Active X: A set of technologies developed by Microsoft that allow software components to interact with each other in a networked environment. Internet components can be interactive and add extra functionality to sites. See also: Applet
Antialias: The blending of pixel colours along the edges to avoid a jagged, stair-step look for curved lines
Applet: A small program with restricted functionality that runs in a browser. The restriction is designed to protect the user's machine from faulty or maclicious code. They give a more advanced interface than HTML is capable of and are downloaded with a web page.
Aspect Ratio: This refers to the dimensions of a screen and is the width compared to the height. A square screen would 1:1.
Access Time: How long a disk takes to find and retrieve a piece of data
ADSL: See DSL.
BABT approval: This is given for modems. They are approved by a body to work on the UK public telephone network. This means that they have been tested and won't foul up the network.
Batch File: A text file consisting of a set of commands that can be executed all at once (in sequence) as if typed in manually.
Bezier Curve: A curve with anchor points and handles that can be dragged to alter the shape of the curve.
BIOS: Basic Input/Output System. A PC's BIOS stores a set of instructions which tell it how to manage input (typically from a keyboard or mouse) and output (typically to monitor or printer).
BIT: Binary digit. A one or a nought.
Bulletin Board: A computer system not usually connected to a network into which outside users can dial. Although downloads are often available bulletin boards were developed primarily as messaging systems. Users can have an ID and leave public messages or email other users. Largely overtaken by the internet, some boards also have feature articles. Many are devoted to one subject. (See also SIGs)
Byte: Set of 8 bits. A kilobyte (1kb) is 1024 bytes.
CCD Charge Coupled Device. An array of photo sensitive elements which can turn light into volts.
Client: A computer that is connected to a server or software running on a computer connected to a server.
CMYK: Cyan, Magenta, Yellow and Black are the colours used in the printing process. K is used for black so as not to confuse it with blue. The four colours can be combined in different sized dots to fool the eye into seeing full colour. CMYK scanning is slightly different in that it is a mode that works in conjunction with a special profile to optimise the scan for a specific printer.
Colour Depth: The number of bits of colour information for each pixel. An 8 bit image can display 256 colours (FF), a 24 bit image over 16.7 million.
Contrast: The difference between light and dark areas.
CPU to PCI Write Buffer: A BIOS setting that when set to Yes sends information from the CPU to the PCI bus.
Desktop: The screen that you ordinarily start at. Applies to a graphical environment. The desktop contains icons which are shortcuts to files (eg programs) and folders. It may also have a toolbar and buttons for particular tasks.
Disk Compression: Identical data is repeated many times. Compression techniques use this to enable more data to be squeezed into a finite space.
Dithering: A process that mixes monochrome and coloured pixels or pixels of two or more colours to display colours that are not available.
DNS: Domain Name Service A program that translates a domain name into an IP address.
Dot pitch: Horizontal distance between the centres of each trio of colour phosphors.
Download: The process of retrieving data from a remote system to your own machine.
DPI: Dots per inch. Describes the resolution. In the case of a printer this is the number of drops of ink in a linear inch, for a monitor the number of "lights", for a scanner the number of elements that make up the CCD. (See also PPI)
DRAM Clock: This is the speed of the memory bus and can sometimes be set independently from the FSB (Front Side Bus). To avoid memory bottlenecks this should be set to the speed of the RAM. BIOS setting.
DRAM Timing by SPD (Serial Presence Detect): This is a setting in the BIOS allowing it to choose the optimal clock timing for the RAM according to the type of motherboard. The default is usually Yes or On. Turning it off allows the timing to be tweaked elsewhere.
DSL: Digital Subscriber Line. A method of achieving relatively high speeds from a normal copper wire ie a traditional phone line.
Duplex: Full allows two way communication or half means that each party has to talk in turn.
FTP: File Transfer Protocol. Tool used to send files across the internet. Although built in to web browsers a dedicated FTP app is more efficient and offers more options.
GUI: Graphical user Interface. Instead of having to type words or letters (often obscure) as commands to get the computer to do something icons (pictures) and on screen buttons are used together with menus.
Halftone: Gives the prerception of full colour when in fact only 4 inks are used. Produces what appears to be a full colour picture by using a mosaic of tiny dots.
Halo: Loss of detail in bright images because of internal reflections between the mask and the screen.
HTML: Hyperext Markup Language. The language in which web pages is written. It is plain text so does not need a special editor.
Interlaced display: This enabled early monitors to work at higher resolutions by drawing the screen in two passes resulting in a flickery display.
Interpolation: The process whereby the computer guesses information between two points in order to increase the apparent resolution of an image.
Intranet: An internal company network of web sites and pages accessible only to those within the company. It is a closed system on the company's own servers.
IP: Internet Protocol. A 32 bit binary number which identifies the address or location of a computer on the internet (or a network using the same protocols).
ISDN: Integrated Subscriber Digital Network. Basically, a digital phone line offering higher transmission speeds than a conventional phone line.
ISP: Internet Service Provider. Provides a user with access to the internet through a server. The user has a mailbox on the ISP's server where mail is stored until collected. The ISP invests in modems and other networking equipment to allow multiple users to connect to their servers and access the internet.
Macro: A set of actions held "in store" that have previously been recorded. It will be a common task or provide a means to extend functionality. Macro languages exist to provide further flexibility and control. The actions (or instructions) are executed when a certain key combination is pressed. It can also be assigned to a screen button. It provides quick access to those instructions.
MIME: Multipurpose Internet Multimedia Extensions. Essentially, tells a web application such as a browser how to deal with particular types of data such as sounds and video.
Modem: A device which allows the computer to send information down a standard phone line by converting the electrical data signals into audio tones. It also receives data converting the tones back into data.
Operating System: A special program under which applications are run. Provides housekeeping tasks and provides the groundwork for programs..
Optical resolution: The number of pixels at which a scanner is capable of displaying. Image information may be filled in using dithering. (See also Resolution)
P2C/C2P Concurrency: A BIOS setting that effects the transfers between the PCI bus and the CPU.
PCI Master WS Write: BIOS setting. Increase this value if you have stability issues. Ideally set to 0 wait states.
Phosphors: Chemicals which glow when struck by a beam of electrons.
Pixel: Single dot. Relates to an image on screen or paper. Lots of pixels (dots) are put together to make up an image.
Pixel Bandwidth: The maximum amount of information your monitor can deal with in a second, measured in megapixels a second. But you need to take into account flyback times and sync pulses.
POP: Point of Presence. The bank of modems you dial into locally to access the internet.
Port: Where electrical connection can be made with the CPU. Basic addressable unit of input/output section.
Portable Computer/Software: Can be easily transferred or moved about.
PPI: Pixels per inch. Describes resolution in terms of the actual dots rather than drops of ink. (See also DPI)
Printout: Paper print copy produced by printer.
Procedure: Subroutine.
Processor Status Register: The register containing the flags which are set (1) or clear (0) as the processor executes the instructions of a program.
Program: A set of instructions for the computer to obey so that it can perform various tasks (eg add up numbers, find angles, solve equations etc.). See the Programming Manual for the particular machine or processor you wish to deal with for full details.
Program Counter: Register containing the address of the next instruction to be fetched and executed.
PROM: Programmable Read Only Memory. A chip which can be programmed by the user. Once programmed its contents are non-volatile and permanent.
QIC - Quarter Inch Tape: Specially coated magnetic tape 1/4 inch (6.25mm) in width.
RAM: Random Access Memory. Memory into which information (data) can be put (written) and from which it can instantly be retrieved (read) no matter which section it is in. RAM is the 'working memory' into which external files can be loaded and then executed. Read/Write Memory (RWM) is a more appropriate name.
Real Time: If the processing is virtually instantaneous the computer is said to be operating in real time. See also TIME SHARING.
Record: A related data item or set of items eg.Name and address.
Register: A storage location inside the microprocessor which is several bytes wide.
Resolution: The number of pixels within a given line length. Usuallay denoted as dpi (dots per inch). The optical resolution of a scanner is the actual number of physical elements within the CCD in a given line length.
RGB: Red, Blue and Green are the three lights used by displays. Combining each of these gives the full range of the visible colour spectrum.
RISC: Reduced Instruction Set Computer. Type of microprocessor pioneered by Acorn Computers (amongst others) which has an instruction set less than that of its counterparts and hence operates faster.
ROM: Read Only Memory. Memory circuit where the information stored is built into the chip when made and cannot be subsequently changed. Information can only be copied out. Also called FIRMWARE.
SDRAM Column Address Strobe (CAS) Latency: This is the refresh rate for a machine's RAM and is set in the BIOS. RAM has to be refreshed with an electrical charge because it can only keep information for a short period.If the setting is too low it can cause instability but a low setting is best.
Serial: Type of data transmission where each individual item is transmitted down a single data line one after the other. Common standard RS232. See PARALLEL.
Server: A computer with others connected to it which allows others to use its data and facilities. Resources available on the server which may not be available on other computers include a printer and hard disk space.
SIG: Special Interest Group. Typically used on bulletin board systems where an area is devoted to one particular subject rather than being for general messaging etc.
Speech Recognition: See VOICE RECOGNITION
Speech Synthesis: See VOICE SYNTHESIS
Stack: Section of memory that can be accessed only in last in/first out manner. Grows downwards usually through memory. Temporary store or 'dustbin'.
Stack Pointer: Register that contains the address of the next available (empty) STACK location.
Status Bit: See FLAG
String: A chain of letters and/or numbers. A string variable can be manipulated using various commands to perform certain tasks.
Synchronous: Operating at regular intervals according to an overall timing source. See also ASYNCHRONOUS.
T1: A leased phone line with a speed of 1.5M bits/s (equivalent to 24 connections or kilostreams of 64k bits).
Time Sharing: A way of sharing out computer facilities between a number of people who want to use the computer at the same time. Each has a separate terminal and gets the impression that they have sole use of the computer with their own 'account'. Similar to NETWORKING.
TSR: Terminate and Stay Resident. This applies to some programs. They will run (usually when your machine starts) and when they have finished they will stay in the machine's memory.
Two's Complement: A binary number system that includes the representation of negative numbers. The two's complement may be obtained by subtracting the number (in binary form) from zero, or by adding one to the one's complement.
UART: Universal Asynchronous Receiver/Transmitter. A device that acts as an interface between systems that handle data in parallel and devices which handle data in asynchronous form.
Upload: The process of sending data from your own (local) machine to a remote machine (see also: Download).
Variable: A label that can mean anything and can vary in value and meaning. Can be alphanumeric or just numeric.
VDU: Visual Display Unit. Sometimes referred to as a screen or monitor.
VIA Versatile Interface Adaptor. A parallel interface device (probably contained on a chip). See also PIA, UART.
Videotex: See VIEWDATA
Viewdata: Examples are teletext and Prestel. It is a way of receiving digital information at a distance and displaying it on a screen. The original specification defined various stages which led the way from chunky blocky graphics to high quality photographic images.
Voice Synthesis: The ability to use stored
patterns of sounds to assemble words that can be put through a loudspeaker.
Voice Recognition The ability to match signals coming in from a microphone with
stored patterns held in memory and hence recognise words.
Volatile Memory: Memory where information is lost when the power is turned off.
Wand: Similar to light pen. Reads optically coded labels (bar codes).
Word: The minimum number of bits the central processor can handle at any time.
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