Dictionary of Computer Technology
copied from the Glossary of Terms in:
"Information Technology & Electronics, Demographics Roadmap",
Technology Foresight Programme
API. Application Programming Interface. A standard interface between an application program and the operating system or system software.
Artificial Intelligence. The emulation of intelligent behaviour by machine. Attempts to realise this have spun off a large number of new techniques, eg. expert systems and rules, natural language understanding, speech recognition, pattern recognition, image processing, object oriented functional and logic programming, neural nets and genetic algorithms.
Artificial Life. This discipline involves the study of man-made systems that exhibit the behavior characteristics of living systems.
ATM. Asynchronous Transfer Mode. A method of transferring data in fixed packets or cells which are 53 bytes long (48 bytes for data). Speeds of up to 2 Gbps can be reached. Information in the cells can be data, voice, image, etc, and therefore an ATM channel can carry all three forms of information simultaneously. Note that this is not an asynchronous transmission protocol as such: the term asynchronous refers to the arrival rate of the various cells themselves. Will be of increasing importance in the next ten years.
Asynchronous. A communications protocol where data is transferred character by character usually, but not necessarily, at the speed which an operator is entering data through a keyboard.
Bandwidth. A measure of a communication system's capability of carrying information. Normally measured in bits per second, or MHz.
Baseband. Data which is encoded and transmitted without modulation of a carrier wave. On an electrical conductor the voltage would be raised and lowered in accordance with the 0 and 1 bits of the data.
Bit. The basic unit of data in a computer (a contraction of BInary digiT). Its value is either 'O' or 'l' and a combination of which represents a character or number.
BPI. Bits Per Inch. The density at which data bits are recorded on a media.
BPR. Business Process Re-engineering - is an engineering-based methodology and set of tools that enable one to de-construct, re-think and then reconfigure an organisation's business processes and method of operation.
Broadband. A communications channel where data is transmitted as variations in a carrier waveform. As a number of waveforms, at different frequencies, may be present at the same time this method allows many parallel streams of information to be transmitted on the same physical carrier.
Byte. A storage unit of 8 bits. Can hold one character or two digits.
C. The C programming language.
C++. A programming language used for developing object oriented programs.
CASE. Computer Aided Software Engineering. The production of software by means of a methodology and specialised tools using a high quality graphics workstation.
CDPD. Cellular Digital Packet Data. The technique of transmitting information over a digital cellular network.
CD-ROM. Compact Disk-Read Only Memory. The storing of data, image, sound, etc, on a small disk which is then read by laser technology. The information, in the form of 'ones' and 'zeros' is retrieved from the disk surface by it either reflecting or not reflecting a laser beam.
Cellular Automata. An emerging field with strong links to parallel control structures. Cellular automata refers to concepts for using machines made up of a few standardized elements. Potential applications include computer graphics, simulations - particularly of biological systems (artificial life) and physical systems (heat and air flow) - and design of massively parallel systems.
CISC. Complex Instruction Set Computer. A computer processor with a rich and varied instruction set. This enables it to be suitable for supporting a variety of operating systems and compilers and to have many different uses.
Client/server. The division of an application between the logic and user interface portion (which usually resides on a workstation) and the data associated with the application (and other applications) which resides on a central server system.
CMOS. Complementary Metal Oxide on Silicon. The fabrication technology used to build most of the current series of mid-range computers and because of its reduced cost and power requirements, is increasingly used for large systems as well.
Communications Protocols. The method, standards, formats and specifications for transmitting information along a communications link. The protocol handles such aspects as transmitting/receiving the information, polling/addressing the nodes and routing through them, and handling error situations.
Compression. The technique of reducing the number of bits required to represent information during data transmission or storage. Particularly required where image and multimedia is used.
CPU. Central Processing Unit. The component of a computer which performs computation and logic operations. This is increasingly composed of separate units for executing specific functions such as floating point operations, fixed point, branching, etc. This is the unit which actually executes software instructions
CRT. Cathode Ray Tube. The type of screen normally found in workstations and terminals.
Cyberspace. The simulation of a three dimensional world, as in Virtual Reality.
Database. A way of organising data on a storage media so that relationships can be maintained between data elements. This enables application programs to process certain data elements or related data elements with simple programming statements.
Data Mining. A term used to describe the activity of accessing very large volumes of data to retrieve only those which have particular significance for satisfying a given set of criteria. Eg. all those credit card customers who have bought single items of over ?1,000 in value in the preceding two years.
DBMS. Data Base Management System. A software system for building, maintaining and accessing a database.
DCE. Distributed Computing Environment. A software technology which enables a network of computers to interwork and thus behave as one integrated computing system.
Digital Signal Processing. A technique whereby analog signals (representing real-time physical phenomena such as sound or images) are processed into a stream of digital data.
Digital Transmission Technology. The technology for transmitting digital signals, that is as a series of 'ones' and 'zeros' as opposed to an analogue waveform. The advantage is that whereas a waveform can gradually deteriorate over a long transmission distance - ones and zeros do not, thus perfect quality is maintained. Another advantage is that many different types of digital information (image, voice, data) can be transmitted over the same link simultaneously.
Distributed Environments. An environment where either the data or the processing applicable to an application is distributed over a number of physically separate nodes.
DOS. Usually refers to the Personal Computer operating systems from IBM (PC-DOS) or from Microsoft (MS-DOS).
DRAM. (Pronounced DeeRam). Dynamic Random Access Memory. The memory of a computer into which the software is loaded prior to execution by the CPU. Needs periodic refreshes to avoid loss of data. Measured in units of bits.
ECL. Emitter Coupled Logic. The fabrication technology used to build the highest powered computer systems. It is very costly and is giving way to CMOS technology.
EDI. Electronic Data Interchange. The networking system used by companies to trade with each other. (Sending each other orders, invoices, etc).
EL. Electroluminescent Panel. A type of visual display.
Emergent Computation. As an alternative to parallel decomposition into isolated subunits, emergent computation exploits the interaction among simultaneous computations to improve efficiency and flexibility and realistic response. The computational model is a nonlinear system in which the behaviour of the system is more than the sum of the parts. It has applications in software development, parallel processing, data searching, artificial networks and heuristic and adaptive systems.
Ethernet. A type of LAN (Local Area Network) protocol. A set of standards, formats and control sequences which define how a LAN of this type works. It is the most common form of LAN.
Expert Systems. A computer system which embodies the knowledge of experts and emulates their problem solving abilities in some narrow area of expertise, eg. fault diagnosis, making financial recommendations, etc. These systems often use a collection of rules gleaned from the expert, sometimes with uncertainty values. They often engage the user in a question and answer session about the case in hand.
Facilities Management. Describes the situation where a services company is contracted to manage the IT facilities of an organisation, usually on site and usually with the organisation actually retaining ownership of the facilities.
FCS. Fibre Channel Standard. Defines a standard interface between computer processors and peripherals.
FDDI. Fibre Distributed Data Interface. A communications standard for 100 Mbps LANS. Originally developed for fibre optic technology, but now available over copper wires.
FDM. Frequency Division Multiplexing. Using multiple frequencies over a communications channel to form multiple logical channels for carrying information.
Flash Memory. A RAM-based non-volatile memory module which emulates a disk, for use mainly in hand held computers.
Frame Relay. A form of packet switching system which can operate at up to 2Mbps. Error correction is the responsibility of the end computing services, since it is assumed that the probability of errors occurring on the network is so small as to be not worth the network nodes trying to detect or correct them.
Fuzzy Logic. One of several alternative calculi for attaching numeric uncertainty values to rules and facts in expert systems. This enables the system to handle imprecise information. As the rules and facts are combined to infer the answer to a problem, the numeric value attached to each one are also combined arithmetically. This gives an uncertainty value to any conclusion drawn from them. Whereas rule-based systems are composed of rules of the form: 'if this set of criteria is satisfied exactly, then take action', fuzzy logic systems' rules resemble the following: 'if this set of criteria is satisfied, in combination, to a given degree, then take action'.
Genetic Algorithms. These are built by a process of evolution, that mimics the development of biological systems. At each stage of evolution the best algorithms are selected for 'breeding'. They are cut and combined with each other to produce the next generation of algorithms. These are then tested against some success criteria to determine which are the best. The process terminates when some threshold of goodness is reached or a time limit expires. Genetic algorithms are useful in many applications where it is difficult to design an algorithm for the task.
Giga Byte (GB). 1,024 MB. Approximately equal to the number of characters in 1,000 novels, or 510 times the capacity of a typical Personal Computer.
GMR. Giant Magneto Resistance. A technique for producing very fine but strong magnetic fields to enable very dense packing of data on magnetic media.
GPS. Geographic Positioning System. A satellite based system for giving the position of a suitable receiver anywhere in the world.
Groupware. The system software and applications which allow a group of people in a network to work cooperatively, sharing such applications as calendars, diaries, libraries, files, electronic mail, business processing, etc.
GSM. Global System for Mobile communications. A digital communications service for voice and data,
GUI. Graphical User Interface. A way of communicating with a computer system by means of a screen capable of displaying graphics, a movable 'mouse' which displays a pointer and selects images on the screen and a keyboard.
HSSI. High Speed Serial Interface. A standard for a high speed link between communications interface equipment and a computer.
Human Computer Interaction. The interaction between a person and a computer with the person, for instance using a keyboard, keypad, mouse, voice, joystick, etc and the computer using characters, menus, graphics, images, sound, etc.
Hypermedia. This is a method of constructing or authoring training material. Eg: See something you want to examine? Freeze the frame and click on the object to zoom in for a closeup and a voice-over description. Click on a picture of a car and the body becomes transparent; click on the transmission and it explodes into a complete disassembly diagram with animated step-by-step procedures for dismantling.
Hz. Hertz. A measure of electromagnetic frequency or the clock rate of a processor in cycles per second.
IEEE. Institute of Electrical and Electronic Engineers. A body responsible for producing standards in computing, communications and other areas.
Inference. (Automated inference). The central enabling technology in Artificial Intelligence. Lies behind rule-based programming, logic programming, deductive databases, automatic programming, uncertainty, planning, etc.
Information Superhighway. The creation of a secure broadband communications infrastructure widely accessible and used to carry data, voice, video and provide a vehicle for related services.
Internet. A worldwide computer network, generally available to subscribers for about ?10 per month. It currently has some 25 million subscribers and is growing at 1m new ones per month. It can be used for electronic mail and for access to various libraries and databases.
ISDN. Integrated Services Digital Network. International standards for interfacing to digital networks and the services provided by those networks. Each access interface has two logical channels of 64kbps (one voice, one data) and a signalling channel of 16kps.
ISO. International Standards Organisation. A cooperative of national standards bodies for setting standards in many areas of technology, industry and commerce.
ITU. International Telecommunications Union. The body which agrees interworking standards between the telecomms operators. Its role is defined by treaty.
JPEG. Joint Photographic Experts Group. An industry compression standard for still images.
K. Abbreviation for Kilo, meaning one thousand. A more precise figure is 1,024.
Kb. Kilobit. 1,024 bits.
KB. Kilobyte. 1,024 bytes. Approximately equal to the contents of half a page of A4 text.
LAN. Local Area Network. A method of connecting together a heterogeneous range of devices on a single user site.
M. Abbreviation for Mega, meaning one million. A more precise figure is 1,048,576.
Mac. Macintosh. A single user computer designed by Apple using Motorola or PowerPC processor technology. Usually running under the System 6 or System 7 operating system.
Magnetic Storage Technology. The technology of storing information by the interaction of a concentrated magnetic field with a physical media, such as the surface of a disk or tape.
Mb. Megabit. 1,048,576 bits
MB. Megabyte 1,048,576 bytes. Approximately equal to the contents of 500 pages of A4 text, or one graphics image on a computer display.
MFLOPS. MegaFlops. Millions of Floating Point Operations per Second. This measures a processor's performance at supporting technical, scientific and graphical interface workloads (since they consist of a large proportion of mathematical floating point operations).
MIPS. Millions of Instructions Per Second. A way of defining the power of a microprocessor. The amount of real work accomplished varies very much from one processor architecture to another and depends on the instructions themselves and what else the processor is doing (in the way of I/O, etc).
Moore's Law. 1964 - The density of semiconductor chips doubles every year. 1975 - The density of chips doubles every year and a half.
MPEG. Motion Picture Experts Group. This has produced two industry compression standards for video - MPEG1 and MPEG2. Compression ratios of 100:1 can be achieved.
Multimedia. This covers the bringing together of a broad spectrum of technologies to the desktop, including image, video, sound, voice, fax, mail as well as the usual desktop applications.
MVS. Multiple Virtual Storages. IBM's operating system for large mainframe systems. It is now embracing the programming interfaces and standards of the UNIX environment.
MHz. MegaHertz. (1 million cycles per second). Used to measure the clock rate in microprocessors.
Neural Nets. A computer system designed to emulate the human nervous system. Such systems are trained instead of programmed, and have been used for the kind of classification tasks that expert systems are good at (eg. fault diagnosis) and other applications such as pattern recognition, speech recognition and machine vision
NiCd. Nickel Cadmium. Conventional battery technology.
NIMH. Nickel Metal Hydride. A technology now being used in electrical batteries.
NMF. Network Management Forum. A consortium to promote standards for network management. It is attempting to accelerate 150 standards and promote compliant products.
Noyce's Corollary. Corrollary to Moore's Law states that all semiconductor chips are destined to approach a cost of $2 except those that cost less.
NT. Windows New Technology. An operating system from Microsoft for servers and high function networked workstations.
OMG. Object Management Group. A consortium promoting object technology. It formulates standards by selecting/merging existing product specifications. Members pay a fee to belong.
Object Oriented Systems. A method of programming where data, its description and the software to process it are stored as an 'object'. Permits the building of very complex software systems from many basic building blocks (objects). The advantages of this technology are better reliability due to using well tested modules, the reuseability of the modules themselves and the added integrity and security as a result of the fact that the data can only be processed in certain defined ways.
Optical Computing. The use of optical techniques for carrying information and control data inside a computer processor.
Objectware. The software systems, tools and technology which go to build Object Oriented Systems.
Operating System. The software which manages a computer system and includes such activities as: memory management, job scheduling, error detection and correction, operator interface, security, peripheral management, etc.
Optical Storage Technology. The technology of storing information by the interaction of lasers with a physical media, such as the surface of a disk. Since the resolution of a laser beam is much finer than a magnetic field, much denser storage can be obtained.
OSI. Open Systems Interconnection. A set of communications protocols, recognised as an international standard, for the purpose of interconnecting computer systems of different vendors.
OS/2. A multitasking operating system for IBM and compatible personal computers
OSF. Open Software Foundation. A consortium promoting Unix related technology - including operating systems (OSF/1), distributed computing environment (DCE), graphical user interface (Motif) - through a jointly owned software house in Cambridge, Mass, USA. Members pay a fee to belong.
Outsourcing. Describes the situation where a services company owns and manages the IT facilities required by an organisation, either on or off site.
Parallel Processing. Parallel systems employ many processors (perhaps hundreds or thousands), all working together on the same problem. The problem thus has to be able to be broken down into a number of parts which can be worked on simultaneously. Complex technical/scientific applications and data mining (see glossary) applications are examples.
PC. Personal Computer. A single user computer using lntel processor technology and usually running a DOS, Windows or OS/2 operating system. Manufactured by a large number of companies, but all compatible from a software point of view.
PCMCIA. Personal Computer Memory Card International Association. A standard interface for credit card sized modules allowing them to be fitted into portable and notebook personal computers to give additional memory, provide interfaces to peripherals, emulate devices, digitize sound, etc.
PDA. Personal Digital Assistant. A small handheld computer system.
PDP. Plasma Display Panel. A form of display for a computer system.
Peripheral. A device which is connected to the central processing unit of a computer. It falls into one of three broad categories - input device, output device or data storage device.
Petabyte. 1,000 terabytes.
Pixel. Picture Cell. The smallest area which can be addressed on a graphics type screen.
Protocol. Used in data communications to define the rules for transferring data and dealing with error situations.
RAM. Random Access Memory. The semiconductor memory used in computer processors. Used to hold the software when it is being executed.
RDBMS. Relational Data Base Management System. A database where the data appears to held in the form of tables divided into rows and columns.
RISC. Reduced Instruction Set Computing. A computer using a small, fixed format and highly optimised set of instructions. Each instruction can be executed in one or less clock cycles of the processor.
ROM. Read Only Memory. Internal store of a computer where special system programs are stored for execution. These programs are permanently resident in this area and are not lost when the power is switched off. These programs are known as firmware.
Server. A computer system which acts as a central store of data and with which other computers (clients) communicate to access that data.
Smart Cards. A typical smart card is a solid-state or optical system operating within a plastic, creditcard-sized unit. It can store thousands of characters in the solid state system and millions in the optical one. Most smart cards consist of semiconductor devices embedded within the card which can store, retrieve or encrypt the data.
Smart Hubs. The intelligent hardware devices which provide the focal points for the cabling and physical management of an in-house wiring network.
Spec1170. A set of 1,170 application programming interfaces, file formats and utilities, which the X/Open group will use to define a standard for UNIX. However, this standard will also be implemented in some non-UNIX operating systems.
SRAM. (Pronounced Esse-RAM). Static Random Access Memory. Very fast memory used by microprocessors during their operation. Not used for application or system software.
SSPE. Solid State Polymer Electrolyte. A new technology for future use in electrical batteries.
Supercomputers. Supercomputers are characterised by very fast operation, many times faster than conventional general purpose systems and a design which achieves highest speeds on calculative work. They therefore tend to be used in scientific and high-tech applications.
Superhighway. See Information Superhighway.
Synchronous. A communications protocol where data is transmitted in blocks with periodic synchronizing characters.
TB. Terabyte. 1,048,576 MB. Approximately the amount of data collected by the world's scanning systems in one day. Also approximately the total amount of online storage of very large organisations.
TCP/IP. Transmission Control Protocol Internet Protocol. A standard communications protocol which has been adopted over the years to interconnect networks and computer systems.
TF. Taper Fibre. A way of concentrating a laser beam into a very fine point to enable data to be written on a storage media at very high densities.
TFT-LCD. Thin Film Transistor Liquid Crystal Display. An advanced technology used in display systems.
UNIX. An operating system originally developed by AT&T, but now adopted by all the major computer vendors, particularly for workstations and mid-range systems and subject to much standardisation by international and industry bodies. Also now maturing into an operating system suitable for large complex computer systems. 'Unix' is a Registered Name now owned by the X/Open group.
VAN. Value Added Network. A computer network with specific user facilities. Examples are: Internet providers for email, EDI for business trading, etc.
Very Large Systems Engineering. The term used for large computer systems encompassing, for example, distributed computing within a digital communications infrastructure. Important components are also security, integrity, fault-tolerance and the ability to manage the whole system.
Very Small Systems Engineering. This covers small computing appliances, such as displays, voice, radios, batteries, etc. It covers typical home and domestic computing.
VFD. Vacuum Fluorescent Display. A form of display system for a computer.
Video Compression. The compression of video information to make transmission more efficient.
Video Conferencing. The technology which enables a number of people to partake in a conference without leaving their offices through the use of microphones, cameras and displays.
Virtual Reality. A way of simulating the real world. It uses a special helmet so that the computer can project a separate image to each eye to give a 3-D effect. The position of the person's head is tracked by the computer from the movements of the helmet and that of the person's hands through the use of special gloves. The person enters into a simulation of the real world which responds to their movements; thus they can 'walk through' a computer simulated building, aircraft interior, etc, or be taught to service products which have not yet been built.
Volatile Memory. Memory such as traditional semiconductor memory which loses data when the electrical power is switched off.
WAN. Wide Area Network. A communications network which links together different sites, either over private or public communications facilities.
WDM. Wavelength Division Multiplexing. The use of multiple wavelengths to enable a communications channel to be divided into multiple parallel logical channels, each of which can be used to carry information.
Windows NT. See NT.
Wireless Local Area Networks. Local Area Networks where the communicating media between the nodes is radio waves - each node having a receiver and transmitter communicating to a central point.
WWW. World Wide Web. A facility providing subscribers an interface and access to various services via the Internet, such as files and libraries.
X/Open. A consortium promoting standards for computer systems related to software portability and interworking. It operates mostly by selecting profiles of standards from other sources, sells product 'branding' as X/Open compliant and provides documentation and related services to members who pay a fee to belong.
X.25. A communications protocol for transmitting and receiving packets of data over a network. The packets contain their own destination and source addresses and hence packets with different sources and destinations may be carried over the same network link.
X.400. A series of international standards which define services and protocols for electronic mail.
X.500. The international standards defining directory services for networks of computers.