UniForum's Open Systems Glossary

All technical languages breed their share of acronyms and our industry is no exception. UniForum's Open Systems Glossary contains acronyms which we believe will be of use to all members. We don't expect we've captured them all, and new ones pop up all the time. We welcome new submissions (together with short to-the-point definitions) via e-mail to pubs@uniforum.org.

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IEEE 802.3 LAN specification using unshielded twisted-pair wiring and running at 10 Mbps. 10BaseT and Ethernet are very similar.

16-Bit Character Set
Character sets that require more than 200 characters, often considerably more: 16-bit character sets of 1,000 or more characters are common. (See Bit.)

100Base TX
See Fast Ethernet.

100VG AnyLAN
An alternative 100 Mbps specification to Fast Ethernet. 100VG AnyLAN was sent to the 802.12 Token-Ring working group. 100VG is an attempt to make a faster Ethernet better suited to multimedia LAN communication. (See also Fast Ethernet.)

3-Tier System
Comprises client-middleware-legacy system or server.

4GL (Fourth-Generation Language)
High-level programming languages generally associated with database applications. The name is derived from a comparison with languages such as C, which are labeled 3GLs. 4GLs are increasingly associated with graphical development tools which automatically generate the text of the programming language.

8-Bit Character Set
Character set than can be defined within the ANSI Latin-1 definition: usually around 200 characters total. (See Bit.)

ABI (Application Binary Interface)
Application interfaces that enable binary applications to function compatibly on operating system environments with minor differences, such as varying implentations of Unix System V for Intel-based computers.

ACD (Automatic Call Distribution)
Telephony facility/resource that automatically routes inbound phone calls to specific phone desksets on an enterprise PBX.

Microsoft's external API link that will link Microsoft compatible objects to other external resources.

AFS (Andrew File System)
An alternative networked file system developed at Carnegie Mellon University as part of Mach and later incorporated into the OSF/1 operating system. (See NFS.)

A simple name substituted for a complicated name, e-mail address or company. Used frequently as an easily remembered name for an e-mail address or a list of e-mail addresses.

Anonymous FTP
A process for document retrieval using the FTP. The user logs on (as "anonymous") but does not need a password to access documents on the server. (See FTP.)

Second-generation specification of the C programming language accepted by ANSI in the late 1980s. Many of the changes between K&R C and ANSI-C simply formalized popular extensions that had been created within the programming community, and specified a standard library.

ANSI (American National Standards Institute)
The coordinating body for voluntary standards groups within the United States. ANSI is a member of the International Organization for Standardization (ISO).

API (Application Programming Interface)
A specification of function-call conventions that define an interface to a service. If two incompatible computers both support the same API, then a single version of source code should compile on each.

A Java applet; a dependent Java program that requires a Java Virtual Machine (the JVM can be embedded either in an operating system or built into an Internet browser).

A series of related communication protocols introduced and maintained by Apple Computer. Two phases currently exist: Phase I and Phase II. Phase II, the more recent version, includes support for internetworks.

Application Layer
Set of related functions that provide application services between hosts.

A search device for documents using anonymous FTP server machines. It is a system for locating information in files and directories that are publicly available.

ARP (Address Resolution Protocol)
A method of finding a host's Ethernet address via the broadcast mechanism. A sender using ARP broadcasts a packet containing the Internet address of another host and waits for it (or some other host) to send back its Ethernet address. Each host maintains a cache of address translations to reduce delay and loading. ARP allows the Internet address to be independent of the Ethernet address but it only works if all hosts on the net support it.

ASCII (American Standard Code for Information Interchange)
An eight-bit code for character representation; includes seven bits plus parity. (See EBCDIC, UniCode.)

ASIC (Application-Specific Integrated Circuit)
A custom computer chip designed to perform a specialized function, hence application-specific.

AT/IDE (Integrated Drive Electronics)
The IBM AT hard disk controller interface that was moved off dedicated controller cards and onto the actual drive electronics (hence the name). The IDE interface is inexpensive and widely used but limits the system to two devices, a master and a slave. An updated specification, called ATA, is being discussed.

ATM (Asynchronous Transfer Mode)
A CCITT standard for cell relay. Multiple types of information, such as voice, video and data, are conveyed in small, fixed-size cells. Also, a BISDN transfer mode wherein an accelerated version of asynchronous time division multiplexing (ATDM) is used to move multiple streams of information across a communication channel. ATM is both a LAN and WAN technology.

awk is a text selection and alternation tool in the same family as grep and sed. It provides a means to search for text patterns and extends the capabilities to selecting specific fields from lines and testing relationships between those fields. awk can be thought of as a "programmable report generator."

Backbone in a Box
Using a router with a high-speed backbone to function as a network backbone. All primary LAN segments are run to the router, and communication between those segments flows at high speed. It is easy to integrate several protocols, and the router centralizes backbone management.

Backbone Network
The central data highway that connects other networks. A backbone can be the network infrastructure that connects several LAN segments within a building or campus, or a national or international infrastructure connecting network operations in various cities.

The capacity of a network, usually measured in bits per second. Network systems need higher bandwidth for audio or video than for e-mail or other services.

The number of times per second the signal can change on a transmission line. Usually, the baud rate equals the number of bits per second that can be transferred.

BBS (Bulletin Board Service)
A service that permits one person to post a message for others to read. Each bulletin board contains the discussion of a single topic. A bulletin board is sometimes called a computer conference.

Beta Software
Preproduction, unfinished software that has not been completely tested/verified for final release. Typically a class of software after the initial development/implementary phase of the product life cycle.

Binary File
A file with nontext characters. Often, a directly executable file that can be run as a program. Binary characters use all the bits in a (8-bit) byte. (See also ASCII.)

BISDN (Broadband ISDN)
Communication standards being developed by the CCITT to handle high-bandwidth applications such as video. BISDN can use ATM technology over SONET-based transmission circuits to provide data rates of 155 Mbps to 622 Mbps and beyond. Other physical layers can be used (T-1, T-3). (See BRI, ISDN and PRI.)

Bit (Binary Digit)
A unit of information; the amount of information obtained by asking a yes-or-no question. A computational quantity that can take on one or two values, such as true or false or 0 or 1. The smallest unit of storage -- sufficient to hold one bit.

Bps (Bits per Second)
A measure of the rate of data transmission. Usually, the measure refers to the capacity of a network. (See Bandwidth.)

BRI (Basic Rate Interface)
The ISDN interface composed of two B channels and one D channel for circuit-switched communication of voice, data and video. (See BISDN and ISDN.)

A hardware device used to connect multiple networks by passing packets. A bridge works at the data link layer (i.e., Layer 2 of OSI).

Broadband communications can carry multiple types of information by allocating different services to different frequencies. This characteristic enables it to more easily accommodate voice, video and data.

Another term for "viewer"; that is, a software package that permits you to look around the World Wide Web. Examples of browsers are Netscape Navigator and Internet Explorer.

BSD (Berkeley Software Distribution)
A Unix version released by the University of Calif. at Berkeley's Computer Systems Research Group, sold only to AT&T Unix licensees because it contains some AT&T source code. Earlier versions of SunOS were derived from BSD roots. A commercial implementation of BSD, cleansed of AT&T source code, is available from BSDI.

An amount of memory or data, usually eight bits. The smallest unit of memory referenced by an addressable unit of storage.

Byte Code
Java interpretive execution code that makes up a Java program ready for execution.

A programming language originally developed by Ken Thompson and Dennis Ritchie. C has since been extended and standardized and is used throughout the world.

An object-oriented programming (OOP) extension of the C programming language. OOP languages offer improved ability for developers to reuse software modules but require a fundamentally different mindset in development projects.

Cable Modem
High-speed modem.

Cache Memory
Area of memory in the computer set aside for temporary storage of the data that has most recently been taken from main memory. The computer anticipates what data the programs in operation will need and pulls this into the cache memory. This results in faster access and transfer of data than would be possible if the information had to be retrieved from main memory.

Making copies of data in local, high-speed storage.

CAD (Computer-Aided Design or Drafting)
CAD and related terms are often used with varying meanings. Generally CAD refers to the computer-based design work for architects, civil and mechanical engineers, etc. Some call this MCAD (Mechanical CAD).

CAE (Computer-Aided Engineering)
Generally refers to the computer-based design, simulation and testing work of electrical engineers. Some refer to this market as ECAD (Electrical CAD).

CAM (Computer-Aided Manufacturing)
Generally refers to the use of computers in the manufacturing process. Manufacturing equipment is increasingly fitted with computer-based monitoring components, and some are computer-controlled. Centralized, real-time computer monitoring of manufacturing processes is now common.

CASE (Computer-Aided Software Engineering)
Computer-based software design tools (Upper CASE) and code-generation tools (Lower CASE). CASE generally refers to software development tools intended for the development of large, complex projects, often by large development staffs.

CAT (Common Abstract Tree)
A universal intermediate language, used by Norsk Data in their family of compilers. It is a multi-language compiler system with automatically generated code generators.

CBT (Computer-Based Training)
Software applications generally designed for self-paced, independent learning. CBT often enables trainees to work through what-if scenarios.

CCD (Computer-Created Design)
A design created by computer.

See ITU.

CDDI (Copper Distributed Data Interface)
Standard for FDDI implementation on top of existing twisted-pair copper cable.

CD-ROM (Compact Disk Read-Only Memory)
Generally mass produced compact disks with computer applications and data. Data can only be read from, not written to, these optical disks. (See WORM.)

CD-RW (CD-Rewritable)
Allows users to read, write and erase data on compact disks.

CDE (Common Desktop Environment)
A specification under review by X/Open to establish a common graphical user interface. Part of COSE.

Cell Relay
The basis of several high-speed network protocols, including the SMDS Interface Protocol and ATM. Small, fixed-size packets, or cells, contain identifiers specifying the data stream to which they belong. Fixed-length cells can be processed and switched in hardware at very high speeds.

Particle physics institute located in Geneva, Switzerland. It is the home of the World Wide Web.

CGI (Common Gateway Interface)
A program or script, usually executed on a Web server, that carries out actions as a user clicks on active portions of a Web screen.

CGM (Computer Graphic Metafile)

A type of file used for graphics.

Character Set
Mapping of numeric values to specific characters, as with ASCII, ISO 8859 (Latin-1) and so on.

CICS (Customer Information Control System)
A transaction monitor used for large end-to-end transaction processing in a client/server environment. Can reset and restart a transaction if it fails.

CIM (Computer Integrated Manufacturing)
An alternative term for CAM. Manufactuing equipment is fitted with computer-based monitoring or control components and networked so that manufacturing processes can be monitored in real time.

CISC (Complex Instruction Set Computing)
A type of CPU. CISC processors use a more complex instruction set with multiple operand addresses, which may be out of memory. Intel 80386 and 80486 processors are CISC CPUs. RISC processors, in contrast, are more efficient and faster.

Any uniquely identified abstration of a set of logically-related instances that share the same or similar characteristics.

The computer running client software that connects to server machines holding information. The client makes requests to a server for documents and is responsible for displaying the information.

Client/Server Computing
The interaction between two programs when they communicate across a network. A program at one site sends a request to a program at another site and awaits a response. The requesting program is called a client; the program satisfying the request is called the server.

CLI (Command-Line Interface)
A simple computer interface for commands whereby all the characters make up a command, including additional command arguments or options.


A particular set of characters. (See Character Set.)

Collision Detection
Process of determining when data transmission has failed because a sending and receiving device has transmitted data simultaneously.

A translator that produces an executable file from a collection program source code.

Any class or metaclass operation that constructs (i.e., instantiates) or creates an instance (i.e., an object or class, respectively).

CORBA (Common Object Request Broker Architecture)
A specification jointly published by OMG and X/Open, to define a software layer responsible for accepting and fulfilling requests for objects. Version 1.1 was completed in 1991. Version 2.0 is, among other things, tackling interoperability issues.

COSE (Common Open Software Environment)
A process undertaken initially by Sun Microsystems, IBM, Hewlett-Packard, USL (Novell) and SCO to develop com- mon sets of specifications and interfaces to promote greater interoperability. COSE has generally deferred to X/Open's formal standardization process where X/Open is actively addressing issues.

CPU (Central Processing Unit)
The microprocessor responsible for the core processing of computers. The "brain" that coordinates all the computer's functions.

csh (C shell)
This script writing tool was developed at the University of California, Berkeley, during 1979 through 1981. The C shell includes a symbolic language to address previous commands that are entered at the command line. It executes Bourne and Korn shells. (See ksh, sh.)

CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
The channel access method used in Ethernet and IEEE 802.3. If two devices transmit simultaneously, a collision occurs, and both devices wait a random period of time before retransmission.

CSO (Central Services Organization)
A service that facilitates user and address lookup in databases.

CTI (Computer Telephone Integration)
Connection of a computer to a telephone switch and having the computer issue commands to move calls around. Also, more generally, any interfacing of computer and telephone systems.


A library designed at the University of California, Berkeley to draw on a character-mode CRT screen in a terminal-independent fashion. Curses is included with every Unix release and is now available for many non-Unix environments, such as DOS.

DAT (Digital Audio Tape)
Refers to a specification that enables digital data to be written to tape in a form factor similar to audio tape. Because DAT devices are generally less expensive and smaller, they have become popular backup devices for stand-alone personal computers.

Communications packet that contains both data and complete address information for the user who is to receive the data.

DBMS (Database Management System)
A generic term referring to a variety of software applications designed to enable users to enter, store, manipulate and retrieve data. Relational DBMSs are most common. Some low-end DBMSs, as well as large-scale mainframe DBMSs are flat-file databases. Object DBMSs are a relative newcomer that is popular for some applications.

DCE (Distributed Computing Environment)
DCE is an application suite developed by OSF and focused upon communications, distributed file services, naming services and security. Both DCE and ONC, an alternative, are supported by COSE member companies.

DDE (Dynamic Data Exchange)
An MS Windows service enabling applications to share data. For example, DDE could enable a spreadsheet to be shared with a word-processing application.

DDK/DDI (Device Driver Kit/Device Driver Interface)
A device driver standards specification that provides a uniform interface for compatiblity and portabitly between a hardware device and an operating system.

A group of communications products (including a protocol suite) developed by Digital Equipment Corp. The most recent iteration is DECnet Phase V, which is largely based on the OSI protocols.

DES (Data Encryption Standard)
Standard cryptographic algorithm developed by the U.S. National Bureau of Standards (now NIST).

Any class or metaclass operation that destroys or removes an instance (i.e. an object or class respectively).

DFS (Distributed File System)
An element of OSF's Distributed Computing Environment (DCE) and part of Unix SVR4. A common set of commands for NFS and RFS, providing a set of tools for managing distributed network environments.

Digital-to-Analog Converter

An electronic device that converts a sequence of numbers into an analog electrical signal. As one example, a D-to-A converter is needed to change the numbers on a compact disc into sounds.

DLL (Dynamic Link Library)
Application library layer used to store components of an application software.

DMA (Direct Memory Access)
A scheme where controllers access memory on a system without CPU intervention. For example, many PC SCSI controllers perform their own DMA to/from memory, thus eliminating the CPU overhead found in "programmed I/O" environments like the PC AT/IDE interface, which requires that the CPU read or write all data from or to the IDE device.

DME (Distributed Management Environment)
An OSF suite of services and applications for distributed system and network management.

DNS (Domain Name System)
Distributed name system used primarily to locate host IP addresses based on host names. It consists of a hierarchical sequence of names, from specific to general.

DPI (Dots per Inch)
The number of dots printed or displayed in one inch. Usually used to describe printer and scanner resolutions, but sometimes to describe computer graphics monitors.

DQDB (Distributed Queue Dual Bus)
Communication protocol proposed by the IEEE 802.6 committee for use in MANs.

Dedicated 56 kbps digital lines. DS0 lines are the most common private lines in use. (See T-1, T-3.)

DSP (Digital Signal Processing)
A chip dedicated to processing data such as voice and music. In much the same way as a floating-point processor offloads math functions from the CPU, the DSP offloads a lot of the load in multimedia applications.

DSS (Decision Support System)
Orginally from IBM, designed to provide planners and decision model developers faster methods to analyze corporate data and to make projections.

DTMF (Dual Tone Multifrequency)
Use of two simultaneous voice-band tones for dialing (such as touch tone).

DTP (Desktop Publishing)
A computing market generally referring to graphical page design and layout software, and related peripherals. In some quarters "DTP" is developing a low-end, amateurish, connotation, while "electronic publishing" is used for commercial computer-based publishing work.

Dynamically Load Drivers
The ability of an operating system to load device drivers while in runtime operation. Device drivers are loaded and linked to the operating system.

EBCDIC (Extended Binary Coded Decimal Interchange Code)
An eight-bit character code developed by IBM for data representation in their large mainframe computer systems.

A basic editor in the Unix system. Every Unix system has ed available. ed is a line editor; whatever operation you want to perform, you must specify what line or lines on which to perform that operation. Copies your original file into a buffer and lets you explore the text in whatever order you want.

EDI (Electronic Data Interchange)
The electronic communication of operation data such as order and invoices between organizations.

EISA (Extended Industry Standard Architecture)
An alternative to the IBM PC/XT/AT ISA architecture. EISA cards are software configured, so jumpers are eliminated, and they can access system resources via a 32-bit bus. It also is backward-compatible to eight- and 16-bit ISA cards.

Electronic Mail
A service that permits one to send text to another person, a group or a computer program. Messages automatically pass from one computer to another through computer networks and/or via modems over telephone lines. Electronic mail software permits, for example, one to reply to a memo, save it, and many other features. Memos are usually stored as text files.

An abbreviation for electronic mail.

Low-level, realtime system computing.

The packaging of operations and data together into an object type such that the data is only accessible through its interface.

ESDI (Enhanced Small Device Interface)
ESDI is an aging hard-disk controller specification, which provided substantially better performance than the ST-506 interface. (See SCSI.)

ESQL (Embedded SQL)
The inclusion of SQL statements within another programming language (such as C), making it easier to integrate external application modules or procedures with a database.

A baseband LAN specification invented by Xerox Corp. and developed jointly by Xerox, Intel and Digital Equipment Corp. Ethernet networks operate at 10 Mbps using CSMA/CD to run over coaxial cable. Ethernet is similar to a series of standards produced by IEEE and referred to as IEEE 802.3.

Ethernet Address
The physical address identifying a controller board. The Ethernet address is hard-wired on some controllers or stored in a ROM, and others allow it to be changed from software.

Ethernet Switching
A strategy to dedicate the full bandwidth of an Ethernet connection between two network devices, such as a workstation and a switching hub. Full duplex switched Ethernet offers a theoretical bandwidth of 20 Mpbs (10 in each direction), while standard switched Ethernet provides 10 Mbps.

An extension to an intranet that has a special secured line (e.g., ATM kiosk to a private bank network).

FAQ (Frequently Asked Questions)
FAQ is seen quite often on World-Wide Web pages. It is a place where people can get most of their questions answered without having to contact the Webmaster.

Fast Ethernet
A proposed specification in the 802.3 Ethernet working group to boost Ethernet speeds to 100 Mbps, and referred to as 100BaseTX. Early implementations promise to offer automatic sensing of LAN speeds between 10 Mbps and 100 Mbps. (See also 100VG AnyLAN.)

Fast Small Computer System Interface. Protocol within the SCSI-2 standard. Allows data to be transmitted at 10 megabytes per second and provides an 8- or 1-bit data path. (See SCSI and SCSI-2.)

FDDI (Fiber Distributed Data Interface)
An ANSI-defined standard specifying a 100 Mbps token-passing network using fiberoptic cable. Uses a dual-ring architecture to provide redundancy.

FIFO (First In, First Out)
A form of queuing where the order of removal from the queue is the same as the order of insertion into the queue. Hardware FIFOs are often used to buffer data streams between devices that may transfer data at different rates.

File Record Level Locking
Ability of computer system to limit access by users to a record in a file. Allows only one user at a time to access a record and prevents others from making modifications (although record reading may be allowed).

FIPS (Federal Information Processing Standard)
A collection of standards and specifications endorsed by the U.S. government in its attempt to achieve greater interoperability between its hardware and software systems.

Web software protection. System that limits access to information in an organization's internal network.

FOIRL (Fiber-Optic Inter-Repeater Link)
Fiberoptic signaling methodology based on the IEEE 802.3 fiberoptic specification, which allows Ethernet and IEEE 802.3 traffic to pass over fiberoptic cabling.

Frame Relay
A WAN protocol generally considered a replacement for X.25, providing more efficient transmission. Frame Relay is offered at speeds from 56 kbps up to T-1 speeds.

Free software.

FTP (File Transfer Protocol)
A high-level Internet file transfer protocol, usually implemented at the application layer.

Full Duplex (Duplex)
The ability to send communications in both directions at the same time over a commincations link.

A graphic image format in common use.

GIS (Geographic Information System)
A category of highly visual and graphical applications designed to present information within its geographic context, usually as an overlay to a map or satellite image. Often used for urban growth management, natural resource planning or to determine the best location for a retail outlet.

GNU (Gnu's Not Unix)
Developed by Richard Stallman, then of MIT, now with the Free Software Foundation, a Unix-look-alike operating system more similar to BSD than System V.

A distributed document retrieval system developed by the University of Minnesota. Gopher servers organize information in a menu hierarchy, and menu selections may reference files on other Internet hosts.

GOSIP (Government OSI Profile)
A government procurement specification for OSI protocols. Through GOSIP, the government has mandated that all federal agencies standardize on OSI and implement OSI-based systems as they become commercially available.

GUI (Graphical User Interface)
A general term used to distinguish newer application presentation methods, such as Motif, OpenLook, MS Windows and Macintosh OS, from applications displayed on character-based terminals. GUIs are characterized by multiple overlapping, resizable windows, buttons and the ability to use pointing devices, such as a mouse.

Half Duplex
The method of communications that allows for information to be transmitted back and forth between a computer and a device but only in one direction at a time.

HIPPI (High-Performance Parallel Interface)
High-performance network interface standard defined by ANSI.

Home Page
Start-up document that serves as home base for Internet explorations.

A computer connected to a network. Also called a "node."

An Internet browser that is written in the Java language and executes Java applets.

HotPlug Peripherals
The feature/ablitiy of hardware/operating system to accept and recognize a peripheral device for use while the computer system is in full operation. The reverse operation of the removal of a peripheral device is also consistent with the feature.

HTML (Hypertext Markup Language)
HTML is the page description language used to format pages for viewing on the World Wide Web. Formatting tags are embedded in a text file. These formatting commands are interpreted when the document is viewed with a Web browser. A superset of HTML, called HTML+, is being proposed to extend the language. HTML is derived from SGML and uses hypertext.

HTTP (Hypertext Transfer Protocol)
HTTP is the client-server TCP/IP protocol used on the World Wide Web for the exchange of documents.

A device used to connect several other devices together, e.g. in a hub/spoke architecture, a central connection box, or hub, is used to pass messages or data from a computer to one or more other computers connected to the hub.

Word or graphic in a file displayed on screen with some form of highlighting (color or underlining or both). The word or graphic represents hidden text containing the URL information of another document, which is displayed when you click on the highlighted word or graphic.

A system for storing pages of textual information that each contain embedded references to other pages of information.

I/O (Input/Output)
Input and output of text from software or hardware.

IAB (Internet Architecture Board)
The group responsible for guiding the research and development of the Internet. They are all volunteers who attend to hear about the latest developments and participate in efforts to refine and improve the software. It has two task forces: the IETF and the IRTF.

IDL (Interface Definition Language)
See OMG.

IEEE (Institute of Electrical and Electronics Engineers)
A professional and trade association that also promulgates information industry standards. IEEE LAN standards are the predominant LAN standards today, including protocols similar or virtually equivalent to Ethernet and Token Ring. (See Posix.)

IEEE 802.3
LAN protocol that specifies an implementation of the physical layer and MAC sublayer of the link layer. IEEE 802.3 uses CSMA/CD access at a variety of speeds over a variety of physical media. One physical variation of IEEE 802.3 (10Base5) is very similar to Ethernet.

IEEE 802.6
IEEE MAN specification based on DQDB technology. It supports data rates of 1.5 Mbps to 155 Mbps, and also supports data packets and circuits.

IETF (Internet Engineering Task Force)
The primary subgroup responsible for technical matters within the IAB.

A working version of a specification, such as a programming language or an application.

Information Superhighway
A term used by the popular press to refer to the emerging national information infrastructure in the United States. The Internet is the best example of the first part of the information infrastructure.

The process of construction of a new instance from its definition using a constructor.

The Internet consists of thousands of computer networks interconnected by routers. It is an extensive computer network that is accessed through the telephone system making it possible to reach millions of people all over the world. The IP transforms a collection of networks and routers into a seamless communication system by making the Internet function like a single, large network.

Cooperative activity between the National Science Founcations, Network Solutions, Inc and AT&T. InterNIC provides IP and domain name registration services for the Internet community such as domain administrators, network coordinators and Internet service providers.

A company internal, enterprise or campus internet; either separate or connected to the Internet via a protective firewall.

IP (Internet Protocol)
A Layer 3 (network layer) protocol that contains addressing information and some control information that allows packets to be routed. (See TCP/IP.)

IPX (Internetwork Package Exchange)
Novell Layer 3 protocol similar to XNS and IP that is used in NetWare networks.

IRQ (Interrupt Request Line)
A hardware signal (bus line) that allows a peripheral device to request processing by the CPU.

IS (Information Systems)
Information pertaining usually to computer systems.

ISA (Industry Standard Architecture)
The name given to the original PC/XT/AT bus designed by IBM in the early 1980s. The bus supports both eight- and 16-bit-wide devices as well as a degree of board vendor independence. (See EISA, MCA.)

ISAM (Indexed Sequential Access Method)
A somewhat crude but effective database format that originated in the mainframe world. Records in the database are logically accessed sequentially, by walking through the database index in the desired order.

ISDN (Integrated Services Digital Network)
Communication protocols used by telephone companies to permit telephone networks to carry text, voice and other types of data. ISDN typically operates at 56/64 kbps. (See BRI, BISDN, and PRI.)

ISO (International Organization for Standardization)
An international organization that is responsible for a wide range of standards, including those relevant to networking. ISO is responsible for the well-known OSI networking reference model. Often incorrectly referred to as the International Standards Organization.

ISP (Internet Service Provider)
A company that provides customers with a connection to the Internet. The connection can range from just supplying an e-mail address, to hosting a Web site, to installing a fast connection to the Internet.

IT (Information Technology)
Information pertaining to technology.

ITU (International Telecommunications Union)
The renamed CCITT. The standards setting functions are handled by the ITU-T, the Telecommunications Standardization Sector.

IVR (Interactive Voice Response)
A system to automate the retrieval and processing of information by telephone, using touchtones instead of a computer keyboard. IVRs use digitized human voices to present information to the user. (See VRU.)

A computer programming language and computer software platform developed by Sun Microsystems that is open, object-oriented in architecture, has interpretively executed programs, and requires lightweight Java Virtual Machine to execute Java programs on virtually any operating system or hardware platform. This is especially well-suited for the Internet/intranet and small "intelligent" devices (appliances) such as cellular phones or pagers.

Java Application
Independent stand-alone Java program that only requires the Java runtime engine. This contrasts with the Java applet which requires the JVM in an Internet browser.

Java Object Environment (JOE)
Java API for the object request broker (ORB).

Java Virtual Machine (JVM)
A Java program execution utility that is usually built into an Internet browser.

Java platform supplementary API that will link Java executables to other external resources.

JIT Compiler
Just-In-time compiler usually in context of Java byte code compiler to native code.

JPEG (Joint Photographic Experts Group)
The original name of the committee that designed the standard image compression algorithm. The algorithm, JPEG, is designed for compressing either full-color or grey-scale digital images of "natural," real-world scenes.

Jughead (Jonzy's Universal Gopher Hierarchy Excavation And Display)
A tool for gopher administrators to get menu information from various gopher servers across the Internet.

K&R C (Kernigan & Ritchie C)
The original C programming language as specified by Brian W. Kernighan and Dennis M. Ritchie. C is a relatively low-level, highly portable, general-purpose programming language created by Ritchie on the Unix operating system. (See ANSI-C.)

Japanese character set.

Kbps (Kilobits per second)
Data transmission rate of 1,000 bits per second. (See Bit.)

A popular, public-domain file-transfer program.

The part of the operating system that provides memory management, I/O services and all other low-level services. The kernel is the "core" or "heart" of the operating system.

ksh (Korn shell)
The Korn shell is the third of the three standard shells to be incorporated into the standard Unix environment. It used both sh and csh. It allows the user to access vi or emacs to edit commands. (See csh, sh.)

LAN (Local-Area Network)
A network covering a relatively small geographic area (usually not larger than a building or campus). Compared to WANs, LANs are usually characterized by relatively high data rates and relatively low error rates. (See WAN, MAN.)

LEC (Local Exchange Carrier)
Local telephone companies, including the RBOCs and other specialty and private companies.

Legacy proprietary online database resource.

LIFO (Last In, First Out)
Better known as a "stack," a LIFO queue behaves opposite of a FIFO queue. A LIFO queue only allows access to the most recently queued item, then the next most recently, etc. This form of queuing is most often used to "stack" the return addresses when performing subroutine calls.

A Unix-like operating system originally developed by Linus Torvolds for freeware/shareware distribution.

Software that distributes e-mail messages to registered subscribers such as major-domo, listserv, etc. Automates almost all the processes necessary to enable distributed discussion groups via e-mail.

Lempel-Ziv type data compression algorithm. Developed by Abraham Lempel and Jacob Ziv in the late 1970s.

A utility oriented towards easy maintenance of computer programs. It helps the process of going from the original source text of a computer program to the final executable form of that program.

MAN (Metropolitan-Area Network)
Generally, a network that spans a larger geographic area than a LAN but a smaller geographic area than a WAN. (See DQDB.)

Mbps (Megabits Per Second)
Data transmission rate of 1 million bits per second. (See Bit.)

MCA (Micro Channel Architecture)
An IBM proprietary bus architecture used in most of the PS/2 series of machines and the RS/6000 line of workstations and servers. The architecture supports multiple CPUs on the bus, like EISA and unlike ISA.

MFLOPS (Million Floating-Point Operations Per Second)
A measurement of speed in handling complex calculations, based on floating-point arithmetic. (See MIPS.)

MHS (Message-Handling System)
A CCITT X.400 recommendation that provides message handling services for communications between distributed applications. NetWare MHS is a different, although similar, entity that also provides message-handling services and is marketed by Novell.

MHz (Megahertz)
Millions of Hertz (cycles per second). MHz is an indication of frequency, often used to refer to the clock speed at which a given processor or bus runs. It is named to honor Heinrich Hertz.

Set of services independent of the operating system that is used to make development of application software easier, e.g. drivers and application programming interfaces. Isolates the application development from the specifics of an operating system or networking protocol, providing the communication requirements related to distributed applications.

MIF (Maker Interchange Format)
A text format used by FrameMaker to exchange files across platforms.

MIME (Multimedia Internet Mail Extensions)
A method of processing multipart, multimedia messages on the Internet.

MIPS (Million Instructions Per Second)
The performance measure for modern CPUs. (See MFLOPS.)

MIS (Management Information Systems)
Generally refers to corporate business computing services and the department responsible for them.

NCSA's browser (client) for the World Wide Web. Mosaic is a true second-generation Internet client application for browsing HTML documents on the World Wide Web. It supports full multimedia capabilities, and has been extended to access gopher servers, as well as handle news and e-mail. It is now being licensed and bundled with some operating systems.

CPU board.

A graphical user interface developed by OSF and now endorsed as part of COSE.

MPEG (Moving Pictures Experts Group)
An ISO committee that generates standards for digital video compression and audio. Also the name of their algorithm.

MRP (Manufacturing Resource Planning)
Computer systems and software used in planning and procurement of materials.

MTA (Message Transfer Agent)

An element of the X.400 standard. The part of an e-mail system that routes messages to their destinations.

MTBF (Mean Time Between Failures)
An indication of expected duration between successive failures of a given device. MTBF ratings are usually specified to give an indication of the expected or predicted reliability under specific operating conditions. For example, most disk drives today have predicted MTBF values between 100,000 and 800,000 hours.

Ability of an operating system to preform more than one task or run more than one program at a time.

NAS (Network Applications Support)
A broad middleware architecture designed by Digital Equipment Corp. to enable application interoperability over a network of heterogeneous computer systems.

NC (Network Computer)
A device designed to deliver networked information and applications to the user. It is a low-cost, low-horsepower, processor-neutral and OS-neutral hardware platform able to run Internet client applications.

NCSA (National Center for Supercomputing Applications)

The birthplace of the first version of the Mosaic World Wide Web browser, at the University of Illinois at Urbana-Campaign, IL.

Net, The
A term for two particular networks: Usenet and Internet. For instance, "I read it on the Net" or "You can get that file on the Net."

NetBios (Network Basic Input/Output System)
Software interface for a controller on personal computer local-area networks. Accepted standard for Token Ring interface. (See LAN.)

A network management architecture, operating system and related applications, commercially developed and sold by Novell.

Hardware and software data communications system. Networks are often also classified according to their geographical extent: LAN, MAN and WAN, and also according to the protocols used.

Network Link Layer or Network Layer
The network layer (e.g., Internet Protocol) is responsible for routing or determining the links necessary to get data from the sending to the receiving host. (See TCP/IP).

NFS (Network File System)
As commonly used, a distributed file system protocol suite developed by Sun Microsystems that allows remote file access across a network. In actuality, NFS is simply one protocol in the suite. RNFSS protocols include NFS, XDR (External Data Representation), RPC (Remote Procedure Call) and others. These protocols are part of a larger architecture that Sun refers to as ONC (Open Networked Computing).

NIST (National Institute of Standards and Technology)
Formerly the National Bureau of Standards (NBS), this U.S. government organization supports and catalogs a variety of standards.

NMS (Network Management System)
A system responsible for managing part of a network. An NMS is generally a reasonably powerful and well-equipped computer such as an engineering workstation, with a megapixel color display, large memory and disk space, and a fast processor. NMSs communicate with agents to help keep track of network statistics and resources. (See SNMP.)

NNTP (Network News Transfer Protocol)
A common method by which articles are transferred over Usenet.

NOS (Network Operating System)
Any operating system designed to operate and manage a computer network.

A text formatting program that is designed for use with laser printers and professional typesetting equipment. It supports only monospaced fonts and was developed before troff was written.

NSF (National Science Foundation)
A federally funded organization that manages the NSFnet, which connects every major research institution and campus in the United States.

Apple Computer's bus architecture used in its Macintosh systems.

OCR (Optical Character Recognition)
The ability to scan text and have the computer recognize letters, words and text formats on a page. OCR enables computers to turn images of documents into text files that can be edited in word-processing applications.

ODBMS (Object Database Management System)
Sometimes referred to as Object-Oriented DBMS. ODBMSs emphasize data classes and methods. Proponents claim object databases excel at storing complex groups of data as single objects. Examples might include a parts schematic or CAD diagram.

OEM (Original Equipment Manufacturer)
Use varies, but refers to the manufacturer or designer of a technology, which then licenses the technology to another company.

OLAP (On-Line Analytical Processing)
Database processing that supports advanced decision support, often using a multidimensional database.

OLE (Object Link Environment)
The compound document protocol from Microsoft that allows one document to be linked to or embedded in another.

OLTP (On-Line Transaction Processing)
Database processing that supports data entry at high speeds, such as traditional high-volume order-entry applications.

OMG (Object Management Group)
An industry group promoting standards for exchanging objects in an interoperable manner, perhaps best known for its work on CORBA.

OMT (Object Modeling Technique)
An object-oriented programming strategy.

ONC (Open Network Computing)
Sun Microsystems network protocols.

Open Group, The
An organization created through the combination of the Open Software Foundation (OSF) and X/Open Co., dedicated to the furtherance of open systems.

Graphics platform (library and graphics standards).

The graphical user interface developed by AT&T and Sun Microsystems. Until recently, a competitive peer to Motif. With COSE, Sun has acquiesced to Motif as the standard Unix windowing environment.

ORB (Object Request Broker)
The OMG client request manager. A standard for passing objects among heterogeneous computers on a network.

OS (Operating System)

The software on a computer that manages all the resources of the system, including file system management, memory, reading and writing files, scheduling processes, printing and communication.

OSF (Open Software Foundation)
An industry consortium responsible for the development of Motif, OSF/1, DCE and DME. One of the constituent organizations of The Open Group.

OSI (Open System Interconnection)
An international standardization program created by ISO and CCITT to develop standards for data networking that facilitates multivendor equipment interoperability. The OSI seven-layer model is frequently used to describe the various levels of network technology.

Any polymorphism whereby the same name or operation is overloaded for different but analogous abstractions or uses. Also operator overloading.

PA-RISC (Precision Architecture-RISC)
Hewlett-Packard's microprocessor architecture.

A unit of data sent across a network.

PBX (Private Branch Exchange)
A telephone switch on the user's premises.

PC (Personal Computer)
A general-purpose single-user microcomputer designed to be operated by one person at a time.

PCI (Peripheral Component Interconnect)
A self-configuring personal computer local bus designed by Intel. It runs at 33 MHz. It is currently used mostly on Pentium-based computers, but is processor independent and so can work with other processor architectures such as PowerPC and Motorola 680X0 series.

PCL (Printer Control Language)
A proprietary vendor- and device-specific control language used for laser printer control defined by Hewlett-Packard in the 1980s.

PCMCIA (PC Memory Card International Association)
An industry standard covering the mechanical and electrical specifications needed to interface to these credit card-size hard disks, modems, network adapters and memory cards with computer systems.

PDF (Portable Document Format)
Designed by Adobe Systems specifically to aid in the transfer of documents across platforms. PDF is a file format used to represent a document in a manner independent of the application software, hardware and operating system used to create it.

Based on Tcl/Tk, a higher level of language integration.

Perl (Practical Extraction and Report Language)
A freeware interpretive scripting language that is ideally suited for data manipulation. Originally developed by Larry Wall.

PEX (PHIGS Extensions to X)
A combination of the X Window system and PHIGS designed to create a networked, interoperable 3-D graphics environment.

Pretty Good Privacy encryption software (freeware).

PHIGS (Programmer Hierarchical Interactive Graphics System)
An ANSI/ISO standard 3-D graphics programming library that runs on almost all graphics computers, from laptops to supercomputers.

Plan 9
A distributed operating system designed by Lucent (AT&T-Bell Labs) and the Richie, Thompson, Kernighan, Pike Bell Labs group.

POS (Point of Sale)
Essentially a computer-based cash register. As the retail industry is increasingly computerized, most POS systems are computers with specialized peripherals, networked to an in-store server.

Posix (Portable Operating System Interface)
IEEE's standardization effort to promote interoperable computing interfaces and specifications.

A device- and resolution-independent page definition language developed by Adobe Systems, popularized with laser printers, and used to compose documents one page at a time before printing.

PPP (Point-to-Point Protocol)
A successor to SLIP, this protocol provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. (See SLIP.)

PRI (Primary Rate Interface)
ISDN interface to primary rate access. Primary rate access consists of a single 64 kbps D channel plus 23 (in the case of the 1.544 Mbps) or 30 (in the case of 2.048 Mbps) B channels for voice and/or data. (See BISDN, ISDN.)

The rules two or more computers must follow to exchange messages. A protocol describes both the format of data that can be sent, as well as the way a computer should respond.

Proxy ARP (Address Resolution Protocol)
The technique in which one host, usually a router, answers ARP requests intended for another machine. By "faking" its identity, the router accepts responsibility for routing packets to the "real" destination. Proxy ARP allows a site to use a single IP address with two physical networks.

Public Key Encryption
An encryption scheme using two keys, one public and the other private. The message is encrypted using the intended recipient's public key. The message can only be decrypted by the recipient using the recipient's private key. (See also RSA.)

QBE (Query By Example)
A form of database query where the user enters a form of the database query rather than having to enter actual SQL commands.

QIC (Quarter-Inch Cartridge)
An industry standard form factor that covers tape capacities from 20 megabytes to several gigabytes. The QIC committee provides media specifications, the actual format of the data tracks on the tape and interoperability specifications.

A digital video format developed by Apple Computer that integrates synchronized video and audio with compression techniques.

RAID (Redundant Array of Independent Disks)
A product niche where multiple hard-disk drives in a single enclosure operate in unison to increase read/write throughput, and/or increase data integrity and high availability, by continuing to function even if a single drive fails. The RAID Advisory Board has designated RAID levels 0-5 as a standard way for vendors to specify how their products read and write data.

RBOC (Regional Bell Operating Company)
The "Baby Bell" phone companies created in the divestiture of AT&T, such as NYNEX, Pacific Bell, Bell South and Ameritech.

RCS (Revision Control System)
A publicly available source code control system developed at Purdue University. Most Berkeley-style Unix vendors ship RCS but not as part of their official OS distribution. The System V counterpart to RCS is SCCS.

RDBMS (Relational Database Management System)
The de facto database paradigm that is the core for the new generation of client/server application infrastructures being developed. Relational databases supply tables of rows and columns, making it possible to access data in a more flexible manner than in heirarchial databases.

The ease with which software may be used for purposes other than those originially intended.

RF (Radio Frequency)
Generic term referring to frequencies that correspond to radio transmissions. Cable TV and broadband networks use RF technology. RF is also being used to communicate between handheld client computers and database servers.

RFC (Request for Comments)
Documents used as the primary means for communicating information about the Internet. Some RFCs are designated by the IAB as Internet standards. Most RFCs document protocol specifications such as Telnet and FTP, but some are humorous and/or historical. RFCs are available from the Internet Network Information Center.

RFP (Request for Proposal)
A document generally issued by a prospective purchaser of technology systems, describing their requirements so that prospective sellers can respond with detailed proposals.

RFS (Remote File System)
An alternative networked file system to NFS and AFS.

RISC (Reduced Instruction Set Computing)
RISC processors employ a more simple instruction set that generally executes within a single clock cycle and makes better use of the chip's registers. This combines to provide far faster processing than chips with a CISC architecture.

RMON-MIB (Remote Monitoring - Management Information Base)
A standard developed by the Internet Engineering Task Force (IETF) recently finalized for Ethernet, but still in transition for Token Ring networks. A key benefit of the RMON-MIB is that it requires less network traffic and overhead than proxy agents.

Robust or Robustness
Ability of a system to continue to operate while handling internal or hardware errors.

ROM (Read-Only Memory)

A router can interconnect two networks that use different technologies. Therefore a router can connect a LAN to another LAN, to a WAN, or a WAN to another WAN.

RPC (Remote Procedure Call)
NFS interface for interhost connectivity over a network.

Asynchronous, bidirectional bit-wide data standard typically used to connect peripherals (modems, printers, terminals) to computers.

The initials of the authors of a study on encryption and decryption regarding computer security. RSA Data Security Company markets public-key or dual-key encryption technology, widely used in security products.

RTF (Rich Text Format)
A file interchange format from Microsoft to facilitate document exchange.

RTOS (Real-Time Operating System)
A mode of action and reaction by an operating system and application software. It allows priorities to be changed instantly and data to be processed rapidly enough that the results may be used in response to another process taking place at the same time, as in transaction processing. It has the ability to immediately respond, in a predetermined and predictable way, to external events.

SAA (System Application Architecture)
A broad architecture defined by IBM to integrate applications across its proprietary systems that uses SNA as its communications layer.

The bus architecture used on most Sparc workstations. Sparc multiprocessing systems generally use an additional CPU/Memory architecture (MBus).

Ability of a computer system to be optimized to perform a specific function by adjusting the size of the central processing unit and the throughput to the needs of the application software being run.

SCCS (Source Code Control System)
A version-control utility incorporated in Unix System V implementations. RCS is an alternative publicly available versioning system.

SCSI (Small Computer Systems Interface)
Widely used byte-wide controller interface specification standard on workstations and Macintoshes which is capable of transfering 5 Mbps. Peripherals of different types (hard disks, scanners) can be combined on one SCSI bus.

Newer SCSI specification that supports a 10 Mbps data transfer rate and a broader range of devices. SCSI-2 is becoming more common on high-performance systems.

SDL (Specification and Description Language)
CCITT specification language with both graphical and character-based syntaxes for defining interacting extended finite state machines. Used to specify discrete interactive systems such as industrial process control, traffic control and telecommunication systems.

SDLC (Synchronous Data Link Control)
Synchronous communications protocol that allows data to be transferred bit by bit.

sed (stream editor)
The stream editor is a non-interactive text editor. sed works on your file from the beginning to the end and allows you no choice of edit commands once you have invoked it. It is a text editor that is used to make modifications to the content of a file. It is designed to deal with files containing strings of characters in a particular character set. sed is ideal for changes of a transient nature, rather than permanent modifications to a file.

Software locking device.

The computer that provides services (documents, software) to other machines that run specific software (clients) and request those services. (See Client/Server Computing.)

Group id. (See SUID.)

SGML (Standard Generalized Markup Language)
An ISO standard designed to ensure that electronic documentation is interoperable between dissimilar hardware and software systems. SGML is increasingly being adopted as a requirement by commercial and governmental organizations.

sh (Bourne shell)
The Bourne shell in Unix that is used for script writing. It is the most common shell for software testing purposes. (See csh, ksh.)

A class of software that is made available at low or no initial cost but requests some cost later for full support or useage.

SIMM (Single In-line Memory Module)
A small circuit board populated with memory chips. SIMMs are considered more convenient to work with than placing or exchanging individual memory chips on a board.

SLIP (Serial Line Internet Protocol)
A protocol used to run IP over serial lines such as telephone circuits via a modem or leased lines.

A popular shareware program that emulates a PPP link within a standard Unix shell account environment link.

SMDS (Switched Multimegabit Data Service)
A high-speed, packet-switched WAN technology offered by some RBOCs and Interexchange carriers. SMDS is generally run at speeds between DS-1 and DS-3.

SMP (Symmetrical Multiprocessing)
A multiprocessor design where all the processors have equal status versus the master and slave relationship of asymmetric multiprocessing. The processors are identical and share common memory; each runs its own copy of the operating system kernel. With SMP, processes are not tied to a specific processor and can be run by any available processor.

SMTP (Simple Mail Transfer Protocol)
A protocol for electronic mail services popular in Internet environments.

SNA (Systems Network Architecture)
Developed by IBM, it defines the rules for transmitting and receiving data between mainframe computers and dumb terminals over a network.

A device that can "sniff" or detect LAN packets for analysis.

SNMP (Simple Network Management Protocol)
An Internet network management protocol that provides a means to monitor and set network configuration and run-time parameters.

SNMP-2 (Simple Network Management Protocol - Version 2)
An update of the SNMP standard by the Internet Engineering Task Force (IETF). One enhancement addresses the security of network management packets.

A combination of the port address and the network address used to uniquely identify processes operating a specific node of a network.

SONET (Synchronous Optical Network)
High-speed synchronous network standard. Used by RBOCs as a transmission system for voice and data. (See ATM.)

Indiscriminate and unwelcome Internet advertising. Viewed as abuse of NES groups and listserver-based discussion groups.

Sparc (Scalable Processor Architecture)
The microprocessor architecture popularized by Sun Microsystems.

A floating-point performance measure developed by the Systems Performance Evaluation Cooperative, an industry consortium. SPECfp is the geometric mean of six floating-point performance benchmarks.

An integer performance measure developed by the Systems Performance Evaluation Cooperative, an industry consortium. SPECInt is the geometric mean of four integer performance benchmarks.

SQL (Structured Query Language)
A higher-level language used for database applications. ANSI has certified both a 1989 and a 1992 SQL standard.

System Signaling 7, a packet switching standard established by ANSI and ITUTSS (CCITT).

(1) An early 1980 hard disk-drive interface specification named after the industry standard 5 MB (yes, five megabytes) formatted capacity. (2) A 5.25-inch disk drive using MFM encoding. (See ESDI, SCSI.)

User id. (See SGID.)

SVR4 (System V Release 4)
The latest major release of the Unix operating system from Novell's Unix Systems Group, and the release on which most Unix implementations are based.

System V
The current generation of the Unix operating system produced by AT&T. The two most significant previous generations were System III and Version 7.

Digital leased-line supporting 1.54 Mbps (DS-1).

Digital leased-line supporting 44.7 Mbps (DS-3).

Microsoft's Telephony Application Programming Interface that provides a computer telephony interface (CTI) platform.

A scripting language (pronounced Tickle).

TCP/IP (Transmission Control Protocol/Internet Protocol)
The two best-known Internet protocols, often erroneously thought of as one protocol. TCP corresponds to Layer 4 (the transport layer) of the OSI reference model, and provides reliable data transmission. IP corresponds to Layer 3 (the network layer) of the OSI reference model and provides connectionless datagram service. TCP/IP was developed by the U.S. Department of Defense in the 1970s to support the construction of worldwide internetworks.

This utility allows the user to log into a remote computer over a network (such as the Internet) using TCP/IP. The user can work on a remote computer as if it were their local computer. The telnet program is available on many operating systems.

A class template specifies how a family of individual classes can be constructed.

Terminal Emulator
A program that makes a computer display act like a terminal. For example, many terminal emulator programs emulate the Digital Equipment Corp. VT100 terminal.

Page formatting language with capabilities similar to troff, written by Donald Knuth of Stanford.

Thick Client
Clients are devices and software that require information. A client is a name fo a PC on a local area network. It used to be called a workstation. Now it is the "client" of the server. Clients come in two varieties, Thick and Thin. Thick clients are generally the full PC platform, which is fully functional offline, but can still exploit a network connection.

Thin Client
The Thin client stores and processes more data on the server, but keeps the user interface and application functions on the client device. Thin clients can access a broad range of applications, but depend primarily on remote resources on a network. The Thin client will be used as a potential way to reduce the capital and support costs of end-user computing. It will be most useful in enterprises where network dependency is increasing.


A term in multiprocessing or parallel processing for independent basic units of computation or action.

A measurement of a computer's productivity in the amount of data that is usefully processed in a set period of time.

A common graphic image file format.

Token Ring
Local area data communications network that uses a ring topology and was developed by IBM Corp. It is the process of passing a short electronic message, called a token, in sequential order. A host on the network cannot access the network until it receives the token. Once the host has completed the transmission, it releases the token. A Token Ring network transfers data at 4 megabits per second or 16 megabits per second. Depending on the type of wiring used, up to 270 devices, including mainframe, mini- and microcomputers, can be connected to this kind of network.

TPM (Transaction Processing Monitor or Manager)
Provides the ability to optimize response time and throughput, realtime database access and manage multiple concurrent updates of data. It is the element of an online transaction processing system which manages the sequence of multiple transactions, routing, load balancing, scalability, fault resistance and recovery from failures.

A text formatting program designed for use with laser printers and professional typesetting equipment. troff can support proportionally spaced fonts. (See nroff.)

A class of software that is available for limited use with "locks" that when "unlocked" make it for unlimited use.

Novell and AT&T's Telephony System Application Programming Interface that provides a CTI platform.

TSR (Terminate and Stay Ready or Resident)
A program strategy used to work around the inherently single-user, single-tasking nature of MS DOS. Examples of common TSRs include print spoolers, keyboard enhancers and memory managers.

Two-Phase Commit

Distributed process protocol under which transactions must be accepted or rejected by all the hosts on a network. A resource manager for load balancing, in which the system's work load is spread out equally among its resources. In the first phase, the protocol checks the network to determine if the message may be sent. In the second phase, the receiving system indicates if it can receive the message. Used to ensure an all-or-nothing guarantee of the completion of a database transaction.

High-speed network developed by Ultra Network Technologies. Supports up to 125 Mbps.

64-bit Version 9 Sparc microprocessor architecture used by Sun Microsystems, HaL Computers and licensees.

A two-byte character set developed by the UniCode Consortium, which was incorporated in 1991. UniCode integrates ASCII, Latin character sets and Far Eastern languages into a single character set.

Unified Messaging System
The unification of various communication messaging types into one concise (i.e., E-mail, Fax and voice mail) user management system.

Unshielded Twisted Pair
Standard telephone cable, rated at Category 3 or above. (See 10BaseT.)

UPS (Uninterruptable Power Supply)
A family of battery devices from multiple vendors that take over when normal electrical power fails. Their size, sophistication and cost vary widely.

URL (Universal Resource Locator)
An addressing syntax used on the Internet and used extensively on the World Wide Web. URLs generally have the form service://address, such as "http://www.uniforum.org." URLs can also specify ftp, news, mail and other internet host servers.

Usenet is a collection of thousands of computers worldwide that exchange files called news articles. This "net news" system has hundreds of discussion groups, from technical topics to art.

UUCP (Unix-to-Unix Copy Program)
A Unix file transfer application that is the basis for some E-mail systems.

An international standard for 1200 bps data transmission.

v.22 bis
An international standard for 2400 bps data transmission.

An international standard for 9600 bps data transmission.

v.32 bis
An international standard for 14.4 kbps data transmission.

A new modem serial line protocol that covers 19.2 kbps, 24.4 kbps and 28.8 kbps. With v.42 bis data compression, effective throughput can top 200 kbps. (See also v.Fast.)

An international standard error-correction protocol.

v.42 bis
An international standard error-correction protocol that added data compression to the V.42 standard, allowing for speeds up to 57.6 kbps.

The working name for the new v.34 standard that covers 19.2 kbps, 24.4 kbps and 28.8 kbps.

VAR (Value-Added Reseller)
A term whose meaning varies widely. Often a company that sells its own software together with another firm's software or hardware.

Veronica (Very Fast Rodent Oriented Net-wide Index to Computer Archives)
A service that maintains an index of titles of gopher items and provides keyword searches of those items. Veronica does for gopher servers what archie does for FTP servers.

VGA (Video Graphics Array)
IBM Corp. color video monitor with 640 x 480 pixel resolution and capable of displaying 256 colors. Also can provide black-on-white grayscale. Provides excellent resolution for use with graphics packages.

Names of two text editors found on almost every Unix operating system.

Visual Basic
Basic programming language package by Microsoft.

Visual C++
Microsoft product of C++.

VRML (Virtual Reality Markup Language)
Language based on the Inventor file format from Silicon Graphics. Inventor is a mature file format used for 3D graphics.

VRU (Voice Response Unit)
A system to automate the retrieval and processing of information by telephone, using touchtones instead of a computer keyboard. VRUs use digitized human voices to present information to the user. (See IVR.)

DEC terminal types.

WAIS (Wide-Area Information Servers)
WAIS is an index and retrieval system. When a keyword is entered, a search is performed on indexed documents, which then can be retrieved. It is supported by Apple Computer, Thinking Machines and Dow Jones.

WAN (Wide-Area Network)
A network spanning a large geographic area. (See LAN, MAN.)

The use of the TCP/IP Protocol, usually over a high bandwidth Ethernet line, to conduct voice communication using audio resources on a computer platform. (also referred to as IP-Phone, EtherNet Phone)

The administrator responsible for the management (and often is the designer) of a World Wide Web site.

A rectangular area on a screen devoted to one particular application program. Windows can overlap, and a user can move windows on top of other windows.

A class of groupware software that automates daily routine operations of a group in an organization.

Single-user microcomputer which is normally part of a network that is capable of high-performance and high-resolution sophisticated graphics.

WORM (Write Once Read Many)
A compact disk optical storage technology that enables data to be written permanently to the optical platter. Data can be accessed repeatedly but not overwritten.

WWW (World Wide Web)
The World Wide Web (the Web) is a distributed information retrieval system on the Internet. Information is presented in hypertext objects using HTML links to other Web servers or information pages. The information pages are specified as URLs. The Web originated from the CERN high-energy physics laboratories in Geneva, Switzerland. A client application is required, like Mosaic, for browsing information on Web servers.

WYSIWYG (What You See Is What You Get)
A representation of data on a monitor such that when printed, it is an exact facsimile of what appeared on the screen.

X Window System
Distributed, network-transparent, device-independent, multitasking windowing and graphics system originally developed by MIT for communication between X terminals and Unix workstations.

X11R5 (X Window System Release 5)
Version 11, release 5 of the X protocol, it is a hierarchial windowing system developed at MIT that is network-transparent and architecture-independent.

X11R6 (X Window System Release 6)
This is Version 11, release 6 of the X protocol, and is the latest version of the X Window protocol. (See X11R5.)

An established CCITT standard that defines the packet format for data transfers in a public data network. Frame relay is similar but requires less control information in each packet. Many establishments have X.25 networks in place that provide remote terminal access. These networks can be used for other types of data, including IP, DECnet and XNS.

A CCITT recommendation specifying an OSI standard for electronic mail transfer.

The X/Open Company, Ltd. is an international organization promoting open, multivendor application environments. It is, perhaps, best known for its XPG. Recently Novell transferred ownership of the Unix trademark from USL to X/Open. X/Open is one of the constituent organizations of The Open Group.

One of the original file transfer protocols that uses 128-byte packets.

XPG (X/Open Portability Guide)
A comprehensive set of voluntary APIs, protocols and other specifications designed to promote open, interoperable computing. XPG4 is the current version of this multivolume document.

An file transfer protocol that improved upon XMODEM and uses 1-kb packets. (See ZMODEM.)

A file-transfer protocol that improved upon YMODEM. When a ZMODEM file transfer fails, the retransmission can pick up with the last successfully transferred packet, rather than needing to retransmit the entire file.