A section of very high-speed memory that is used to temporarily store data before it is used by the PC's processor. A cache can dramatically speed up the effective rate at which data is read from a hard disk drive. The computer reads more data than is requested and stores the excess in the cache ready to be accessed with the next request to read data. The memory used for the cache can be up to 100,000 times faster than a hard disk drive!


Stands for Computer Aided-Design. It is a special software that allows designers and architects to draw precise blueprints on screen, then model them in 3D to see how the design will appear in real life before a product is manufactured or a building erected .


A set of wires connecting pieces of computer hardware.


A flat plastic container used to hold a CD, inserted into a CD-ROM drive.


A software utility that's supplied with Windows and works just like a normal calculator. To start the Calculator, double click on the icon in the Accessories group of Windows 3.1 or choose Start/Programs/Accessories in Windows 95 .


A simple calendar and diary supplied with Windows .


To adjust a monitor or joystick so that it is responding correctly and accurately to the signals or movements. For example, this ensures that the monitor is displaying a true representation of the colour that will be printed .

Carriage Return

The <ENTER> or < RETURN> key on your keyboard. On-line commands often must be followed by <CR>.

Cascading Windows

A way of arranging lots of windows on screen so that they overlap, with only the title bar and caption showing. This is a neat and efficient way of displaying lots of windows at once. An alternative is to tile the windows. Each is displayed beside the next with no overlap. Another alternative is to reduce each window to an icon, or, in windows 95, on to the status bar at the bottom of the screen .


Carbon copy. The prompt in an e-mail program which allows the user to enter one or more ID's to send copies of a message.


Stands for Compact Disc. A small plastic disc that is used to store up to 650 Mb of data. The data is stored in the form of tiny holes etched on to the surface of the disc. A CD drive spins the disc and uses a laser beam to read the holes in the surface. A CD can store any type of computer data from images to text to music. However it can only be read by a user. You cannot save data on to a CD. A CD normally refers to a normal music disc which can be played in your hi-fi or in your PC's CD player. You just plug in a pair of headphones and use the MediaPlayer utility to start playing. In the computer world, the same type of plastic disc is used to store files and data and is called a CD-ROM (Read Only Memory) .


Compact disc for audio and visual for movies, reference, training courses and video games. It can be interactive but is not programmable; it is viewed through a television and CD-i player, not a computer.

CD-audio or CD-DA

Stands for Compact Disc- Digital Audio. Standard that defines how music can be stored as a series of numbers (digital form) on a CD.

CD-ROM drive

A computer accessory used to access CD-ROM discs. Internal CD-ROM drives are installed inside of the computer system. External versions have their own enclosure and power supply and are connected to the computer by a cable. Many computers now include a built-in CD-ROM drive as standard equipment .

CHAP (Challenge-Handshake Authentication Protocol)

An authentication method that can be used when connecting to an Internet Service Provider. CHAP allows you to login to your provider automatically, without the need for a terminal screen. It is more secure than the Password Authentication Protocol (another widely used authentication method) since it does not send passwords in text format.


A letter or number that is displayed or printed. The shape of each character is determined by the typeface and font that's used. Each font includes 256 different characters, normally with a-z and A-Z together with foreign characters, symbols and punctuation marks .

Character Map

A utility that is provided with Windows to allow you access to all 256 characters that make up a font rather than the limited range that you can access from the keyboard. The extra characters include foreign characters and symbols.


Another term for IRC . Also, an acronym meaning Conversational Hypertext Access Technology.


Small electronic device at the heart of every PC. A chip is a small thin piece of silicon crystal on to which is etched a tiny circuits with hundreds of thousands of components. These components will do simple mathematical operations such as adding and subtracting numbers (in a memory chip). If ever you open your PC you'll see a mass of small black boxes with tens of metal legs on each side, they are the chips .

Clip art

A library of drawings or photographs that you can use in your presentations, reports or desktop publishing documents. Normally, there are no copyright fees if you use the images for non-commercial use. You'll find that most presentation programs, like Harvard Graphics or Microsoft Powerpoint, come with hundreds of pre-drawn images, borders and icons in a clip art library .


In Internet terms, it's an application that performs a specific function, such as Telnet or FTP. It's the front-end to an Internet process. In more general terms, a client is computer system or process that requests a service of another computer system or process. The much talked about client-server architecture refers to a workstation requesting the contents of a file from a server.


1) A tiny crystal in your computer that sends out a regular signal hundreds of thousands of times every second. It's used by all the electronic components to keep in time with each other so that data is not lost when it's transferred. The central processing unit normally carries out instruction every clock pulse, so the faster the clock, the more the instructions it carries out. The speed of a processor, and so the clock, is measured in megahertz (MHz), which represent one million pulses every second. A processor that runs at 50MHz uses a clock that sends 50 million signals every second.

2) Windows 3.1 includes a utility called Clock that displays the current time in a window or as an icon. To start the utility, double-click on the Clock icon in the Accessories group. Windows 95 displays the time in bottom right-hand corner of the screen. To see the data, move the pointer over the time and wait a couple of seconds, then the data will pop up. To change how the time is displayed in Windows 95, move the pointer over the time display and click on the right-hand mouse button.


Substantially different from hackers, crackers are users who try to gain illegal access to computers. They are usually malicious in their intentions.


The smallest element that the DOS operating system software that controls your PC can read from or write to a disk .


Stands for Cyan, Magenta, Yellow and black. A method of describing any colour by the percentages of these colours. Normally used in a high-end graphics programs .


To print multiple copies of a document in correct order. If you want three copies of a document, instead of the usual method of printing three copies of page and so on, the word processing software is clever enough to print all the pages in order and repeat this three times .

Colour depth

The number of different colours that can be displayed by any single pixel in a display. Determined by the number of colour bits in each pixel .

Colour palette

The selection of colours that is currently being used in an image. Even though a pixel might have only eight colour bits, and so can display 256 different colours, you can choose these 256 colours from a range of millions of different colours: your choice of colours is the colour palette .


An instruction you give to an on-line network to carry out a specific action.


To reduce the size of a file by encoding the data. For example, if the file contains five letter As next to each other, which takes five bytes of space, the compression software could encode this to 5A which takes two bytes of space. The compression uses all sorts of encoding tricks to code the way data is stored to reduce the space it takes. Software is normally used to compress a file or all the data on a disk drive, but don't forget that decompression software is needed when you want to read the data again .


An electronic meeting place dedicated to a particular subject where users come to participate in discussions or group projects. Conferences can be used to post a variety of information such as news services, newsletters, and statistics; also called "newsgroups," "bulletin boards," or "echoes." An electronic conference provides a many-to-many communication medium, as opposed to the person-to-person nature of e-mail. All conferences have a particular subject or purpose, and the topics and responses they contain might provide items of news, ideas, questions, or other information in almost any form. Some special-purpose conferences may have restricted access, allowing some users to write messages, some only to read, and some neither. The person responsible for the technical maintenance and/or community communication is called the "conference facilitator."


To set the function of software or hardware to your particular setting. You can configure Windows so that it displays a different colour background, of so that it uses a larger font that's easier to read. If you install a new software application there are two main steps: the first is the installation, which simply creates a new folder and copies the files on to your hard disk from the floppy disk or CD-ROM. Once the program is installed, you can configure it to work the way you want. For example, if you are adding Microsoft Word, you install it and then configure the way it looks and works. The Tools/Customize option lets you change the icons and menus that are displayed, while the Tools/Customize option lets you change the initial settings for the software .

Control key (Ctrl)

This is a key on the keyboard (in the bottom right and left corners of the main character pad) that is used for special functions. The control key is used with another key. You press and hold down the control key and then press a second key and you will activate a special function. The keys and their functions all depend on the way the software was written. In many Windows-based applications there is a set of standard control key functions. Ctrl-S will usually save the current document, Ctrl-N will create a new document, and Ctrl-P will print the document out. To move around any Windows application, Ctrl-right-arrow will move the cursor one word to the right and Ctrl-left-arrow will move it one word to the left. Ctrl-up-arrow will move you to the beginning of the paragraph and Ctrl-down-arrow will move to the end of the paragraph. Ctrl-Home will move to the start of the document and Ctrl-End will move you to the end of the document .

Control Panel

This a collection of icons that allow you to configure the basic functions of Windows and your PC. In Windows 3.x, open the Main group and double-click on the Control Panel icon. In Windows 95, click on the Start/Settings button option. Within the Control Panel there are icons to define the fonts that are installed on your computer, the colour of the background to Windows, the type of printer that's installed, how a network works, as well as a mass of other options.


Educational programs designed for in-school use.

CPU or central processing unit

The main processor chip in a computer which responds to software instructions and controls peripherals and memory.


A highlighted or blinking block, line or underscore on a computer monitor that indicates where you are currently typing.


The world of computers and the society that gathers around them, as referred to by William Gibson in his fantasy novel Neuromancer. It now loosely refers to the online world and even more loosely to the Internet.