Peripheral Component Interconnect Details, Meaning Peripheral Component Interconnect Article and Explanation Guide

Peripheral Component Interconnect Guide, Meaning , Facts, Information and Description

For other meanings of PCI, see PCI (disambiguation).

]] The Peripheral Component Interconnect standard (in practice almost always shortened to PCI) specifies a computer bus for attaching peripheral devices to a computer motherboard in a so-called local bus. These devices can take the form of:

integrated circuits fitted on the motherboard itself (called planar devices in the PCI specification); or
expansion cards that fit in sockets.

Table of contents

1 Configuration
2 Basic PCI bus specifications
3 Basic PCI variants
4 Other PCI variants
5 See also
6 External links

Configuration

PCI occurs commonly in PCs, where it has displaced ISA as the standard bus, but it also appears in other computer types. Unlike ISA buses, the PCI bus enables dynamic configuration of a peripheral device. At boot-up time the PCI card's BIOS and the system BIOS interact and negotiate the resources that the PCI card requests. This enables allocation of IRQs and port addresses through a dynamic process, unlike the ISA bus scenario, which required manual configuration of IRQs using external jumpers. Apart from this, the PCI bus provides a detailed description of all the connected PCI devices through the PCI Configuration Space, making plug and play very practical.

The PCI specification covers the physical size of the bus (including wire spacing), electrical characteristics, bus timing and protocols. The PCI Special Interest Group (PCISIG) sells copies of the specification at http://www.pcisig.com/.

Basic PCI bus specifications

33.33 MHz clock with synchronous transfers
peak transfer rate of 133MB per second
32-bit or 64-bit bus width
32-bit address space (4G bytes)
16-bit port space (now deprecated)
256 byte configuration space
3.3- or 5-volt signalling
reflected-wave switching

Basic PCI variants

PCI 2.2 allows for 66MHz signalling (requires 3.3 volt signalling) (peak transfer 533 MB/s)

PCI-X changes the protocol slightly and increases the data rate to 133MHz (peak transfer 1066 MB/s)

PCI-X 2.0 specifies a 266MHz rate (peak transfer 2133 MB/s), expands the configuration space to 4096 bytes, adds a 16-bit bus variant and allows for 1.5 volt signalling

Mini PCI is a new form factor for use mainly inside laptops

Cardbus is a PCMCIA form factor for 32-bit, 33MHz PCI

Compact PCI, uses Eurocard-sized modules plugged into a PCI backplane.

Other PCI variants

PCI-Express (or 3GIO), a serial bus using PCI signalling and programming concepts

External links

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