-2|page=39}}</ref> 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]]).<ref name="SumathiSurekha2007">{{cite book|last1=Sumathi|first1=S.|last2=Surekha|first2=P.|year=2007|title=LabVIEW based Advanced Instrumentation Systems|url=https://books.google.com/books?id=TTP1KDSzMg4C&pg=PA305|publisher=Springer|isbn=978-3-540-48501-8|page=305}}</ref>

PCI and PCI-X sometimes are referred to as either ''Parallel PCI'' or ''Conventional PCI''<ref>[https://documentation.euresys.com/Products/MultiCam/MultiCam_6_16/Content/MultiCam_6_7_HTML_Documentation/PCI_Bus_Variation.pdf PCI Bus Variation]</ref> to distinguish them technologically from their more recent successor [[PCI Express]], which adopted a [[Serial communication|serial]], lane-based architecture.<ref name="Williams2008" /><ref name="Bachmutsky2011">{{cite book|last=Bachmutsky|first=Alexander|year=2011|title=System Design for Telecommunication Gateways|url=https://books.google.com/books?id=q9ky8sw8LoAC&pg=PT81|publisher=John Wiley & Sons|isbn=978-1-119-95642-6|page=81}}</ref> PCI's heyday in the desktop computer market was approximately 1995 to 2005.<ref name="Williams2008">{{cite book|last=Williams|first=John|year=2008|title=Digital VLSI Design with Verilog: A Textbook from Silicon Valley Technical Institute|url=https://books.google.com/books?id=CGZPGmac9JwC&pg=PA67|publisher=Springer|isbn=978-1-4020-8446-1|page=67}}</ref> 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|lc=on}} for the purposes of [[backward compatibility]] and the relative low cost to produce. Another common modern application of parallel PCI is in [[industrial PC]]s, 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.