PCI Technologies

Home Downloads Order  

Site Map
Tech Info


PCI Technologies
SATA to PATA Power Adapter
Serial/Parallel Card








PCI Technology Overview
􀂄 PCI Technologies
􀂃 Conventional PCI
􀂃 PCI Express
PCI Technologies

Conventional PCI
􀂾 Initial PCI 1.0 proposal by Intel in 1991
􀂾 Introduced by PCI-SIG as PCI 2.0 in 1993
􀂾 Version 2.1 approved in 1995
􀂾 Recent version 2.3 approved in March 2002

PCI Express
􀂾 Formerly known as 3GIO
􀂾 Version 1.0 approved in July 2002

􀂾 Version 1.0 approved in September 1999
􀂾 Version 2.0 approved in July 2002

Definition of PCI
PCI: Peripheral Component Interconnect
PCI is a local bus standard for connecting peripherals to a personal computer. Within a computer, the bus is the transmission path on which signals and data transfers occur between the CPU, system memory, and attached devices such as a network card, sound card, or CD-ROM drive.

Conventional PCI 􀂄 Plug-and-Play Functionality
􀂄 Standard PCI is 32 bit and operates at 33 MHz
    32-Bit throughput 133 MB/sec
􀂄 PCI 2.1 introduced
    Universal PCI cards supporting both 3.3V and 5V
    64 Bit slots and 66 MHz capability
    32-Bit throughput @ 66 MHz: 266 MB/sec
    64-Bit throughput @ 66 MHz: 532 MB/sec
􀂄 PCI 2.3 system no longer supports 5V-only adapters
    3.3V and Universal PCI products are still fully supported

The PCI Local Bus (usually shortened to PCI), or Conventional PCI, is a computer bus for attaching hardware devices in a computer.  The PCI bus is common in PCs, where it displaced ISA Local Bus as the standard expansion bus. Despite the availability of faster interfaces such as PCI-X and PCI Express, conventional PCI remains a very common interface.

The PCI specification covers the physical size of the bus (including wire spacing), electrical characteristics, bus timing, and protocols.

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. Historically video cards were typically PCI devices, but growing bandwidth requirements soon outgrew the capabilities of PCI. replaced by AGP or PCI Express cards.

Many PCI devices traditionally provided on expansion cards are now  integrated onto the motherboard itself.


Comparison of 5v and 3.3v PCI Slots & Cards

Note: 32-Bit PCI boards can normally be used in 64-bit slots


PCI Express 􀂄 High-speed point-to-point architecture that is essentially a serialized, packetized version of PCI
􀂄 General purpose serial I/O bus for chip-to-chip communication, USB 2.0 / IEEE 1349b interconnects, and high-end graphics. A viable AGP replacement.
􀂄 Bandwidth 4 Gigabit/second full duplex per lane
    Up to 32 separate lanes
    128 Gigabit/second
􀂄 Software-compatible with PCI device driver model
􀂄 Expected to coexist with and not displace technologies like PCI-X in the foreseeable future


PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP standards. Introduced by Intel in 2004, PCIe (or PCI-E, as it is commonly called) is the latest standard for expansion cards that is available on mainstream personal computers

PCI Express is used in consumer, server, and industrial applications, both as a motherboard-level interconnect (to link motherboard-mounted peripherals) and as an expansion card interface for add-in boards. A key difference between PCIe and earlier PC buses is a topology based on point-to-point serial links, rather than a shared parallel bus architecture.

  Tech note
Since PCI Express is a serial based technology, data can be sent over the bus in two directions at once. Normal PCI is Parallel, and as such all data goes in one direction.

Each 1x lane in PCI Express can transmit in both directions at once. PCI Express bandwidth is not shared the same way as in PCI, so there is less congestion on the bus.

The "x" in an "x16" connection stands for "by." PCIe connections are scalable by one, by two, by four, and so on.

When the computer starts up, PCIe determines which devices are plugged into the motherboard. It then identifies the links between the devices, creating a map of where traffic will go and negotiating the width of each link.



PCI-X (PCI eXtended) is a computer bus and expansion card standard that enhanced the PCI Local Bus for higher bandwidth demanded by servers. It is a double-wide version of PCI, running at up to four times the clock speed, but is otherwise similar in electrical implementation and uses the same protocol. It has itself been replaced in modern designs by the similar-sounding PCI Express, which features a very different logical design, most notably being a "narrow but fast" serial connection instead of a "wide but slow" parallel connection.

PCI-X 1.0
􀂄 Based on existing PCI architecture
􀂄 64-Bit slots with support for 3.3V and Universal PCI
􀂾 No support for 5V-only boards
􀂄 Fully backwards-compatible
􀂾 Conventional 33/66 MHz PCI adapters can be used in PCI-X slots
􀂾 PCI-X adapters can be used in conventional PCI slots
􀂄 Provides two speed grades: 66 MHz and 133 MHz
􀂾 The slowest board dictates the maximum speed on a particular bus
􀂄 Targeted at high-end data networking and storage network applications

PCI-X 2.0
􀂾 Based on PCI-X 1.0
􀂾 Still fully backwards-compatible
􀂄 Introduces ECC (Error Correction Codes) mechanism to improve robustness and data integrity
􀂄 Provides two additional speed grades
􀂾 PCI-X 266: 266 MHz (2.13 GB/sec)
􀂾 PCI-X 533: 533 MHz (4.26 GB/sec)
􀂄 Bandwidth sufficient to support new breed
of cutting-edge technologies
􀂾 10 Gigabit Ethernet / Fiber Channel
􀂾 4X / 12X InfiniBand

PCI-X 3.0
􀂾 Became available in  2004
􀂄 Backwards-compatible with PCI-X 1.0 / 2.0
􀂄 PCI-X 1066 provides 1066 MHz data rate with 8.5 GB/sec bandwidth

PCI-X Speed Limitations
􀂄 PCI-X supports point-to-point and multi-drop loads
􀂄 Highest speed grades are supported exclusively with point-to-point loads
 PCI-X 133
 PCI-X 266
 PCI-X 533
 PCI-X 1066
􀂄 Two PCI-X 133 loads operate at 100 MHz
􀂄 Four loads operate at a maximum of 66 MHz
􀂄 OEMs can build connector-less systems with multiple loads utilizing high speed grades

Some technical information provided by Digi.com


  Products | Specials | Site Map | Support | Tech Info | Contact | Search | Search
Copyright 2010 Beagle Software. All rights reserved
Last reviewed January 07, 2010