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Computer Hardware

3D Graphics Card An expansion card designed to handle the three-dimensional graphics seen in many of today's top games.
ADF Automatic Document Feeder.  A facility of most printers and some scanners, enabling documents to be automatically fed through the printer or scanner mechanism without user intervention.
AGP Accelerated Graphics Port. A PC interface (either an expansion slot or built-in) used for super-fast 3D graphics facilities. Ideal for handling the 3D worlds depicted in many of today's top games.
ATAPI Advanced Technology Attachment Packet Interface.  A control technology for devices like CD-ROM and hard drives.
Bi-Directional Refers to an ability for two-way communication. Most printer cables, for example, are bi-directional, so the computer can send data to the printer and the printer is able to respond with print-job progress information.
BIOS Basic Input Output System. Software built into all PC's, to control the basic operation of devices such as the screen, hard disk and keyboard. When a PC is switched on, the BIOS automatically starts, and looks for a drive (like the hard disk) from which the operating system can be launched.
Blanking Plates Plastic or metal plates on the back and front of a PC, fitted by manufacturers to cover unused expansion bays. Blanking plates can be easily removed when new devices are fitted.
Bluetooth A technology that allows devices (computers, phones and printers, etc.) to communicate with each other wirelessly.
Boot The process a PC goes through after it is switched on such as performing a quick self-test, loading Windows, etc.
Boot Sector Area of a disk containing instructions enabling a computer to launch an operating system (such as Windows). These instructions are executed every time the computer starts up.
Burn Proof Technology used by some CD-RW drives to ensure error-free and foolproof disc creation.
Bus The data path on the motherboard that devices use to communicate with the processor.
Capture Cards A video card that slots into a spare PCI slot in your computer and has the input and output sockets necessary for digitizing video.
CD-Rom Drive Used for installing software (on CD-ROM discs) and playing multimedia audio and video. Audio CD's can also be inserted.
CD-Writer A special type of CD-ROM drive, which allows you to create, or 'burn', your own CD's.
Celeron Cheaper but slower version of the Intel Pentium processor, used in budget PC's.
Chipset Broadly speaking, any group of computer chips working together to perform certain functions. For example, a graphics card will have a number of chips, designed to handle all graphics output.
Clock Speed Term used to describe the speed of a computer processor, measured in megahertz or, increasingly, gigahertz - 700MHz or 1GHz (1,000MHz) for example.
CMOS Complementary Metal-Oxide Semiconductor.  Pronounced 'see-moss'. This is a special computer chip that looks after system set-up information, like date and time, etc.
COM Port Communications Port.  A PC generally has up to four of these - COM1 to COM4. It is through these ports that devices can talk to the rest of your PC. Anything fitted to a serial port will be allocated one of these, as will a modem.
Compact Flash Matchbook-size memory cards with no moving parts. These slot into various devices to store data. Popular with digital cameras and handheld computers.
CPU Central Processing Unit.  Otherwise known as the processor, the heart of a computer. The CPU does most of the hard work and the faster it is, the better the PC is likely to be.
CRT Cathode Ray Tube.  The glass tube-based technology used to produce an image in most TV sets and computer monitors.
DDR A type of memory that's twice as fast as ordinary memory. DDR memory is often used in graphics cards can now be found in PC's too.
Degauss To remove the magnetism from a device, usually a monitor. Most monitors degauss automatically but some have a button.
DIMM Dual Inline Memory Module. A slot-in card used to expand the memory of a desktop PC.
Dock A receptacle for a portable device, like a palmtop computer or a digital camera, and connected to a PC. Through this, the linked machines can exchange documents and data.
Dot Pitch The distance between the dots which make up the image on a monitor.
Drive Bay A blanked-off space at the front of a desktop PC originally designed for additional floppy disk drives. Now drive bays accommodate all manner of peripherals.
DSTN Double-layer SuperTwisted Nematic.  Also known as Dual Scan Screens.  A type of flat-panel display used primarily on budget notebook PCs. They are of lower quality than TFT screens.
DVI A video connection used on some TFT monitors and graphics cards that provides a purely digital connection between a PC and monitor. This gives a higher quality image than using a standard VGA connection.
ECP Enhanced Capabilities Port.  A type of high-speed printer port which offers improved performance.
EIDE This is an interface for connecting hard disks and CD-ROM drives inside your PC.
EISA An enhanced version of the ISA expansion slot, offering faster data transfer speeds for suitable expansion cards.
EPP
 Enhanced Parallel Port.  A modern version of the parallel (or printer) port, which is the 25-pin connector at the rear of your PC where the printer normally plugs in. If your PC was bought in the last few years, it should have an EPP port. This can be important as scanners that plug into the parallel port do require the enhanced version.
Expansion Card A card that can be fitted in an expansion slot within your PC to enhance its capabilities in some way, for instance to improve its video or graphics performance.
Expansion Slot A socket on a computer's motherboard designed to accommodate expansion cards.
Firewire A super-fast data link between your PC and devices such as digital camcorders. Also known as IEEE1394.
Firmware Basic software permanently stored on a device (such as a graphics card or dvd writer) that controls it's basic operation. Firmware can be upgraded using a process known as 'flashing'.
Flash Memory A special type of memory that maintains its contents even when the host machine, like a palmtop computer, is switched off.
Flat Panel Display Slim monitors, similar to the Liquid-Crystal Displays (LCD) found in notebook computers, designed for use with desktop PCs.
Flatbed A type of image scanner that resembles a small photocopier. Place a document face down on the glass scanning bed and the scan-head is moved across it, building up a digital image as it goes.
Floppy Disk A small, rigid square of plastic used to store data. Inside the case is a circular magnetic disk (the floppy bit). The most common type of floppy disk is the 1.44Mb 3.5inch version used by almost all PCs.
Footprint The desk area occupied by a peripheral, like a printer or scanner.
Fragmentation When there's not enough contiguous room to save a file in one physical location on your hard disk, the file will be spread over several smaller locations. This fragmentation is an inevitable consequence of constantly saving and deleting files, especially if space is scarce. Eventually your hard disk will need to be tidied up, or defragmented.
Graphics Card The part of a PC that displays the image you see on your computer's monitor. Some are more advanced than others, featuring connections for video recorders or other similar devices.
Graphics Processor A dedicated chip on a graphics card designed to controls the images displayed on a monitor.
Hard Disk / Drive
 A high-capacity disk drive fitted in almost all PCs and used to store both applications and the documents and files they create. Hard disks are so-called because they use rigid magnetic disks to store data. Hard disk storage capacity is measured in gigabytes.
Hardware Your computer set-up is split into two parts - hardware and software. Software covers the programs that run on your machine, while hardware describes the physical components, like the monitor and keyboard.
Heatsink A block of machined metal, usually aluminium, used to dissipate heat from a hot component, such as a processor.
Hyper Threading Technology developed by Intel that enables one of its newest Pentium 4 processors to behave as two processors for certain tasks, speeding up performance.
IDE Integrated Device Electronics.  A standard interface for connecting devices such as hard disks and CD-ROM drives to a PC.
Interface In hardware terms, it usually refers to a physical connection, like a parallel printer interface.
IRQ Interrupt Request. Settings that determine the memory addresses and processor usage for PC add-in cards and devices. You shouldn't change these unless you really know what you're doing.
ISA Industry Standard Architecture.  An old type of expansion slot inside a PC.
Jumpers Little metal pins, found on expansion cards and motherboards, which allow you to change settings manually.
LCD
 Liquid-Crystal Display.  Technology used to create low-power, slim display panels. Used in everything from digital watches to flat-screen monitors.
LED Light Emitting Diode. A low-power electronic device that emits light when an electric current is passed through it.
MBR Master Boot Record. Part of a hard disk read by a computer as soon as it is switched on. The MBR contains information about which hard disk to boot from.
Memory (or RAM) Random Access Memory.  A computer's temporary storage area, measured in megabytes (Mb). Anything written to memory will be lost when the power is switched off.
Memory Cards Small cards that can store many megabytes (Mb) of computer data or documents. Often used as a removable storage medium in digital cameras and palmtop computers.
Memory Sticks A type of proprietary memory card designed by Sony. Used to provide slot in, removable storage, for devices such as digital cameras.
Mic In Sound cards have different sockets at the back so you know what plugs in where. The Mic In socket is for the microphone.
MIDI Musical Instrument Digital Interface.  A standard for controlling electronic musical instruments by computer. One MIDI instruments can be used to control and communicate with another, so that music created on one can be edited on another.
MMC MultiMedia Card. A postage stamp-size solid-state memory card used by some digital cameras and MP3 players. See also SD card.
Moiré These are interference patterns that may be visible when a monitor displays certain images or patterns. Moiré is a nuisance that can generally be resolved by changing the background colour.
Motherboard The main circuit board inside any PC into which every other component connects to and communicates through.
Notebook A portable computer, usually around the size of an A4 notebook. Also referred to as a Laptop.
Onboard Already fitted to your PC as part of the main circuitry on the motherboard. So 'onboard AGP graphics', would mean the PC with built-in AGP graphics facilities. The alternative is a separate expansions card which is attached to the motherboard via a special port.
Optical Resolution The true resolution a scanner can 'see' as it passes across a document. Resolution is measured in dots per inch (dpi), so a 300dpi scan will pick up 300 lines of information for each inch of the scanned page.
Overclocked Processor A processor that has had its operating speed improperly increased.
Palmtop A PDA or small computer about the size of a pocket calculator. Usually without a keyboard and with a touch-sensitive screen, it will use text recognition for data entry. Most palmtops are supplied with contact management, diary and memo software, while many can access the internet and download email using a mobile phone. Third parties may supply on-screen maps, electronic books and the like.
Parity Error Some types of computer memory have a built-in 'parity checking' system to warn of memory errors that otherwise might not be noticed. If a problem is detected, a parity error warning is produced. If this is repeated frequently, the memory module is probably faulty.
Partition A large hard disk can be divided into two or more partitions or 'virtual' drives. Once partitioned, each section is treated by Windows as though it were a completely separate, smaller hard disk.
PC Card A credit card-size device for adding anything from a modem to a hard drive to a notebook PC. Requires a PC Card slot (standard on almost all notebooks).
PCI Peripheral Component Interconnect. A high-performance expansion slot for desktop PCs, allowing simple installation of PCI components like sound cards and modems.
PDA
 Personal Digital Assistant.  A palmtop computer about the size of a pocket calculator. Usually without a keyboard and with a touch-sensitive screen, it will use text recognition for data entry. Most PDA's are supplied with contact management, diary and memo software, while many can access the internet and download email using a mobile phone or normal phone line.
Pentium 4 A member of Intel's Pentium line of processors.
Pixel Short for picture element, which is the smallest part of an image displayed on a monitor or captured by a scanner or digital camera.
Plug and Play A standard for Windows PC's that allows peripherals to be connected and used in a matter of moments. In theory, Windows will automatically detect the new device and install any needed drivers from its own database.
Port A socket, which is located at the back of the computer's base, where you plug in items like the printer and keyboard.
Power Management Power-saving features on a PC, printer or monitor, designed to turn off or put on standby any part of the system that is not needed.
Processor The chip that is the 'brain' of the computer. The faster the processor, the better a computer will perform.  See also CPU.
PS/2 A set of standards for such things as mouse and keyboard interfaces, originally used by IBM.
PS/2 Port A small, round 6-pin connector, for plugging a keyboard and/or mouse into a computer.
QWERTY Keyboard The standard English keyboard layout, so called because the first six letters on the top row of the keyboard are QWERTY. Similarly, French keyboards can be referred to as AZERTY while some other languages, including German, use a QWERTZ keyboard layout.
RAM Random Access Memory. The computer's working area, used for data storage while the PC is switched on. Its capacity is measured in megabytes (Mb): the more memory your PC has, the more things it can process simultaneously and the faster it will seem. Note that any information in RAM will be lost when the power is switched off.
RDRAM Rambus DRAM. A design of memory claimed to offer very high performance, albeit at a high price. Developed by Rambus Inc and licensed to RAM manufacturers, it is found in Pentium III and Pentium 4 systems.
Refresh Rate Measured in Hertz (Hz) the number of times per second that the image on your monitor is redrawn. Slight changes in the image each time it is updated combine to give the illusion of movement. For a steady image, the higher the refresh rate, the less flicker you will see. A refresh rate over 85Hz is generally accepted as being flicker-free.
Removable Storage Device Disk drives that use high-capacity disks which can be removed and stored remotely. Typical examples include the Iomega Zip and Jaz products.
Resolution The amount of detail shown in an image, whether on screen or printed. For a monitor, it is the number of pixels it can display (typically 1024 x 768 pixels for a 17inch monitor).
RGB A colour picture created as on a monitor, by combining a value for red, green and blue channels to determine the colour of each individual pixel.
RISC Reduced Instruction Set Computer.  These processors are designed using a very limited number of simple instructions. They can combine these instructions at high speed to perform much more complex calculations.
ROM Read Only Memory. Any memory that can be read but not written to. A PC's BIOS uses ROM to store basic system information and instructions which cannot be changed.
RTC Real-Time Clock. The battery-powered clock inside every PC which keeps track of time while the system is switched off.
Scanner A device which uses a light sensor to convert a drawing, photograph or document into data which can then be interpreted by software on your PC. A flatbed scanner has a flat sheet of glass on which the image or document is placed. The scan head moves below the glass, while with a handheld scanner you move the scanner over the image.
Screen Resolution The number of pixels that are displayed on the screen, making up the image. The more pixels, the higher the resolution and the sharper the picture.
SCSI Small Computer System Interface.  Pronounced 'skuzzy'. An extremely fast connection between such things as disk drives and scanners, and a PC. Up to seven devices can be daisy-chained together and connected to a normal SCSI controller.
SD Card Secure Digital Card. A secure variant of the postage stamp-size solid-state MMC memory card used by some MP3 players.
SDRAM Synchronous Dynamic RAM. The type of memory to be found in most modern PC's. It is significantly cheaper than its biggest rival, RDRAM.
Serial Port A socket on the back of a PC used to connect serial devices, also known as a COM port. Often used on a PC to connect an external modem, some digital cameras and PDA's or, formerly, to plug in a mouse.
Server A computer on a network (such as the Internet) that stores shared information. Servers can also manage shared resources, such as printers.
SmartMedia A form of solid-state storage used by some digital cameras and MP3 players. Data files, normally photos or music, are stored on small removable cards. These are about the same size as CompactFlash cards, but physically more flexible, being less than 1mm thick.
Socket 7 Connector on your PC's motherboard for Pentium processors or equivalent non-Intel chips.
Solid State A device, such as an MP3 player or memory card, which has no internal moving parts.
Sound Blaster Sound card made by Creative Labs. The Sound Blaster was one of the first de facto PC audio standards, and many cards emulate it so they can be used with the hundreds of games that support it.
Sound Card An expansion card that lets a PC create sounds, ie, game sound effects, music, and so on. Almost all PC's have a sound card as standard but more powerful sound cards can be bought and fitted.
Spooling Temporarily transferring data to the hard disk or to some other temporary storage place, before passing it on to its final destination. Most often seen in printing, where the PC spools data to the hard disk to finalise it before passing it to the printer.
Stylus A plastic pointer styled like a pen, used for operating palmtop computers (such as PDA's) with touch-sensitive screens.
System Disk This is a disk that contains all the programs you need to get your PC working, with enough system files to make it boot up and allow you access to the disk drives
Tablet PC A type of notebook PC with a touch sensitive screen that can be written on, like a writing pad.
Tape Drive A high capacity storage device based on magnetic tape used for making backups.
TFT Thin-Film Transistor.  Technology used to create thin, flat colour screens for such things as computer monitors and digital cameras. TFT displays are very high quality and will display clear and bright images using thousands or millions of colours.
Touch Pad A small, touch-sensitive pad, usually a couple of inches square, which acts as an alternative to a mouse on some notebook/palmtop computers. It works by sensing fingertip pressure.
Tower A computer system unit which stands upright (as opposed to a 'desktop' version which lays flat). Although bulky, they give plenty of room for future expansion.
TV Out A socket found on a graphics card that can be used to make a connection to a TV sets aerial-in socket.
TV Tuner An expansion card, which, when fitted into a PC, receives TV signals and allows a TV picture to be displayed on your PC's screen.
TWAIN Technology Without An Interesting Name. A standard way for scanners and some other devices to talk to your PC. In theory, all TWAIN-compliant image-editing applications, including Paint Shop Pro and PhotoShop, should be able to directly access the image data produced by any TWAIN-compliant scanner or digital camera.
Type II PC Card The most common type of credit card-size expansion card used to add peripherals such as modems to a notebook PC. Fits into a Type II PC Card slot, which is standard on all notebooks.
UPS Uninterruptible Power Supply. An device that sits between a computer and its main supply to provide a (usually brief) emergency power supply in the event of a power cut.
USB Universal Serial Bus.  A standard which allows quick and easy connection of external peripherals such as scanners and printers to your PC. It supports plug and play, and devices can be added or removed with your PC switched on.
USB Hub A small external or built-in device with several USB ports. It connects to your PC and serves as a relay station, allowing you to add multiple devices. External USB hubs can usually be placed on a desk for easy access to USB ports.
USB 2 Universal Serial Bus 2. Also known as Hi-Speed USB.  Faster but backwardly-compatible successor to USB that is used by such things as MP3 players and external disk drives.
VGA Video Graphics Array. A very basic standard for graphics output, specifying that the monitor and graphics card should be able to display 16 different colours at a resolution of 640x480 pixels.
Video Capture Card An expansion card for PC's that allows them to record full-motion video sequences to disk from TV receivers, camcorders and other video recording equipment.
Video Conferencing Linking two or more PC's to capture and display video and audio in real time so distant people can see as well as talk to each other.
Video Memory Memory installed on your PC's graphics card and used to generate the on-screen image. The more memory on the card, the higher the possible graphics resolution and the more colours that can be displayed. 64Mb should be considered the minimum standard today, with 128Mb or even 256Mb common in high-end gaming systems.
Virtual Memory A reserved area of hard disk space that your PC can use as 'virtual' memory, or RAM, whenever it is running short of the genuine article. Also called a swapfile, this allows you to have more programs open at once but will be slower than having an equivalent amount of real RAM.
Zip-Drive A high-capacity disk drive designed by Iomega capable of storing 100 or 250Mb of information on sturdy pocket-sized disks. These can be used for back-up, as extra storage or to transfer files between machines or users. Zip drives can be built into your PC or connected externally, using a USB, parallel