All content - simplified definitions Flashcards
1
Q
Arithmetic Logic Unit (ALU)
A
Performs operations on data e.g. Addition, subtraction
2
Q
Control Unit (CU)
A
Coordinating activities of the CPU
3
Q
Registers
A
Quick, 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
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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, 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
24
Q
ADV: cheap,easy to transport
A
25
DIS: slow, less storage than hard drives, stored data degrades over time, cannot be written over
26
Magnetic storage
Hard drives
27
ADV: fast access, stores large amounts of data, low cost
28
DIS: not very portable, easily be broken
29
Solid State storage
USB, flash memory, SD
30
ADV: fast, small, light, easily potable, quiet
31
DIS: more expensive, storage capacity less, limited number erase/write cycles
32
Cloud stotage
Data is stored on multiple servers in a remote location
33
ADV: secure, can be accessed anywhere, no need to buy
34
DIS: needs internet, download and upload can be effected by internet connection, less control if data is held
35
Operating System
essential software that links the hardware and other software together and generally manages the computer system
36
Command-line Interface
Text commands where user has to type in command
37
Graphical User Interface (GUI)
uses icons and other visual indicators to navigate and issue commands
38
Utility Software
maintains a computer
39
Defragmentation Software
reorganises data on the hard drive to put fragmented files back together and moves files to collect all the free space
40
Backup Software
Full Backup - a copy is taken from from every file on the system
41
Incremental Backup - only files created or edited since last backup are copied
42
Compression Software
reduces file size so they take up less space on hard disk
43
Encryption Software
scrambles data to stop others from accessing it
44
Open Source Software
source code is made freely available and users can modify it
45
ADV: free, ,made for greater good, can be adapted
46
DIS: small, buggy, security holes, no warranties, no customer support
47
Proprietary Software
only the compiled code is released and the source code is kept a secret
48
ADV: warranties, well-tested, reliable, cheaper
49
DIS: expensive, software may not fit user needs
50
Personal Area Network (PAN)
within the range of an individual person
51
Local Area Network (LAN)
a network that connects devices close to each other e.g. school, house
52
Wide Area Network (WAN)
a network within a large geographical area e.g. internet
53
Bandwidth
amount of data that can be transferred in a given time
54
Network Interface Card (NIC)
allow a device to connect to a network
55
Switch
connect devices on a LAN
56
Router
responsible for transmitting data between networks
57
Ethernet
a set of standards for connecting computers
58
Client-server Network
client has connection to server, servers can backup and store centrally but can be expensive and difficult to maintain
59
Peer-to-peer Network
no central server, each computer equal in responsibility, have to work as both server and a client.
60
Star Topology
ADV: better performance, rest of network not affected in one fails, simple to add more devices
61
DIS: wire needed for all devices, expensive
62
Mesh Topology
ADV: faster
63
DIS: expensive
64
MAC Address
assigned to all devices, unique to all devises and cannot be changed, permanent, identifies the actual device.
65
IP Adress
assigned either manually or automatic, the location of your device on the internet
66
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.
67
TCP/IP
sets of rules for how devices connect on the network.
68
Hyper Text Transfer Protocol (HTTP)
used to access websites and communicate with web servers
69
HTTPS
more secure - encryption
70
File Transfer Protocol (FTP)
used to access, edit and move files between devices
71
Post Office Protocol (POP3)
used to retrieve emails from a server, holds until download - then deletes from server
72
Internet Message Access (IMAP)
used to retrieve emails, server holds until you actually delete it- only download a copy
73
Simple Mail Transfer Protocol (SMTP)
used to send emails, used to transfer emails between servers
74
Layer
ADV: manageable pieces, self-contained can change without effecting others
75
Application Layer
turning data into websites
76
Transport Layer
controlling data flow - splitting data into packets
77
Network Layer
making connections between networks
78
Data link Layer
passing data over physical network-
79
Domain Name Server (DNS)
translates websites' domain name into its IP address
80
Virtual Network
network that is entirely software based, created by partitioning of some physical network
81
Blagging
invented scenario to engage a targeted victim in a manner that increases the chance the victim will divulge information
82
Phishing
used to gain personal information for purposes of identity theft, using fraudulent e-mail messages that appear to come from legitimate businesses.
83
Shouldering
used to obtain information such as personal identification numbers (PINs), passwords and other confidential data by looking over the victim's shoulder.
84
Malware
malicious software - computer programs designed to infiltrate and damage computers without the users consent.
85
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.
86
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.
87
Trojan Horse
program which misleads users of its true intent.
88
Spyware
aims to gather information about a person or organization without their knowledge
89
Adware
unwanted advertisements to the user of a computer
90
Brute Force Attack
trail and error to gain information
91
Denial of Service Attack (DOS)
hacker stop users from accessing a part of a network, flooding network with useless traffic making computer very slow
92
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.
93
SQL Injection
programming language used to search and query databases.
94
Zero-day Attack
before software is released it is tested as much as possible
95
Penetration Testing
organisations employ specialists to stimulate potential attacks on their network
96
Anti-malware Software
designed to find and stop malware from damaging a network
97
Encryption
data is translated into code which only someone with the correct key can access
98
Data Protection Act
your data should be protected and kept safe from hackers
99
Freedom of Information Act
allows members of the public to access information held by a public organisation
100
Computer Misuse Act
stop hacking and cyber crime - stop unauthorized access to private network
101
Copyright Act
protect intellectual property - anything someone has created
102
alphanumeric
collective name for letters, digits, symbols
103
analogue signal
a continuous signal which can't be processed by a computer
104
argument
a value that a parameter of a subprogram actually takes
105
ALU
part of CPU that carries out arithmetic and Boolean operations
106
array
data structure where all data is stored and defined under one variable name
107
ASCII
A 7-bit character set consisting of 128 characters
108
assembler
a program that turns assembly language into machine code
109
assembly language
low-level langauge
110
authentication
a process for checking user identity
111
binary
a counting system using base-2 consisting of 0s and 1s
112
binary shift
moving the bits in a binary number left or right and filling gaps with 0s
113
BIOS
Basic Input Output System
114
bitmap image
a graphic made up of pixels
115
bit
a binary digit either 0 or 1
116
bit rate
number of bits used per second of sampled audio
117
breakpoint
a programming tool used to halt a program at a specific place
118
byte
8 bits
119
casting
a way of changing from one data type to another
120
character
a single alphanumeric symbol
121
code editor
part of an IDE where you write and edit your source code
122
colour depth
the number of bits used for each pixel in an image file
123
comment
a note added to source code to say what part of a program does
124
comparison operator
compares two values and outputs either true or false
125
compiled code
an executable file created by a compiler
126
compiler
a programming tool to translate source code into machine code
127
compression
process of making the size of a file smaller
128
computational thinking
tackling a problem through decompostion, abstraction and algorithmic thinking
129
concatenation
joining strings together
130
constant
named value which cannot be altered as program is running
131
debugging
identifying and fixing errors in a program
132
dedicated system
a computer system designed to carry out a specific task
133
denary
system using base-10
134
digital signal
the representation of an analogue signal using binary data
135
DO WHILE loop
type of iteration statement
136
erroneous data
test data that a program isn't designed to accept
137
error diagnostics
information about an error once it is detected
138
extended ASCII
an 8-bit character set consisting of 256 characters
139
extreme data
Test data on the boundary of what a program will accept
140
field
A column of a database used to store a category of data
141
file handling
reading from and writing to external files
142
file sharing
copying files between services of work
143
final testing
when the testing stage of the software developing cycle is only done once to check the software.
144
flat-file database
A database that only contains one table of data
145
flow diagram
a graphical way of showing an algorithm
146
FOR loop
A type of count-controlled iteration statement
147
functionality testing
A type of testing that assesses how well a program meets the requirements
148
function
A sub program that takes parameters and returns a value
149
Gigabyte
1000 megabytes
150
global variable
a variable available throughout the whole program
151
GPU
A circuit for handling the processing of graphics and images
152
GUI
Allows the user to interact with the computer in a visual and intuitive way
153
GUI builder
an IDE tool for giving a program a graphical user interface
154
hexadecimal
a counting system using base-16 consisting of 0-9 digits and letters a-f
155
high-level language
A programming language like C++ or Java
156
IF statement
type of selection statement
157
indentation
Spaces put at the beginning of a line of code to help show a programs structure
158
input sanitation
removing unwanted characters from an input
159
input validation
Checking that an input meets a certain criteria
160
integer
A numerical data type for whole numbers
161
interpreter
A translator that turns source code into machine code
162
iteration statement
A statement which make a program repeat a series of instructions
163
iterative testing
Repeated testing done during the development of a program
164
kilobyte
1024 bytes
165
linker
a program tool which can combine codes
166
local variable
a variable that is only defined and useable within certain parts of a program
167
logic circuit
An electronic circuit for performing logic operations on binary data
168
logic error
when a program does something that was not intended
169
logic gate
an electronic circuit component that performs a Boolean operation
170
loop
A set of instructions that repeat until a condition is met
171
lossless compression
Temporarily removing a file to decrease file size
172
lossy compression
permanently removing a file to decrease file size
173
machine code
the lowest level of programming language formed of 1's and 0's
174
maintainability
a characteristic of a defensive design that helps programmers modify their creation
175
megabyte
1024 kilobytes
176
metadata
extra data stored in a file which gives information about the file's properties
177
Bit
one binary number (1 or 0)
178
Nibble
4 bits
179
real (or float)
numbers that have a decimal part
180
Boolean
can only take one of two values, usually TRUE or FALSE
181
string
used to represent text, collection of characters
182
decomposition
breaking a complex problem down into smaller problems and solving each one individually
183
abstraction
picking out important bits of information from the problem
184
algorithmic thinking
a logical way of getting from the problem to the solution
185
decisions
diamond boxes - flow diagram
186
start/stop
box with rounded corners - flow diagram
187
inputs/outputs
parallelogram - flow diagram
188
processes (instructions, calculations, processes)
rectangle - flow diagram
189
sub routine (reference other flow diagrams)
box with another boxes - flow diagram
190
sequences
only one way from start to finish
191
selections
multiple ways to get from start to finish
192
iterations
loops that allows to repeat a task
193
exponentiation
raise a number to a power
194
DIV operator
returns whole number part of division
195
MOD operator
returns remainder part of division
196
==
is equal to
197
<> or !=
is not equal to
198
<
is less than
199
>
is greater than
200
<=
is less than or equal to
201
>=
is greater than or equal to
202
comparison values
produce boolean value
203
x.upper
changes all characters in string x to upper case
204
x.lower
changes all characters in string x to lower case
205
x.length
returns number of character in string x
206
x[i]
extracts the character in position i from string x
207
x.subString(a,b)
extracts string starting at portion a with length b from string x
208
switch-case statements
check value of a variable
209
for loops
example of a count-controlled loop
210
AND
&&
211
OR
| |
212
NOT
!
213
element
each piece of data inside array
214
records
rows of tables in databases - store a category
215
fields
columns of tables in databases - story details about specific item
216
primary key
uniquely identifies record in table (database)
217
data values in same record
have different data types
218
data values in same field
have same data types
219
flat file database
only one table, viewed by opening one data file
220
relational database
combine flat-file databases, linked together by key fields
221
SQL definition
structured query language
222
SQL function
create, update, query databases, consists of standard commands called statements
223
Text - SQL data types
stores strings
224
Date - SQL data types
stores date in the form DD MM YYYY
225
Boolean - SQL data types
stores TRUE or FALSE
226
CREATE TABLE - SQL command
creates table with required number of fields
227
INSERT INTO - SQL command
adds records to table (complete records no specific field vs specific record assign field)
228
UPDATE-SET-WHERE - SQL command
updates record in database
229
SELECT - SQL command
tells database what information you want to achieve
230
FROM - SQL command
tells database which tables to look in
231
WHERE - SQL command
specifies condition that a record must satisfy before it is returned
232
WHERE with AND and OR - SQL command
makes search more specific
233
WHERE with LIKE - SQL command
searches for a pattern
234
LIKE - SQL command
% used to represent any combination of letters and numbers
235
ORDER BY - SQL command
sort records into ascending (ASC) or descending (DESC) order
236
parameters
special variables used to pass values into a sub program (specify name, data type, default value)
237
arguments
actual values that parameters take when sub program called
238
total number of colours
2^n (where n = number of bits per pixel)
239
24 bit colour depth
average device colour depth
240
resolution
density of the pixels in an image
241
bit rate equation
sampling frequency x sample size
242
range check - input validation
checks the data is within a specified range
243
presence check - input validation
checks data has been entered
244
check digit - input validation
checks numerical data has been entered accurately
245
format check - input validation
checks data has correct format
246
look-up table - input validation
checks data against a table of acceptable values
247
length check - input validation
checks data is correct length
248
syntax errors
rules or grammar of programming language is not followed so compiler or interpreter doesn't understand
249
logic errors
when compiler or interpreter is able to run program but program does something unexpected
250
diagnosing logic errors
found through general use of program and by systematically testing
251
performance test
tests how quickly certain features run and their impact on computer resources
252
usability test
tests how user-friendly the interface and features are
253
security test
tests vulnerability to attacks and how securely data is stored
254
load/stress test
tests how it copes under extreme conditions
255
functionality test
tests if program meets initial requirements
256
software development cycle
requirements, design, implementation, testing, maintenance
257
normal data
data that user is likely to input
258
assemblers
turn assembly language into machine code
259
AND - Conjunction
e.g. A /\ B
260
OR - Disjunction
e.g. A\/B
261
NOT - Negation
e.g. -|A
