Macmillan Dictionary of Microcomputing Third Edition I0fLkCCOOll~~A~ 11C C1lll IQ) CD) ~Affiif @IF MICROCOMPUTING THIRD EDITION CHARLES J.SIPPL M MACMILLAN PRESS LONDON © The Macmillan Press Ltd, 1985 All rights reserved. No reproduction, copy or transmission of this publication may be made without written permission. No paragraph of this publication may be reproduced, copied or transmitted save with written permission or in accordance with the provisions of the Copyright Act 1956 (as amended). Any person who does any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims for damages. First edition 1975, second edition 1981 Third edition ftrst published 1985 by THE MACMILLAN PRESS LTD London and Basingstoke Associated companies in Auckland, Delhi, Dublin, Gaborone, Hamburg, Harare, Hong Kong, Johannesburg, Kuala Lumpur, Lagos, Manzini, Melbourne, Mexico City, Nairobi, New York, Singapore, Tokyo British Library Cataloguing in Publication Data Sippl, Charles J. Dictionary of microcomputing-3rd ed. 1. Microcomputing-Dictionaries I. Title. 001.64'04'0321 QA76.5 ISBN 978-0-333-37082-7 ISBN 978-1-349-17843-8 (eBook) DOI 10.1007/978-1-349-17843-8 The paperback edition of this book is sold subject to the condition that it shall not, by way oftrade or otherwise, be lent, resold, hired out, or otherwise circulated without the publisher's prior consent in any form of binding or cover other than that in which it is published and without a similar condition including this condition being imposed on the subsequent purchaser. A A AND NOT B gate: A specific binary logic laboratory tested by most manufacturers to coincidence (two-input) circuit used to a specified percentage value, e.g., 1%. complete the logic operations of A AND Then, if more than 1% of these parts fail, NOT B, i.e., the result is true only if the entire lot fails to meet the acceptable statement A is true and statement B is false. quality level and is rejected. abend: An error condition that results in access time: The time between the appli the abnormal termination of a program. cation of a specified input pulse and the availability of valid data signals at an out abend recovery program: A program that put. Access time varies with temperature, permits a system (a data base, for example) supply voltage, input conditions, and out to be reloaded and restored to the point put loading. It can only be defined with where the abend occurred. reference to an output signal. absolute address: 1. An actual location in accumulator (ACC): A 4-, 8-, 12-, 16-, or storage of a particular unit of data; an 32-bit register that functions as a holding address that the control unit can interpret register for arithmetic, logical, and input/ directly. 2. The label assigned by an output (1/0) operations. Data words may engineer to a particular storage area in the be fetched from memory to the ACC or computer. 3. A pattern of characters that from the ACC into memory. Arithmetic identifies a unique storage location or device and logical operations involve two oper without any further modification. (Synony ands, one held in the accumulator, the other mous with machine address.) fetched from memory. The result of an operation is retained in the accumulator. absolute load module: A unit, consisting of The ACC may be cleared, complemented, procedures translated separately and linked tested, incremented, or rotated under pro together by the linker to be run as a unit. gram control. The ACC also serves as an 1/0 register. Programmed data transfers absolute maximum rating: The limiting pass through the accumulator. values of the operating and environmental conditions applicable to any electronic ACIA: See asynchronous communi device, as defined by its published data, cations interface adapter. which are not to be exceeded under the worst conditions. It is the rating beyond ACK: Signal for affirmative acknow which the reliability of a device can be ledgement as used in a transmission to expected to decline. indicate that a previous transmission (block) has been accepted by the receiver. absorption current: The current flowing ACK signifies that the ·receiver is ready to into a capacitor, following its initial charge, accept the next block of transmission. . due to a gradual penetration of the electric stress into the dielectric. It also relates to the acoustic coupler: An inductive device that current that flows out of a capacitor follow converts specific characters to multiple ing its initial discharge. tones that can be transmitted on a commu nications line. acceptable quality level (AQL) test: The AQL of groups of parts and components is acoustic delay line: A specific delay line 1 2 action cycle that bases its operation on the time of restricted. Thus, new names can be intro propagation of sound waves. duced without fear of conflict with previous names. action cycle: The complete operation per formed on data. Includes basic steps of adapter: A connective device designed to origination, input, manipulation, output, affect operative capability between and storage. different parts of one or more systems and/or subsystems. active element: 1. An element in its excited or being-used state, i.e., a tube, adapter plug: A fitting designed to change transistor, or device that is on or alive rather the terminal arrangement of a jack, socket, than off, dead, or in a grounded state. 2. A or other receptacle, so that electrical con file, record, or routine that is being used, nections other than the original are contacted, or referred to. Computer possible. components are active when they are directed or excited by the control unit. ADC: See analog-to-digital converter. active transducer: Any transducer in which the applied power either controls or ADCIMPS support hardware: The modulates locally supplied power, which support hardware usually required to link becomes the transmitted signal, as in a radio an analog-to-digital converter (ADC) to a transmitter. microprocessor system (MPS). It includes leveltranslation buffers for handling the Ada language: A modern programming control-bus transistor-transistor logic language that has been developed at the (TTL)levels, control logic to start conver initiative of the U.S. Department of sion, read data and service interrupts, Defense, in cooperation with the United 3-state buffers to drive the data bus, and a Kingdom, French, and German Defense data register to hold previous results while a Ministries and with extensive contributions new conversion occurs. A typical MPS-to from industry and universities world wide. ADC interface has such key items as input, The language is specifically aimed at reference and supply voltages, clock fre improving software reliability, portability, quency, control lines, external parts, and and maintainability while significantly bus-interface devices. reducing system life cycle costs. Ada is designed for implementations ranging from adder-accumulator: In some systems, the large complex systems to embedded real adder is a 4bit parallel binary adder with an time applications and is expected to become internally connected carry for imple the dominant language of the 1980s and 90s. menting precision arithmetic operations. The Ada language gives preference to full The adder operates with the 4-bit accumu English words and has 62 words reserved. It lator to form the arithmetic logic unit requires very specific tasking controls, most (ALU) section of the CPU. In addition to of which are neglected by other high-level its arithmetic functions, the accumulator is languages. In Ada, the task declaration the primary working register in the CPU simplifies task coordination. A task is very and is the central data interchange point for similar to a module, the major building most all data transfer operations occurring block of an Ada program. For timing pur in the system. During internal data transfer, poses, delay and select statements the accumulator is the interfacing data supplement interrupts. General program register for both random-access memory structure and visibility of program (RAM) and read-only memory (ROM). components are other focal points in Ada's For external data changes (input/output) design. A program consists of a nested the accumulator is the source of the output structure (package, module, procedure), data and the receiver register for the input and names can be declared private or data. alignment 3 address: l.A character or group of tured (in character strings, arrays, lists, characters that identifies a register, a parti etc.), and the addressing mode provides for cular part of storage, or some other data efficient and flexible handling of structured source or destination. 2. To refer to a device data. or item of data by its address. address path: The selection path for address format: 1. The arrangement of memory and input/output (1/0) data. For the address parts of an instruction. The data processing, memory and I/0 often use expression "plus-one" is frequently used to separate addressing or selection schemes. indicate that one of the addresses specifies This suits the need for maximum memory the location of the next instruction to be and extensive peripherals. For logic pro executed. Expressions used are, for cessors, a combined addressing path for example, one-plus-iOne, two-plus-one, memory and I/0 is the most efficient. Inter three-plus-one, four-plus-one. 2. The connection is simplified and the package pin arrangement of the parts of a single address limitation is not overextended. such as those required for identifying chan nel, module, track, etc., in a disk system. address space: The space of possible addresses consisting of the total number of addressing capacity: The programming addressable words of memory. The number addressing range, which determines how of addressable words depends only on the large a program can be written without number of bits in an address, and is not resorting to special external hardware and related to the number of memory words internal software techniques. A range that actually available. On a computer with is too small means that extra hardware will 50,986 16-bit number (addresses), the be required to extend the addressing. address space would consist of 0, 1, 2, ... , Excessive capacity means that extraneous 50,985, which is the set of possible address bits will be carried in every instruc addresses. tion that refers to storage. add time: The time required, in microse addressing level: 1. In zero-level conds, to acquire from memory and execute addressing, the address part of an instruc one fixed-point add instruction using all tion is the operand (for instance, the features such as overlapped memory addresses of shift instructions). 2. In first blanks, instruction look-ahead, and parallel level addressing, the address of an instruc execution. The add is either from one full tion is the location in memory where the word in memory to a register, or from operand may be found or where it is to be memory to memory, but not from register stored. 3. In second-level addressing (indi to register. rect addressing), the address part of an instruction is the place in memory where the algorithm: A prescribed set of well address location of the operand may be defined rules or processes for the solution of found or is to be stored. a problem in a finite number of steps; for example, a full statement of an arithmetic addressing mode: A specification of how procedure for evaluating sin x to a stated selected register(s) are to be used. Data precision. Contrast with heuristic. stored in memory must be accessed and manipulated. Data handling is specified by algorithmic language (ALGOL): One of instructions (such as MOV, ADD, etc.) the international program languages which usually indicate the function (opera designed for the concise, efficient expres tion code), the generalp urpose register to sion of arithmetic and logical processes, and be used when locating the source operand for the control of these processes. and/or the destination operand, and the addressing mode. A large portion of the alignment: The process of adjusting data handled by a computer is usually struc- components of a system for proper inter- 4 alignment pin relationship. The term is applied especially ALU: See arithmetic logic unit. to the synchronization of components in a system. ambient conditions: The conditions of the surrounding medium (pressure, noise, etc.). alignment pin: Any pin or device that will insure the correct mating of two American Federation of Information Pro components designed to be connected. cessing Societies (AFIPS): An organiz ation of computer-related societies. Its allocate: The assignment of storage in a members include: The Association for computer to main routines and subroutines, Computer Machinery; The Institute of thus fixing the absolute values of symbolic Electrical and Electronic Engineers addresses. Computer Group; Simulation Councils, Inc.; American Society for Information alloy: A composition of two or more Science. Its affiliates include: American elements, of which at least one is a metal. It Institute of Certified Public Accountants; may be either a solid, a solution, a heter American Statistical Association; Associ ogeneous mixture, or a combination of ation for Computational Linguistics; both. Society for Industrial and Applied Mathe matics; Society for Information Display, alphabetic coding: A system of abbre Association of Data Processing Services viation used in preparing information for Organizations. input into a microcomputer. Information may then be reported in the form of letters American National Standards Institute and words as well as in numbers. (ANSI): Formerly the American Stan dards Association (ASI) and, prior to that, the United States of America Standards alpha flux: The number of alpha particles Institute (USASI). An organization which emitted from a surface over a period of organizes committees formed of computer time. It is measured in alpha particles per users, manufacturers, etc., to develop and square centimeter per hour (oocm2/hr). publish industry standards, e.g., ANSI FORTRAN, ANSI Standard Code for alpha-particle sensitivity: A response to Periodical Identification, etc. It is a non alpha radiation. It is a problem in metal profit, nongovernmental organization oxide semiconductor (MOS) dynamic which serves as the national clearing house memory arrays. The impact of an alpha and coordinating body for voluntary stan particle in certain areas of a semiconductor dards in the United States. causes the generation of close to one million electron-hole pairs. When scaling reduces American Standard Code for Information the charge stored in a memory cell to about Interchange (ASCII): A standard data the same size, an alpha-particle hit can transmission code introduced to achieve effectively wipe out the stored charge and compatibility between data devices. It con cause a soft error. Depending on where the sists of 7 information bits and 1 parity bit for alpha particle hits the device, it can cause an error-checking purposes, thus allowing 128 error in a binary 1 or 0, or both. code combinations. If the eighth bit is not used for parity, 256 code combinations are alpha radiation: Radiation which can be possible. found almost everywhere, since it comes from naturally occuring substances. For analog: In electronic computers, the term examRle, typical soil samples produce 1 or 2 refers to a physical system in which the oocm /hr. (As little as one part per million performance of measurements yields of a radioactive contaminant will produce information concerning a class of mathe this level.) matical problems. AND operation 5 analog amplifier: In some systems, an digitizing of almost all of the entire audio analog amplifier performs 2 functions. spectrum. First, it supplies the dual delayed sweep comparators with the proper direct current analog output card: A module that per (de) levels. Second, it accepts the de level mits the generation of analog data to many from the vertical channel, processes this devices, such as oscilloscopes, amplifiers, level, and provides two pieces of informa motor drivers, XY recorders, and other tion for the processor through the input voltage controlled devices. Unlike some interface. The two pieces of information are multichannel converters which require the polarity ofthe de level, and whether the cumbersome software refresh, some units level is greater or less than some reference. contain their own memory and refresh If it is greater, the processor increases the circuitry. Up to 16 channels of analog out reference until it is within 1least significant put are available, and the output range is bit of the unknown. In both cases, it dis user-adjustable, on many systems. plays the reference level that is now equal to the unknown. analog channel: A channel that will pass alternating current, but not direct current. A switched voice channel is an analog All UNITS ARE COMPLETELY COMPATIBLE WITH channel, while most teletypewriter circuits MICROPROCESSOR BUS are digital channels (de). If an analog chan SIGNALS nel is said to carry digital data, it is actually Analog output card. carrying analog representations of the digital data in the form of various fre analog representation: A representation quencies. having discrete values but continuously variable. analog computer: A computer which operates on the principle of creating a analog-to-digital converter (ADC): Refers physical (usually electrical) analogy of a to a device which produces a digital output mathematical problem to be solved. Varia from an input which is in the analog form of bles such as temperature or flow are repre physical motion or electrical voltages. sented by the magnitude of a physical phenomenon such as voltage or current. anciUary equipment: A term, often inter These variables are manipulated by the changeable with peripheral equipment, computer in accordance with mathematical which relates to all types of input/output, formulas analogued on it. communication, and interface equipment. analog gate: A logic gate, the output AND gate: A gate circuit in an electronic signal of which is a linear function of one or computer that has more than one control more input signals. (input) terminal. No output signal will be produced unless a pulse is applied to all analog input card: A module that contains inputs simultaneously. an instrumentation amplifier, an input mul 0+0=0 tiplexer (that can select up to 16 single 0+1=0 ended or 8 differential-mode signals), a 1+0=0 track and hold buffer, and a high-speed 1 + 1 = 1 analog/digital (A/D) coverter. Amplifier gain and input, bipolar or monopolar, are AND operation: A basic operation in user selectable. Low input drift permits the Boolean algebra which, for the two integers connection of transducers, such as thermo I and J, may be defined by the couples, and a short conversion time allows statement: If I and J are both 1, then the 6 ANSI result is 1. Otherwise, the result is zero. The necessary to using a computer for definite dot is used to indicate the AND operation. functions or operations, and the estab When letters are used (in general cases), the lishing of specifications to be used as a base dot is sometimes omitted; thus I and J may for the selection of equipment suitable to be represented as I·J or IJ. the specific needs. ANSI: See American National Standards APT (Automatically Programmed Tools): Institute. A language for programming numerically controlled machine tools. There are many anticoincidence circuit: A specific logic other similar languages with different element which operates with binary digits names. and is designed to provide input signals according to specific rules; i.e., one digit is APT III: A system for the computer obtained as output only if two different assisted programming of numerically con input signals are received. trolled machine tools, such as flame cutters, drafting machines, and similar equipment. APL language: A programming language It is production-oriented; that is, it was writ developed by Iverson. An unusually exten ten to simplify the effort, time, and money sive set of operators and data structures are needed to take full advantage of numerically used to implement what is considered by controlled techniques in engineering and many to be the most flexible, powerful, and manufacturing. In addition to providing concise algorithmic/procedural language in machine-tool programming capabilities that existence. Primarily used from conversa are virtually impossible by manual methods, tional terminals, its applicability to produc numerical control permits: reduced lead tion job processing is limited but its value for time, greater design freedom and flexibility, educational and investigative work is great. lower direct costs, greater accuracy, improved production forecasting, lower application notes, microcomputer: A par tooling costs, better engineering control of ticular form of documentation endemic to the manufacturing process, and simplified the semiconductor business; they are not introduction of changes. common in the community of computer vendors. However, the rapid engineering AQL test: See acceptable quality level changes and the problems of designing test. microprocessors into final systems virtually require the use of application notes for architecture: Any design or orderly release rapidity. Some microprocessor arrangement perceived by man, i.e., the vendors publish one circuit diagram. Others architecture of the microprocessor. Since publish ,alternate ways of accomplishing the the extant microprocessors vary considera same objectives, complete with hardware bly in design, their architecture has become and software considerations. a bone of contention among specialists. applications package: A set of computer argument: An independent variable. For programs and/or subroutines used to solve example, when looking up a quantity in a problems in a particular application, i.e., table, the number, or any of the numbers, business, scientific, financial, etc. that identifies the location of the desired value. applications program: A program written to accomplish a specific user task (such as arithmetic logic unit (ALU): The micro payroll) as opposed to supervisory, general processor in the central processing unit purpose, or utility programs. which executes the logical and arithmetic operations required by an input command. applications study: The detailed process A microprocessor can constitute an ALU of determining a system or set of procedures and control portions of a general-purpose