EXPANSION SLOT

Bus

When referring to a computer, the bus also known as the address bus, data bus, or local bus is a data connection between two or more devices connected to the computer. For example, a bus enables a computer processor to communicate with the memory or a video card to communicate with the memory.
A bus is capable of being a parallel orserial bus and today all computers utilize two bus types, an internal bus or local bus and an external bus, also called the expansion bus. An internal bus enables a communication between internal components such as a computer video card and memory and an external bus is capable of communicating with external components such as a USB or SCSI device.
A computer or device's bus speed or throughput is always measured in bits per second or megabytes per second.

AGP

Short for Accelerated Graphics Port, AGP is an advanced port designed for Video cards and 3D accelerators. Designed by Intel and introduced in August of 1997, AGP introduces a dedicated point-to-point channel that allows the graphics controller direct access the system memory. Below is an illustration of what the AGP slot may look like on your motherboard.
The AGP channel is 32-bits wide and runs at 66 MHz. This translates into a total bandwidth of 266 MBps, which is much greater than the PCI bandwidth of up to 133 MBps. AGP also supports two optional faster modes, with throughput of 533 MBps and 1.07 GBps. It also allows 3-D textures to be stored in main memory rather than video memory.
Each computer with AGP support will either have one AGP slot or on-board AGP video. If you needed more than one video card in the computer, you can have one AGP video card and one PCI video card or use a motherboard that supports SLI.
Tip: Not all operating systems support AGP because of limited or no driver support. For example, Windows 95 did not incorporate AGP support. See the Windows versions page for information about Windows versions that support AGP.

What is AGP Pro?
AGP Pro is an AGP interface extension specification for advanced workstations. This specification delivers additional power to video cards, includes an extended connector, thermal envelope, updated mechanical specifications, I/O bracket, and motherboard layout requirements.

AMR

Released September 8, 1998, AMR is short for Audio/Modem Riser and allows OEMs to make one card that has the functionality of either Modem or Audio or both Audio and Modem on one card. This specification allows for the motherboard to be manufactured at a lower cost and free up industry standard expansion slots in the system for other additional plug-in peripherals. In the picture to the right, is an example of what the AMR slot looks like on the Motherboard. This slot is often on the far edge of the motherboard, next to a PCI slot.

CNR

Short for Communication and Network Riser, CNR is a specification that supports audio, modem USB, and Local Area Networking interfaces of core logic chipsets. This technology and the CNR slot was first introduced by Intel February 7, 2000 and was mainly developed by leading hardware and software developers who helped release the AMR (Audio Modem Riser). Today, this slot is no longer found on motherboards.
Additional information about CNR and other computer buses can be found on our computer bus help page.

EISA

Short for Extended Industry Standard Architecture, EISA, also known as Extended ISA, is a standard first announced in September of 1988 for IBM and IBM compatible computers to compete with the IBM MCA bus. The EISA bus is found on Intel 80386, 80486 and early Pentium computers and was designed by nine competitors to compete with IBM's MCA bus. These competitors were AST Research, Compaq, Epson, Hewlett Packard, NEC, Olivetti, Tandy, WYSE, and Zenith Data Systems.
The EISA bus provided 32-bit slots at an 8.33 MHz cycle rate for use with 386DX or higher processors. In addition, the EISA can accommodate a 16-bit ISA card in the first row.
Although the EISA bus is backwards compatible and not a proprietary bus, it never became widely used and is no longer found in computers today.

ISA

1. Short for Industry Standard Architecture, ISA was introduced by IBM and was originally an 8-bit computer bus that was later expanded to a 16-bit bus in 1984. When this bus was originally released it was a proprietary bus, which allowed only IBM to create peripherals and the actual interface. However, in the early 1980's other manufacturers were creating the bus.
In 1993, Intel and Microsoft introduced a PnP ISA bus that allowed the computer to automatically detect and setup computer ISA peripherals, such as a modem or sound card. Using the PnP technology, an end-user would have the capability of connecting a device and not having to configure the device using jumpers or dip switches.
All recent computers today no longer included the ISA slots and instead are using more PCI and AGP slots. Below is a graphic of what an ISA expansion card may look like as well as the slot it connects into on the motherboard.

Mini PCI

Mini PCI is a standard that measures at 2.75-inch x 1.81-inch x 0.22-inch is a new standard developed by leading notebook manufacturers. This technology could allow manufacturers to lower their prices, as the motherboards would be simpler to design.
Type I - Identical to Type II, except requires extra cables for connectors like the RJ-11 and RJ-45. However, offers more flexibility to where it can be placed in the computer.
Type II - Used when size is not important. Type II is able to integrate the RJ-11 and RJ-45 connectors and did away with extra cables.
Type III - SO-DIMM style connector that can be installed with a mere 5 mm overall height above the system board. In addition, cabling to the I/O connectors allow Type III cards to be placed anywhere in the system.

MCA

Short for Micro Channel Architecture, MCA was introduced by IBM in 1987 as a competitor to the ISA bus. The MCA bus offered several additional features over the ISA such as a 32-bit bus (although there was also a 16-bit bus), ran at 10MHz, automatically configure cards (similar to what Plug and Play is today), and bus mastering for greater efficiency. The primary downfall of the MCA bus was that it was a proprietary bus and required licensing fees. Because of its proprietary format and competing standards the MCA bus never became widely used and has been fazed out of the desktop computers. Below is an example of a MCA network card and what a MCA card may look like.

PCI

Short for Peripheral Component Interconnect, PCI was introduced by Intel in 1992, revised in 1993 to version 2.0, and later revised in 1995 to PCI 2.1 and is as an expansion to the ISA bus. The PCI bus is a 32-bit computer bus that is also available as a 64-bit bus and was the most commonly found and used computer bus in computers during the late 1990's and early 2000's. Today's computers have replace PCI with PCI-Express. Below is a graphic illustration of the PCI slot on a motherboard.
Examples of PCI devices
Modem
Network card
Sound card
Video card

PCI device drivers
If you're looking for PCI drivers, you most likely need to get the drivers for the installed PCI device. For example, if you need a PCI Ethernet adapter driver you need the drivers for the PCI network card. See our drivers section for all computer drivers.

PCI Express

Originally known as 3rd Generation I/O (3GIO), PCI Express, or PCIe, was approved as a standard on July 2002 and is a computer bus found in computers. PCI Express is designed to replace PCI and AGP and is available in several different formats: x1, x2, x4, x8, x12, x16 and x32.

SCSI

Short for Small Computer System Interface, SCSI, pronounced as "Scuzzy", is the second most commonly used interface for disk drives that was first completed in 1982. Unlike competing standards, SCSI is capable of supporting eight devices, or sixteen devices with Wide SCSI. However, with the SCSI host adapter located on ID number 07 and boots from the ID 00. This leaves the availability of six device connections.
SCSI-1 is the original SCSI standard developed back in 1986 as ANSI X3.131-1986. SCSI-1 is capable of transferring up to eight bits a second.
SCSI-2 was approved in 1990, added new features such as Fast and Wide SCSI, and support for additional devices.
SCSI-3 was approved in 1996 as ANSI X3.270-1996.
SCSI is a standard for parallel interfaces that transfers information at a rate of eight bits per second and faster, which is faster than the average parallel interface. SCSI-2 and above supports up to seven peripheral devices, such as a hard drive, CD-ROM, and scanner, that can attach to a single SCSI port on a system's bus. SCSI ports were designed for Apple Macintosh and Unix computers, but also can be used with PCs. Although SCSI has been popular in the past many users are switching over to SATA drives.
SCSI connectors
The below illustrations are examples of some of the most commonly found and used SCSI connectors on computers and devices and illustrations of each of these connections.

VL Bus

Also abbreviated as VLB, VL Bus is short for VESA (Video Electronics Standards Association) Local Bus first introduced in 1992. The VLB is a 32-bit computer bus that had direct access to the system memory at the speed of the processor, commonly the 486 CPU (33/40 MHz). VLB 2.0 was later released in 1994 and had a 64-bit bus and a bus speed of 50 MHz. Unfortunately, because the VLB heavily relied on the 486 processor, when the Pentium processor was introduced manufacturers began switching to PCI.