Appendix A Glossary
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A-1 UNCLASSIFIED APPENDIX A GLOSSARY ACCESS TIME—The amount of time between the time a request for data from a storage device is made and the time the data is delivered.
ADA—A high -level programming language designed by the Department of Defense.
ALPHAMERIC (ALPHANUMERIC) CHARACTER SET—The set of characters that includes letters, numbers, and special characters.
ANALOG COMPUTER—A computer that solves problems using continuous data from physical quantities like voltage or temperature.
APPLICATION (PROGRAMS) SOFTWARE—Programs written to solve user problems.
ARITHMETIC-LOGIC UNIT—The part of the cpu that contains the logic capability and performs all the arithmetic functions (addition, subtraction, multiplication, and division).
ARTIFICIAL INTELLIGENCE—The capability of a machine to perform human -like intelligence functions, such as learning, adapting, reasoning, and self-correction.
ASCII (American Standard Code for Information Interchange)—A standa rdized 8- bit code (originally a 7-bit code) designed for transmitting and processing data.
ASSEMBLER—A computer program that translates source programs written in assembly language into machine language (object) programs.
ASSEMBLY LANGUAGE—A low- level, machine-oriented programming language in which each instruction (written as a mnemonic) translates into a single machine language (computer) instruction.
AUTOMATIC DATA PROCESSING (ADP)—A general term used to define a system for automatically performing a series of data processing functions by means of machines using mechanical, electromechanical, and electronic circuitry.
AUXILIARY EQUIPMENT—The peripheral equipment or devices that may or may not be in direct communication with the central processing unit of a computer.
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A-2 UNCLASSIFIED AUXILIARY STORAGE—See storage, secondary.
BACKUP FILE—A copy of a program or data file to be used in the event something happens to the original.
BASIC (Beginners All Purpose Symbolic Instruction Code)—A high -level, general- purpose programming language primarily used on microcomputers. See NAVEDTRA 10079, Introduction to Programming in BASIC.
BAUD—A unit for measuring data transmission speed. For practical purposes, it is now used interchangeably with bits per second as the unit of measure of data flow.
BINARY—Two values (0 or 1) or states (ON or OFF); the number system used in computers.
BIT—An abbreviation for binary digit; the smallest unit of data, either a 0 or 1.
BLOCKED RECORDS—One or more logical records grouped and treate d as a unit (physical record or block) for input/output processing.
BLOCKING FACTOR—The number of records stored in a record block.
BOOT OR BOOTSTRAP— (1) A set of instructions that causes additional instructions to be loaded until the complete computer program is in storage. (2) A technique or device designed to bring itself into a desired state by means of its own action; e.g., a machine routine whose first few instructions are sufficient to bring the rest of itself into the computer from an input device. (3) That part of a computer program used to establish another version of the computer program.
BUG—A mistake in a program.
BYTE—A group of bits next to each other that is considered a unit; for example an 8- bit byte.
CENTRAL PROCESSING UNIT (cpu)—The part of the computer hardware that directs the sequence of operations, interprets the coded instructions, performs arithmetic and logical operations, and initiates the proper commands to the computer circuits for execution. It controls the computer operation as directed by the program it is executing.
CHARACTER—One symbol; for example, A, Z, a, z, 0, 1, 9, !, ".
CHIP—A small piece of silicon impregnated with impurities in such a way as to form transistors, diodes, and resistors. Electrical paths are formed on the silicon by depositing thin layers of aluminum or gold.
NEETS MODULE 22-Digital Computing UNCLASSIFIED
A-3 UNCLASSIFIED COBOL (COmmon Business Oriented Language)—A high -level programming language designed for business-type applications.
COMPATIBLE SOFTWARE—Programs that can be run on more than one type of computer. These programs come in several different versions so they can be run under several different operating systems.
COMPILER—A program that translates source programs written in a high -level programming language (for example COBOL or FORTRAN) into machine language.
COMPUTER—A programmable electronic device that can store, retrieve, and process data.
COMPUTER OPERATOR—The person who sets up and operates the computer system.
COMPUTER PROGRAMMER—A person who designs, writes, tests, debugs, and doc uments programs.
COMPUTER SYSTEM—The cpu (mainframe) with its console, input, and output devices, and secondary (auxiliary) storage devices. COMPUTER USERS—See users.
COMPUTER WORD—See word, computer.
CONSOLE—The unit of the computer used by the compute r operator to communicate with and control the computer system.
CONTROL SECTION—The part of the cpu that directs the flow of operations and data, maintains order in the computer, and initiates execution of the instructions.
CRT (Cathode-Ray Tube) TERMINAL—A computer terminal that displays its output on a television like screen that may be black and white or color.
CURSOR—A pointer (a dot of light) on a crt screen to let you know the next position in which data will be entered. By depressing cursor control keys, the operator can move the cursor from line to line and from character to character.
CUSTOM SOFTWARE—Programs designed and written to the specifications of a user or an organization.
DATA—Facts represented by numbers, letters, or symbols to which meaning is or can be assigned.
DATA BASE—A structured collection of data that can be extracted, organized, and manipulated by a program.
DATA COMMUNICATIONS—The means by which data is transmitted electronically from one location to another over a communications channel.
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A-4 UNCLASSIFIED DATA ELEMENT—One item of information; the smallest unit of data that can be referenced.
DATA FLOWCHART—See flowchart.
DATA, REFERENCE—The source document identification.
DATA REPRESENTATION—The symbols and codes used by compute rs to represent letters, numbers, and special characters.
DEBUGGING—The process of finding errors (bugs) in a program or system and correcting them so that the program or system runs correctly.
DENSITY, RECORDING—The number of bits, bytes, characters, or frames per linear inch on a recording medium, like tape or disk.
DIGITAL COMPUTER—A computer that solves problems on discrete data using 0's and 1's (OFF and ON states) to represent data and operations.
DIRECT ACCESS—A storage method that allows the com puter to locate and read a particular record without having to search through an entire file. The computer is able to access data independent of its location. Magnetic disks, diskettes, and drums are considered direct access devices.
DISK DRIVE—A direct -access storage device for recording and retrieving data on hard (rigid) disk or floppy disks (diskettes).
DISK PACK—A mass storage device in which information is stored on one or both sides of a rigid disk that can be magnetized. The disk is rotated by a disk drive and information is stored and retrieved by one or more magnetically sensitive read/write heads.
DISKETTE—A mass storage device in which information is stored on one or both sides of a flexible disk that can be magnetized. The diskette is rotated by a diskette drive and information is stored and retrieved by one or more magnetically sensitive read/write heads. Diskettes are also called floppy disks because the disk bends easily.
DOWNTIME—The length of time the computer is not operat ing, either because of preventive maintenance (scheduled downtime) or a malfunction (nonscheduled downtime).
EBCDIC (Extended Binary Coded Decimal Interchange Code)—An 8 -bit coding system for representing uppercase and lowercase letters, numbers, and special characters.
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A-5 UNCLASSIFIED EPROM—The acronym for erasable programmable read -only memory.
FIELD, DATA—An item of information in a data record. One or more related characters that are treated as a unit of information.
FILE—A collection of related records; for examp le, a payroll file. Any collection of records holding similar data or transactions that are stored together to permit systematic access and modification.
FILE, MASTER—The file that contains all the data records in up -to-date form. It is a main reference file of relatively more permanent information, which is usually updated periodically.
FIRMWARE—A set of program instructions, a microprogram, permanently stored in read-only memory.
FLAT PANEL DISPLAY—A display device that consists of a grid of electrodes in a flat, gas-filled panel. The image can persist for a long period of time without refresh.
FLOPPY DISK—See diskette.
FLOWCHART—A graphic representation of the processing steps (logic) of a program (a program flowchart) or the inputs, outputs, and processing steps of a system (a systems [data] flowchart). The graphic representation uses symbols to represent operations and directional lines to indicate sequence and direction of flow.
FORMAT—The arrangement or layout of data in or on a data medium.
FORTRAN (FORmula TRANslator)—A high -level programming language for scientific and mathematical applications.
FULL-DUPLEX CHANNEL—A channel that provides for simultaneous transmission in both directions, such as the telephone.
GENERAL-PURPOSE COMPUTER—A computer designed to operate on a program of instructions for the purpose of solving many different types of processing problems.
GENERATIONS OF COMPUTERS—Historically, the distinctive types of computers from the 1940s to the present; the first generation was based on vacuum tubes, the second on transistors, the third and current features integrated circuits. Recent developments involve the use of VLSI (very large scale integration) and semiconductor memories.
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A-6 UNCLASSIFIED GRAPHICS—The use of pictorial means to prese nt data in the form of plotted curves, graphs (bar, pie, line, and so on), or diagrams. These may be displayed on a crt or printed.
HANDSHAKING—The process through which the rules for exchanging data over a communications line are defined for the two devices involved.
HARD COPY—The term given to humanly readable printed output from a computer.
HARDWARE—The visible, physical equipment of a system, including the computer (cpu) and related peripheral equipment; as distinguished from software.
HEAD POSITIONING—Placing a read/write head over a specified track on a disk or drum.
HEXADECIMAL—The number system with base 16 (0- 9 and A-F). A represents 10; B represents 11; C represents 12; D represents 13; E represents 14; and F represents 15. Used in some computer systems.
HIGH-LEVEL LANGUAGES—Programming languages that allow the programmer to write programs in English-like terms and symbols and mathematical notation, rather than the 0's and 1's used by the computer. These high-level programs must be translated into machine language before the computer can execute them. FORTRAN, Ada, COBOL, and BASIC are examples.
HOST COMPUTER—The main or controlling computer in a distributed data processing network (ddp).
HYBRID COMPUTER—A computer that combines the functions of both analog and digital computers.
I/O— Input/Output.
INPUT—The data entered into a computer system for processing.
INPUT DEVICES—Devices for reading data and programs into the computer system for processing.
INPUT/OUTPUT DEVICES—Secondary storage devices for writing and reading data. Magnetic tape drives, magnetic disk drives, and drums are examples.
INTEGRATED CIRCUIT—A miniaturized chip in which semiconductor components and other such technology combine the functions of a number of conventional components (such as transistors, resistors, capacitors, and diodes).
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A-7 UNCLASSIFIED INTERNAL STORAGE (MEMORY)—See storage, primary.
INTERRECORD/INTERBLOCK GAP—A blank section of recording surface separating each record or block of records on a magnetic data medium.
K—An abbreviation for the value 1,024 which is 210. Often used to express the memory capacity of a computer. For example, a 512K computer has 524,288 bytes of memory.
KEY-TO-DISK— A process, similar to key-to-tape, in which data is transmitted from a keyboard to magnetic disk.
KEY-TO-TAPE—An operation in which data is transmitted from a keyboard to magnetic tape.
LANGUAGE TRANSLATOR—A program that reads a source program and converts it into an object (machine language) program. Assemblers and compilers are examples.
LOCAL-AREA NETWORK—A network that normally operates within a well- defined and generally self-enclosed area. The communication stations or terminals are usually linked by cable and are within 1,000 feet of each other.
LOGICAL RECORD—A record th at includes all the data that belongs together as a unit regardless of the physical size or storage location of the data.
M—A unit of measurement approximately equal to one million and used to express the capacity of a computer memory. 1M is about 1,000,000 units. Memory size is usually measured in words or bytes.
MACHINE LANGUAGE—Machine instructions in binary bit patterns that the central processing unit can execute directly without additional interpretation or translation.
MACHINE (TAKE-UP) REEL—A reel that remains on the tape drive and on which magnetic tape is wound during the processing of a tape.
MAGNETIC MEDIA—Magnetic cards, tapes, disks, drums, cartridges, and cassettes used to record data or information.
MAGNETIC TAPE— A mass storage device in which information is stored on a plastic tape coated with a magnetic film. The tape is wound on reels that are rotated by tape drives. Information is stored and retrieved sequentially by magnetically sensitive read/write heads.
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A-8 UNCLASSIFIED MAINFRAME COMPUTERS—Th is term is usually used to designate large-scale computer systems, although the precise definition of mainframe is the cpu and the control elements of any computer system.
MAIN STORAGE (MEMORY)—See storage, primary.
MASS STORAGE—Any external storage medi um (magnetic tape, disk, drum, and so on) that supports and can be linked to the cpu's main memory in the computer. When the power is turned off, information in the mass storage is retained (not lost).
MEDIUM—The material on which data and instructions ar e recorded, such as punched cards, paper tape, and all forms of magnetic media (tape, disk, drum, and so on).
MEMORY—A device or section of the computer in which computer instructions and data can be stored for retrieval (synonymous with primary or internal storage).
MICROCOMPUTERS—The smallest category of computers, usually with the entire central processing unit on a single chip. Unlike large-scale and minicomputer systems, they are designed to be used by one person at a time (hence the term, personal computer [PC]).
MICROPROCESSOR—The semiconductor central processing unit (cpu) of a microcomputer that fits on a small silicon chip. The microprocessor is the central chip containing the control units of the computer.
MICROSECOND—One millionth of a second.
MILLISECOND—One thousandth of a second.
MINICOMPUTERS—Midsize computers that are smaller than large -scale systems but with the same components. They are less expensive and have less strict environmental requirements.
MODEM—Acronym for MOdulator -DEModulator. A device that converts data from digital-to-analog format for transmission on analog transmission lines and converts data in analog format to digital format for computer processing.
MULTIPROCESSING—A computer processing mode that provides for simultaneous processing of two or more programs or routines by use of multiple cpu's.
MULTIPROGRAMMING—A computer processing mode that provides for overlapping or interleaving the execution of two or more programs at the same time by a single processor.
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A-9 UNCLASSIFIED NANOSECOND—A billionth of a second.
NETWORK—Computers and terminals linked together through a communications system to allow users at different locations to share data files, devices, and programs.
ONLINE PROCESSING—Processing from terminals under the direct control of a computer.
OPERATING SYSTEM—Software that controls the execution of programs. An operating system may provide services such as input/output control and data management. It may also provide job scheduling, memory allocation, and other general functions. It is usually loaded by a bootstrap program.
OUTPUT—The results of computer processing. It may be data transferred to tape, disk, paper, and so on.
PACKAGED SOFTWARE—Programs already written (and tested) to solve specific types of problems; usually designed by a central design agency (CDA) or purchased from a software firm or computer manufacturer.
PACKED DECIMAL— In ASCII and EBCDIC, the representation of two digits stored in one eight-bit byte.
PAPER TAPE—See punched tape.
PARALLEL TRANSMISSION—A method of data transmission in which all bits of a particular character are transmitted simultaneously.
PARITY BIT—A check bit; an extra bit added to a group of bits for use in detecting errors during data transfer.
PARITY CHECK—An internal error checking method in which the binary digits in a character or word are added and the sum is checked against a single previously computed parity digit. The check tests whether the number of one bits in a character or word are odd or even, depending on the parity of the computer.
PASSWORD—A protected word or string of characters that identifies or authenticates a user for access to a specific resource, such as a file or record.
PERIPHERAL EQUIPMENT—Equipment used for data entry, storage, or retrieval, but which is not a part of the central processing unit. Peripherals include crt displays, terminals, printers, and mass storage (tape, disk, and drum) devices.
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A-10 UNCLASSIFIED PERSONAL COMPUTER (PC)—A computer, usually a microcomputer, that is more affordable than minicomputers or mainframes and is used by one person at a time.
PICTURE ELEMENT—Synonym for pixel. See pixel.
PIXEL— In computer graphics, the smallest element of a display surface that can be independently assigned color or intensity.
PRIMARY STORAGE—S ee storage, primary.
PRINTER—A device used with a computer to produce hard copy, printed output.
PROGRAM—(1) Verb —The act of writing instructions for computer execution. (2) Noun—The set of instructions that tells the computer the steps to execute to automatically solve a problem.
PROGRAM FLOWCHART—See flowchart.
PROM—Acronym for programmable read -only memory.
PUNCHED CARD— A card punched with hole patterns that represent data or program instructions. Punched cards can be read by an input device (card reader) to a computer.
PUNCHED TAPE—A tape punched with hole patterns that represent data or program instructions. Tape can be read by an input device to a computer.
RAM—Acronym for random -access memory.
RANDOM ACCESS—A method of accessing data (or instructions) without having to scan any preceding information. Magnetic core, semiconductor, and bubble memories are considered random access storage devices.
REAL-TIME PROCESSING—A computer processing method in which data about a particular event is entered directly into the computer as the event occurs and is immediately processed so it can influence future processing.
RECORD—A group of related fields, all pertaining to the same subject.
RECORD BLOCK—Several records blocked together.
RECORD LENGTH—The number of characters in a record.
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A-11 UNCLASSIFIED REMOTE TERMINAL—A display terminal, such as a crt or other piece of equipment, which is not located with the computer but is connected by a communications line. In a typical online, real-time communications system, the remote device is usually a teletypewriter or a crt visual display unit.
ROM—Acronym for read -only memory.
ROTATIONAL DELAY—The time required for the read/write head to find a specified record on a disk, diskette, or drum once head positioning has occurred.
SECONDARY STORAGE—See storage, secondary.
SECTORS—The pie -shaped segments of a disk's recording surface.
SEQUENTIAL ACCESS—A storage technique in which the stored items of information become available only in a one after the other sequence, whether or not all the information or only some of it is desired. Magnetic tape is an example.
SOFT COPY—Output of a computer displayed on a display terminal or monitor (crt). It is nonpermanent.
SOFTWARE—Programs, routines, codes, and other written informati on used to direct the operation of a computer; as distinguished from hardware.
SORT—The process of arranging data records in a predefined sequence by use of sort keys; for example, to sequence personnel records by social security number (the sort key).
SOURCE DATA—The data in its initial state to be processed by a computer system.
SOURCE DOCUMENT—The document that contains the initial (raw) data for computer processing.
SOURCE PROGRAM—A computer program written in a language like COBOL, FORTRAN, or assembly language. It must be translated into an object program before it can be executed by a computer.
SPECIAL-PURPOSE COMPUTER—A computer designed to perform one specific function such as a weather computer.
STORAGE, PRIMARY (MAIN, INTERNAL)—The section of the cpu in which instructions and data are held. Also called main memory.
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A-12 UNCLASSIFIED STORAGE, SECONDARY (AUXILIARY, EXTERNAL)—Storage outside the cpu where programs and data are stored for future computer processing; for example tapes, disks, and punched cards.
STORED PROGRAM—The set of instructions stored in computer memory for execution.
SUBROUTINE LIBRARY—A set of standard and proven computer routines that are kept on file for use at any time.
TELECOMMUNICATIONS—The transmission of data between computer systems and/or terminals in different locations.
TELEPROCESSING—A method of data processing in which communication devices are used.
TERMINAL—A device linked to the central processor for entering or receiving data and programs.
TIME SHARING—A processing mode in which many users share the computer systems' resources through online terminals. Each user gets a slice of computer time.
TRACK—(1) One of seven or nine, horizontal rows stretching the entire length of a magnetic tape and on which data can be recorded. (2) One of a series of concentric circles on the surface of a disk. (3) One of a series of circular bands on a drum.
UNBLOCKED—Having a blocking factor of one logical record per block.
USER PROGRAMS— Programs written to solve specific user problems, called applications software.
USERS—(1) The people who use the output from computer processing. (2) The people who operate a computer for their own purposes.
UTILITY PROGRAMS (UTILITIES)—Programs designed to perform often needed general functions.
WIDE AREA NETWORK—A network that usually covers large geographical areas. Communications between stations or terminals usually occur using standard telephone lines or microwave relays.
WORD, COMPUTER—A group of related bytes treated as a single addressable unit or entity in computer memory.