Glossary of Computer Software Development Terminology
The terms are defined, as much as possible, using available standards. The source of such definitions appears immediately following the term or phrase in parenthesis, e.g. (NIST).
The source documents are listed at the bottom of this page.
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HDD. hard disk drive.
HIPO. hierarchy of input-processing-output.
Hz. hertz.
half duplex. Transmissions [communications] which occur in only one direction at a time, but that direction can change.
handshake. An interlocked sequence of signals between connected components in which each component waits for the acknowledgement of its previous signal before proceeding with its action, such as data transfer.
hard copy. Printed, etc., output on paper.
hard disk drive. Hardware used to read from or write to a hard disk. See: disk, disk drive.
hard drive. Syn: hard disk drive.
hardware. (ISO) Physical equipment, as opposed to programs, procedures, rules, and associated documentation. Contrast with software.
hazard. (DOD) A condition that is prerequisite to a mishap.
hazard analysis. A technique used to identify conceivable failures affecting system performance, human safety or other required characteristics. See: FMEA, FMECA, FTA, software hazard analysis, software safety requirements analysis, software safety design analysis, software safety code analysis, software safety test analysis, software safety change analysis.
hazard probability. (DOD) The aggregate probability of occurrence of the individual events that create a specific hazard.
hazard severity. (DOD) An assessment of the consequence of the worst credible mishap that could be caused by a specific hazard.
hertz. A unit of frequency equal to one cycle per second.
hexadecimal. The base 16 number system. Digits are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, & F. This is a convenient form in which to examine binary data because it collects 4 binary digits per hexadecimal digit; e.g., decimal 15 is 1111 in binary and F in hexadecimal.
hierarchical decomposition. See: modular decomposition.
hierarchy of input-processing-output. See: input- processing-output.
hierarchy of input-processing-output chart. See: input-process-output chart.
high-level language. A programming language which requires little knowledge of the target computer, can be translated into several different machine languages, allows symbolic naming of operations and addresses, provides features designed to facilitate expression of data structures and program logic, and usually results in several machine instructions for each program statement. Examples are PL/1, COBOL, BASIC, FORTRAN, Ada, Pascal, and "C". Contrast with assembly language. |
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Source Documents
The bulk of this information was obtained from FDA.gov. |
BIOS. basic input/output system.
bps. bits per second.
band. Range of frequencies used for transmitting a signal. A band can be identified by the difference between its lower and upper limits, i.e. bandwidth, as well as by its actual lower and upper limits; e.g., a 10 MHz band in the 100 to 110 MHz range.
bandwidth. The transmission capacity of a computer channel, communications line or bus. It is expressed in cycles per second [Hz], and also is often stated in bits or bytes per second. See: band.
bar code. (ISO) A code representing characters by sets of parallel bars of varying thickness and separation that are read optically by transverse scanning.
baseline. (NIST) A specification or product that has been formally reviewed and agreed upon, that serves as the basis for further development, and that can be changed only through formal change control procedures.
BASIC. An acronym for Beginners All-purpose Symbolic Instruction Code, a high-level programming language intended to facilitate learning to program in an interactive environment.
basic input/output system. Firmware that activates peripheral devices in a PC. Includes routines for the keyboard, screen, disk, parallel port and serial port, and for internal services such as time and date. It accepts requests from the device drivers in the operating system as well from application programs. It also contains autostart functions that test the system on startup and prepare the computer for operation. It loads the operating system and passes control to it.
batch. (IEEE) Pertaining to a system or mode of operation in which inputs are collected and processed all at one time, rather than being processed as they arrive, and a job, once started, proceeds to completion without additional input or user interaction. Contrast with conversational, interactive, on-line, real time.
batch processing. Execution of programs serially with no interactive processing. Contrast with real time processing.
baud. The signalling rate of a line. It's the switching speed, or number of transitions [voltage or frequency change] made per second. At low speeds bauds are equal to bits per seconds; e.g., 300 baud is equal to 300 bps. However, one baud can be made to represent more than one bit per second.
benchmark. A standard against which measurements or comparisons can be made.
bias. A measure of how closely the mean value in a series of replicate measurements approaches the true value. See: accuracy, precision, calibration.
binary. The base two number system. Permissible digits are "0" and "1".
bit. A contraction of the term binary digit. The bit is the basic unit of digital data. It may be in one of two states, logic 1 or logic 0. It may be thought of as a switch which is either on or off. Bits are usually combined into computer words of various sizes, such as the byte.
bits per second. A measure of the speed of data transfer in a communications system.
black-box testing. See: testing, functional.
block. (ISO) (1) A string of records, words, or characters that for technical or logical purposes are treated as a unity. (2) A collection of contiguous records that are recorded as a unit, and the units are separated by interblock gaps. (3) A group of bits or digits that are transmitted as a unit and that may be encoded for error-control purposes. (4) In programming languages, a subdivision of a program that serves to group related statements, delimit routines, specify storage allocation, delineate the applicability of labels, or segment parts of the program for other purposes. In FORTRAN, a block may be a sequence of statements; in COBOL, it may be a physical record.