Glossary

A B C D E F G H IJK L M N O P QR S TUV W XYZ

Address

One or a group of characters specifying the recipient or originator of transmitted data. An address can also denote the position of data in computer memory or the data packet itself while in transit through a network. IEEE 802.3 and 802.5 recommend having a unique address for each device worldwide.

Alerts

Messages that Microsoft's LAN Manager network operating system sends under certain conditions. The three classes of alerts are admin alerts, error alerts and printer alerts

Application

A program which performs a particular function such as word-processing, or manipulating a database or spreadsheet -- as opposed to Operating System programs which control the way a computer works. Also known as 'software' or 'package'.

Back End

The server part of a client/server application. It provides services across the network that have been requested by the client. For example, a back end may be a database server that responds to SQ L requests from a workstation running a front-end application.

Back-Up

IT Services recommend that students/staff make a second copy of their work should something go wrong with the hardware upon which files are stored, or the file on which important work is stored, is corrupted

Back-Up Server

Software or hardware which copies files so that there are always two current copies of each file. Also known as a Shadow Server.

Back-up Domain Controller

A server in a network domain that keeps and uses a copy of the domain's user accounts database to validate logon requests.

Bandwidth

The range of frequencies a transmission line or channel can carry: the greater the bandwidth, the greater the information – carrying capacity of a channel. For a digital channel this is defined in bit/s. For an analogue channel it is dependent on the type and method of modulation used to encode the data.

10Base2

A form of Ethernet and IEEE 802.3 network cabling using thin coaxial. It refers to 10Mbit/s speed Baseband transmission over 200 metres maximum length – in practice 185m) and is commonly known as Cheapernet.

10BaseS

A form of Ethernet and IEEE 802.3 network cabling using thick coax. It refers to 10Mbit/s speed Baseband transmission and 500m maximum length.

10BaseT

A form of Ethernet and IEEE 802.3 network cabling using twisted pair cabling. It refers to 10Mbit/s speed Baseband transmission twisted pair cable with a maximum segment length of 100m.

100BaseT

IE EE standard from proposals by the Fast Ethernet Alliance (including 3Com and SynOptics). It will support Category 3,4 & 5 UTP cabling.

100BaseVG-AnyLAN

A competing proposal to 100BaseT (promoted by Hewlett-Packard, IBM and Proteon among others) to the IEEE for a 100Mbit/s standard over voice-grade UTP – the cable most users already have installed in existing 10BaseT systems. Based on Quartet Signaling and demand priority protocol, it preserves the infrastructure and will need only a new hub and upgraded adapters in PCs/workstations. It claims support for Category 3,4 & 5 UTP cabling for both Ethernet and Token Ring.

Baseband

A term defining any network in which the information is modulated onto a single carrier frequency. The digital input is applied directly to the transmission media without the intervention of a modulating device, which works well if there is wide bandwidth and distances no more than several hundred metres are involved. It is common in LANs and limited-distance modems. All stations attached to the network have to participate in every transmission. Simpler and cheaper than Broadband, it permits only one "conversation" at a time as the whole of the bandwidth is used to transmit a single digital signal. Ethernet is a Baseband network.

BIOS Basic input/output system

A program usually inside a ROM memory chip called the Bios ROM . The Bios ROM performs test routines when a system is switched on; it searches for and loads the operating system from disk; and it contains programs to access the system hardware. [ABios, OS, Post, ROM]

Bit

A binary unit of information that can have two values, 0 or 1. The word comes from a contraction of binary digit.

Blue Screen of Death (or Blue Screen)

(Humour)

is the white-on-blue text screen or just blue screen without text which appears when Microsoft Windows crashes. It is most likely to be caused by a GPF (General Protection Failure). It is often impossible to recover cleanly from a Blue Screen of Death (BSOD).

Boot

To load and initialise the operating system on a computer.

Other expressions using the word Boot:

Reboot: A boot with the implication that the computer has not been down for a long time, or that the boot is a bounce intended to clear some state of wedgitude.
Cold boot: A boot from power off.
Warm boot: A boot from power on, where the CPU and peripherals are already powered up (warm). A warm boot might be performed after a software crash or a hardware reset.

Bridge

Device connecting two separate networks at the OSI Data Link Layer (Level Two Media Access Control Layer). Once bridging is accomplished, the bridge makes interconnected LANs look like a single LAN, passing data between the networks and filtering local traffic. There are two key classifications of bridge: those supporting Spanning Tree and, for Token Ring networks, those supporting Source Routing. Bridges connect networks using dissimilar protocols and do not interpret the data they carry. They control network traffic and security, filtering where necessary to boost network performance and contain sensitive data to particular [an areas.

Broadband

Also referred to as wideband. A term describing any networks that multiplexes multiple, independent network carrier frequencies on to a single cable. It allows multiple simultaneous "conversations", since the independent networks operate on different frequencies and do not interfere with each other. In LAN terminology, it refers to a system in which multiple channels access a medium, for example co-axial cable that has a large bandwidth using Radio Frequency (RF) modems. This may allow the co-axial cable to carry multiple separate LANs whose transmission is being modulated at different frequencies. In cable television (CATV), broadband describes the ability to carry 30 or more tv channels and is synonymous with wideband.

Broadcast

The simultaneous transmission of data via a network from one terminal to a set of destinations or to all destinations.

Byte

Eight bits forming a unit of data. Usually each byte stores one character.

CAD Computer-aided design or computer-aided drawing

The use of a computer to assist in the preparation of drawings or the design of some object or system. [CadMat, CAE, Cam, CNC]

CD-R Compact disc record able

A general term to describe compact disc computer storage systems where users may record their own data. Specific examples are CD-MO and CD- W0. [CD-MO, CD ROM, CD-WO]

CD ROM Compact disc read-only memory

The familiar audio CD used to store a large amount (over 600Mb) of computer data, which can include text, pictures and/or music. CD ROM drives can only read (but not write) data from these optical discs, but other optical storage devices are now available that can be both written to and read from. Error-detection codes (EDC) and error- correction codes (ECC) provide reliability for the stored data. [CIRS, CD+G, CD-I, CD-MO, CD-R, CD ROM XA, CDTV, DCT, DVI, ECC, EDC, FSFMV, MB, M0, MPeg, Worm]

Client/Server Computing

The division of an application into two parts – a front-end client and a back-end server. It allows multiple front-ends running on a PC or Unix workstation (client) to access the same 9QL-based server database at the same time over the LAN. The aim is to off-load as much processing as possible to the intelligent desktop leaving only the shared information and the software for managing it at the central server. An application that is running in such a fashion with client and server linked by a LAN is termed a bifurcated application.

Cloud Computing

Cloud computing is Internet- ("cloud-") based development and use of computer technology. The term cloud is used as a metaphor for the Internet. Typical cloud computing providers deliver common business applications online which are accessed from a web browser, while the software and data are stored on servers.

Cluster Controller

An IBM device that allows multiple 3270 terminals to be linked directly to a host computer, or into a S NA network through the use of a communications controller. A cluster controller is a Control Unit in IBM-speak.

CPU Central processing unit

The heart of a computer. The CPU works on information in digital form, processing it according to the steps specified in the program. A micro-processor is a CPU on a single chip. [ALU, CU]

Connectivity

A blissful state of 'network nirvana' at all communication layers sought by all communications professionals.

Crash

Means to fail suddenly. ‘Has the system just crashed?’, ‘Something crashed the OS (Operating System)?’ This may mean that the system failed for whatever reason (loss of server connection, loss of network connection). The computer may crash which is also called the Blue Screen of Death (refer to section B in the Glossary).

Cursor

Movable light spot on a VDU used to indicate the position of the next character.

Data Compression

A way of reducing the amount of data to be transmitted by applying one of several techniques that reduce the number of bits needed to represent the information. When the data is received it is decompressed into its original form.

Database Server

A database installed as a back-end or server component of a client-server system, which can be accessed over a LAN by one or more client, or front-end applications through the use of query LANguage, typically SQL. The server part of the program is responsible for updating the records, ensuring that multiple access is available to authorised users, protecting the data and communicating with other servers holding relevant data. The client end of the program requests records and then modifies them, while the server tracks records down for the client and adds new ones.

Data Link

A direct serial data communications path between two devices without intermediate switching nodes.

Debug

To locate, diagnose and correct errors

Device Driver

In the context of computer networking a device driver is a software module forming part of a computer operating system, or software that interacts with the operating system. It aims to control communications equipment, such as a LAN network adapter card and facilitate the transfer of information to and from the network. Other examples of device driver programs include software to support the activities of printers, disks and mice.

Digital signal

A signal with only two values, normally 0 and 1, during transmission, unlike an analogue signal whose values constantly vary.

Disk Server

A device equipped with disks and a program permitting users to create and store files on those disks. Each user has access to their own section of disk on the disk servers. The aim is to give users access to disk space that they would not normally have on their PC. The disk server is linked to the PCs via a LAN. The next level of sophistication would be a file server.

Diskless Workstation

A PC or workstation attached to a LAN that has neither floppy nor hard disks, but relies on disk storage provided by a file server attached to the same LAN. When the diskless workstation is first initialised it uses a remote boot program stored in a remote boot prom/eprom on its network adapter card to initialise a session with the file server. The workstation then loads its operating system, such as MS Dos, from the server and executes the normal server login procedure.

Domain

A group of nodes on a network that form an administrative entity. It could also be a number of servers grouped together and named to simplify network administration and security. Every computer on the LAN belongs to at least one domain. Being logged in on one domain, however, does not limit resources in other domains to which the user has access permissions.

Dos

Disk Operating System comprising one or a suite of programs managing a disk-based computer system. Dos schedules and supervises work, allocating computer resources and the operation of peripherals. Versions of Dos from different vendors exist: Microsoft's MS-Dos is the most common. Dos 3.1 was the first version of MS and PC Dos able to support LAN functions separate, of course, from the network's own operating system – notably including record and file locking which is now standard on multi-user systems.

Down

Down may mean that the computer, printer or monitor is not operating or functioning. You may hear the expression: ‘the system is down’, which means that a server or the network may be un-operational. This may affect several users.

The opposite of down is obviously up.

Dumb Terminal

A display monitor that has no processing capabilities. A dumb terminal is simply an output device that accepts data from the CPU. In contrast, a smart terminal is a monitor that has its own processor for special features, such as bold and blinking characters. Dumb terminals are not as fast as smart terminals, and they do not support as many display features, but they are adequate for most applications.

Dump

To copy from an area of memory, or a peripheral device, to a peripheral device; often used to denote the print-out of the contents of an area of memory

Electronic Mail (Email)

Messages sent from computer to computer, across the network. Email combines the best qualities of the letter and the telephone, and is moreover developing so that it can be used for things they cannot do - such as sending pictures and sounds. Thanks to the Internet people almost anywhere in the world can send each other messages by email.

Environment

A computing environment is a complete system of hardware and software, including the computer, its peripherals, its operating system and application software. The more modern the hardware and software, the better the environment - and the easier it is to do your work.

Ethernet

The most widely LAN transmission network. Based on a bus network topology, it runs at a maximum 10Mbit/s – in practice far less – and adopts CSMA/CD techniques operating over convention co-axial cable, thin wire co-axial cable and unshielded twisted pair cabling. A fibre-optic implementation has also been defined. Originally developed by Xerox, Intel and Dec, Ethernet has moved through Vl and V2 proprietary definitions, and has now been standardised by the IEEE as the IEEE 802.3 standard. This has several implementations 10Base5 for use over conventional co-axial cable, 10BaseF for use over optic fibre, and 10BaseT for use over Unshielded Twisted Pair (UTP) cabling.

Ethernet Switching

A technique inspired by Kalpana bringing the advantages of a parallel networking architecture to current contention based Ethernet LANs. Each LAN can be segmented each with its own 10Mbit/s path. When users on different segments exchange data, an Ethernet switch dynamically connects the two separate Ethernet channels without interfering with other network segments. The switch can create multiple independent connections between separate segments, allowing multiple parallel data exchanges. This multiplies network bandwidth without modification to Ethernet end station hardware or software. Once disparaged by other vendors, it now forms part of the portfolio of the major hub and router manufacturers.

Fast Ethernet

100Mbit/s technology for workstation LANs from the eponymous Fast Ethernet Alliance. It has been adopted by the IEEE as the basis for the 100BaseT Ethernet standard.

Files

Information stored on a computer system. Usually the information is stored on one of the following: floppy disk, hard disk, or a file server.

File Server

A computer, attached to a LAN, that runs a Network Operating System (NOS). This lets the file server regulate communications among the workstations connected to it across the LAN, and to manage shared resources available on the file server, such as hard disk storage and printers. A file server may be dedicated: the computer is used only as a file server; or non-dedicated: the underlying computer that the LAN NOS runs on is used for another task simultaneously, for example as a workstation.

File Transfer

The transmission of bodies of information in bulk from a storage medium on one computer system directly to a storage medium on another computer system, through a communications network.

Floppy Disk/Diskette

A flexible magnetic disk of 3.5" (or 5.25" on older PCs) diameter, enclosed in a square protective sheath of plastic or paper. The magnetic heads in a Floppy Disk Drive can record data on the disk and read it back, much as music is recorded on a domestic audio cassette. The drive mechanism is much cruder than a hard disk's, so storage capacity is limited to around one megabyte (compared to anything in the range 500-64,000 Mb on a hard disk).

Frame

A group of bits sent over a link. A frame may contain control and addressing information, as well as error detection – for example CRC information – and forward error correction information. The size and composition of the frame varies according to the protocol. Often used synonymously with packet.

Front End

The client part of a client/server application that requests services across a network from a server, or back end. It typically provides an interactive interface to the user, for example, a data entry front end, allowing data to be entered into a server through the use of SO L.

FTP (File Transfer Protocol)

The basic way of transferring files across the Internet. If you want to get files from another computer then you'll need an FTP client (available as shareware or there's one built into most WWW browsers).

Gb Gigabyte

A memory size of 1,073,741,824 bytes, or 1,024 megabytes (Mb). [GHz, K, Mb]

GHz Gigahertz

The Hertz (Hz) is a unit of frequency; it means cycles per second. 'Giga' - outside the field of computing - means multiplied by one thousand million; thus lGHz equals 1,000,000,000Hz. (For an explanation of the discrepancy between terms like 'giga', 'mega' and 'kilo' in computing and other fields. see under K.) [Gb]

Gateway

Network interconnection device and software that operate at OSI Layer Seven. A gateway supports a ful I stack of the relevant protocol, such as SNA, DecNet, ISO, TCP/IP, and can covert to a non-seven layer protocol, such as async or BSC. It is typically used to provide access to wide area networks over asynchronous or X.25 links from a LAN environment. Examples include pads and protocol converters.

Gif Graphics interchange format

A bitmap graphics format (and a file extension used to indicate it) from CompuServe which stores screen images economically and aims - with considerable success - to maintain their correct colours even when transferred between different computers. [DXF, EPS, IMG, PCX, TIF, WMF, WPG]

Graphical User Interface

(Operating system)

The use of pictures rather than just words to represent the input and output of a program. A program with a GUI runs under some windowing system (e.g. Microsoft Windows). The program displays certain icons, buttons, dialogue boxes etc. in its windows on the screen and the user controls it mainly by moving a pointer on the screen (typically controlled by a mouse) and selecting certain objects by pressing buttons on the mouse while the pointer is pointing at them. This contrasts with a command line interface where communication is by exchange of strings of text.

Group

In the context of network security, a group is a set of users who share common permissions for one or more resources. Individually assigned user permissions take precedence over those assigned through groups.

Hang

Look at the following expressions:-

“The system is hanging because it can’t read from the crashed drive” means to wait for an event that will never occur.
“The program displays a menu and then hangs until you type a character” means to wait for some event to occur.
“We are going to hang another tape drive off the file server” means to attach a peripheral device.

HD Hard disk

These are similar to Floppy disks, but cannot be removed from their host computer. They generally store between 100 to 1000 times the data stored on a floppy disk. Most PC computers connected to the campus network, generally, do not have hard disks.

A hard disk drive contains at least one aluminium 'platter' which stores digital information in magnetic form on its coated surface. The disk spins at high speed, typically 3,600rpm, with the read/write head floating above its surface. The mechanism is similar to that of a floppy disk drive, but the clearance between the head and the disk is so small, about one millionth of a metre, that the whole unit - including both drive and disks - must be sealed to prevent the slightest speck of contamination. This allows more data to be packed onto the disk: typical capacities range from 80 to 1000Mb, compared to a maximum of 1.4Mb on a conventional floppy.

Header

The control information added to the beginning of a transmitted message. This may consist of packet or block address, destination, message number and routing instructions.

Hertz

A measure of radio frequency. One Hz one cycle per second. KHz = 1,000Hz, MHz 1,000,000Hz, GHz – 1,000,000,000Hz.

Hot Fixing

The ability to detect and mark bad sectors of a disk, then assign alternate disk sectors during routine LAN operation. This automatically updates the original defect map.

HTML (Hyper Text Mark-up Language)

The language used to create documents on the world wide web.

Hub

The centre of a star topology network or cabling system. A multi-node network topology that has a central multiplexer with many nodes feeding into and through the multiplexer or hub. The other nodes do not usually directly interconnect. LAN hubs are increasingly popular with the growth of structured cabling and the need for LAN management.

Hybrid Bridge/Router

Network interconnection device with a standard mode of operation as a router. It can support multiple OSI Layer Three routing protocols, but also supports bridging capabilities for network traffic that cannot be routed – non-routable traffic.

IMAP Internet Mail Access Protocol

IMAP is an email standard for email clients to interactive with messaging services such as email servers and bulletin boards. IMAP allows email to be stored centrally but managed remotely by the user.

Ingres

A large relational database management system

Input Device

Anything that relays information from the user, or any electronic equipment (e.g. a tape drive), to the computer. For most users, relevant input devices are keyboards and mouses (mice?).

Internet

A large "network of networks" that originated from the United States Department of Defense's Advanced Research Projects Agency network (ARPAnet) during the Cold War. It provided a network originally between DoD sites and then Universities undertaking research for the DoD. It then grew rapidally to become the network which is in place today - a large network which has links and gateways into other networks, so becoming extremely well interconnected.

IP (Internet Protocol)

The TCP/IP standard protocol that defines the I P datagram as the unit of information passed across an internet and provides the basis for connectionless packet delivery service. IP includes the ICMP control and error message protocol as an integral part. It provides the functional equivalent of ISO OSI Network Services.

IP Address

The 32-bit address assigned to hosts that want to participate in a TCP/IP Internet.

IP Datagram

The basic unit of information passed across a TCP/I P Internet.

ISDN (Integrated Services Digital Network)

A form of public network currently being installed by BT in the UK and several other European countries. ISDN is an approach to switched digital networking that can handle a range of digital voice, data and digital image transmission. It is intended to provide end-to-end, simultaneous handling of digitised voice and data traffic on the same digital links via integrated switches. There are different access channels, according to geographic location. These include Basic Rate Access (2 x 64Kbit/s + 16Kbit/s) and Primary Rate Access (1.544 (US) and 2.048 Mbit/s (Europe). ISDN standards are defined in the ITU TS's I- Series Recommendations.

JANET Joint Academic NETwork

A system which connects computers in educational and research establishments and allows easy exchange of information between them. [Lan]

JPEG (pronounced "jay-peg") Joint Photographic Experts Group

Is an image compression mechanism (where JPEG stands for the original name of the committee that wrote the standard) and is designed for compressing either full-colour or grey-scale images work best on photographs but not so well on lettering, simple cartoons, or line drawings.

K, Kb, KB, Kbyte Kilobyte

One byte is eight binary digits (bits) or one 'byte', so lK is 1,024 bytes. [K, M, Mb]

Kernel

(Operating system) The essential part of Unix or other operating systems, responsible for resource allocation, low-level hardware interfaces, security etc.
(Language) An essential subset of a programming language, in terms of which other constructs are defined. Also known as a core language.

LAN Manager

LAN Network Operating System developed by Microsoft, which runs on top of OS/2 and recently Windows NT.

LAN Network Manager

IBM's network management software for Token Ring networks.

LAN Segment

A part of a LAN that is separated from the rest by one or more bridges.

LAN Server

IBM version of IBM LAN Manager.

Laser printer

A non-impact printing device which operates in similar fashion to a photocopier, in which a laser draws the image of a page on a photosensitive drum which then attracts toner on to the paper, where it is subsequently bonded by heating. More expensive to buy than an inkjet printer, but usually cheaper to run. Now the most popular type of printer for reasonable quality at reasonable cost.

LCD Liquid crystal display

LCDs are useful because they're flat, small compared with CRTs, light in weight, and use very little power. They make ideal displays for portable computers.

LDAP (Lightweight Directory Access Protocol)

Login

(or log in, log on, logon) means to start a session with a system, usually by giving a user name and password as a means of authentication.
The term is also used to mean the ability to access a service (also called an account) e.g. Have you been given a login yet?
“Log in/on” is occasionally misued to refer to starting a session where no authorisation is involved, or to access where there is no session involved e.g. Log on to out Web site!
“Login” is also the Unix program which reads and verifies a user’s user name and password.

Logon Script

A batch program containing LAN Manager, NetWare and other operating system commands used to configure workstations. Logon scripts can be written for one or more users.

MAC (Media Access Control)

Layer A sub-layer of the Data Link Layer (Level Two) of the ISO OSI Model responsible for media control.

Macintosh

A computer developed by Apple Computer Corporation. It originally had a text based interface, but soon developed one of the first GUI's. It is claimed to be one of the easiest interfaces to use (hmmm) and grew up to be popular with desktop publishing companies, artists, musicians and other, graphical applications.

Mb, MB, M, Mbyte Megabyte

1 Mb of memory is 1,048,576 bytes, or 1,024K. [Gb, Kb, M, Tb]

Memory Stick

A Memory Stick is a digital data storage technology with up to 10 times the storage capacity of a 3.5 diskette. Sony is promoting the Memory Stick as a new way to share and transfer pictures, sound, and other. About the size of a flat AA battery, Memory Sticks are available in 4mb, 8mb, 16mb, 32mb and 64mb sizes. They are smaller in size than comparable data storage devices.

Modem

A device named from an amalgam of the words modulator and demodulator. A modem will modulate an outgoing binary bit stream on to an analogue carrier, and demodulate an incoming binary bit stream from an analogue carrier

MPEG Moving Picture Expert Group

An industry association set up to fix standards for the digital storage and playback of moving video, particularly with regard to compression. [CD- ROM, FSFMV]

Multimedia

Generic description of the generation and transfer of voice/data/video traffic between users. Applications to exploit multimedia to the full are emerging in the wake of advanced switching techniques and developments in desktop and server processing architectures. It may be essential to a physically separated group that communicates as if it was physically networked.

NetWare

An operating system designed so that a network of PCs (and Mac's) can be linked together and provide central administration of files and devices. Except for serving files, the processing is not done by a central server or computer but by the machine on the desktop.

Network Architecture

The communication equipment, protocols and transmission links that constitute a network and the methods by which they are arranged.

Network Computing

A term analogous to client/server computing.

Network Device

A computer, peripheral or other related communications equipment attached to a network.

Network Device Driver

A program that enables the operating system software to communicate the network adapter cards. Also a software module running on a host or workstation that is responsible for the communications between the computer and the network or a device attached to the network.

Network Interface

The point of interconnection between telephone network operator's communications facilities and terminal equipment, protective apparatus or wiring at a subscriber's premises. This demarcation point is on the subscriber's side of the phone company's protector or its equivalent.

Nodes

Devices on a network that demand or supply services or where transmission paths are connected. Node is often used instead of workstation.

Online

Connected to a computer, or supplied by one. Can also mean connected to a network, particularily the Internet.

Operating System

Software which runs permanently in a computer to handle basic tasks such as receiving input from mouse and keyboard, displaying output on screens, and managing files. Programs which perform actual tasks -- such as word processors, databases and spreadsheets -- sit on top of the operating system and use its services.

It is the low-level software which handles the interface to peripheral hardware, schedule tasks, allocates storage, and presents a default interface to the user when no application program is running.

Examples of operating system: Linux, MS-DOS, Macintosh operating system, Microsoft Windows, Novell NetWare, Unix.

OS

Common acronym for 'Operating System'.

Output Device

Anything that supports the output of information from a computer, for users or to electronic equipment (e.g. tape unit). The output devices relevant to most users are Monitors, Printers and Disks.

Parallel Interface

An interface that can handle a group of bits transmitted at the same time, by sending each bit over a separate wire. Probably the best known parallel interface of all is the one developed by Centronics, a printer manufacturer, that has 36 pins and can handle a byte of data at a time. The transmission of the data is controlled by' a computer generated strobe pulse.

Password

A set of characters known only to the user and which enable him/her to maintain restricted access to his/her data.

PCI Peripheral Component Interconnect

Intel's version of the local bus system. Peripherals such as hard disk drives, network connectors and video monitors are usually controlled by circuit 'cards' that plug into the main computer circuit board via connectors or 'expansion slots'. The connectors are attached to the set of wires, or 'bus', that carries signals to and from the CPU . Different varieties of expansion slot are available with names like Isa Eisa and MCA. These methods of connection provide data at a rate which is lower than the latest CPUs are capable of handling, meaning that the whole system is working more slowly than necessary - a bus 'bottle-neck'. The local bus system aimed to improve this position by allowing a much more direct connection between the CPU and the peripheral controller cards. The PCI system goes further still, in providing a system where the controller cards themselves can contain the 'intelligence' to take over the connection system (becoming the bus 'master') from the CPU and send data to a chosen 'target' also connected to the bus. [CPU, Eisa, Isa MCA, VL-Bus]

Port

A computer interface capable of attachment to another device, such as a modem for communicating with a remote terminal or, if the port is within a hub, to a workstation.

Print Operator

An operator privilege that allows a user to create, share, and modify printer queues and control print jobs.

Print Server

A computer and/or software to provide users on a network with access to a central printer. The printer server acts as a buffer, holding the information to be printed out in memory until the printer is free. It is possible to program the printer server to print jobs in the order they arrive or to give priority to particular users who, in effect, jump the queue. The advantages of a printer server include maximum exploitation of expensive resources like laser printers and not having to retry if the printer is initially busy.

Printer Driver

A program that controls printing and sets options such as print quality and paper size for a particular printer. For example, in LAN Manager, each printer queue has a single printer driver associated with it.

Profile

A set of parameters defining the way in which a device acts. In the LAN world, a profile is often used by one or more workstations to determine the connection they will have with other devices. Profiles work like batch files, executing a number of commands to save a user time and effort.

Protocol

A set of rules governing the information flow within a communications infrastructure, often known as "data link control". Protocols control format, timing, error correction and running order. They are essential for a device to be able to interpret incoming information. Suites of protocols are often used in networks, with each protocol responsible for one part of a communications function. Example: Internet Protocol TCP/IP

RAM Random-Access Memory

Chip memory whose contents may be read by the system CPU and overwritten when necessary. All chip memory is best thought of as consisting of boxes, each of which stores digital information. The CPU can contact any individual box directly (either to read the data item in it or overwrite it with a new item) without going through the preceding boxes first - hence 'random access'. Ram chips are of two main types- DRAM and SRAM. [Bit, CPU, Dram, FRAM, PSRAM, ROM, RWM, SRAM]

RJ45

Popular name for the eight-pin modular connector in the 10BaseT standard for UTP connections to workstations or smart wiring hubs. The actual connector is described in ISO standard 8877. Riogin (Remote Login) – The service offered by Berkeley 4BSD Unix systems that allows users of one machine to connect to other U nix systems across an internet and interact as if their terminals connected to the machines directly. Although Riogin offers essentially the same service as Telnet, it is superior because the software passes information about the user's environment to the remote machine.

Router

Network interconnection device operating at OSI Network Layer (Level Three) that supports a particular Network Layer protocol and related stack, such as TCP/IP, DecNet, XNS, SNA, OS] IP, IPX. These days routers tend to support multiple protocols by a variety of methods, such as Protocol Independent Routing. A router can be used to link LANs together locally or remotely as part of a wan. A network built using routers is often termed an Internetwork.

Routing

Process of delivering a message across one or more networks via the most appropriate path.

Routing Table

Information stored within a router that contains network path and status information. It is used to select the most appropriate route to forward information along.

Scanner

A device which converts text or images from a piece of paper into a form which can be used in a computer; essentially performing the reverse of the process carried out by a printer.

SCSI Small Computer Systems Interface

'Scuzzy', as it's pronounced, is a means of connecting devices such hard disks, tape drives, CD-Rooms, Worms and erasable optical discs to a computer.

Serial Interface

Hardware for sending and receiving data one bit at a time.

Server

A node that permits other nodes on the LAN to access its resources. The server may be dedicated, in which case this is its sole function, or non-dedicated, where the node can be used in other ways, such as a workstation.

Server Operator

In LAN Manager terminology, an operator privilege that allows a user to start and stop services, and control and administrate network resources users' sessions.

Server Role

In LAN Manager terminology, the user mode in which a node is operating, and determines the class of users who are allowed access to the server via Netlogon. The server role can be backup domain controller, member server, primary domain controller, or standalone server.

Session

A logical connection between two nodes on a network for the exchange of data; alternatively, any live link between any two data devices, such as a minicomputer and a dumb terminal. A session is also used simply to describe connection time. Session Layer Level Five of the OSI data communications model, drawn up by the ISO, ensures the management of dialogue between applications by providing the protocols for assembling physical messages into logical messages to all dialogue between end systems.

Software

A general term for computer programs of all kinds, including the Operating System and individual application programs such as word-processors and games. In contrast to a computer's hardware, which is relatively fixed, software is easily modified or replaced to change a computer's performance or function.

Software licence

The terms and conditions under which a piece of software may be used.

Spreadsheet

A package which implements a table of columns and rows in which data may be entered and displayed, and a variety of calculations performed on it. Used initially as an accountancy tool, spreadsheets have become so sophisticated that they can now operate as databases and word-processing programs as well, and can often present results in sophisticated graphical form. Spreadsheets are a fundamental component of Integrated Packages. Excel is the best known spreadsheet package.

SQL (Structured Query Language)

A standardised query language that can be used for querying databases across a network in client/server applications. It can be used to interrogate the database, and extension to the language allows the database to be updated through it as well.

Standalone

A computer system which can function independently of any other computer system or device.

Surfing

“Internet surfing” is used by analogy to describe the ease with which a user can use the waves of information flowing around the Internet to get where he/she wants. The term became popular in the early 1990s as access to the Internet became more widespread and tools such as the World Wide Web browsers (i.e. Internet Explorer, Netscape) made its use simpler and more pleasant.

System

Can be the following:

The supervisor program or operating system on a computer
The entire computer system, including input/output devices, the supervisor program or operating system and possibly other software

Switch

Equipment used to connect and distribute communications between a trunk line or backbone and individual nodes.

TCP/IP (Transmission Control Protocol Internet Protocol)

The suite of protocols developed and used by Darpa and the US DoD. They build up to Layer Four of the ISO OSI model, but there is no direct correspondence layer for layer. Three main protocols sit above TCP/IP: Telnet, FTP and SMTP.

TFT LCD Thin-film transistor liquid crystal display

A technology used to manufacture LCD displays capable of high-quality grey scale or colour images. [CRT, EL, FLCD, LC, LCD]

Telnet

The TCP/IP standard applications-levej protocol for remote terminal connection service, allowing a user at one site to transparently interact with, or pass through to, a remote network or timesharing system at another site, while appearing as a local terminal.

Timeout

The expiration of a pre-defined interval which then triggers some action. For example, in a 30- second, no activity timeout, disconnection occurs after 30 seconds of no data activity. Simple eh? Alternatively, the length or existence of such an interval.

UNIX, Unics Uniplexed information and computing service

An operating system written by Ken Thompson of Bell Labs which was a slimmed-down version of the earlier Multics system. Traditionally used for mainframe and minicomputer installations, but is now available for micros - though it has the reputation of being rather more difficult to use and considerably more cumbersome than DOS. [AIX, COSE, DOS, Multics, NT, OS, OSF]

UPS (Uninterruptible Power Supply)

A battery, attached to a piece of hardware, for example a server, that provides backup power for conducting an orderly shutdown if the server's normal power supply fails.

URL Uniform Resource Locator

(Formally called Universal Resource Locator) A unique identifier for the type and location of information available over the Internet.

USB Universal Serial Bus

is an interface between the computer and an external peripheral such as a camera, joystick or printer. USB devices do not need a dedicated or specific adapter card for the computer.

Username

A unique identification. This informs any computer system who you are and that you have registered to use that system.

VDU Visual display unit

A general term for any computer monitor or real-time read-out.

Videoconferencing

Video and audio communication between two or more parties via a video-codec (coder/decoder) at either end linked by digital circuits. Formerly needing in excess of 300Mbit/s bandwidth, systems are now available offering acceptable quality for general use at 128Kbit/s and high-quality 7KHz audio. Factors influencing the growth of videoconferencing is improved compression technology, reduced cost through VLSI chip technology, low-cost switched digital networks – particularly ISDN – the emergence of standards and applications. Main players include BT, PictureTel and Compression Labs Inc.

Virus

Code that attaches itself to a program and makes copies of itself. It may or may not cause accidental or malicious damage, but is a serious nuisance particularly in a networked environment and where dependence on IT is heavy. Anti-virus applications such as Norton are available, but secuurity should be augmented by procedures and regular backups.

WAN Wide-Area Network

A system for connecting together computers which are geographically remote from each other. [ARPANET, Clans, CSMA/CD, IPX, LAN, Lawn, MAU, NOS, ODI, OSI, PSS, Raid]

WAP Wireless Application Protocol

Allows mobile phones to receive data from the internet

Web browser

A program which runs on a computer to display `pages' (screensful) of information which has been created according to the rules of the World Wide Web. A browser displays text and images, and also links to other pages; by clicking on such a link a user can go straight to a new Web page.

Windowing

Generic method of displaying data on screen, mimicking looking at several pieces of paper at once. Each window can be resized, moved and otherwise manipulated. It lies at the heart of making multi-user systems user-friendly and points the way for presenting tomorrow's applications.

Windows

The now ubiquitous Microsoft standalone operating system with integral graphical user interface, running on top of MS Dos.

Windows (Microsoft)

A family of operating systems for personal computers. Windows dominates the personal computer world, running, by some estimates, on 90% of all personal computers. The remaining 10% are mostly Macintosh computers. Like the Macintosh operating environment, Windows provides a graphical user interface (GUI), virtual memory management, multitasking, and support for many peripheral devices.

Windows Terminals

A dumb terminal especially designed to run Windows applications. Windows terminals are connected to a Windows NT server through a network. All processing and data storage is handled by the server; the terminal does nothing more than send the user's input (keystrokes and mouse movements) to the server and display the results on the display screen.

Windows 95 and 98

A Microsoft operating system running on each PC that allows users to run applications and allows many users to share information such as files and e-mail by clicking on icons. There is no server as such.

Windows NT (New Technology)

Microsoft's scalable 32-bit version of Windows aimed at high-end workstation "power" users. It is a standalone operating system that is also a "network ready" system capable of being a small application server for a workgroup of Windows based PCs.

Word-processor

A software package which enables the user to edit, format and print documents, and generally to process textual information. Many word-processing packages include useful extras such as a spelling checker, thesaurus, concordancing, mailing list management, and bibliographic reference retrieval.

Workstation

Term used freely to mean a PC, node, terminal or high-end desktop processor (for CAD/CAM and similar intensive applications) – in short, a device that has data input and output and operated by a user.

WWW (World Wide Web)

Also known as the Web, this is the generic name given to all hypertext-based HTML documents on the Internet that have links to each other and are accessible from HTTP or Web servers. (also known as the world wide wait - the time taken to pass information is dependant upon the slowest link)

XML eXtensible Mark-up Language

Extensible Markup Language (XML) is a simple, very flexible text format derived from SGML (ISO 8879). Originally designed to meet the challenges of large-scale electronic publishing, XML is also playing an increasingly important role in the exchange of a wide variety of data on the Web and elsewhere.

Zip Disk/Zip Drive

Proprietary portable storage medium and the propietary drive used to access it. Zip disks are similar in look and design to floppy disks, but have a higher storage capacity - about 250Mb.