Dictionary of Computing - 5th Edition

A1 /e / symbol the hexadecimal equivalent of the decimal number 10

A2 /e / abbr ampere

A: used in some operating systems to denote the first disk drive on the system

Å abbr angstrom

abandon /ə b ndən/ verb to clear a document, file or work from a computer’s memory without saving it Once you have abandoned your spreadsheet, you cannot retrieve it again.

abb. add. abbr abbreviated addressing abbreviated address /ə bri vie tid ə

dres/ noun (in a network) a user name that has fewer characters than the full name, making it easier to remember or type in or faster to decode

abbreviated addressing /ə

bri vie tid ə dres ŋ/ noun the use of abbreviated addresses. Abbr abb. add.

abbreviated installation /ə

bri vie tid nstə le ʃ(ə)n/ noun the installing of new hardware or software without restoring the previous backup settings of the operating system

abbreviation /ə bri vi e ʃ(ə)n/ noun a short form of a word, command or instruction Within the text, the abbreviation proc is used instead of processor.

ABD abbr Apple Desktop Bus

abend / bend/ noun an unexpected stoppage of a program that is being run, caused by a fault, error or power failure

An interrupt from a faulty printer caused an abend. Also called abnormal end, ab-

normal termination

abend code / bend kəυd/ noun a special number, generated by the operating system, that identifies the type of error that has caused a particular problem

abend recovery program / bend rk v(ə)ri prəυ r m/ noun a piece of

software that will reload a program or system software and restart it at the point at which an abend occurred

aberration / bə re ʃ(ə)n/ noun 1. distortion of a light beam or image caused by defects in the optical system 2. distortion of a television picture caused by a corrupt signal or incorrect adjustment

ablation /ə ble ʃ(ə)n/ noun a method of writing data to an optical storage device in which a laser burns a hole or pit, representing digital bits of data, into the thin metal surface of the storage device

COMMENT: A laser burns a hole or pit (which represents digital bits of data) into the thin metal surface of the storage device.

abnormal end / b nɔ m(ə)l end/ noun same as abend

abnormal termination / b nɔ m(ə)lt m ne ʃ(ə)n/ noun same as abend

abort /ə bɔ t/ verb to end a process in the event of a malfunction occurs by switching the computer off manually or by an internal feature The program was aborted by pressing the red button.

aborted connection /ə bɔ t d kənekʃ(ə)n/ noun a connection to a net-

work or online service that has not been shut down correctly

abort sequence /ə bɔ t si kwəns/ noun a unique sequence of bits that indicates that the transmission will be terminated because of a fault, error or power failure

About… /ə baυt/ a menu selection in the SAA CUA front end that tells you who developed the program and gives copyright information

above-the-fold /ə b v ðə fəυld/ adjective referring to the part of a webpage that is seen by all users who call up the page, because they do not have to scroll down to read it. Compare below-the-fold

ABR / e bi ɑ / noun a service provided by an ATM network that tries to provide the bandwidth requested by a customer, though it cannot guarantee to do so. Full form available bit rate

AB roll / e bi rəυl/ noun (in a multimedia application) a sequence of two video or music segments that are synchronised so that one fades as the second starts ABS / e bi es/ noun a programming instruction that returns the magnitude of a number without the number’s sign The command ABS(-13) will return the answer 13. Full form absolute function absolute address / bsəlu t ə dres/ noun 1. a computer storage address that directly, without any modification, accesses a location or device Program execution is slightly faster if you code only with absolute addresses. Compare indexed address 2. a computer storage address that can only access one location also called actual address, machine address

absolute addressing / bsəlu t ədres ŋ/ noun the locating of a data word stored in memory by the use of its absolute address

absolute assembler / bsəlu t əsemblə/ noun a type of assembly lan-

guage program designed to produce code that uses only absolute addresses and values

absolute cell reference / bsəlu t sel ref(ə)rəns/ noun a spreadsheet reference that always refers to the same cell, even when copied to another location absolute code / bsəlu t kəυd/ noun binary code that directly operates the central processing unit, using only absolute addresses and values. Also called actual code, basic code

absolute coordinates / bsəlu t kəυ ɔ d nətz/ plural noun coordinates that describe the distance of a point from the intersection of axes

absolute device / bsəlu t d va s/ noun an input device such as a tablet or mouse that returns the coordinates of a pointer within specified axes

absolute error / bsəlu t erə/ noun the value or magnitude of an error, ignoring its sign

absolute expression / bsəlu t kspreʃ(ə)n/ noun (in assembly language)

the value of an expression that is not affected by program relocation

absolute function / bsəlu tf ŋkʃən/ noun full form of ABS

absolute instruction / bsəlu t nstr kʃən/ noun an instruction that com-

pletely describes the operation to be performed, requiring no other data absolute loader / bsəlu t ləυdə/ noun a program that loads a section of code into main memory

absolute maximum rating

/ bsəlu t m ks məm re t ŋ/ noun a statement of the maximum values or limits of a system

absolute positioning / bsəlu t pəz ʃ(ə)n ŋ/ noun the position of an object in relation to a point of origin

absolute priority / bsəlu t praɒr ti/ noun (in the OS/2 operating system) the priority of a process that cannot be changed by the operating system absolute program / bsəlu tprəυ r m/ noun a computer program written in absolute code

absolute time / bsəlu t ta m/ noun

(in CD-audio) the length of time that an audio disc has been playing

absolute value / bsəlu t v lju / noun the size or value of a number, regardless of its sign The absolute value of – 62.34 is 62.34.

absorb /əb zɔ b/ verb to take in light, liquid or a signal

absorptance /əb zɔ ptəns/ noun a measure of how completely an object or substance absorbs radiant energy. Opposite reflectance

absorption /əb zɔ pʃən/ noun the power loss of a signal when travelling through a medium, due to its absorptance abstract data type / bstr kt de təta p/ noun a general data type that can store any kind of information

A-bus /e b s/ noun the main internal bus in a microprocessor

ac abbr academic organisation (NOTE: used in email and website addresses)

AC abbr alternating current

ACAP / e si e pi / noun an email system developed to work with the IMAP4 email protocol to provide extra features such as management of an address book. Full form application configuration access protocol (NOTE: It was originally termed IMSP (Interactive Mail Support Protocol).)

ACC / e si si / noun the most important internal CPU storage register, containing the data word that is to be processed

Store the two bytes of data in registers A and B and execute the add instruction –

the answer will be in the ACC. Full form accumulator

accelerated graphics port /əkseləre t d r f ks pɔ t/ noun full

form of AGP

acceleration time /ək selə re ʃ(ə)n ta m/ noun 1. the time taken for a disk drive to spin a disk at the correct speed, from rest Allow for acceleration time in the access time. 2. the total time between an access instruction’s issue to a peripheral and the transfer of the data

accelerator board /ək selə re tə bɔ d/, accelerator card /ək selə re tə

kɑ d/ noun a circuit board that carries a faster or more advanced version of the same processor that runs your computer. Adding an accelerator board to your computer makes it run faster.

accelerator key /ək selə re tə ki / noun a key that, when pressed together with another, carries out a function that would otherwise have to be selected from a menu using a mouse Instead of selecting the File menu then the Save option, use the accelerator keys Alt and S to do the same thing and save the file.

accept /ək sept/ verb to establish a session or connection with another computing device

acceptable use policy /əkseptəb(ə)l ju z pɒl si/ noun a set of

rules that describe what a user can write or do on the Internet without offending other users. Abbr AUP

acceptance sampling /ək septənssɑ mpl ŋ/ noun the testing of a small random part of a batch to see if the whole batch is up to standard

acceptance test /ək septəns test/ noun a test to check that a piece of equipment will perform as required or will reach required standards

acceptance testing /ək septənstest ŋ/ noun the performing of an acceptance test

access / kses/ noun 1. the fact of being able to reach or use something to have access to the computer room 2. the fact of being allowed to use a computer and read or alter files stored in it. This is usually controlled by a security device such as a password. to deny access to refuse access to a circuit or system for reasons of workload or security verb to call up data which is stored in a computer

She accessed the employee’s file stored on the computer.

access arm / kses ɑ m/ noun a mechanical device in a disk drive used to position the read/write head over the correct track on a disk The access arm moves to the parking region during transport. access authority / kses ɔ θɒrəti/ noun permission to carry out a particular operation on data

access-barred / kses bɑ d/ adjective prevented from accessing particular data

access category / kses k tə (ə)ri/ noun a category that defines which files or data a user can access and which he or she cannot

access channel control / ksestʃ n(ə)l kən trəυl/ noun (in a Token-

Ring network) the set of protocols that manage the data transfer between a station and a medium access control

access charge / kses tʃɑ d'/ noun a cost due when logging onto a system or viewing special pages on a bulletin board access code / kses kəυd/ noun a series of characters or symbols that must be entered to identify a user before access to a computer is permitted

access control / kses kən trəυl/ noun a security device such as a password that only allows selected users to use a computer system or read files

access control byte / kses kəntrəυl ba t/ noun (in a Token-Ring net-

work) a byte following a start marker in the token that indicates if the station can access the network

access controller / kses kəntrəυlə/ noun (in CD-i) an electronic de-

vice that transfers image data to the video controller

access control list / kses kən trəυl l st/ noun full form of ACL

access counter / kses kaυntə/ noun counter

access head / kses hed/ noun the part of a disk drive that moves to the correct part of the disk’s surface and reads information stored on the disk

access hole / kses həυl/ noun an opening in both sides of a floppy disk’s casing allowing the read-write head to be positioned over the disk’s surface accession number /ək seʃ(ə)nn mbə/ noun a number in a record that