Glossary of Selected Computer Terms UIC ADN Computer Center Document #102 30 Pages December 28, 1993 ABSTRACT This document contains an alphabetically arranged glossary of common computer related terms. There is further information on many of the concepts introduced here available in other Computer Center Documents. Many of the words defined there can be used as INFORM keywords to obtain a list of references. In some cases, a specific reference is given. Please see also RFC 1206: Condensed Glossary of Internet Related Terms for additional Internet and computer communications related terms, Dic- tionary of Acronyms for the obvious, and the IBM HELP Glossary of Com- puter Related Terms for an astonishing glossary with the emphasis on IBM and CMS related terms. (Use INFORM with the search keyword GLOSSARY; on UICVM CMS enter INFORM GLOSSARY .) [Editor's Note: As a means of sharing information, the Computer Center exchanges newsletters with many other colleges, universities and research institutions. Many of the definitions in this glossary are adapted from articles published in these outside newsletters. Too many of these resources have been used to cite each one individually, but without the information they contain, this glossary would be very much less complete. Their collective input is gratefully acknowledged. Also, Internetworking Terms and Acronyms, a small book produced and dis- tributed by Cisco Systems, Inc., was used as the source of the defini- tions of a number of the networking terms, and Webster's New World Dic- tionary of Computer Terms was used to check or clarify many additional definitions.] Glossary of Computer Terms +--+ Numerics and Others +--+ 10BaseT: The IEEE 802.3 LAN protocol specification which is used on the ADN-ii ethernet network, running at 10Mbps over unshielded twisted pair wiring. :-) A "smiley" -- turn your head ninety degrees counter-clockwise and you will see why it is called that. You type this in electronic mes- sages to indicate that what you've just said is meant to be funny. Glossary of Selected Computer Terms page 2 ======================================================================== For example: "... Oh, I'm telling your mother on you!!" sounds harsh, but: "... Oh, I'm telling your mother on you!! :-)" would be taken lightly. There are many other recognized smileys which express different emotions, for example, :-(, or which draw the smiley face differently, for example, 8-), a smiley face with glasses. +--+ A +--+ Abend: Abnormal ending. Various things may cause your program to abend, for example, exceeding job resource estimates. Academic Data Network: ADN: The ADN is the UIC computer communications network managed by the ADN Computer Center which campus facilities and offices. It consists of a pair of campus-wide backbone networks: the ADN-ii, a fiber optic based network, and the ADN-i, an older broadband network. In addition to connecting terminals, personal computers, local area networks (LANs) and distributed printers with each other and the Center's IBM mainframe and other computer systems at both the Chicago and Urbana-Champaign campuses of the University of Illinois, the ADN backbone network provides links to NSFnet, a national network sponsored by the National Science Foundations; the Internet, a world- wide network, including NSFnet, which uses the TCP/IP communications protocol; and BITNET, a national and world-wide network of universi- ties and research institutions. ADN-I Sytek Network: The oldest portion of the ADN computer network, which uses broadband (cable TV) type of communications. ADN-II Ethernet Network: A local UIC Ethernet network which is part of the nationwide Internet computer network. The TCP/IP protocol suite is used to communicate on the ADN-II Ethernet network. See also FDDI, Ethernet and 10BaseT. Account: A data record in the computer indicating a person's authoriza- tion level and available resources. At the Computer Center, there are two levels of accounts: master accounts and subaccounts. See the Com- puter Center document Account Identification and Dataset Prefixes for a description of each. ACF: The Access Control Facility: ACF allows users to choose who can access their stored data. See the Computer Center document The Access Control Facility: ACF Rules for Dataset, Minidisk, and CMS Tape Access for more information. Ada: A programming language developed by the Department of Defense in the early 1970's as a standard language for real-time and concurrent applications. It is a general purpose, block-structured language. ADN: See Academic Data Network, ADN-I or ADN-II. ANSI: American National Standards Institute: The principle United States organization for the development and publication of industry standards. APL: A Programming Language: A high level computer language used for mathematical manipulations; not available on the Computer Center's machines. ARC: Data compression and file packaging programs for personal comput- ers. See ARCUTIL. Glossary of Selected Computer Terms page 3 ======================================================================== Archive: Offline storage system for data which is not actively being used. At the Computer Center, on MVS we use the Hierarchical Storage Manager (HSM), and CMS we use VM ARCHIVE. Enter INFORM ARCHIVE on CMS for more information. ARCUTIL: The ARCUTIL program provides VM/CMS mainframe systems (includ- ing the UICVM ADN CMS system) a collection of functions for the manip- ulation of distribution files from public domain software archive sys- tems. Among the functions provided to UICVM CMS by ARCUTIL are: uu- and xxencoding and decoding (encoding allows you to transfer binary files or files with longer record lengths by electronic mail), recov- ery of data files which have been squeezed or crunched, expansion of .ARC, .LBR or .ZIP files, and translation of ASCII files to EBCDIC. ARPANET: Advanced Research Projects Agency Network: A research orient- ed network developed by the Defense Advanced Research Agency using the Internet protocols. ARPANET evolved into the Internet; the name ARPANET was officially retired in 1990. Ascenders: A text formatting term: The portion of any character which extends above the height of a lower case "m". See also descenders. ASCII: American Standard Code for Information Interchange: The ANSI standard code for sending alphanumeric characters through electronic equipment such as computers and terminals. ASCII uses an 8-bit code for character representation; 7 data bits and a parity bit. IBM is big and powerful enough to stick with their own code for their main- frame computers: EBCDIC. Assembler: The assembler language is a symbolic programming language which allows writing machine level instructions with simple mnemonics rather than numeric instructions. On ADN CMS, we have IBM 360/370 assembler, for the IBM system/360 and upwardly compatible machines. The term "the assembler" also refers to a program that translates sym- bolic machine language into actual machine language. Asynchronous: A method of transmitting blocks (or packets) of data that permits arbitrary spacing between individual characters. Transmission is controlled by start and stop bits at the beginning of each block. AUI: Attachment Unit Interface: An IEEE 802.3 (ethernet) cable con- necting the MAU (Media Access Unit) to the networked device. Also called a transceiver cable. +--+ B +--+ Backbone network: A local area network like the Computer Center's ADN, which acts primarily as a conduit for traffic to and from other net- works. Background: Using computer resources in a non-interactive way, at the discretion of the operating system. Background jobs usually do not interfere with your ability to use your account interactively. For example, MVS batch jobs and jobs run on CMS with the VM Batch utility are background processes. Backup: To make a copy of a data set for safety purposes. Backups can be either to disk or tape. Daily backups of MVS datasets and CMS minidisks which were modified are taken automatically by the system. Weekly backups are also taken of all user data stored on CMS or MVS public disk storage. See INFORM BACKUP for more information. Glossary of Selected Computer Terms page 4 ======================================================================== Bandwidth: The range of useful frequencies of a communications signal or channel. See also baseband and broadband. Baseband cable: A type of cable connection used in computer networks which is highly reliable and easy to manage, but which uses only one carrier frequency, and therefore is capable of transmitting only one message at a time. See also broadband cable. Baseline: A text formatting term: The baseline of a text is the lower- most point of the body of the letters, not including descenders (the lower parts of letters like "g" and "j"). BASIC: Beginner's All-purpose Symbolic Instruction Code: A simple to learn and easy to use programming language. We have a student version on CMS called WBASIC which was written at the University of Waterloo. Batch Jobs or Batch Processing: In batch processing, the program and data to be processed is collected with the commands needed to execute the program, and submitted to the operating system. The submitted batch jobs are kept in disk storage until execution; and they are selected for execution by the operating system in order by job class and priority. There are two batch facilities on the Computer Center mainframes: batch on UICMVS which uses JCL and is scheduled with the SCHED command on CMS; and batch run on CMS, which uses CMS execs and which is scheduled on CMS with the VM Batch facility. see also Inter- active processing. Baud: A measure of the speed of data transmission, equal to the number of discrete conditions or signal events that can be sent or received per second. For example, the terminals in the Computer Center termi- nal rooms communicate at 9600 baud, which is about 960 characters per second. Baud is the same as bps (bits per second) only if each signal event transmits only one bit. Bell 103A: An AT&T standard for modems providing full duplex, 300 bits per second, asynchronous or synchronous transmission over the public telephone network. Bell 212A: An AT&T standard for modems providing full duplex, 1200 bits per second, asynchronous or synchronous transmission over the public telephone network. Binary: A numbering system with only two digits; 0 and 1, where 0=off and 1=on. Bit: A BInary digiT: The smallest piece of data possible, a "1" or a "0". 8 bits make up a "byte"; one byte can represent a single charac- ter. BITNET: Because It's There NETwork: A low cost, low speed (mostly 9600 bps leased telephone lines) nationwide academic network of university computer systems using mostly VM/CMS. The network allows you to interactively send messages, data, and programs to users at other com- puter centers. The individual computer systems which belong to BITNET are called nodes. Many institutions (including ours) have more than one system which is a BITNET node. BITNET has recently merged with CSNET (Computer Science Network) to form CREN (Corporation for Research and Educational Networking.) BITNIC: The BITNIC computer provides user support and information facilities to BITNET users. These facilities include online informa- tion services; file servers providing help files, protocol documents, Glossary of Selected Computer Terms page 5 ======================================================================== network policy information, news, instructions for using network gate- ways, and information about electronic mail conferences; and a data- base server providing access to various online databases. Some infor- mation from BITNIC which may be of interest to the UIC community is on the CMS minidisk with the GETDISK nickname BITNET. Enter GETDISK BITNET and browse through the files on the disk. BISYNC: Binary Synchronous Communication, aka BSC. A transmission pro- tocol used by IBM mainframes. BISYNC gathers a number of message characters and puts them in a single, large message block that includes special characters, synchronized bits, and station-addressing information. Block: In communications, a group of individual data elements sent, received or stored as a unit to increase transmission efficiency. See also packet. Also a text formatting term: In some text editors or word processing packages, there are block commands which allow you to mark a block of text to be treated or processed as a unit. BMDP: BioMeDical computer Programs: A set computer programs that pro- vide a wide variety of analytical capabilities that range from plots and simple data descriptions to advanced statistical techniques. BootP: A protocol that is used by a network node to determine the IP address of its Ethernet interfaces, in order to effect network boot- ing. bpi: Bits Per Inch per track: A measure of the recording density on magnetic computer tape. For example, on a nine track tape written at 1600 bpi, you can store 1600 bytes (200 80 character records) on an inch of tape. bps: Bits Per Second: A measure of the speed of transmission of com- puter data. See also Baud. Bridge: A communications device which is used to connect two networks which communicate in an essentially similar manner. See also Gateway. Broadband cable: A type of cable used in computer networks which can carry several messages at the same time, but which is somewhat diffi- cult to install and manage. In contrast to baseband cable, broadband cable multiplexes multiple independent signals onto one cable. Buffer: A storage device which compensates for the differences in the rate of data flow during data transmission between devices. Bug: An error in either computer hardware or software. Finding and correcting errors is known as debugging. Bulletin board systems: BBS: An electronic information system. See also NETNEWS. Byte: A byte is 8 bits; one byte can represent a single character. On most machines, the byte is the basic unit of addressable memory. On IBM mainframes, a word is 4 bytes (32 bits). Glossary of Selected Computer Terms page 6 ======================================================================== +--+ C +--+ Carrier detect: A signal from an RS-232 connection indicating that a communication connection has been established with a remote system. CCITT: Consultative Committee International Telegraph and Telephone: An international committee that sets standards for international com- munications. The CCITT standard data modems needed for telephone com- munications on the ADN Computer Center's public dial-in telephone lines are: CCITT V.22-bis for 2400 baud; CCITT V.32 for up to 9600 baud; and CCITT V.32-bis for up to 14.4 Kbaud. Channel: A special purpose computer used for communication between a main computer and an external device, such as a disk or tape. Client: A front end device (a node or software program that requests services from a server. See also Server. Client-server computing: A distributed computing network system in which each transaction is divided into two parts: a front end client, and a back end server, which are two different devices or programs. See RPC. See also Peer-to-peer computing. Clock cycle: The unit of type used by the basic timing system of a com- puter. The clock cycle is used to measure the computer's theoretical performance. The clock cycles of the Computer Center's IBM 3090/300J/VF computer is 14.5 nanoseconds. CMS: Conversational Monitor System: The most widely used interactive computer system at UIC. CMS runs under the VM operating system on UICVM. VM/CMS is an efficient, easy-to-learn interactive system for executing programs. Its file system is separate from that used on MVS and batch, but it has links to submit jobs to, and receive output from, the batch system. Many useful applications programs, compilers and utilities can be used interactively in CMS. Most of compilers and packages which are available on batch are available on CMS for inter- active use, so programs can be developed in CMS and then the same pro- gram can be used for production work in batch. CMS Mail: See Electronic Mail. Coaxial cable: A cable with a hollow outer cylindrical conductor sur- rounding a single inner while conductor. COBOL: COmmon Business Oriented Language: An old but still commonly used programming language primarily for business applications. See also WATBOL. Compiler: A program that translates a high level symbolic language to a low level machine language, FORTRAN, Pascal, and PL/I are familiar compilers. COM port: The DOS name of the serial ports on PC's. Compression: Running data through an algorithm which reduces its size to reduce the space or bandwidth needed to store or transmit it. CREN: Corporation for Research and Educational Networking: The result of the merger of BITNET and CSNET (Computer Science NETwork). Control character: A byte of data (a character) whose occurrence initi- ates, modifies or stops an operation. Coupler: An acoustic device sometimes used to establish a phone connec- tion between electronic devices such as a terminal and a computer. Glossary of Selected Computer Terms page 7 ======================================================================== CP: Control Program: The interactive part of the VM operating system. CMS users encounter CP when they LOGON and LOGOFF, or if their CMS session is interrupted. CPU: Central Processing Unit: The "brain" of the computer which per- forms most computing tasks. Crop: A text formatting term: To trim the edges of a graphic image, removing part of the image. CRT: Cathode Ray Tube: A terminal with a TV screen and keyboard. CSNET: Computer Science Network. A larger computer communication net- work consisting of universities, research institutions, and commercial concerns, which merged with BITNET to form CREN. CTS: Clear To Send: When using DCE (Data Communications Equipment; a modem is a common example), the CTS indicates that the DCE is ready to accept data. Cylinder: As related to magnetic disks, a cylinder is a vertical column of tracks on a magnetic disk pack; since the read/write heads can read from any track on the cylinder without being moved in or out, storing multi-track files on cylinders is quite efficient. Cylinder is also used as a unit of storage space. On CMS, a one cylinder minidisk has storage for about 600K bytes. +--+ D +--+ DARPA: Defense Advanced Research Projects Agency: The US government agency that funded research and experimentation which lead to the Internet network. DASD: Direct Access Storage Device. A data storage device such as a magnetic disk storage unit which allows the operating system to directly access specific data stored on it without having to read through the data before it. This is as opposed to a sequential access device such as magnetic tape. Dataset: On MVS, the name given to a collection of information stored in any of numerous forms on any of numerous devices. A data set may contain programs, data, or text. Called a file in CMS and on many other computer systems. Dataset name: On MVS, the name of a dataset; called a file identifier on CMS. An MVS dataset name is up to 36 characters long (not includ- ing the account prefix, which adds 7 to 8 more characters), can have as many parts as you wish (within the length restriction), and the parts are separated by the periods (not blanks). A dataset name is "fully-qualified" when the account prefix identifying the ownership of the dataset is included with the dataset name. See Account Identifi- cation and Dataset Prefixes for more information. Debug: The process of finding and eliminating software or hardware "bugs" (errors). Default: The assumed value or action taken when no explicit one is specified. Descenders: A text formatting term: The portion of any character which extends below the baseline. See also Ascenders and Baseline. Dial-up lines: A telephone line reserved for communication between the computer and remote terminals. When you call a dial-up line, the com- Glossary of Selected Computer Terms page 8 ======================================================================== puter answers and a connection is made which enables you to logon to your account. Dial-up lines enable you to use a computer system from any location that has a telephone, a modem or coupler, and a terminal or a microcomputer running a terminal emulation program. Use the INFORM keywords MODEM or DIAL-UP for more information. Disk Drive: A very fast input/output device that consists of one or more spinning magnetic disks. A moving arm allows direct read or write access to data recorded on the disks. DISSPLA: The DISSPLA graphics package is a library of FORTRAN subrou- tines. It was designed to be used by scientific and business program- mers. The DISSPLA library routines must be called from a user written and executed program (written in FORTRAN, or another higher level lan- guage such as Pascal or PL/I that supports FORTRAN subroutine calls). Distributed computing: See client-server computing. Domain style name: See Internet address. DOS: Disk Operating System: The name of the operating systems on most brands of personal computer contains the acronym DOS. Often when DOS is used without further description, the operating system being referred to is either PC DOS, the operating system used on IBM person- al computers, or MS DOS, the variety of DOS that runs on IBM compati- ble computers. Dots per inch: See Resolution. Download: To transfer information stored in a remote computer to your (local) microcomputer. Driver: When information is passed from one type of device to another, usually the electrical and mechanical requirements of the two devices are different; software drivers are used to translate data which is to be sent another device so that device can properly process it. (For example, a printer specific driver may be used to prepare a document formatted by a word processing package for printing on different types of printers, or the same printer used in different modes.) Duplex: (2) A text formatting term: Printing on both sides of the paper. (2) A computer communications term: Half duplex: data trans- mission in only one direction at a time; and Full duplex: simultaneous data transmission in both directions. DSR: Data Set Ready: When using DCE (Data Communications Equipment; a modem is a common example), the DSR indicates that the DCE is ready to use. +--+ E +--+ EBCDIC: Extended Binary Coded Decimal Interchange Code: A scheme of assigning characters to each of the 256 possible combinations of 8 bits (1 byte). Several other schemes are also used, such as BCD and ASCII. Echo or Echoplex: Governs the appearance of characters on your VDT screen. Echo on means that the characters are sent back to the screen by the receiving computer; Echo off means that they are not. Editor: An interactive program that allows you to input, update, delete and store information on the computer. The information may be pro- grams, data, or actual textual material such as letters or disserta- tions. Glossary of Selected Computer Terms page 9 ======================================================================== Electronic Form: A text formatting term: The name that Xerox systems uses for a predefined graphic overlay form. The must common use of an overlay at UIC is to print a departmental letterhead. Departments may contact the Computer Center to arrange to have a letterhead overlay developed for their departments. Electronic Mail: A computer system which allows users to exchange mes- sages, notes and files. You can use electronic mail on CMS at UIC to communicate with people who use our CMS, or who use a computer that is connected to ours via BITNET or the Internet. On ADN CMS, the Rice Electronic Mail system (the MAIL and MAILBOOK commands) is used to send, receive and manage electronic mail. See also POP and IMAP. EIA: Electronic Industries Association: A standards development organ- ization for electrical and functional characteristics of interface equipment. Emulation: Using software which makes a PC behave as though it were a terminal, or which alters the characteristics of a user's terminal to act as a different type of terminal. Encrypt: To make temporarily unreadable. Datasets can be encrypted to ensure privacy. EPIC: Electronic Printer Image Construction: A subroutine library which allows graphics to be constructed from a FORTRAN or other higher level language program for printing on the Xerox page printers. The EPIC library is available on CMS. Ethernet: Baseband protocol and technology for the cables and special- ized circuitry which is used to physically connect the machines on a (local) network. The UIC ADN-II is an Ethernet network. An Ethernet is a specific type of network which was developed by Xerox, and is now supported by many manufacturers. Communication is at 10 Mbps, in a "broadcast medium" (similar to a party line telephone): every machine on a particular Ethernet network looks at the Ethernet address on each packet as it goes by to see if it is for them. The ethernet network at UIC (the ADN-ii) follows the IEEE 802.3 series of standards. See 10BaseT. When a transmitting data station on an ethernet detects another signal being transmitted (a "collision"), it stops sending, sends a jam sig- nal, and then waits for a variable time before trying again. EXCP: EXecute Channel Program: The execution of a program in the chan- nel (see Channel). The number of EXCP's in a job is generally the number of blocks of data sent or received from input/output devices. +--+ F +--+ FDDI: Fiber Distributed Data Interface: An ANSI standard specifying a 100-Mbps token-passing network using fiber-optic cable and a dual-ring architecture to provide redundancy. The ADN-ii is an FDDI network. Fiber-optic cable: A thin, flexible cable which conducts modulated light transmissions. It is more expensive than other types of network cabling, but it is not susceptible to electromagnetic interference and is capable of higher data transmission speeds. The ADN-ii uses fiber- optic cable. Glossary of Selected Computer Terms page 10 ======================================================================== File: A collection of information stored in any of numerous forms on any of numerous devices. A file may contain programs, data, or text. Called a dataset on MVS. File Identifier or Fileid: The name of a CMS file. On CMS, a fileid consists of three parts: the filename, filetype and filemode. These parts are separated by blanks. The filename and filetype are 1 through 8 letters, digits, and/or national characters long; either may start with any of these characters. The filemode is always one letter followed by a single digit in the range 0 to 6. See the Computer Cen- ter document Quick Facts for File Management on CMS (which is included in The UICVM CMS System: An Introductory Guide) or the VM/ESA CMS Primer for more information on CMS fileids. File server: A device holding files which are available to everyone connected to a LAN. The file server's software allows it to provide the machines on the LAN with remote disk drives which function as if they were attached directly to their machine. Examples of file server software are Microsoft's LAN Manager, IBM's LAN Server and Novell's NetWare. Finger: A protocol (an on UICVM CMS and on the public personal comput- ers a command) which allows you to get information on people using computer systems on the Internet network. Fixed Pitch Fonts: A text formatting term: A font in which all the characters have the same width (as in a mechanical typewriter). Also known as "mono-spaced fonts". Flame: A code word in electronic messages indicating a heated argument. Electronic communications lack the the clues given by the body or voice in more personal methods of communication, are are therefore much more easily misunderstood. See also ":-)". FLOP: FLoating point OPeration: An operation is a computer action which is specified by a single computer instruction or a high level language statement, and a floating point operation is an operation made on a floating point number. The time used for an average FLOP is a measure of a computer's speed (see Megaflop). Floppy Disk: A small portable flexible magnetic disk used for data storage on many microcomputers. Floppies come in 3 and a half and 5 and a quarter inch sizes, with several densities and formats. Folio: A text formatting term: The lines at the top or bottom of a page that contain the page number, publication name, publication data, volume numbers, and so on. Font: A text formatting term: A complete assortment of printer charac- ters in a particular type style, typeface, size and orientation. Most fonts include letters, numbers, punctuation and some special symbols. Note that the Roman (normal), Italic, Bold and BoldItalic typeface forms of any type style and size are each separate fonts (even though on the Xerox 8790 and 2700 page printers at UIC you will generally have all four of these fonts available when you specify a style and size). A font family is a complete set of characters in the same type style, including all sizes and typefaces, such as bold, italic, underline, et cetera. Glossary of Selected Computer Terms page 11 ======================================================================== Footer: A text formatting term: One or more lines of text that appear at the bottom of every page. Foreground: The interactive portion of the a computer system; e.g. when you are using CMS interactively, your commands are executed in the foreground, when you issue them. FORTRAN: FORmula TRANslating language: An old but still very common programming language used in the scientific field. FORTRAN was the first high-level language to become widely used. The current language standard was developed in the 1970's, and is known as FORTRAN 77. FTP: File Transfer Protocol: A protocol in the Internet suite which allows a user on any computer to get files from another computer, or to send files to another computer. FTP is used for file transfer on the ADN-ii network. Full Screen: This term refers to the ability of a system to manipulate and edit the text on the screen as a whole, as opposed to one line at a time. Full duplex: A method of communication between two computers (or devices) that enables simultaneous transmission in both directions. +--+ G +--+ Gateway: A protocol translating device (software and hardware) used to pass information from one network, with its set of protocols, to another network, which may have a different set of protocols. On BITNET, gateways refer to sites which belong to two or more networks allowing data to "cross over" from one network to another. See also Bridge. Generic Font: A text formatting term: A representation of alphameric characters on a screen that may not reflect what the final characters will look like. Utilities that allow the viewing of printer formatted text on your screen generally use generic fonts. GETDISK: A locally-written CMS utility which allows users to attach (CP LINK and ACCESS) system or other user's minidisks by easy to remember descriptive nicknames. Enter HELP GETDISK for information on its use. GML: A text formatting package: Generalized Markup Language may be used to format large structured documents such as books manuals, reports, theses, etc., without having to be concerned with the overall layout of the finished document: the same input text may be formatted in any of the available GML layouts. GML is also a defined as a language, so that the GML language provided by IBM looks the same as our version of the GML language from the Uni- versity of Waterloo. Waterloo GML is written in the Waterloo SCRIPT text formatting language. For this reason, the input file containing GML commands is saved and processed on CMS in the same way as a SCRIPT file, and you can use both GML and SCRIPT commands in the same text file. GOPHER: Internet Gopher is a set of client-server protocols which pro- vides a distributed information delivery system around which a world/ campus-wide information system (CWIS) can readily be constructed. While providing a delivery vehicle for local information, Gopher facilitates access to other Gopher and information servers throughout Glossary of Selected Computer Terms page 12 ======================================================================== the world. On UICVM and on the Computer Center's public DOS personal computers, GOPHER is also a command which allows you to access the GOPHER.UIC.EDU Gopher Server, and, through it, a vast array of gopher servers at other institutions around the country and around the world. GPSS: General Purpose Simulation System: A powerful general purpose simulator which provides a wide range of capacities for discrete sys- tem modeling. Graphics: A generic term used to describe the pictorial representation of data. Graphic devices include printers, plotters, or special ter- minals. DISSPLA and SAS/Graph are two of the graphics packages avail- able on the ADN CMS system. +--+ H +--+ Half duplex: A method of communication between two computers (or devices) that allows transmission in only one direction at a time. Handshaking: An exchange of predetermined signals between two computers or between a computer and a peripheral device such as a modem or a printer. Handshaking allows the computer to ascertain whether another device is present and ready to transmit or receive data. Hard copy: Usually hard copy means paper, but presumably can mean any printed computer output, such as microfilm. Hardware: The physical devices that make up a computer system. Hard disk: A magnetic disk storage device used on larger microcomput- ers. Hard disks are similar to the disk storage on mainframes, and are permanently installed in the micro. Hardwired Connections: Lines that are physically connected to the ADN-I Sytek communications network. Terminals connected with hardwired con- nections can communicate at 9600 baud. HASP: Houston Automatic Spooling Program: The forerunner of JES. A program that automatically schedules jobs and handles the printer/ reader devices. Header: (1) A text formatting term: One or more lines of text that appear at the top of every page of a document. (2) A computer commu- nications term: Control information which is added before data when it is encapsulated for network transmission. HELP: An online system of information about various commands and pro- grams, available on all of our mainframe interactive systems, and also internally in many interactive software packages. Host: A computer which is used for general computing purposes, which is also connected to a network. HSM: Hierarchical Storage Manager: The automatic archiving system used on MVS at the Computer Center. HSM has two levels of "migration": the first is to special disk storage, the second to tape. On CMS, enter INFORM MVS SPACE MANAGEMENT for a list of references. Hub: Generally, a device which serves as the center of a star shaped network. In Ethernet/IEEE 802.3 networks, a hub is an Ethernet multi- port repeater (a concentrator). Hyphenation: A text formatting term: Breaking up words at syllables or other natural dividing points so that the lines of text are properly balanced. Hyphenation can be achieved in several ways: some programs Glossary of Selected Computer Terms page 13 ======================================================================== let you manually insert discretionary hyphens which are only visible when they fall at the end of a line of text, some programs insert hyphens automatically based on a dictionary of words, and some pro- grams use a logic formula or algorithm to hyphenate words. The Water- loo SCRIPT and GML packages use an algorithm, and you may also specify hyphenation rules for selected words. You may also choose the level of hyphenation. (Use the SCRIPT control word .hy.) +--+ I +--+ IAD: The VS FORTRAN InterActive Debugger. Among other things, the IAD allows you to set conditions for program interruption, ask for the current values of variables, and follow the instruction-by-instruction execution of your program. IBMNET: The name of a software package that runs on special hardware, and allows mainframes with IBM architecture to accept TCP/IP proto- cols. The TELNET remote login facility on CMS uses IBMNET. IEEE: Institute of Electrical and Electronics Engineers: An interna- tional professional society that issues standards and is a member of ANSI and ISO. IEEE LAN standards are the predominant LAN standards today, including standards similar or virtually identical to Ethernet and Token Ring. IMAP: Interactive Mail Access Protocol: A client-server protocol simi- lar to POP which allows electronic mail be retrieved from a server to a personal computer; but is better suited to having the PC manipulate mail that stays on the host machine. INFORM: An local interactive index to the documentation and manuals in the reference documentation racks in the Computer Center's User Infor- mation areas. Also, printed copies of all Computer Center produced documents are available through INFORM. INFORM is available on CMS and through the UICVM Gopher server. Interactive processing: A computer system where a person can communi- cate directly with the machine by means of a terminal. The user enters commands which are immediately executed by the computer which sends the results of the command back to the user's terminal. See also Batch processing. Input: The information that a computer or a particular computer program takes in. Inside Margin: A text formatting term: The left margin of a right-hand (odd-numbered) page, and the right margin of a left-hand (even- numbered) page. The inside margin is often wider than the opposite margin to accommodate binding. Interface: A shared boundary defined by a common physical interconnec- tion and signal characteristics and meanings. Interrupt: A signal which causes the machine's hardware to break the normal program flow and transfer control to a specific interrupt han- dling routine. Once the interrupt has been processed, the interrupted program is resumed. The Internet: The Internet is a collection of networks, including the ARPANET, NSFnet, regional networks such as NYsernet, local networks at a number of University and research institutions, and a number of mil- Glossary of Selected Computer Terms page 14 ======================================================================== itary networks. The term "Internet" applies to this entire set of networks. Internet address: A unique number identifying each host machine on the Internet network. Also called the IP address. In addition to the Internet address, each machine has an Internet domain style name which usually has the form machine.location.domain or machine.group.location.domain; for example, the UICVM system's domain style name is UICVM.UIC.EDU. Internet protocol suite: A set of protocols developed by the Defense Advanced Research Projects Agency network (DARPA) to support a relia- ble host-to-host packet-switched network with hosts using different operating systems, of different sizes, and made by different manufac- turers. This suite is referred to as TCP/IP because TCP and IP are the best known of the protocols in the suite. Inverse Landscape printing: A text formatting term: The rotation of a page design to print text and graphics horizontally, and upside down across the 11 inch width of the paper. Duplex landscape texts are sometimes printed in landscape on the front of the page and inverse landscape on the back; then when the pages are joined at the top, the reader can flip though the packet with all the text in the same orien- tation. The duplex version of the UIC Computer Center type style DATA prints in this manner. See also Landscape, Portrait and Inverse Por- trait printing. Inverse Portrait printing: A text formatting term: With a sheet of paper held with the 8.5 inch side horizontal and the 11 inch side ver- tical (up), text which is printed upside down is called inverse por- trait. See also Portrait and Landscape and Inverse Landscape print- ing. I/O: Input/Output: The receiving or sending of data to or from the computer. IP: Internet Protocol: A protocol from the Internet protocol suite that provides the means to transmit blocks of data between hosts on a network. See also Internet address. ISO: International Standards Organization: An organization established to develop standards to facilitate the international exchanges of goods and services and to develop mutual cooperation in areas of intellectual, scientific, technological, and economic activity. +--+ J +--+ JANET: Joint Academic Network: A university network in the United Kingdom. JCL: Job Control Language: A highly specialized and inflexible control statement language used to define a job to the MVS operating system. JES: Job Entry Subsystem: The part of the MVS operating system that schedules batch jobs and controls the printers. Justification: A text formatting term: Adjusting the spacing within a line of text such that each line of text begins - "left justified" - or ends - "right justified" - at the same place. An exception to jus- tification is the line before a forced break or a blank line (such as the last line of a paragraph, which may not contain enough text to Glossary of Selected Computer Terms page 15 ======================================================================== allow right justification. Paragraph indents are an exception to left justification. +--+ K +--+ K: Kilo: In most areas, "kilo" stands for 1000, but in computer usage a K is 1024 or 2 to the 10th power. Kbps: 1024 (or kilo) Bits Per Second: A measure of the speed of trans- mission of computer data. See also Baud. KERMIT: KERMIT provides error checking file transfer and terminal emu- lation for IBM compatible DOS machines. KERMIT is one of three commu- nications programs available for these machines through the Computer Center. The other two are YTERM (please note, however, that MS-DOS Kermit is much more highly recommended than is YTERM), and SLIP, for efficient file transfer on a Computer Center ADN-ii dialup line. MACKERMIT, KERMIT for Apple Macintosh computers, is also available. Kerning: A text formatting term: The amount of space between letters, especially certain combinations of letters that must be brought closer together than others in order to create visually consistent spacing between all letters. The letters AW, for example, may appear to have a wider gap between then than the letters NM unless there is a special kerning formula set up for the AW combination. +--+ L +--+ LaTeX: A set of TeX document layout macros which can be used with TeX commands to relatively easily use TeX to format a variety of types of documents. LAN: Local Area Network: Communication systems which link several com- puter devices and allow them to use each other's resources effective- ly. The machines are usually geographically close to one another (a maximum of one or two miles). The "devices" linked by a LAN may include computers terminals, printers, disk drives. Each device on a LAN is a "node". LAN Manager is a distributed file system developed by Microsoft, and LAN Network Manager and LAN Server are IBM products. Landscape printing: A text formatting term: The rotation of a page design to print text and graphics from left to right horizontally across the 11 inch width of the paper. See also Inverse Landscape, Portrait and Inverse Portrait printing. Laser printing: A text formatting term: Printers which use a toner based laser system for printing. Laser printers use a laser to scan an image onto a photosensitive drum or belt and then transfer the image to the paper. Some typesetters also use laser technology in conjunction with their photochemical processing, but these are usually referred to as phototypesetters rather than as laser printers. See also xerographic printing engine. Layout: A text formatting term: The arrangement of text and graphics on a page. Leading: A text formatting term: The amount of vertical spacing, expressed in points, between the baselines of two lines of text. The Glossary of Selected Computer Terms page 16 ======================================================================== term leading is carried over from the days of metal type; it referred to placing strips of lead between lines of type to increase the space between the lines. See also Vertical Justification. Line Edit: The old method of working interactively with a computer, where you work one line at a time. Line printer: A text formatting term: A printer which prints pages (even graphics) one line at a time, as opposed to a page printer, which prints an entire page at once. LISP: LISt Processor: A high level, list processing language commonly used in artificial intelligence and computer research. LISP is dif- ferent from most other programming languages in several ways; a major difference is that recursion is used as a control structure rather than iteration (looping) which is common in most programming languag- es. Local Area Network: See LAN. Local echo: Specifies that the characters you type are to be "echoed", or set to your terminal for display, by your terminal. This is needed only when neither the remote computer you are using nor the communica- tions system echoes the characters, as in half duplex communication. Logon: The process of initiating an interactive computer session. Dur- ing logon, you tell the computer which system you want to use and who you are. You will also enter your private password during logon. Logoff: The LOGOFF command is used to tell the computer that you are done with an interactive session. It must be entered at the close of each of your sessions, or you may find all your units used up the next time you logon (either because someone stole your account, or because the computer continued executing your last instruction indefinitely). +--+ M +--+ MACKERMIT: MACKERMIT provides error checking file transfer and terminal emulation for Apple Macintosh computers and is available from the Com- puter Center. KERMIT, for IBM compatible DOS machines, is also avail- able. macro: A single, symbolic programming language statement that, when translated, expands to a predefined series of statements. Mail: See Electronic Mail. Mainframe: a large, multi-user computer. M: Mega: In most areas M stands for a million, but in computer usage M represents 1024K or 2 to the 20th power. Megabyte: About a million bytes, exactly 1024K bytes. Megaflop (MFLOP): One million operations per second: the unit used to rate computer (especially supercomputer) performance. Memory: The part of a computer system which is used to run programs. The word memory is used to refer to the capacity of the system (for example, a 1 meg machine), and also to the actual chips that provide the memory (a memory upgrade). See also RAM and ROM. Metacode: The internal codes used within a system. Microcomputer: Small computers, inexpensive enough to be purchased by individuals and small businesses. Also called Personal Computers. IBM, AT&T, APPLE, Radio Shack, Zenith and Commodore are common manu- facturers of micros. Glossary of Selected Computer Terms page 17 ======================================================================== Migration: The process of compacting and moving data for the purpose of storage and backup. A secondary purpose of migration is to compress the data to save storage space. See also Archive. Minidisk: A virtual disk, the VM/CMS term for what appears to be a small complete disk pack, but in reality is a section of an actual physical disk. MINITAB: MINITAB is a general purpose, highly interactive statistical computing system designed especially for students and researchers who have little or no previous experience with computers. It is available for interactive use on CMS on UICVM. Modem: MOdulator DEModulator: A device converts characters into a form that can be transmitted over a telephone line, and reconverts trans- mitted signals to characters. See CCITT. Mono-Spaced Fonts: A text formatting term: A font in which all the characters have the same width (as in a mechanical typewriter). Also known as "fixed-pitch fonts". Multiplex: To interleave information from different sources on a single channel. MVS: Multiple Virtual Storage: One of the operating systems running under VM/ESA on the Computer Center's IBM 3090 at UIC. +--+ N +--+ Name server and name resolution: A server provided on a network which resolves network names into network locations. Nanosecond (nsec): One nanosecond is 10 to the -9th seconds. NETNEWS: On UICVM CMS, the command NETNEWS is used to view articles posted to the Usenet newsgroups. See also Usenet. NetWare: Novell, Inc.'s popular file server system. Network: A group of computers and/or other devices (called nodes) linked together by cables or telephone lines. Computers joined in this way often share printers and memory storage devices (See LAN: Local Area Network). Computer networks may also be less intimately connected, with the links between nodes allowing information prepared according to a set convention to be exchanged among the nodes, but without direct sharing of devices. BITNET is an example of this type of network. NFS: Network File System: A distributed file system protocol suite developed by Sun Microsystems that allows remote file access across a network. The NFS is one of the protocols in the suite; others include XDR (External Data Representation) and RPC (Remote Procedure Call). These are part of Sun's ONC (Open Network Computing) architecture. Node: (1) An end point or connection point of a Network, as in a "BITNET node". The UICVM and UICMVS systems are nodes on the BITNET network, and UICVM is a node on the Internet network. (2) In a larger sense, node is a generic term which refers to any entity that can access a network, and in this sense it is used interchangeably with device. See LAN. NSFnet: National Science Foundation NETwork: A network based on the Internet protocol suite established by the NSF to connect the NSF- funded national supercomputer centers. NSFNet is part of the Internet network. Glossary of Selected Computer Terms page 18 ======================================================================== Null modem: A box or cable which joins two computing devices directly rather than over a network. +--+ O +--+ Offline: Logically or physically disconnected from the computer. For example, a reel of tape is offline storage. Online: Connected and accessible to the computer. For example, most disk storage at UIC is online and is therefore easily and quickly accessed. Operating System: The controlling program(s) that oversee the operation of the computer. Some operating system functions are job scheduling, low level input/output handling, and job accounting. Often abbreviat- ed as "o/s". Orphans: A text formatting term: The first line of a paragraph is called an orphan when it is separated from the rest of the paragraph by a page break. See also Widows. Output: (1) Data transferred from a computer's internal storage unit to some storage or output device. (2) The final result of data that have been processed by the computer or a particular computer program. Overlay: A text formatting term: A predefined graphic overlay form, which is stored on the printer and which may be printed on an output page, independent of any other text or graphics on the page. The must common use of an overlay at UIC is to print a departmental letterhead. Departments may contact the Computer Center to arrange to have a let- terhead overlay developed for their departments. See also Electronic Form. +--+ P +--+ Page Description Language: A text formatting term: In desktop publish- ing, a program that allows you to use a microcomputer to describe to a printer the graphics elements used in page layout and design. Adobe PostScript is the de facto standard of page description languages. Page printer: A text formatting term: A printer which prints an entire page at a time, as opposed to a line printer, which prints pages (even graphics) one line at a time. At UIC, the Computer Center's Xerox 8790 and 4045 printers are page printers. Package: See Software Package. Packet: A sequence of bits including data and call control signals (headers), arranged in a specific format, which is sent (switched) together as a single identity. Parallel communication: A form of computer communication in which data is transmitted using parallel electronic paths. See also serial com- munication. Parallel processing: The ability to process "chunks" or blocks of a program simultaneously. To do this, the computer has to have several CPU units and the software to coordinate them, or it must be able to simulate such a situation. Parity Bit: An extra check bit added to the binary representation a character to make it conform to the parity checking method used. Glossary of Selected Computer Terms page 19 ======================================================================== Parity Check: A method of error detection that checks whether the sum of bits in each character received conforms to a given protocol. In odd parity, the sum of the bits (including the parity bit) must be odd; if a pattern would otherwise be even, the parity bit is set to 1 to maintain oddity. In even parity, the opposite convention is used. In mark or no parity, as is used on the ADN-I network and on the direct UICVM CMS connections at UIC, no parity checking is done. Pascal: A modern block-structured programming language, with a simple and well defined syntax. Pascal was designed to be a simple language for teaching purposes, and is widely used as such. Passthrough: A software facility which, when used during an interactive computer session, allows you to open another session on the same or a different computer, while keeping your original session. See also TELNET. Password: All computer subaccounts must have a private password to identify the account's ownership when logging on. The same password is used when logging on to any of the Computer Center's interactive systems. Peer-to-peer computing: As opposed to client-server computing, in peer- to-peer computing, each network device runs both the client and server portions of an application. See also client-server computing. Peripherals: Any device which is attached to a computer system or LAN. Devices such as printers, disks and tape drives which are often attached to computers or LANs. Personal Computer: See Microcomputer. Phototypesetting: A text formatting term: Producing a page image on photosensitive paper, as when documents are printed on a Linotronic 100 or 200 typesetter. This process is sometimes referred to as cold type to distinguish it from the older method of casting characters, lines, or whole pages in lead, which is called hot type. Pica: A text formatting term: A unit of measure equal to 1/6 inch, or 12 points. Pica is also used to describe a font which is 10 charac- ters per inch. PING: Packet INternet Groper: The ICMP (Internet Control Message Pro- tocol) provides message packets to report errors and other information in IP processing; PING uses ICMP echo messages and its reply to test the reachability of a network device. Pitch: A text formatting term: The unit of measure for the size of (fixed width or mono-spaced) fonts; it is equal to the number of char- acters which will print in an inch; e.g. a 12-pitch type prints twelve characters per inch. See also CPI. Pixels: See Resolution. Point: A text formatting term: The smallest unit of measure in typo- graphic measurement. There are 12 points in a pica, and 72 points in an inch. PNS: Personal Name Service: An electronic mail alias service which allows personalized aliases for electronic mail addresses. Every fac- ulty and staff member who is included in the online faculty/staff directory database may select a PNS alias from a set of suggested ali- ases, all of which are based on his or her full name. (At UIC, PNS aliases must must follow some general guidelines which ensure their uniqueness.) Glossary of Selected Computer Terms page 20 ======================================================================== POP: Post Office Protocol: A client-server protocol which allows elec- tronic mail be retrieved from a server to a personal computer. Eudora (for the Apple Macintosh) and NuPop (for DOS personal computers) are examples of clients that use POP. PLATO: An interactive educational computer system using text and graph- ics to teach a wide range of subjects. An example of Computer Assist- ed Instruction. PLC (PLC/T): A student version of PL/I written at Cornell University. PL/I: Programming Language One: A high level programming language written to be applicable in arithmetic, scientific and business envi- ronments. Post Processing: A post processing program process the output from another program. The most common use of a post processor is with sys- tems which have one general program which processes user input and generate generic output, which contains no system or device dependent information. This device independent output is then passed to a post processor which creates final output which is specific for a particu- lar machine or output device. Port: A pathway for data flow in and out of a computer. On PC's, a port is a slot or plug where cables for input and output devices are attached. Portrait printing: A text formatting term: The normal printing orien- tation for a page, i.e., printing horizontal text across the 8.5 inch dimension of a 8.5 by 11 inch page. See also Inverse Portrait and Landscape and Inverse Landscape printing. PostScript: A text formatting term: In desktop publishing, PostScript is the page description language used by the Apple LaserWriter and other high resolution printers and typesetters. At UIC, several of the remote Xerox 4045 laser printers can print PostScript output. Prefix: Under most dataset naming systems, the first portion of the name gives an indication of the owner of the dataset. This portion is known as the prefix. On MVS at UIC, the prefix can be in one of three forms called prefixing modes: Project prefix, Master userid, and Subaccount userid. (See the Computer Center document Account Identi- fication and Dataset Prefixes for more information.) Print server: A networked computer system that receives and manages print requests from other network devices. PF Key: Program Function Keys: When using Full Screen CMS, the PF keys allow you to enter long commands by pressing a PF key sequence, which usually is only one or two keys. Print server: Like a file server, a print server allows the machines on a LAN to share a single printer and also handles the printing queue for the printer. Protocols: A set of rules or procedures implemented in both hardware and software to facilitate communications and provide a well defined interface between different hardware and software systems. The proto- col rules govern format, timing, sequencing and error handling. A protocol converter is a device which translates between one communica- tions protocol and another. Proportional Fonts: Printer type styles in which each character occu- pies a different width in the output line, depending on the actual Glossary of Selected Computer Terms page 21 ======================================================================== physical width of the character. Thus, in a proportional font, the character "i" is much less wide than the character "w". Many types and sizes of proportional fonts are available on the Computer Center's Xerox 8790 and 4045 printers. +--+ R +--+ RAM: Random Access Memory: The memory that is available on a computer for storing data and programs that are currently being processed. It is automatically erased when the power is turned off. Information in the RAM which needs to be stored for future use must be saved onto a disk or a tape. See also ROM and memory. Random Access: The process of selecting information in a arbitrary order, not based on the physical order or sequence of its storage. Recto page: A text formatting term: The right-hand page of a duplex printed document with facing pages. See also verso page. Required Blank: A text formatting term: A blank or space which is pro- cessed by a word processing package in a slightly different manned from a normal blank. Required blanks print as blanks, but a line break cannot occur at a required blank, nor will additional space be added at a required blank to justify a line of text. Resolution: A text formatting term: The number of dots per inch used to represent a graphics image. The term "pixels" is also used for "dots" in this context. High resolution images look smoother and have more dots per inch than do low resolution images. The resolution of images displayed on the screen is usually lower than that of the final laser printout. Laser printers print 300 dots (or pixels) per inch or more (the Computer Center's Xerox 8790's highest resolution is 300); typesetters print 1,200 dots (or pixels) per inch or more. Response Time: The time measured from when you enter a command until you receive a response at the terminal. RFC: Request For Comment: The Internet network standards are called RFC's. A proposed Internet standard is initially issued as a propo- sal, and given an RFC number. When it is finally accepted, it is add- ed to Official Internet Protocols, but it is still referred to by the RFC number. There are many RFC's; some of the most important are introduced in the Computer Center document Introduction to the Inter- net Protocols (TELNET), and many of the RFC standards are available on the BITNET disk, in files with the fileids RFCnnn STANDARD, where "nnn" is the RFC number. RJE: Remote Job Entry: Refers to an application which is batch rather than interactive. In RJE environments, jobs are submitted to a com- puting facility and output received later. ROM: Read Only Memory: Stored permanent systems instructions which are never changed; ROM is generally installed by the manufacturer as part of the system. See also RAM and memory. Router and Routing Table: A network device which decides which of sev- eral paths network traffic will follow; a routing table is a table stored on a router or other internetworking device which keeps track of routes to particular network destinations. Glossary of Selected Computer Terms page 22 ======================================================================== RPC: Remote Procedure Call: the basis of distributed (client-server) computing. Remote procedure calls are specified by clients and exe- cuted on servers, with the results returned over the network to the clients. RS-232: A standard connection for serial computer communications as described by the Electronics Industry Association (EIA). The standard specifies the physical connections between computers and other devices, such as modems and printers and defines characteristics of the electrical signals sent through the connection. +--+ S +--+ Sans Serif: A text formatting term: Type styles without serifs, such as Helvetica, Avant Garde and Geneva. See also Serif. SAS: (Formerly Statistical Analysis System) A software system for data analysis. SAS is available on CMS on UICVM and on the public personal computers. SAS provides tools for information storage and retrieval, data modification, report writing, file handling, and statistical analysis. SAS/Graph provides a complete graphics system, for plotting on a variety of printers and graphics terminals. There is also a Full Screen Package for full screen data entry. SAS includes interface routines for linking with the other available statistical packages. SAS/Graph: The graphics portions of the SAS statistical analysis sys- tem. SCA: The Scientific Computing Associates: Although SCA can be used for general statistical analysis, it is mainly a package for time-series analysis. SCA can be run either in batch on MVS on UICVM or interac- tively on CMS on UICVM and on TSO on UICMVS. PC SCA is also available for MS-DOS compatible personal computers. SCRIPT: A text formatting term: A text-formatting program which takes as input a file containing unformatted text and special formatting commands and produces an output file of formatted text suitable for printing. Waterloo SCRIPT is one of the word processing packages available from the Computer Center. See also GML and TeX. Sequential Access: Reading data from a file whose records are organized on the basis of their successive physical positions. To reach a spe- cific record, all records previous to that record must be read, in order. Magnetic computer tapes are sequential access storage device. Serial communication: A form of computer communication in which data is transmitted one bit at a time over a single path. See also parallel communication. Series/1: An IBM minicomputer used at the UIC Center as a communica- tions controller for accessing CMS in full screen mode. The Computer Center also uses two types of Series/1 "clones": the IBM 4994 and IBM 7171, as communication controllers for Full Screen CMS. See also Yale ASCII Communications Program. Serif: A text formatting term: A line crossing the main strokes of a letter. Type styles that have serifs include Times, Courier, New Cen- tury Schoolbook, Bookman, Palatino and New York. See also Sans serif. Server: Server is a special device used to "serve" some system or facility. A server is usually a microcomputer, or, on CMS, a special Glossary of Selected Computer Terms page 23 ======================================================================== account which runs automatically without interactive supervision. Servers act in response to requests which are sent to it. Service Unit (SU): A unit of measure for supercomputer use; it equals one hour of Cray X-MP cpu time. On our IBM 3090 computer, 1 SU = 2 hours of cpu time, and 86,400 of our accounting units. Shared File System (SFS): A part of CMS that lets users organize their files into groups known as directories and selectively share those files and directories with other users. Simplex: (1) A text formatting term: printing only on one side of the paper. (2) A computer communications term: Simplex data transmission is in only one direction. SIMSCRIPT: A higher level language designed specifically for simula- tion. Site: An organization or facility where a host computer is located. SLIP: Serial Line Internet Protocol: SLIP is currently a de facto stan- dard, commonly used for point-to-point serial connections running TCP/IP. It is not an Internet standard but is defined in RFC 1055. The Computer Center's ADN-ii dial-up lines support SLIP. SMTP: Simple Mail Transfer Protocol: A protocol from the Internet suite (e.g., TCP/IP) that is used to send electronic mail between users on different host systems. SNA: Systems Network Architecture: An IBM developed specification for the logical structure, formats, protocols, and operational sequences for reliable transfer of data among SNA users and applications. SNA also includes specifications for controlling the configuration and operation of a network. SNOBOL: SNOBOL4 is a programming language developed at Bell Telephone Laboratories. It is designed to be especially useful when processing character-string data in complex ways. Software: The programs and data that make computer hardware function. Software Package: A program or set of programs that usually perform a specific function. Programming (i.e., the development of a computer program in some higher level programming language) is generally not necessary when using a software package; specialized statements and/or data are used instead. SAS and SPSS are examples of statistical pack- ages. Spooler: A program which manages requests or jobs submitted to it for execution, selection requests for execution in an orderly manner from a queue. Print spoolers are a common example. SPSS: Statistical Package for the Social Sciences: A software system for data management and analysis. SPSS may be used for many univari- ate and multivariate statistical analyses and has facilities for sort- ing and merging files and manipulating data. SPSS can deal automati- cally with complex files. SPSS/PC+ for MS-DOS personal computers is also available from the Computer Center. SPSS/PC+ includes a menu driven method for interacting with the system. Also available is SPSS Data Entry II for the micro. DE II is an add on product for SPSS/PC+ and is a full screen data editor for data stored in an SPSS/PC+ system file. Standard: A set of rules or procedures, either commonly used (de facto standards) or set by official decree (de jure standards). Glossary of Selected Computer Terms page 24 ======================================================================== StarLAN: A LAN developed by AT&T (IEEE 802.3 1Base5.A standard). Start bit: A signal, usually a binary "0", used to alert to the receiv- ing machine the beginning of a byte of data. Stop bit: A signal, usually a binary "1", sometimes used to indicate the end of a byte of transmitted data. Store and forward: A message switching technique in which messages are temporarily stored at intermediate points between the source and the destination until the required network resources are available. BITNET (CREN) is a store and forward network; the Internet is not. Style: A text formatting term: The overall appearance of a font is referred to as the style. The type styles have names, such as Helvet- ica, Courier, and so on. (Note: there is some disagreement on the usage of this term; sometimes "style" is used to refer to the degree of boldness or slant of a particular font within a family [e.g., Bold], which is more commonly referred to as the typeface.) See also typeface. Synchronous transmission: a method of data transmission in which char- acters are sent at a fixed rate, with the transmitter and receiver synchronized. Supercomputer: A large mainframe computer; usually reserved for comput- ers with the fastest speeds and largest memory. These computers usu- ally have an architecture that is different from regular mainframes. The main difference lies in the ability to perform vector and/or par- allel processing. SuperWylbur: A mainframe line-at-a-time text editor. Wylbur is avail- able on UICVM CMS at UIC. System Crash: A breakdown of either the operating system or the hard- ware, resulting in the system's halting, often very abruptly, and throwing its users off. +--+ T +--+ T1: A Bell system facility for transmission of data through telephone lines at 1.544 Mbps. Tape Drive: An input/output device similar to an audio tape recorder which reads or writes computer data on magnetic tape. TCP: Transmission Control Protocol: A protocol in the Internet proto- col suite which is concerned with the transmission of commands between hosts, providing reliable communication between the hosts on the net- work. It keeps track of whatever is sent, breaking it up into smaller packets if necessary, and retransmitting when required. It uses the IP protocol to actually send the information. TCP/IP: Transmission Control Protocol/Internet Protocol: A set of pro- tocols used to allow computers to share resources across a network. TCP/IP was originally developed for ARPANET, but is now in much wider use. These protocols support file transfer, remote logons, and elec- tronic mail between users on the different host computers on the net- work. TCP and IP are actually a protocols in the Internet suite, but the designation TCP/IP is commonly used to describe the entire suite, since TCP and IP are the best known of the protocols in the Internet suite. The IP portion of the Internet suite is used in the NSFNet, however TCP is not. See also Internet protocols. Glossary of Selected Computer Terms page 25 ======================================================================== TELL-A-GRAF: A conversational graphics system, which may also be run in batch mode. The user creates graphics by entering simple commands which resemble English sentences. Only a few commands are required to produce a graph because TELL-A-GRAF will supply values for any unspec- ified features. Graphs may be stored and reused, and data can be read from external files. The TELAGRAF command is available on CMS on UICVM. TELNET: The network terminal protocol: A protocol in the Internet suite for opening interactive sessions from a local host computer to another computer on the network which is physically remote and which may have a different operating system than the local host. Terminal: A computer input/output device which allows a person to interactively communicate with the computer. Most terminals have typewriter style keyboards and a CRT screen for displaying your com- mands and the computer responses. Personal computers running terminal emulation programs are also commonly used as "terminals". Terminal Emulation Program: Software, which is generally run on person- al computers, which performs terminal emulation, allowing the computer to be used as a terminal for interactive use of another computer. See emulation. TeX: A text formatting package: TeX is a typesetting package developed by Donald Knuth which is particularly well suited for scientific, mathematical or other technical writings. At UIC, TeX is available on CMS, and PCTeX is also available for DOS compatible PCs. Text Editor: An interactive program that allows you to input, update, delete and store information on the computer. The information may be programs, data, or actual textual material such as letters or disser- tations. Text-formatting: The (automatic) layout of a text for the printed page. When used in conjunction with text editors, text formatting programs allow computers to be used for preparing documents: letters, papers, manuscripts, theses, resumes, and the like. The text of the document is specified by the author, using the text editor (at UIC: XEDIT), and its layout on the page is performed by the text formatter (at UIC: Waterloo Script, GML, and TeX), following instructions laid down by the programmer and by formatting commands embedded in the text by the author. Text wrap: A text formatting term: The ability to wrap text around graphic images on a page layout. Some desktop publishing systems have an automatic text wrap feature that will shorten lines of text when a graphic image is encountered (SCRIPT, unfortunately, is not one of them). In other systems, you need to change the length of lines by changing the column margins or by inserting hard carriage returns to shorten the lines. Time-out: A time-out occurs when one network device expects to hear from another but does not receive the reply within a specified period of time. After a time-out, the information is either retransmitted or the link between the two devices is broken. Token passing or token ring: A transmissions protocol in which a token (a control block) circulates around a ring, passing from one machine on the ring to the next. When a machine on the ring wants to trans- Glossary of Selected Computer Terms page 26 ======================================================================== mit, it takes control of the token and attaches the information to be transmitted to the token. Each machine down the ring examines the token, and receives it if is its destination or sends it to the next machine if it is not. When the transmission is received at its desti- nation on the network, the token is sent on again, empty. Because there is only one token in the ring, there cannot be data collisions in token ring network. The Computer Center's public personal comput- ers are linked by a token ring. Very similar to an IEEE 802.5 LAN. Track: A unit of measure for space on a disk. On our MVS disk devices (IBM 3350's), a track holds 19,069 bytes. Tree: A data structure similar to a linked list, except that each ele- ment carries with it the address of two or more other elements, rather than just one. Trees are an efficient way of storing items which must be searched for and retrieved quickly. TSO: Time Sharing Option: An interactive system that runs under MVS on UICMVS. TSO consumes more resources than CMS for equivalent tasks. It is intended only for users which applications require it. TSO users should be aware that TSO is no longer being developed, and the documentation that exists on it is both old and somewhat out of date. TSP: Time Series Processor: A software package designed to develop and use econometric models with time-series data. Twisted pair: A type of data communications cable that consists of pairs of insulated wires which have been twisted together in a regular spiral pattern. A relatively low-speed transmission medium which is commonly used for telephone and, increasingly, for data networks. See also 10BaseT. Typeface: A text formatting term: The degree of slant or boldness in a font, examples are Normal (also known as Roman), Italic, Boldface, Boldface Italic and Slant. (Note: Sometimes "style" is used to indi- cate degree of boldness or slant, and "typeface" used for the overall appearance.) See also Style. +--+ U +--+ UICINFO: The UICINFO command on CMS provides a menu which allows you to easily execute a selection of CMS commands which provide online sourc- es of information (including, for example, HELP, LUIS, PHONEBOOK and TIMETABLE), and other facilities which are available at or through the Computer Center. UICMVS: The BITNET node name of the UIC Computer Center's MVS operating system. UICVM: The BITNET node name of the VM/CMS system run on the UIC Comput- er Center's IBM 3090 mainframe computer. This is the BITNET node to which electronic mail sent to UIC Computer Center users from outside systems should be addressed. UNICOS: Cray Research's interactive operating system for the Cray X-MP supercomputers. UNICOS provides limited interactive Unix services for debugging and interactive graphics. Unit: A measure of computer usage; at the Computer Center, each unit is worth approximately $0.0833. See also Service Unit. UNIX: A multi-tasking operating system frequently used on workstations. Glossary of Selected Computer Terms page 27 ======================================================================== USENET: Usenet is the set of people who exchange articles tagged with one or more universally-recognized labels, called "newsgroups" (or "groups" for short). Usenet began in 1979, and is one of the largest and oldest cooperative networks. On UICVM CMS, the command NETNEWS is used to view articles posted to the Usenet newsgroups. User: Any person who uses a computer or a particular software or hard- ware system. More specifically, user is sometimes used to refer to the user's computer identification tag, used as an address for elec- tronic mail. Its form depends on individual computer center conven- tions. It can be obtained by asking the intended recipient, or for UIC faculty or staff, by using the CMS command IDSEARCH, or for a user at a BITNET node, by sending an electronic mail request to the POSTMAST account at the users' node, if one exists. Userid: The account prefix that is unique to each subaccount. It can also be used to logon to the computer, and is the CMS mail address of each subaccount. At the Computer Center, it is always in the form of a U followed by a five digit number greater than 08191. See also User. User Information Areas: The Computer Center facilities where there are ADN Computer Center reference documentation racks (in Room B001 BSB and Room 105 BGRC). Upload: To transfer information stored in the user's system to a remote computer system. UUCP: UNIX-to-UNIX Copy Program: A protocol for communications between UNIX systems, and also a UNIX based network which is close associated with USENET. uuencoding: Uuencoding allows you to transfer binary files or files with longer record lengths by electronic mail. See also xxencoding and ARCUTIL. +--+ V +--+ V.22-bis, V.32 or V.32-bis: Modem specifications; see CCITT. VAX: A mainframe computer manufactured by Digital Equipment Corporation (DEC). VDT: Video Display Terminal: an input/output device with a display screen and an input keyboard. Vector processing: Processing all the elements of a vector simultane- ously. In order to do this, the computer has to have one or more vec- tor pipes. The length of the pipe differs between supercomputers. Verso Page: A text formatting term: The left-hand page of a duplex document with facing pages. See also Recto page. Vertical justification: A text formatting term: The ability to adjust the spacing between lines of text (leading) in fine increments to make columns and pages end at the same point on the page. The TeX typeset- ting system can do this. Virtual: Virtual refers to anything that seems real but is actually simulated by the operating system. For example, virtual memory is really disk storage made to look like real memory. VM: Virtual Machine: The main operating system running on the Computer Center's IBM 3090 mainframe computer. Under VM, each person is con- Glossary of Selected Computer Terms page 28 ======================================================================== sidered to be the operator of his own "virtual" machine, the function- al equivalent of a real machine. VM/ESA: Virtual Machine/Enterprise Systems Architecture. VM/HPO: Virtual Machine/High Performance Option. VM/SP: Virtual Machine/System Product. VM/XA: Virtual Machine/EXtended Architecture. VMARC: The VMARC program is a data compaction and file archiving utili- ty for VM/CMS; for more information, see VMARC Version 1.2: a CMS Data Compaction and File Archiving Utility. (Use INFORM with the search keyword VMARC; on UICVM CMS enter INFORM VMARC .) VMARCHIVE: A software package on CMS which allows you to copy and recall archived copies of CMS files from CMS archive tapes. In con- trast to HSM on MVS, the CMS archives are completely under the user's control; the CMS files on active accounts are not archived automati- cally by the system. The VMARCHIVE documentation is included in the references listed by the command INFORM CMS SPACE MANAGEMENT . VMBACKUP: A software package on CMS which allows you to recover recent copies of your CMS files from the backup tapes automatically made by the system. These system generated CMS backup copies are available for users who need to recover a recently destroyed CMS file. The VMBACKUP documentation is included in the references listed by the command INFORM CMS SPACE MANAGEMENT. VM/CMS: Virtual Machine/Conversational Monitor System: see CMS. VMS: A mainframe operating system generally used on VAX machines. VMSCHEDULE: A software package on CMS which allows you to execute pro- grams on CMS at your chosen time without your having to logon. VSAM: Virtual Storage Access Method: A very fast random access file system that allows non-sequential retrieval of records based on the value of keys within them. VT100: A common type of terminal for use with mainframe computers. Most communications programs which allow PC's to communicate with mainframe computers such as our UICVM CMS system allow the PC to emu- late a VT-100 terminal. VTAM: Virtual Telecommunications Access Method: a set of program that control communication between nodes and applications programs running on a host system. +--+ W +--+ WAN: Wide Area Network: a network spanning a wide geographic area. See also LAN. WATBOL: WATerloo COBol: A student version of COBOL written at the Uni- versity of Waterloo. WATFIV: WATerloo Fortran IV: A student version of FORTRAN written at the University of Waterloo. WATFIV has been replaced by a newer ver- sion, WATFOR77, and is no longer available at UIC. WATFOR77: WATerloo FORtran 77: An interactive FORTRAN 77 compiler with excellent error messages and program testing facilities; a compatible microcomputer version of WATFOR77 for DOS PC's is available for pur- chase from the Computer Center (call the ADN-Help Desk at (312) 413-8080 for more information). WATFIV is a predecessor of Glossary of Selected Computer Terms page 29 ======================================================================== WATFOR77 which accepts an expanded version of FORTRAN Level 66; it is no longer available at UIC. WDSF: See Workstation Data Save Facility Widows: A text formatting term: The last line of a paragraph is called a widow when it is forced onto a new page by a page break and is sepa- rated from the rest of the paragraph. See also Orphans. Word Wrap: A text formatting term: Automatic adjustment of the number of words on a line of text, as they are being entered and displayed on the screen, to match the margin settings. The carriage returns that result from automatic word wrap are called "soft" carriage returns to distinguish them from the "hard" carriage returns, which result when is pressed to force a new line. Word wrap is usually avail- able in the "what you see is what you get" word-processing systems which are common on microcomputers. Workstations: Micro or minicomputers which are nodes on a computer net- work and which can be used to perform a number of tasks by using their own resources as well as by tapping into the other devices which are shared on the network. Workstation Data Save Facility (WDSF/VM): An IBM product which provides services for backing up, archiving and restoring data files by allow- ing a VM system (such as the ADN/CMS system, UICVM) to act as a server for workstations and personal computers which are properly networked with the VM system. WDSF is available on UICVM CMS, for use with per- sonal computers which are attached to the ADN-ii computer network. WYLBUR: See SUPERWYLBUR WYSIWYG: A text processing term: What-You-See-Is-What-You-Get (pro- nounced "Wizzywig") is a term used to describe systems which display full pages of formatted text and graphics on the screen. Some pro- grams are more WYSIWYG than others. The term is also used to describe word processing programs that display different fonts on the screen. WISCNET: The name of a software package that runs on special hardware, and allows mainframes with IBM architecture to accept TCP/IP proto- cols. WISCNET is a precursor of IBMNET which runs the TELNET passth- rough facility on CMS at UIC. Word Processing: The use of computers to prepare documents. On most mainframe computers, word processing tasks are handled in part by the system text editor (at UIC: XEDIT), in part by text formatting pro- grams (at UIC: Waterloo Script, GML and TeX), and in part by printing facilities (at UIC: the PRINTDOC, DUP and 2700 commands). On micro- computers, integrated word processing packages that handle all three tasks are more common (e.g. WordPerfect and DisplayWrite). +--+ X +--+ XEDIT: The IBM supplied text editor used for full screen editing under CMS; XEDIT is the recommended editor for use with Full Screen CMS. Xerographic printing process: A text formatting term: In the xero- graphic printing process, printed output is produced using a imaging process. A light source (generally a laser) scans the image onto a photosensitive belt. The list discharges areas on the belt where the image is not to appear. A dry toner of carbon mixed with a plastic Glossary of Selected Computer Terms page 30 ======================================================================== binder is then picked up by the remaining charged areas of the belt. The toner is then transferred to a sheet of paper and melted onto its surface. XON/XOFF: A protocol for controlling the flow of data. X Windows: A distributed, network and device independent multitasking windowing and graphics system originally developed at MIT for communi- cations between X terminals and UNIX workstations. xxencoding: Xxencoding allows you to transfer binary files or files with longer record lengths by electronic mail. See also uuencoding and ARCUTIL. +--+ Y +--+ Yale Ascii Communications Program: Software which runs on IBM Series/1 minicomputers (or similar machines, the IBM 4994 and IBM 7171) which acts as an interface between the user's terminal and Full Screen VM/CMS. YTERM: The YTERM terminal emulation and communications program provides error checking file transfer and terminal emulation for IBM compatible DOS machines. If your pc has graphics capacities, YTERM will allow its use as a Full Screen CMS graphics terminal. YTERM is one of three communications programs available through the Computer Center for IBM compatible DOS machines. The other two are MS-DOS Kermit (which is much more highly recommended than is YTERM), and SLIP, for efficient file transfer on a Computer Center ADN-ii dialup line. +--+ Z +--+ ZIP: Data compression and file packaging programs for personal comput- ers. An example is PKZIP which is available on the ADN Computer Cen- ters public personal computers. See also ARCUTIL.