Editing Peripheral Component Interconnect (section)

==History==
[[File:Adaptec AHA-2940AU.png|thumb|A typical 32-bit, 5&nbsp;V-only PCI card, in this case, a [[SCSI]] adapter from [[Adaptec]] ]]
[[File:PCI und PCIe Slots.jpg|thumb|A motherboard with two 32-bit PCI slots and two sizes of PCI Express slots]]

Work on PCI began at the [[Intel Architecture Labs]] (IAL, also Architecture Development Lab) {{circa|1990}}. A team of primarily IAL engineers defined the architecture and developed a proof of concept chipset and platform (Saturn) partnering with teams in the company's desktop PC systems and core logic product organizations.

PCI was immediately put to use in servers, replacing [[Micro Channel architecture]] (MCA) and [[Extended Industry Standard Architecture]] (EISA) as the server expansion bus of choice. In mainstream PCs, PCI was slower to replace [[VESA Local Bus|VLB]], and did not gain significant market penetration until late 1994 in second-generation [[P5 (microarchitecture)|Pentium]] PCs. By 1996, VLB was all but extinct, and manufacturers had adopted PCI even for [[Intel 80486]] (486) computers.<ref>VLB was designed for 486-based systems, yet even the more generic PCI was to gain prominence on that platform.</ref> EISA continued to be used alongside PCI through 2000. [[Apple Computer]] adopted PCI for professional [[Power Macintosh]] computers (replacing [[NuBus]]) in mid-1995, and the consumer [[Macintosh Performa|Performa]] product line (replacing LC [[Processor Direct Slot]] (PDS)) in mid-1996.

Outside the server market, the 64-bit version of plain PCI remained rare in practice though,<ref name="Meyers2012">{{cite book |last=Meyers |first=Michael |year=2012 |title=CompTIA A+ Certification All-in-One Exam Guide |edition=8th |publisher=McGraw Hill Professional |isbn=978-0-07-179512-8 |page=339}}</ref> although it was used for example by all [[Power Macintosh G3|(post-iMac) G3]] and [[Power Mac G4|G4 Power Macintosh computers]].<ref>[http://knowledge.lacie.com/articles/en_US/FAQ/006353en Identify a variety of PCI slots], LaCie</ref>

Later revisions of PCI added new features and performance improvements, including a 66&nbsp;[[MegaHertz|MHz]] 3.3&nbsp;[[Volt|V]] standard and 133&nbsp;MHz [[PCI-X]], and the adaptation of PCI signaling to other form factors. Both PCI-X&nbsp;1.0b and PCI-X&nbsp;2.0 are backward compatible with some PCI standards. These revisions were used on server hardware but consumer PC hardware remained nearly all 32-bit, 33&nbsp;MHz and 5 volt.

The PCI-SIG introduced the serial [[PCI Express]] in {{circa|2004}}. Since then, motherboard manufacturers gradually included fewer or zero PCI slots in favor of the new standard. [[Adapter (computing)|Bridge adapters]] allow the use of legacy PCI cards with PCI Express motherboards.

{| class="wikitable"
|+ PCI history<ref>{{cite web| url = http://www.pcisig.com/specifications/PCI_Family_History.pdf| title = PCI Family History}}</ref>
|-
! Spec !! Year !! Change summary<ref name="pci30"/>
|-
| PCI 1.0 || 1992 || Original issue
|-
| PCI 2.0 || 1993 || Incorporated connector and add-in card specification
|-
| PCI 2.1 || 1995 || Incorporated clarifications and added 66&nbsp;MHz chapter
|-
| PCI 2.2 || 1998 || Incorporated [[Engineering change orders|ECN]]s, and improved readability
|-
| PCI 2.3 || 2002 || Incorporated ECNs, errata, and deleted 5 volt only keyed add-in cards
|-
| PCI 3.0 ||2004|| Removed support for 5.0 volt keyed system board connector
|}