IB Computer Science: SL Vocabulary

A-D converter

A device for converting analog signals into digital ones for subsequent computer processing; sometimes called a "digitizer".

address bus

Pathway from memory to processing unit that carries the address in memory to and from which data is transferred.

algorithm

An ordered set of well-defined instructions for the solution of a problem in a finite number of steps.

analog data

The representation and measurement of the performance or behavior of a system by continuously variable physical entities such as currents, voltages and so on.

applet (Java)

A program that runs in the context of a browser.

application (Java)

A program that runs when translated by a Java compiler.

archive

Data which is held off-line for future research or for legal reasons.

ALU (arithmetic and logic unit)

A part of the computer that performs arithmetic operations, logic operations and related operations.

array

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 referenced 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. ASCII supports most European alphabets. Unicode supports most known alphabets and is increasingly used in data transfer. See also the definition for "Unicode".

B

Byte (KB is to Kilobyte as ___ is to Byte)

Back-up (file)

A second copy of a file, to be used in the event of the original file being corrupted.

bar code

A pattern of vertical lines distinguished from each other by width. It can be read by an optical reader to provide data to a computer.

bar code reader

An optical reader that can read bar codes.

base

The basis of a notation or number system, defining a number representational system by positional representation. In a decimal system the base is 10, in a hexadecimal system the base is 16, and in a binary system the base is 2.

batch processing

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.

binary search

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. See also the definition for "sequential search".

bit (b)

Binary digit. The smallest unit of information for data storage and transmission. Each is considered to be either a "0" or a "1".

block

The smallest unit of data that can be transferred between memory and backing store in one operation.

BMP

An extension given to files in bitmap form.

bps

Bits per second (shortened form of that)

browser

Generally used to give interactive access to information on the World Wide Web, retrieving web pages and displaying in a multi-media format.

bubble sort

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. See also the definitions for "insertion sort", "selection sort" and "quicksort".

buffer

A portion of storage used to hold input or output data temporarily.

bus

The pathway used for sending signals between internal components of a computer. Components can share the same ____ but cannot transmit simultaneously.

bus topology

A network in which all devices are connected to a common cable, known as the "bus".

Byte (B)

A set of bits considered as a unit; it normally consists of 8 bits and corresponds to a single character of information.

cable

Wire or glass fiber used to connect computers over a network. Copper (coaxial and twisted pair) and glass fiber (fiber optic cable) are the most common.

cache

RAM memory that is set aside as a specialized buffer storage and is continually updated. 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.

character set

A finite set of different characters that is complete for a given purpose, for example, the 128 ASCII characters.

check digit

A digit added to numerical data that can be recalculated and hence used to check data integrity after input, transmission and so on.

check sum

A sum generated using individual digits of a number and employed as an error-detecting device.

class

Combination of data and operations that can be performed on that data; specification of the data members and methods of the object.

client

Desktop computer or terminal used to access a computer-based system

client-server

A network architecture in which a system is divided between server tasks performed on the instructions received from clients, requesting information.

collection

A class designed to hold objects (referred to in the syllabus as data structure).

compiler

A program that translates a source program/code into machine code that can be converted into an executable program (an object program). HLL to LLL 3 steps: lexical analysis-remove all spaces and comments and look for reserved words then made new version on code, syntax analysis, code generation. Needs to be loaded in memory to compile. See also the definition for "interpreter".

CASE (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.

computer architecture

The logical structure and functional characteristics of a computer, including the interrelationships among its hardware and software components. Input - Process - Output

computer program

A sequence of instructions suitable for processing by a computer.

constructor method

A method with the same name as the class that initializes the instance variables of an object of the class when the object is instantiated.

CRC cards

Class, responsibility, collaboration cards. A design tool for classes that lists a class's name, its responsibilities and the classes with which it collaborates on an index card.

DBMS (database management system)

A computer-based system for defining, creating, manipulating, controlling, managing and using databases.

data bus

The pathway between the memory or peripheral and processing unit that carries data for processing or data that has been processed.

data compression

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.

data integrity

The correctness of data after processing, storage or transmission.

data member

A data type that is a member of a class.

data packet

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.

data protection

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.

data security

Method of ensuring that data is correct, safe and cannot be read or changed by those who have no right to access it.

debugging tool

A program used to detect, trace and eliminate errors in computer programs or other software.

defragmentation 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. Improves performance by grouping related disk areas together to improve speed data is read.

digital data

Discrete data.

digital signature

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/ random access

Storing data on backing store 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.

distributed processing

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.

encryption

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.

exception

An object that is created when an abnormal situation arises in a program.

exception handler

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.

expression

A sequence of symbols that can be evaluated.

fiber optic

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.

file

An organized collection of data.

file manager

An application software that can access, create, modify, store and retrieve files.

flag

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.

formal parameter

the identifier used in a method to stand for the value that is passed into the method by a caller.
public something(whatIsThis){....

formatted output

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) GUI

An input device on which the user writes or designs. The image is reproduced on the screen. Graphical user interface.

hacking

Obtaining unauthorized access to protected resources.

hexadecimal

A system of numbers with the base 16; ______ digits range from 0 to 9 and from A to F, where A represents 10 and F represents 15.

high-level language

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.

hub

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.

identifier

The name or label chosen by the programmer to represent a variable, method, class, data type or any other element defined within the program.

interface

The hardware and associated software needed for communication between processors and peripheral devices to compensate for the difference in their operating characteristics.

interpreter

A program that translates and executes each instruction of a programming language before it translates and executes the next instruction. Differs form compiler in that analyze and execute each line of code w/out looking at entire prog. More memory b/c needs to be loaded each time. See also the definition for "compiler".

ISO

International Organization for Standardization.

JPEG (joint photographic expert group)

A recognized standard of compression of graphics files that has some loss.

latency

the period of time that one component in a system is spinning its wheels waiting for another component. Latency, therefore, is wasted time. For example, in accessing data on a disk, latency is defined as the time it takes to position the proper sector under the read/write head.

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. See also the definition for "wide area network (WAN)".

logic error

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. See also the definition of "OCR".

mainframe

A computer, usually in a computer centre, with extensive capabilities and resources to which other computers may be connected so that they can share facilities.

master file

A permanent file holding information that can be accessed and that is periodically updated by processing with a transaction file. See also the definition for "transaction file".

memory address register (MAR)

Holds the address in memory of the instruction at present being executed.

memory mapped I/O

uses the same address bus to address both memory and I/O devices - the memory and registers of the I/O devices are mapped to (associated with) address values. So when an address is accessed by the CPU, it may refer to a portion of physical RAM, but it can also refer to memory of the I/O device.

menu

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.

method

1. The behavior or operation of an object. 2. The procedure used by an object as specified within the object class. See also the definition for "method signature".

method signature

The number and types of arguments of a method.

microprocessor

An integrated circuit incorporating the main components of a central processor. Doesn't have the same amnt of memeory as CPU. Has single prog stored in non-volatile memory and some registers for volatile storage; can't change its program.These circuits are used for microcomputers and small devices controlled by computer.

microwave transmission

A method of electronic communication that does not require cables.

modem

An abbreviation for "modulator/demodulator": a piece of electronic equipment that converts digital signals from a computer into audio signals that are transmitted over telephone lines, and converts them back again.

modular language

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. See also the definition for "top-down design".

modularity

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.

module

A self-contained subset of a program.

modulo arithmetic

Arithmetic that uses the integer result and integer remainder of division as two separate entities.

multi-tasking

A mode of operation that provides for concurrent performance, or interleaved execution, of two or more tasks.

multi-user system

A system that allows two or more people to use the services of a processor within a given period of time.

multi-processing

The simultaneous execution of two or more computer programs or sequences of instructions by a computer (parallel processing).