Glossary Flashcards
1
Q
Abstract data type
A
a conceptual model of how data can be stored and the operations that can be carried out on the data
2
Q
Abstraction by generalisation/categorisation
A
the concept of reducing problems by putting similar aspects of a problem into hierarchical categories
3
Q
Accepting state
A
the state that identies whether an input string has been accepted. Also known as the goal state
4
Q
Address bus
A
used to specify a physical address in memory so that the data bus can access it
5
Q
Addressable memory
A
the concept that data and instructions are stored in memory using discrete addresses
6
Q
Addressing mode
A
the way in which the operand is interpreted
7
Q
Adjacency list
A
a data structure that stores a list of nodes with their adjacent nodes
8
Q
Adjacency matrix
A
a data structure set up as a two-dimensional array or grid that shows whether there is an edge between each pair of nodes
9
Q
Algorithm
A
a sequence of steps that can be followed to complete a task and that always terminates
10
Q
Alphabet
A
the acceptable symbols (characters, numbers) for a given Turing machine
11
Q
Analysis
A
the first stage of system development where the problem is identified, researched and alternative solutions proposed
12
Q
AND
A
Boolean operation that outputs true if both inputs are true
13
Q
AND gate
A
result is true if both inputs are true
14
Q
Application program interface (API)
A
a set of subroutines that enable one program to interface with another program
15
Q
Application software
A
programs that perform specic tasks that would need doing even if computers didn’t exist, e.g. editing text, carrying out calculations
16
Q
Arc
A
a join or relationship between two nodes – also known as an edge
17
Q
Argument
A
a value that is passed into a function or subroutine
18
Q
Arithmetic Logic Unit (ALU)
A
part of the processor that processes and manipulates data
19
Q
Arithmetic operation
A
instructions that perform basic maths such as +, –, /, ×
20
Q
Array
A
a set of related data items stored under a single identifier and are accessed based on their position. Can work on one or more dimensions
21
Q
ASCII
A
a standard binary coding system for characters and numbers
22
Q
Assembler
A
a program that translates a program written in assembly language into machine code
23
Q
Assembly language
A
a way of programming using mnemonics
24
Q
Assignment
A
the process of giving a value to a variable or constant
25
Association aggregation
creating an object that contains other objects, which can continue to exist even if the containing object is destroyed
26
Associative array
a two-dimensional structure containing key/value pairs of data
27
Asymmetric encryption
where a public and private key are used to encrypt and decrypt data
28
Asynchronous data transmission
data is transmitted between two devices that do not share a common clock signal
29
Attribute
a characteristic or piece of information about an entity, which would be stored as a eld in a relational database
30
Automation
creating a computer model of a real-life situation and putting it into action
31
Backus-Naur Form (BNF)
a form of notation for describing the syntax used by a programming language
32
Bandwidth
a measure of the capacity of the channel down which the data is being sent. Measured in hertz (Hz)
33
Barcode reader
a device that uses lasers or LEDs to read the black and white lines of a barcode
34
Baudot code
a five-digit character code that predates ASCII and Unicode
35
Big data
a generic term for large or complex datasets that are difficult to store and analyse
36
Binary file
stores data as sequences of 0s and 1s
37
Binary search
a technique for searching data that works by splitting datasets in half repeatedly until the search data is found
38
Binary tree search
a technique for searching a binary tree that traversed the tree until the search term is found
39
Binary tree
a structure where each node can only have up to two child nodes attached to it
40
Bit
a single binary digit from a binary number – either a zero or a one
41
Bit rate
the rate at which data is actually being transmitted. Measured in bits per second
42
Bit-mapped graphic
an image made up of individual pixels
43
Black box testing
using test data to test for an expected outcome
44
Block
in data storage it is the concept of storing data into set groups of bits and bytes of a xed length
45
Block interface
code that describes the data being passed from one subroutine to another
46
BODMAS
a methodology for evaluating mathematical expressions in a particular sequence
47
Boolean expression
an equation made up of Boolean operations
48
Boolean operation
a single Boolean function that results in a TRUE or FALSE value
49
Boundary test data
test data on or close to the boundary of the acceptable range
50
Branch operations
operations within an instruction set that allow you to move from one part of the program to another
51
Breadth first
a method for traversing a graph that explores nodes closest to the starting node rst before progressively exploring nodes that are further away
52
Bubble sort
a technique for putting data in order by repeatedly stepping through an array, comparing adjacent elements and swapping them if necessary until the array is in order
53
Bus
microscopic parallel wires that transmit data between internal components
54
Bus topology
a network layout that uses one main data cable as a backbone to transmit data
55
Bus width
the number of bits that can be sent down a bus in one go
56
Byte
a group of bits, typically 8, used to represent a single character
57
Bytecode
an instruction set used for programming that can be executed on any computer using a virtual machine
58
Cache
a high-speed temporary area of memory
59
Caesar cipher
a substitution cipher where one character of plaintext is substituted for another, which becomes the ciphertext
60
Call stack
a special type of stack used to store information about active subroutines and functions within a program
61
Cardinal number
a number that identies the size of something
62
Cardinality
the number of elements in a set
63
Carry bit
used to store a 0 or 1 depending on the result of binary addition
64
Cartesian product
combining the elements of two or more sets to create a set of ordered pairs
65
Certification Authority
a trusted organisation that provides digital certicates and signatures
66
Chaining
a technique for generating a unique index when there is a collision by adding the key/value to a list stored at the same index
67
Character code
a binary representation of a particular letter, number or special character
68
Charge coupled device (CCD)
in digital cameras it is a sensor that records the amount of light received and convert it into a digital value
69
Check digit
a digit added to the end of binary data to check the data is accurate
70
Checksum
a method of checking the integrity of data by calculating a sum based on the data being sent
71
Child
a node in a tree that has nodes above it in the hierarchy
72
Chip
an electronic component contained within a thin slice of silicon
73
Cipher
an algorithm that encrypts and decrypts data, also known as code
74
Ciphertext
data that has been encrypted
75
Circular queue
a FIFO data structure implemented as a ring where the front and rear pointers can wrap around from the end to the start of the array
76
Class
defines the properties and methods of a group of similar objects
77
Class diagram
a way of representing the relationship between classes
78
Client-server
a network methodology where one computer has the main processing power and storage and the other computers act as clients requesting services from the server
79
Client-server database
a way of implementing a database where the database is put into a server and various users can access it from their workstations. The processing, for example, running a query, will take place on the server
80
Client-server model
a way of implementing a connection between computers where one computer (the client) makes use of resources of another computer (the server)
81
Clock
a device that generates a signal used to synchronise the components of a computer
82
Clustering
when a hashing algorithm produces indices that are not randomly distributed
83
Code of conduct
a voluntary set of rules that dene the way in which individuals and organisations will behave
84
Codomain
all the values that may be output from a mathematical function
85
Collision
when a hashing algorithm produces the same index for two or more different keys
86
Colour depth
the number of bits or bytes allocated to represent the colour of a pixel in a bit-mapped graphic
87
Commitment ordering
a technique to ensure concurrent transactions on a shared database are executed based on the timestamp of when the request is made and also the precedence the request takes over other simultaneous request
88
Compiler
a program that translates a high-level language into machine code by translating all of the code
89
Complementary metal oxide semiconductor (CMOS)
is an alternative technology that performs the same functions as a CCD
90
Components
the values within a vector
91
Composition
building up a whole system from smaller units. The opposite of decomposition
92
Composition aggregation
creating an object that contains other objects, and will cease to exist if the containing object is destroyed
93
Compression
the process of reducing the size of a le
94
Computational hardness
the degree of difculty in cracking a cipher
95
Computational security
a concept of how secure data encryption is
96
Concurrence
the concept of two users trying to access the same data item at the same time
97
Constant
an item of data whose value does not change
98
Constant time
in Big O notation where the time taken to run an algorithm does not vary with the input size
99
Context-free language
an unambiguous way of describing the syntax of a language useful where the language is complex
100
Control bus
controls the ow of data between the processor and other parts of the computer
101
Control unit
part of the processor that manages the execution of instructions
102
Controller
in SSDs a controller is needed to organise data into blocks for storage purposes
103
Convex combinations
a method of multiplying vectors that produces a resulting vector within the convex hull
104
Convex hull
a spatial representation of the vector space between two vectors
105
Copyright
the legal ownership that applies to software, music, lms and other content
106
Countable set
a finite set where the elements can be counted using natural numbers
107
Countably infinite sets
sets where the elements can be put into a one-to-one correspondence with the set of natural numbers
108
CRUD
an acronym that explains the main functions of a database: Create, Read, Update, Delete
109
Cultural issues
factors that have an impact on the ways in which we function as a society
110
Current Instruction Register (CIR)
register that stores the instructions that the CPU is currently decoding/executing
111
Data abstraction
hiding how data is represented so that it is easier to build a new kind of data object, e.g. building a stack from an array
112
Data Bus
transfers data between the processor and memory
113
Data Dictionary
a list of all the data being used in the system including name, length, data type and validation
114
Data flow diagram (DFD)
a visual method of showing how data passes around a system
115
Data misuse
using data for purposes other than for which it was collected
116
Data Structure
a common format for storing large volumes of related data, which is an implementation of an abstract data type
117
Data transfer operation
operations within an instruction set that move data around between the registers and memory
118
Data type
determines what sort of data is being stored, e.g. integer, real, and how it will be handled by the program
119
Database management system
software that enables the management of all aspects of a database including adding, updating and querying the data
120
De Morgan's Law
a process for simplifying Boolean expressions
121
Debug
the process of finding and correcting errors in programs
122
Declaration
the process of defining variables and constants in terms if their name and data type
123
Declarative Language
languages that declare or specify what properties a result should have, e.g. results will be based on functions
124
Decomposition
breaking down a large task into a series of subtasks
125
Decryption
the process of deciphering encrypted data or messages
126
Definite iteration
a process that repeats a set number of times
127
Depth first
a method for traversing a graph that starts at a chosen node and explores as far as possible along each branch away from the starting node before backtracking
128
Design
the second stage of system development where the algorithms, data and interface are designed
129
Dictionary (data structure)
a data structure that maps keys to data
130
Dictionary-based encoding
a method of compressing text files
131
Difference
describes which elements differ when two sets are joined together
132
Digital camera
a device for creating digital images of photographs, which can be printed or transferred onto a computer to be manipulated and stored
133
Digital certificate
a method of ensuring that an encrypted message is from a trusted source as they have a certificate from a Certification Authority
134
Digital signature
a method of ensuring that an encrypted message is from a trusted source as they have a unique encrypted signature verified by a Certificate Authority
135
Direct address
the operand is the datum
136
Directed graph
a graph where the relationship between nodes is one-way
137
Direction
one of the two components of a vector
138
Distributed processing/computing
the principle of spreading large and complex tasks over a number of computers or servers
139
Distributed Program
a program specifically written to be used in a distributed processing environment
140
Domain
all the values that may be input to a mathematical function
141
Domain name
the recognisable name of a domain on the Internet
142
Domain name server (DNS)
a server that contains domain names and associated IP addresses
143
Domain name server (DNS) system
a system of connected domain name servers that provides the IP address of every website on the Internet
144
Dot product
multiplying two vectors together to produce another vector
145
Dry run
the process of stepping through each line of code to see what will happen before the program is run
146
Dynamic data structure
a method of storing data where the amount of data stored (and memory used to store it) will vary as the program is being run
147
Dynamic Host Configuration Protocol (DHCP)
a set of rules for allocating locally unique IP addresses to devices as they connect to a network
148
Edge (programming)
a connection between two nodes in a graph or tree structure - also known as an arc
149
Edge
in a database graph schema, it refers to the link and relationship between two nodes
150
Element
a single value within a set or list - also called a member
151
Email server
a dedicated computer on a network for handling email
152
Empty list
a list with no elements in it
153
Empty set
the set that contains no values
154
Encapsulation
the concept of putting properties, methods and data in one object
155
Encryption
the process of turning plaintext into scrambled ciphertext, which can only be understood if it is decrypted
156
Entity
an object about which data will be stored
157
Entity identifier
an attribute which can uniquely identify each instance of an entity
158
Entity relationship diagram
a visual method of describing relationships between entities
159
Erroneous test data
test data that is clearly incorrect and should produce an error
160
Ethical issues
factors that define the set of moral values by which society functions
161
Evaluation
the final stage of system development where the system is judged according to certain criteria
162
Event
something that happens when a program is being run
163
Exception handling
the process of dealing with events that cause the current subroutine to stop
164
Exponent
the 'power of' part of a number indicating how far a binary point should be shifted left or right
165
Exponent time
in Big O notation where the time taken to run an algorithm increases as an exponential function of the number of inputs. For example, for each additional input the time taken might double
166
Factorial
the product of all positive integers less than or equal to n
167
Feasibility study
an analysis of whether it is possible or desirable to create a system
168
Fetch-execute cycle
the continuous process carried out by the processor when running programs
169
Field
an item of data
170
FIFO
first in first out refers to a data structure such as a queue where the first item of data entered is the first item of data to leave
171
File
a collection of related data
172
File management
how an operating system stores and retrieves files
173
Filter function
a method of creating a subset based on specified criteria
174
Finite
countable
175
Finite set
a set where the elements can be counted using natural numbers up to a particular number
176
Finite state machine (FSM)
any device that stores its current status and whose status can change as the result of an input. Mainly used as a conceptual model for designing and describing systems
177
Firewall
hardware or software for protecting against unauthorised access to a network
178
First-class object
any object that can be used as an argument or result of a function call
179
Fixed point
wheer the decimal/binary point can move within a number
