Analog-digital converter. A device for converting analog signals into digital ones for subsequent computer processing; sometimes called a "digitizer." A digital to analog (D to A) converter operaties in the reverse direction.
Pathway from memory to processing unit that carries the address in memory to and from which data is transferred. See the definitions for "bus" and "data bus."
arithmetic and logic unit (ALU)
A part of the computer that performs arithmetic operations, logic operations and related operations.
The representation and measurement of the performance or behavior of a system by continuously variable physical entities such as currents, voltages and so on.
Data that represents a record of data held and processed at a specific time, which is held off-line for future research or for legal reasons.
1. An arrangement of data in one or more dimensions.
2. In programming languages, an aggregate that consists of data objects, with identical attributes, each of which may be uniquely reference by indexing.
ASCII (American Standard Code for Information Interchange)
The primary encoding character set used in computers for textual data transfer between applications. The set uses eight bits for each character code, one of these bits being a check bit to verify the seven bits needed to represent one character.
A method of processing data in which transactions are collected and prepared for input to the computer for processing as a single unit, for example, payroll.
A search in which, at each step of the search, the set of data elements is divided by two, until the searched element is found.
The smallest unit of data that can be transferred between memory and backing store in one operation.
A sort in which the first two items to be sorted are examined and exchanged if necessary to place them in the specified order; the second item is then compared with the third (exchanging them if required), the third is compared with the fourth, and the process is repeated until all pairs have been examined and all items are in the proper sequence.
A portion of storage used to hold input or output data temporarily.
The pathway used for sending signals between internal components of a computer. Components can share the same pathway but cannot transmit simultaneously.
A network in which all devices are connected to a common cable.
Part of the main store that is between main memory and the processor. It holds a copy of data and instructions that are likely to be used next by the processor and is hence faster than main memory.
A digit added to numerical data that can be recalculated and hence used to check data integrity after input, transmission and so on.
A sum generated using individual digits of a number and employed as an error-detecing device.
Combination of data and operations that can be performed on that data; specification of the data members and methods of the object.
Desktop computer or terminal used to access a computer-based system.
A network architecture in which a system is divided between server tasks performed on the instructions received from clients requesting information.
A class designed to hold objects (referred to in the syllabus as data structure).
A program that translates a source program into machine code that can be converted into an executable program (an object program).
computer-assisted software engineering
The automation of well-defined methodologies that are used in the development and maintenance of products. These methodologies apply to nearly every process or activity of a product development cycle, for example: project planning, product designing, coding and testing.
The logical structure and functional characteristics of a computer, including the interrelationships among its hardware and software components.
A sequence of instructions suitable for processing by a computer.
A method with the same name as the class that initializes the instance variable of an object of the class when the object is instantiated.
database management system (DBMS)
A computer-based system for defining, creating, manipulating, controlling, managing and using databases.
A pathway between the memory or peripheral and processing unit that carries data for processing or data that has been processed.
A method of reducing the size of data. All redundancy in the data is removed to reduce the storage needed or to speed up transfer. The data can be uncompressed back to its original state.
The correctness of data after processing, storage or transmission.
A data type that is a member of a class.
Part of a transmitted message that is sent separately. Apart from containing a portion of the message it will have other data such as check digits, destination address, and so on.
Method of ensuring that personal data is correct and is not misused either by those holding it or others who have no right to access it.
Method of ensuring that data is correct, safe and cannot be read or changed by those who have no right to access it.
A program used to detect, trace and eliminate errors in computer programs or other software.
An application that reads file segments from non-contiguous sections of a storage device and then writes the files to the same device in such a way that each file segment is contiguous (sharing a common border; touching; next or together in sequence).
A digital code attached to an electronic message or document, which is unique and which can be used to authenticate the sender or owner. Most often used in electronic commerce.
direct access file
A file organized in such a way that a calculation provides the address (location) of a record so that the record can be accessed directly. The records in the file may be ordered or unordered.
RAM set aside to speed up access to a hard drive. This may be part of the disk itself or may be incorporated in cache memory.
A network in which some or all of the processing, storage and control functions, in addition to input/output functions, are dispersed among its nodes.
In computer security, the process of transforming data into an unintelligible form in such a way that the original data cannot be easily obtained except by using a decryption process.
An object that is created when an abnormal situation arises in a program.
A program code that handles exceptions that arise during the running of a program. An exception is thrown to the handler rather than causing a fatal error.
A sequence of symbols that can be evaluated.
Cabling used for networking that uses fine strands of glass. The medium can carry a great deal of data and it gives a fast transfer rate.
field (object attribute)
A subdivision of a record containing a unit of information. For example, a payroll record might have the following fields: clock number, gross pay, deductions and net pay.
an organized collection of data
An application software that can access, create, modify, store and retrieve files.
An indicator with two possible states, "set" or "not set", that can be represented by one bit. It can be used to indicate that a record can be deleted, to indicate end of input/output and to sense whether an interrupt has occurred.
Data prepared for output in order to be displayed in a desired format (for example, trailing zero on $7.50 instead of $7.5).
graphics tablet (graphics pad)
An input device on which the user writes or designs. The image is reproduced on the screen.
Graphical User Interface
Obtaining unauthorized access to protected resources.
A system of numbers with the base 16; digits range from 0-9 and from A-F, where A represents 10 and F represents 15.
A programming language whose concepts and structures are convenient for human reasoning. Such languages are independent of the structures of computers and operating systems.
HTML (Hyper Text Markup Language)
A computer language used to construct web pages. Tags are used to denote the way in which text and graphics are to be displayed. The language is interpreted by a browser to display the pages.
In networking, a switch that sends data to the stations to which it is attached.
IDE (integrated development environment)
A programming tool that gives programmers a single environment (that is, the hardware and software environment in which the program runs) for building programs rather than using individual editors and debuggers.
The name or label chosen by the programmer to represent a variable, method, class, data type or any other element defined within the program.
The hardware and associated software needed for communication between processors and peripheral devices to compensate for the difference in their operating characteristics.
A program that translates and executes each instruction of a programming language before it translates and executes the next instruction.
International Organization of Standardization
The process of repeatedly running a set of computer instructions until some condition is satisfied.
JPEG (joint photographic expert group)
A recognized standard of compression of graphics files that has some loss.
local area network (LAN)
A computer network where all the computers are directly linked by cables and/or microwave transmission. This is usually located on a user's premises within a limited geographical area.
A variable that is defined and is capable of being used only in one specified program block.
An error arising from an incorrect appreciation of the problem leading to an incorrect action being performed and hence a false result being produced.
magnetic ink character recognition (MICR)
The identification of characters through the use of magnetic ink.
A computer, usually in a computer center, with extensive capabilities and resources to which other computers many also be connected so that they can share facilities.
A permanent file holding information that can be accessed and that is periodically updated by processing with a transaction file.
memory address register (MAR)
Holds the address in memory of the instruction at present being executed.
A display of a list of optional facilities that can be chosen by the user in order to carry out different functions in a system.
1. The behavior or operation of an object.
2. The procedure used by an object as specified within the object class.
The number and types of arguments of a method.
An integrated circuit incorporating the main components of a central processor. These circuits are used for microcomputers and small devices controlled by computer.
A method of electronic communication that does not require cables.
An abbreviation for "modulator/demodulator": a piece of electronic equipment that converts digital signals form a computer into audio signals that are transmitted over telephone lines, and converts them back again.
A language in which a complete program can be broken down into separate components (modules), each of which is to some extent self-contained. For example, the scope of variables can be limited to a module and does not extend through the entire program.
One aspect of structured programming in which individual tasks are programmed as distinct sections or modules. One advantage is the ease with which individual sections can be modified without reference to other sections.
A self-contained subset of a program.
Arithmetic that uses the integer result and integer remained of division as two separate entities.
A mode of operation that provides for concurrent performance, or interleaved execution, of two or more tasks.
A system that allows two or more people to use the services of a processor within a given period of time.
The simultaneous execution of two or more computer programs or sequences of instructions by a computer (parallel processing).
Any set of interconnected computer systems that share resources and data.
Making use of the services of a network.
1. In the terminology of tree structures, each position in the tree is called a "node."
2. Any device on a computer network that can be addressed so that it can be contacted by other computers.
3. A "host" computer on a network.
A combination of data and the operations that can be performed in association with that data. Each data part of an object is referred to as a data member while the operations can be referred to as methods. The current state of an object is stored in its data members and that state should only be changed or accessed through the methods. Common categories of operations include: the construction of objects; operations that either set (mutator methods) or return (accessor methods) the data members; operations unique to the data type; and operations used internally by the object.
object-oriented programming (OOP)
An approach to programming in which units of data are viewed as active "objects" rather than the passive units envisioned by the procedural paradigm.
OCR Optical character recognition (reader)
Refers to the use of devices and software to "read" characters and translate them into ASCII characters for later processing. Applications include the scanning of printed documents to convert the text into digital ASCII text that can then be edited in word processors.
Optical mark and read forms.
When a user has access to a computer via a terminal.
on-line processing (interactive)
Data processing in which all operations are performed by equipment directly under the control of a central processor, for example, airline reservations.
operating system (OS)
Software that controls the execution of programs and that may provide services such as resource allocation, scheduling, input/output control, and data management.
In programming languages, an order relation defining the sequence of the application of operators within an expression.
The assignment of values to parameters to be used in a procedure.
A binary digit appended to a group of binary digits to make the sum of all the digits, including the binary digit, either odd or even as established beforehand.
The parameter-passing mechanism by which the address of a variable is passed to the subprogram called. If the subprogram modifies the formal parameter, the corresponding actual parameter is also changed. In Java, all objects, including arrays, are passed this way.
The parameter-passing mechanism by which a copy of the value of the actual parameter is passed to the called procedure. If the called procedure modifies the formal parameter, the corresponding actual parameter is not affected. In Java, all primitives are passed this way.
Any device that can communicate with a particular computer, for example: input/output units, auxiliary storage, printers.
An instrument, such as a mouse, trackball or joystick, used to move an icon (sometimes in the form of an arrow) on the screen.
The part of the memory where the data and programs that are in use at the time are stored.
primitive data type
Integer, real, character or Boolean data types.
private class members
Members of a class that are only accessible from methods inside the class.
An internationally agreed set of rules to ensure transfer of data between devices. A standard protocol is one that is recognized as the standard for a specific type of transfer. For example, TCP/IP.
The construction of a simple version of a system in the design stage, showing the user interface but without the full processing behind it. This allows the user to propose changes at the design stage.
An artificial language used to describe computer program algorithms without using the syntax of any particular language. During the development of an algorithm, it often contains sections in natural language that will be replaced later.
public class members
Members of a class that are accessible from anywhere and from any class.
The manipulation of data that is required or generated by some process while the process is in operation; usually the results are used to influence the process, and perhaps related processes, while it is occurring.
An aggregate that consists of data objects, possibly with different attributes, that usually have identifiers attached to them.
A document that usually sets out the customer requirements of a computer system. It is written as part of the systems analysis and can be used later to evaluate the system when implemented.
The techniques used in designing, building and using robots.
A term used to describe the ability of a program to resist crashing due to incorrect input or incorrect intermediate results.
A device that identifies the destination of messages and sends them via an appropriate route.
A program that searches a large database to find matching items. The most common use of a this is to find Internet addresses based on given key words.
A type of memory that allows a user to store data and programs for as long as desired, in, for example, a hard disk drive.
1. risk to hardware
2. risk to software
3. risk to information
A sort in which the items in a set are examined to find an item that fits specified criteria. This item is appended to the sorted set and removed from further consideration, and the process is repeated until all items are in the sorted set.
The relationships of characters or groups of characters to their meanings, independent of the manner of their interpretation and use.
A device that detects measurable elements of a physical process for transfer to a computer.
An access method in which records are read from, written to, or removed from a file based on the logical order of the records in the file.
A file in which records are ordered and are retrieved using sequential access.
A search in which records in a file or in another data structure are examined one by one in the order in which they were entered until a specified criteria is met or until there are no more records to examine.
1. A program that provides services requested by client programs.
2. A computer that provides services to another computer connected over a network.
A combination of specifiers, the method name and the parameter list, that uniquely identifies the method.
The use of a data processing system to represent selected behavioral characteristics of a physical or abstract system.
A mode of operation that allows only one program to be in use at any time.
A system that only allows one user at a time.
The systematic application of scientific and technological knowledge, methods and experience to the design, implementation, and testing of software to optimize its production and support.
speech recognition (voice recognition)
A process of comparing spoken words with those stored in the system.
A network in which each device is connected to a central hub.
static data structure
Data structures of which the size and nature are determined before a program is executed.
A description of how much memory is required during the running of the program.
A diagrammatic form of a prototype showing a planned sequence of screen displays, demonstrating the different paths available to the user.
A diagram that represents the working relationships between the parts of a system or program.
A program invoked by another program.
The rules that govern the structure of language statements; in particular, the rules for forming statements in a source language correctly.
An error in the rules that govern the structure of language statements.
Documentation of the result of the systems analysis stage giving the purpose of the system, the required inputs and outputs, a test plan and the results that are expected.
system life cycle
The course of development changes through which a system passes from its conception to the termination of its use; for example, the phases and activities associated with the analysis, acquisition, design, development, testing, integration, operation, maintenance, and modification of a system.
A person who carries out a systematic investigation of a real or planned system to determine the information requirements and processes of the system, and how these relate to each other and to another system.
The investigation and recording of existing systems and the design of new systems.
A flowchart used to describe a complete data processing system, with the flow of data through the clerical operations involved, down to the level of individual programs, but excluding details of such programs.
TCP/IP (transmission protocol/Internet protocol)
A set of communications protocols used to connect hosts on the Internet.
A method of solving a problem by breaking it down into smaller subproblems. These are then broken down in turn until ultimately a pseudocode representation is obtained that can be used as basis for program construction.
A record of the execution of a computer algorithm exhibiting the sequences in which the instructions were executed.
A temporary file holding data that is later used for processing, generally to update a master file.
A computer program that transforms all or part of a program expressed in one programming language into another programming language or into a machine language suitable for execution.
A network that combines the characteristics of bus and star topologies. Groups of star topologies are connected to a central cable.
A standardized 16-bit character set that represents the character sets of most major languages in the world.
Methods written by the user which are not inherent to the language.
Objects whose members and methods are defined by the user and not inherent in the language.
Hardware, software, or both, that allows a user to interact with and perform operations on a system, program, or device.
A program designed to perform an everyday task such as copying data from one storage device to another.
validation (data input)
The process of checking, with software, that that data input is of the right type and within reasonable limits.
verification (data input)
A method of ensuring that the data in the computer system is the same as the original source data. This may be done by double entry.
The use of secondary memory as if it were primary memory.
A program that infects other programs or files by embedding a copy of itself into the target files.
A utility program that seeks out and eliminates known viruses.
wide area network (WAN)
A network that provides communication services to a geographic area larger than that served by a local area network or a metropolitan area network, and that may use or provide public communication facilities.
A group of bits that can be addressed, transferred and manipulated as a single unit by the central processing unit.