A peripheral (pronounced peh-RIHF-uh-ruhl, a noun truncation of peripheral device) is any computer device that is not part of the essential computer (the processor, memory, and data paths) but is situated relatively close by. A near synonym is input/output (I/O) device. Some peripherals are mounted in the same case with the main part of the computer as are the hard disk drive, CD-ROM drive, and NIC. Other peripherals are outside the computer case, such as the printer and image scanner, attached by a wired or wireless connection.

Network Interface Card (NIC)

A network interface card (NIC) is a computer circuit board or card that is installed in a computer so that it can be connected to a network. Personal computers and workstations on a local area network (LAN) typically contain a network interface card specifically designed for the LAN transmission technology, such as Ethernet or token ring. Network interface cards provide a dedicated, full-time connection to a network. Most home and portable computers connect to the Internet through as-needed dial-up connection. The modem provides the connection interface to the Internet service provider.

Video Card

Also called graphics adapter, display adapter, video adapter. A circuit board that enables a computer to display information on its screen. The resolution, number of colors, and refresh rate of a monitor is determined by the kind of video card used, plus the limitations of the monitor itself.

Slots and Sockets

Peripheral Component Interconnect (PCI) slots

PCI slots are places on a motherboard that you can install peripheral pieces of hardware. Expansion cards, such as sound cards or network interface cards, can be placed into a PCI slot to add functionality to a computer. PCI slots are a part of the computer's bus, which is the system the computer uses to transfer data from one place to another.

The majority of PCI devices are Plug-and-Play, which means that after putting them in, you won't have to install any software in order to use them. If the device isn't plug and play, it should come with a CD that has all of the necessary software on it.

Accelerated Graphics Port (AGP)

An interface specification developed by Intel Corporation. AGP is based on PCI, but is designed especially for the throughput demands of 3-D graphics. Rather than using the PCI bus for graphics data, AGP introduces a dedicated point-to-point channel so that the graphics controller can directly access main memory. The AGP channel is 32 bits wide and runs at 66 MHz. This translates into a total bandwidth of 266 MBps, as opposed to the PCI bandwidth of 133 MBps. AGP also supports two optional faster modes, with throughputs of 533 MBps and 1.07 GBps. In addition, AGP allows 3-D textures to be stored in main memory rather than video memory. You can differentiate a AGP card/slot from a PCI (see definition below), by looking at two things:

• The contacts on the card will be much closer together, and also appear in a staggered formation (see photo).
• The contacts will be flushed back a greater distance from the faceplate than found in PCI cards.