Key terms Flashcards
(191 cards)
1
Q
Iteration
A
A block of code is executed repeatedly, either until a condition is met or for a set number of times.
2
Q
Statement
A
Any individual step or instruction in the code.
3
Q
Assignment
A
Setting the value of a variable, eg score = 10. Do not confuse this with the equality operator!
4
Q
Logic error
A
The program runs but does something different from what the programmer intended.
5
Q
String
A
Text data in the form of a sequence of characters, for example words and punctuation. String data is made up of character data and will usually vary in length.
6
Q
Sequence
A
Each statement in a program is executed in order.
7
Q
Subroutine
A
A sub-program, a set of statements written to perform a given task as part of solving the main problem. It can be called using its identifier.
8
Q
Function
A
A subroutine that returns a value and can therefore be used as if it were a variable.
9
Q
Parameter/argument
A
Data item being supplied to a function or procedure when it is called.
10
Q
Pseudocode
A
A method of writing an algorithm using normal language that mimics programming code but without worrying about specific syntax. Useful for planning programs or explaining them to other people.
11
Q
Embedded system
A
A computer system that forms part of an electronic device.
12
Q
Kernel
A
The lowest level of an operating system that controls the hardware.
13
Q
HTML
A
Hypertext Markup Language - a text based system for defining web pages.
14
Q
A
Portable Document Format - a file standard that displays a document accurately on any computer platform.
15
Q
ISO
A
International Organisation for Standardisation - the world’s largest standards developing organisation. Produces international standards for engineering, agriculture and medicine as well as IT.
16
Q
TCP/IP
A
Transmission Control Protocol/Internet Protocol - a set of standards that control how data is sent across networks including the internet.
17
Q
Computer architecture
A
The internal, logical structure and organisation of the computer hardware.
18
Q
Binary
A
A system of numbers using only two digits, 0 and 1 (base 2), unlike the everyday denary (or decimal) system that uses the 10 digits 0-9 (base 10).
19
Q
CPU
A
Central Processing Unit, containing the control unit, ALU and cache memory.
20
Q
Control unit
A
The part of the CPU that controls the flow of data within the system.
21
Q
ALU
A
Arithmetic and Logic Unit, performs all of the arithmetical and logical operations within the CPU.
22
Q
Random Access Memory
A
Main memory of a computer that stores data, applications and the operating system while in use. When the power is turned off RAM loses its data.
23
Q
Cache memory
A
Special high speed memory used by a computer.
24
Q
Flash memory
A
Solid-state memory used as low cost secondary storage in portable devices and as removable memory.
25
Solid state
Technology based on electronics with no moving parts, for example transistors and capacitors as used in memory chips.
26
Secondary storage
Non-volatile storage used to store programs and files that need to be kept even when the power is not on.
27
Fetch-execute cycle
The process of fetching instructions from memory, decoding them and then executing them so that the CPU performs continuously.
28
Read Only Memory
A store for data in the computer that cannot be overwritten. Data in ROM is always available and is not lost when the computer is turned off.
29
Clock chip
The electronic device in a computer that controls the timing of signals.
30
Bus
A part of the computer architecture that transfers data and signals between the components of the computer.
31
Motherboard
The central printed circuit board (PCB) that holds the crucial components of the system.
32
Dual core/quad core, etc
A CPU with multiple processors (a dual core has two, a quad core has four).
33
Bit
A single binary digit, 0 or 1.
34
Byte
8 bits.
35
Kilobyte
1024 bytes (1000 bytes is acceptable).
36
Volatile
Data lost when there is no power.
37
Non-volatile
Data retained even when power is turned off.
38
Virtual memory
A section of the hard disc used as if it were RAM to supplement the amount of main memory available to the computer. Used when there is not enough memory to run the programs required.
39
Logic gate
A circuit that produces a binary output based on the inputs, eg NOT, AND, OR.
40
NOT gate
A logic gate that outputs the opposite value to the input.
41
AND gate
A logic gate that outputs 1 if both of the two inputs are 1.
42
OR gate
A logic gate that outputs 1 if either or both of the two inputs are 1.
43
Truth table
A method for recording all the possible input combinations and determining the output for each.
44
Logic circuit
A circuit made by combining a sequence of logic gates.
45
Boolean algebra
A method for mathematically expressing a logic circuit.
46
Input device
A hardware device used to input data into a computer system for processing.
47
Keyboard
A device that uses labelled keys to enable data input into a computer.
48
Mouse
A device that controls the movement of a pointer on screen, based on its own movement, and allows the user to select an object by pressing a button.
49
Touch screen
A touch sensitive surface that allows the user to select, control or move objects by touching icons and symbols using fingers.
50
Microphone
A device for capturing sound.
51
Camera
A device to capture still or moving images.
52
Bar code
A pattern of thin and thick lines representing a number that can be scanned by a reader for input into a computer system.
53
RFID
Radio Frequency Identification - uses radio frequencies to represent a number that can be scanned for input into a computer system.
54
Sensor
A device that can detect physical conditions such as temperature, weight, light, sound etc.
55
Accumulator
A register in the CPU that stores data currently being used by the CPU.
56
ACID
Atomicity, Consistency, Isolation, Durability - a set of rules that protects a database from errors during a transaction.
57
Actuator
A device to produce physical movement based on output from a computer system.
58
Address
A location in main memory used to store data or instructions.
59
Algorithm
A series of steps designed to solve a mathematical or other problem.
60
Analogue
Refers to continuously changing values.
61
Applet
A small application that performs one specific task.
62
Application
Software designed to carry out a useful real-world task.
63
ASCII
American Standard Code for Information Interchange - 7 bit system to code the character set of a computer.
64
Assembler
Software that translates assembly language code into machine code.
65
Assembly language
A low-level programming language that uses more memorable mnemonic codes and labels to represent machine-level code. Each instruction corresponds to just one machine operation.
66
Attribute
A characteristic or property of an entity. It becomes a field in a data table.
67
Auto documentation
System that tracks variables, modules and comments for maintenance purposes.
68
Bit rate
The space available for each sample in digital sound, measured in kilobits per second (kbits/s).
69
Boolean
A value that can only be true or false.
70
CD
A type of optical storage with a capacity of 700MB
71
Character
A single alphabetic, numeric or punctuation character.
72
Character set
The characters available to a computer.
73
CHR
Function that uses the ASCII value to look up the character associated with a particular number.
74
Client
Software or hardware that requests services from a server.
75
Code editor
Text are used to enter code in an IDE.
76
Colour depth
The number of bits used for each pixel or dot. The more bits, the more colours that can be represented. Also known as bit depth.
77
Command line
The place where typed commands are given to the operating system.
78
Comparison
Comparing the values of two items and returning True or False depending upon the result of that comparison.
79
Compiler
A translator that converts all of the source code to machine code in one go to produce the object code.
80
Compression
Reduction in file size to reduce download times and storage requirements.
81
Concatenation
Combining two strings into a single string.
82
Constant
A label referring to a location in memory containing a value that can be accessed but not changed by a program.
83
Custom written
Software developed specially for one or a very few customers.
84
Data dictionary
The stored schema of a database.
85
Data integrity
The state of data being as it should be, reflecting reality.
86
Data redundancy
The unnecessary repetition of data.
87
Debugger
Software that helps a programmer track down faults in a program.
88
Decision box
A flowchart symbol used to show a decision stage. May be "yes", "no" or multiple values.
89
Declaration
Identifying a variable, constant or array to a program so that memory space can be allocated.
90
Decode
An instruction is decoded by the CPU into two parts - the operator and the operand.
91
Dedicated
Something which is designed for one particular purpose.
92
Defragmenter
A utility that brings together file fragments on a disc and collects all the free space in one area.
93
Denary
A system of numbers using ten digits, 0-9. Also called the base 10 system.
94
Device driver
A program that enables communication between a computer and a peripheral.
95
Disc organisation
The process of arranging files and data bytes on a secondary storage device.
96
Domain name
A human readable name for a resource on a network. It is changed to a numerical IP address by a DNS server.
97
DVD
Digital Versatile Disc, a type of optical device with a capacity of 4.7GB.
98
Editor
Software used for entering source code when writing a program.
99
Entity
Something that we store data about in a database.
100
Entity relationship diagram
A diagram that shows how different entities used in a database are connected.
101
Erroneous
Data that would not normally be expected, such as the wrong data type.
102
Error diagnostics
System to warn of errors in the code and potential problems.
103
Extreme
Test data at the limits of valid or invalid to check boundary conditions.
104
Failover
Automatic switching to a backup computer system in the event of system failure.
105
Field
A characteristic or property of something stored in a database.
106
File
Stored data on suitable media.
107
Firewall
Software and/or hardware that limits access to and from a computer system.
108
Firmware
Software that is stored permanently in a device, such as control programs for devices.
109
Flat file database
Database consisting of only one table.
110
Flow chart / flow diagram
A diagrammatic method of showing the structure and data flow to define a problem and its solution.
111
Gigabyte
1024 megabytes (1000 megabytes is acceptable).
112
Graphical User Interface
A user interface that makes use of icons for interacting with the user.
113
Hexadecimal
The base-16 number system.
114
High-level language
A programming language that resembles a natural language. Each instruction translates to many machine instructions. It is problem based rather than machine based.
115
Hub
A device for connecting multiple network devices in one segment.
116
Hyperlink
An item on a web page that directs the user to another location when clicked.
117
Icon
A picture on screen that represents a file, program or action.
118
Indexed sequential file
A sequential file that is accessed using an index, which is a separate file.
119
Input device
A hardware device used to input data into a computer system for processing.
120
Instructions
A set of commands that a processor can recognise and act upon.
121
Integer
Whole number, positive or negative, with no decimal or fractional part.
122
Integrated development environment (IDE)
Resources supplied with high-level languages to help the programmer.
123
Interface
The boundary between systems or between systems and humans.
124
Interpreter
Translation software that converts source code or user input into machine code which is immediately executed one instruction at a time.
125
Interrupt
A signal to the operating system to stop what it is doing and perform a different task instead.
126
Intranet
A private data resource using the same technology as the internet, such as browsers and protocols.
127
Invalid
Data used to test a program that should be rejected because it is out of range.
128
IP address
A number that identifies a device on a TCP/IP network.
129
LAN
Local Area Network - confined to one location.
130
Linker
Software that combines together a number of separate object code files.
131
Logic error
When the logical structure of a program produces unexpected results.
132
Low-level language
A programming language that is directed at controlling each machine operation.
133
Machine code
Instructions in binary used by the CPU.
134
Hard disc
Secondary storage device using magnetised platters to store data and files.
135
Metadata
Information about image data that allows the computer to recreate the image from the binary data in the file. This must contain the height and width in pixels and the colour depth in bits per pixel.
136
Monitor
An output device that can display images and text.
137
Nesting
Structures inside other structures.
138
Nibble
4 bits (half a byte).
139
Object code
The machine code produced by a compiler.
140
Off the shelf
Software that is aimed at many users and sold "as is".
141
One to many
A relationship where one record in a table may have links to many records in another table.
142
Operand
The part of the instruction that tells the CPU what to apply the operation to.
143
Operating system
The software that controls the hardware. Acts as an interface between the user and the hardware and also between the applications and the hardware.
144
Operator (programming)
A logical, arithmetical or comparison operator used by the program.
145
Operator (assembly language)
The part of the instruction that tells the CPU what to do.
146
Optical disc
Secondary storage device using lasers to read (and in some cases write) data to a reflective surface.
147
Overflow
When a number becomes too large to fit into the number of bits allocated it is said to "overflow". Some bits are "lost", leaving an incorrect value.
148
Peer to peer
A network arrangement where all computers are equal.
149
Pixel
The smallest element of an image. The dots that make up the image on screen.
150
Platform
A combination of hardware and operating system that supports the running of particular operations.
151
Printer
A device to produce physical copies of output from a computer system.
152
Process box
A flow chart symbol that defines any processing to be completed at that stage.
153
Process (in a program)
A program currently being executed.
154
Program
A stored set of instructions for a computer to execute.
155
Program counter
A register in the CPU that keeps the address of the next instruction.
156
Programming language
A way of writing instructions for a computer to execute.
157
Protocol
A set of rules or standards that control communications between devices.
158
Raster
Graphics format consisting of a matrix of dots. Also known as a bitmap.
159
Real
A number that can have fractional or decimal parts.
160
Record
All the data about one item in a database.
161
Register
Special fast access part of the CPU that stores data in use by the CPU.
162
Resolution
The number of pixels or dots per unit in a bitmap image, for example ppi (pixels per inch) or dpi (dots per inch).
163
Run time environment
Software to support the execution of programs.
164
Sample rate
The number of times a sound is sampled per second, measured in Hertz (Hz).
165
Schema
Definition of a database.
166
Selection
The pathway through a program is selected by using a condition to decide on what instructions to execute next.
167
Self-booting
The ability of a program to load itself. Some small devices load their applications directly without the need for a conventional operating system.
168
Sequential file
A serial file in order.
169
Serial file
A file of items one after another.
170
Server
Software that provides services to a client, or the hardware that is running it.
171
Shell
Software that provides a traditional text based interface to an operating system.
172
Software engineering
Formal methods to guide the writing of software.
173
Source code
The program written by the end user in a high-level language before it is converted to machine code.
174
Speaker
A device to output sound.
175
Spyware
Malicious software that detects what a user is doing and sends the details back to the originator.
176
Switch
A device for connecting multiple network devices. Inspects packets and only sends them to the correct destinations.
177
Syntax error
The rules of the language are broken by the program.
178
Terabyte
1024 gigabytes (1000 gigabytes is acceptable)
179
Trace
A method of using data to check that an algorithm covers all possibilities correctly.
180
Translator
A program to convert high-level or assembly-level commands into machine code.
181
Trojan
Harmful software that is disguised as something useful.
182
Unicode
A 16 or 32 bit system to code the character set of a computer.
183
User interface
The boundary between the computer and the user.
184
Utility
A small program designed to carry out a limited maintenance task.
185
Valid
Test data that represents normal, expected data.
186
Validation
The process of checking that data is correct or appropriate.
187
Variable
A label referring to a location in memory containing a value that can be accessed or changed by a program.
188
Verification
The process of checking that data is true or accurate.
189
Virus detection
The process of discovering possibly harmful viruses in a computer system.
190
WAN
Wide Area Network - covers a large geographical area.
191
Web server
A server than handles requests to a website.
