Definitions Flashcards
1
Q
Arithmetic Logic Unit (ALU)
A
Performs operations on data e.g. Addition and subtraction
2
Q
Control Unit (CU)
A
Coordinating activities of the CPU
3
Q
Registers
A
Quick and small stores of data within the CPU
4
Q
Memory Address Register (MAR)
A
Holds memory address for data or a instruction about to be used by the CPU
5
Q
Memory Data Register (MDR)
A
Holds actual data or instruction
6
Q
Accumulator
A
Stores results of calculations in the ALU
7
Q
Program Counter (PC)
A
Holds memory address of the instruction for each cycle
8
Q
Fetch
A
The next instruction is retrieved by CPU from main memory
9
Q
Decode
A
The instruction is broken down and decided so computer can understand
10
Q
Execute
A
The CPU performs what the instructions told
11
Q
Embedded System
A
A computer system built within a large device e.g. Camera/washer/car
12
Q
Volatile
A
Memory loses its data when power of
13
Q
Non-volatile
A
Memory retains its data when power is lost
14
Q
Random Access Memory (RAM)
A
Read/write - function is to load open programs and operating system data currently in use - volatile
15
Q
Read Only Memory (ROM)
A
Can only be read and can’t be changed - stores essential programs to be run in order to boot the computer - non-volatile
16
Q
Cache
A
A type memory that stores copies of frequently used data - much faster than RAM - lower capacity - closer to CPU
17
Q
Buses
A
Collection of wires that carry signals between various components of the computer system
18
Q
Central Processing Unit (CPU)
A
Processes all of the data and instructions that make the system work - can be effected by clock speed/number of cores/cache size
19
Q
Clock speed
A
How fast the computer does the FDE cycle
20
Q
virtual memory
A
A memory management procedure needed when the RAM is full so a temporary section is made which acts like a part of RAM
21
Q
Flash memory
A
Solid state storage - non-volatile - more reliable/durable but can only be overwritten a limited number of times
22
Q
Graphics Processing Unit (GPU)
A
Handles graphics and image processing
23
Q
Optical storage
A
CD - DVD - Blue-ray ADV: cheap - easy to transport DIS: slow - less storage than hard drives - stored data degrades over time - cannot be written over
24
Q
Magnetic storage
A
Hard drives ADV: fast access - stores large amounts of data - low cost DIS: not very portable - easily be broken
25
Solid State storage
USB - flash memory - SD ADV: fast - small - light - easily portable - quiet DIS: more expensive - storage capacity less - limited number erase/write cycles
26
Cloud stotage
Data is stored on multiple servers in a remote location ADV: secure - can be accessed anywhere - no need to buy DIS: needs internet - download and upload can be effected by internet connection - less control if data is held
27
Operating System
essential software that links the hardware and other software together and generally manages the computer system
28
Command-line Interface
Text commands where user has to type in command
29
Graphical User Interface (GUI)
uses icons and other visual indicators to navigate and issue commands
30
Utility Software
maintains a computer
31
Defragmentation Software
reorganises data on the hard drive to put fragmented files back together and moves files to collect all the free space
32
Backup Software
Full Backup - a copy is taken from from every file on the system
33
Incremental Backup
only files created or edited since last backup are copied
34
Compression Software
reduces file size so they take up less space on hard disk
35
Encryption Software
scrambles data to stop others from accessing it
36
Open Source Software
source code is made freely available and users can modify it ADV: free - made for greater good - can be adapted DIS: small - buggy - security holes - no warranties - no customer support
37
Proprietary Software
only the compiled code is released and the source code is kept a secret ADV: warranties - well-tested - reliable - cheaper DIS: expensive - software may not fit user needs
38
Personal Area Network (PAN)
within the range of an individual person
39
Local Area Network (LAN)
a network that connects devices close to each other e.g. school and house
40
Wide Area Network (WAN)
a network within a large geographical area e.g. internet
41
Bandwidth
amount of data that can be transferred in a given time
42
Network Interface Card (NIC)
allow a device to connect to a network
43
Switch
connect devices on a LAN
44
Router
responsible for transmitting data between networks
45
Protocol
a set of standards/rules for connecting computers
46
Client-server Network
client has connection to server - servers can backup and store centrally but can be expensive and difficult to maintain
47
Peer-to-peer Network
no central server - each computer equal in responsibility - have to work as both server and a client.
48
Star Topology
ADV: better performance - rest of network not affected in one fails - simple to add more devices DIS: wire needed for all devices - expensive
49
Mesh Topology
ADV: faster DIS: expensive
50
MAC Address
assigned to all devices - unique to all devises and cannot be changed - permanent - identifies the actual device.
51
IP Adress
assigned either manually or automatic - the location of your device on the internet
52
Packet Switching
split data into packets to be sent across the network - each packet given a number order of data - each router reads packet header and decides which way to send it according to IP rules - packets then arrive and reassemble them in the right order.
53
TCP/IP
sets of rules for how devices connect on the network.
54
Hyper Text Transfer Protocol (HTTP)
used to access websites and communicate with web servers
55
HTTPS
more secure - encryption
56
File Transfer Protocol (FTP)
used to access - edit and move files between devices
57
Post Office Protocol (POP3)
used to retrieve emails from a server - holds until download - then deletes from server
58
Internet Message Access (IMAP)
used to retrieve emails - server holds until you actually delete it - only download a copy
59
Simple Mail Transfer Protocol (SMTP)
used to send emails - used to transfer emails between servers
60
Layer
ADV: manageable pieces - self-contained can change without effecting others
61
Application Layer
turning data into websites
62
Transport Layer
controlling data flow - splitting data into packets
63
Network Layer
making connections between networks
64
Data link Layer
passing data over physical network-
65
Domain Name Server (DNS)
translates websites' domain name into its IP address
66
Virtual Network
network that is entirely software based - created by partitioning of some physical network
67
Blagging
invented scenario to engage a targeted victim in a manner that increases the chance the victim will divulge information
68
Phishing
used to gain personal information for purposes of identity theft - using fraudulent e-mail messages that appear to come from legitimate businesses.
69
Shouldering
used to obtain information such as personal identification numbers (PINs) and passwords and other confidential data by looking over the victim's shoulder.
70
Malware
malicious software - computer programs designed to infiltrate and damage computers without the users consent.
71
Virus
program loaded onto a user's computer without the user's knowledge and performs malicious actions. It can self-replicate - inserting itself onto other programs or files - infecting them in the process.
72
Worm
program that replicates itself in order to spread to other computers. Often it uses a computer network to spread itself - relying on security failures on the target computer to access it.
73
Trojan Horse
program which misleads users of its true intent.
74
Spyware
aims to gather information about a person or organization without their knowledge
75
Adware
unwanted advertisements to the user of a computer
76
Brute Force Attack
trail and error to gain information
77
Denial of Service Attack (DOS)
hacker stop users from accessing a part of a network - flooding network with useless traffic making computer very slow
78
Data Interception And Theft
The unauthorized taking or interception of computer-based information. Data theft is the act of stealing computer-based information from an unknowing victim with the intent of compromising privacy or obtaining confidential information.
79
SQL Injection
sql
80
Zero-day Attack
before software is released it is tested as much as possible
81
Penetration Testing
organisations employ specialists to stimulate potential attacks on their network
82
Anti-malware Software
designed to find and stop malware from damaging a network
83
Encryption
data is translated into code which only someone with the correct key can access
84
Data Protection Act
your data should be protected and kept safe from hackers
85
Freedom of Information Act
allows members of the public to access information held by a public organisation
86
Computer Misuse Act
stop hacking and cyber crime - stop unauthorized access to private network
87
Copyright Act
protect intellectual property - anything someone has created
88
alphanumeric
collective name for letters/digits/symbols
89
analogue signal
a continuous signal which can't be processed by a computer
90
argument
a value that a parameter of a subprogram actually takes
91
ALU
part of CPU that carries out arithmetic and Boolean operations
92
array
data structure where all data is stored and defined under one variable name
93
ASCII
A 7-bit character set consisting of 128 characters
94
assembler
a program that turns assembly language into machine code
95
assembly language
low-level langauge
96
authentication
a process for checking user identity
97
binary
a counting system using base-2 consisting of 0s and 1s
98
binary shift
moving the bits in a binary number left or right and filling gaps with 0s
99
BIOS
Basic Input Output System
100
bitmap image
a graphic made up of pixels
101
bit
a binary digit either 0 or 1
102
bit rate
number of bits used per second of sampled audio
103
breakpoint
a programming tool used to halt a program at a specific place
104
byte
8 bits
105
casting
a way of changing from one data type to another
106
character
a single alphanumeric symbol
107
code editor
part of an IDE where you write and edit your source code
108
colour depth
the number of bits used for each pixel in an image file
109
comment
a note added to source code to say what part of a program does
110
comparison operator
compares two values and outputs either true or false
111
compiled code
an executable file created by a compiler
112
compiler
a programming tool to translate source code into machine code
113
compression
process of making the size of a file smaller
114
computational thinking
tackling a problem through decomposition/abstraction/algorithmic thinking
115
concatenation
joining strings together
116
constant
named value which cannot be altered as program is running
117
debugging
identifying and fixing errors in a program
118
dedicated system
a computer system designed to carry out a specific task
119
denary
system using base-10
120
digital signal
the representation of an analogue signal using binary data
121
DO WHILE loop
type of iteration statement
122
erroneous data
test data that a program isn't designed to accept
123
error diagnostics
information about an error once it is detected
124
extended ASCII
an 8-bit character set consisting of 256 characters
125
extreme data
Test data on the boundary of what a program will accept
126
field
A column of a database used to store a category of data
127
file handling
reading from and writing to external files
128
file sharing
copying files between services of work
129
final/terminal testing
when the testing stage of the software developing cycle is only done once to check the software.
130
flat-file database
A database that only contains one table of data
131
flow diagram
a graphical way of showing an algorithm
132
FOR loop
A type of count-controlled iteration statement
133
functionality testing
A type of testing that assesses how well a program meets the requirements
134
function
A sub program that takes parameters and returns a value
135
Gigabyte
1000 megabytes
136
global variable
a variable available throughout the whole program
137
GPU
A circuit for handling the processing of graphics and images
138
GUI
Allows the user to interact with the computer in a visual and intuitive way
139
GUI builder
an IDE tool for giving a program a graphical user interface
140
hexadecimal
a counting system using base-16 consisting of 0-9 digits and letters a-f
141
high-level language
A programming language like C++ or Java
142
IF statement
type of selection statement
143
indentation
Spaces put at the beginning of a line of code to help show a programs structure
144
input sanitization
removing unwanted characters from an input
145
input validation
Checking that an input meets a certain criteria
146
integer
A numerical data type for whole numbers
147
interpreter
A translator that turns source code into machine code
148
iteration statement
A statement which make a program repeat a series of instructions
149
iterative testing
Repeated testing done during the development of a program
150
kilobyte
1024 bytes
151
linker
a program tool which can combine codes
152
local variable
a variable that is only defined and useable within certain parts of a program
153
logic circuit
An electronic circuit for performing logic operations on binary data
154
logic error
when a program does something that was not intended
155
logic gate
an electronic circuit component that performs a Boolean operation
156
loop
A set of instructions that repeat until a condition is met
157
lossless compression
Temporarily removing a file to decrease file size
158
lossy compression
permanently removing a file to decrease file size
159
machine code
the lowest level of programming language formed of 1's and 0's
160
maintainability
a characteristic of a defensive design that helps programmers modify their creation
161
megabyte
1024 kilobytes
162
metadata
extra data stored in a file which gives information about the file's properties
163
Bit
one binary number (1 or 0)
164
Nibble
4 bits
165
real (or float)
numbers that have a decimal part
166
Boolean
can only take one of two values (usually TRUE or FALSE)
167
string
used to represent text/collection of characters
168
decomposition
breaking a complex problem down into smaller problems and solving each one individually
169
abstraction
picking out important bits of information from the problem
170
algorithmic thinking
a logical way of getting from the problem to the solution
171
decisions
diamond boxes - flow diagram
172
start/stop
box with rounded corners - flow diagram
173
inputs/outputs
parallelogram - flow diagram
174
processes (instructions/calculations/processes)
rectangle - flow diagram
175
sub routine (reference other flow diagrams)
box with another boxes - flow diagram
176
sequences
only one way from start to finish
177
selections
multiple ways to get from start to finish
178
iterations
loops that allows to repeat a task
179
exponentiation
raise a number to a power
180
DIV operator
returns whole number part of division
181
MOD operator
returns remainder part of division
182
==
is equal to
183
<> or !=
is not equal to
184
is less than
185
>
is greater than
186
<=
is less than or equal to
187
>=
is greater than or equal to
188
comparison values
produce boolean value
189
x.upper
changes all characters in string x to upper case
190
x.lower
changes all characters in string x to lower case
191
x.length
returns number of character in string x
192
x[i]
extracts the character in position i from string x
193
x.subString(a[comma]b)
extracts string starting at portion a with length b from string x
194
switch-case statements
check value of a variable
195
for loops
example of a count-controlled loop
196
AND
&&
197
OR
| |
198
NOT
!
199
element
each piece of data inside array
200
records
rows of tables in databases - store a category
201
fields
columns of tables in databases - story details about specific item
202
primary key
uniquely identifies record in table (database)
203
data values in same record
have different data types
204
data values in same field
have same data types
205
flat file database
only one table - viewed by opening one data file
206
relational database
combine flat-file databases - linked together by key fields
207
SQL definition
programming language used for creating, maintaining and accessing databases
208
SQL function
create/update/query databases - consists of standard commands called statements
209
Text - SQL data types
stores strings
210
Date - SQL data types
stores date in the form DD MM YYYY
211
Boolean - SQL data types
stores TRUE or FALSE
212
CREATE TABLE - SQL command
creates table with required number of fields
213
INSERT INTO - SQL command
adds records to table (complete records no specific field vs specific record assign field)
214
UPDATE-SET-WHERE - SQL command
updates record in database
215
SELECT - SQL command
tells database what information you want to achieve
216
FROM - SQL command
tells database which tables to look in
217
WHERE - SQL command
specifies condition that a record must satisfy before it is returned
218
WHERE with AND and OR - SQL command
makes search more specific
219
WHERE with LIKE - SQL command
searches for a pattern
220
LIKE - SQL command
% used to represent any combination of letters and numbers
221
ORDER BY - SQL command
sort records into ascending (ASC) or descending (DESC) order
222
parameters
special variables used to pass values into a sub program (specify name/data type/default value)
223
arguments
actual values that parameters take when sub program called
224
total number of colours
2^n (where n = number of bits per pixel)
225
24 bit colour depth
average device colour depth
226
resolution
density of the pixels in an image
227
bit rate equation
sampling frequency x sample size
228
range check - input validation
checks the data is within a specified range
229
presence check - input validation
checks data has been entered
230
check digit - input validation
checks numerical data has been entered accurately
231
format check - input validation
checks data has correct format
232
look-up table - input validation
checks data against a table of acceptable values
233
length check - input validation
checks data is correct length
234
syntax errors
rules or grammar of programming language is not followed so compiler or interpreter doesn't understand
235
logic errors
when compiler or interpreter is able to run program but program does something unexpected
236
diagnosing logic errors
found through general use of program and by systematically testing
237
performance test
tests how quickly certain features run and their impact on computer resources
238
usability test
tests how user-friendly the interface and features are
239
security test
tests vulnerability to attacks and how securely data is stored
240
load/stress test
tests how it copes under extreme conditions
241
functionality test
tests if program meets initial requirements
242
software development cycle
requirements - design - implementation - testing - maintenance
243
normal data
data that user is likely to input
244
assemblers
turn assembly language into machine code
245
AND - Conjunction
e.g. A /\ B
246
OR - Disjunction
e.g. A\/B
247
NOT - Negation
e.g. -|A
248
What does SQL stand for?
Structured Query Language
249
What does SQL allow people to do?
Allows people to search for records that contain a particular item or items of data
250
procedure
a set of coded instructions that tell a computer how to run a program or calculation
251
translator
converts program code into machine code to be executed by the CPU
252
IDE
a software application that provides facilities to computer programmers for software development
253
Character set
List of binary codes that can be recognised by computers as being usable characters
254
Sampling frequency
Number of samples per second in a sound
255
Sample size
a measure of how many bits a sample contains which is directly a measure of quality
256
Ethernet
a wired way of connecting computers to a network
