GCSE key terms Flashcards
1
Q
What does the ALU stand for?
A
Arithmetic Logic Unit
2
Q
What does the ALU do?
A
The part of the CPU where data is processed.
This is normally arithmetic operations/logical comparisons so a program can make decisions
3
Q
what does the CU do?
A
manages execution of instructions.
Fs, Ds and Es instructions by sending control signals to other components
4
Q
what is a register?
A
tiny, fast memory in cpu,
designed for a specific purpose
temporarily stores 1 piece of data/control info
5
Q
what does the PC do?
A
Holds the address of the next instruction to be executed
6
Q
what is the ACC?
A
register in the ALU
holds data currently being processed.
7
Q
What does PC stand for?
A
Program Counter
8
Q
What does ACC stand for?
A
Accumulator
9
Q
What does the MAR contain?
A
the address of the memory location in use.
in fetch it’s the instruction being loaded
in excecute it’s the address of the data being used
10
Q
What does the memory data register (MDR) do?
A
holds the data/instruction ready for transfer to or from memory
11
Q
What is the CIR?
A
A register in the CU that stores the address of the instruction currently being executed and decoded
12
Q
What does MAR stand for?
A
Memory Address Register
13
Q
What does MDR stand for?
A
Memory Data Register
14
Q
What does CIR stand for?
A
Current Instruction Register
15
Q
What is a bus?
A
A common physical pathway, a wire, shared by signals to and from several components of a computer
16
Q
What is a data bus?
A
The part of a bus that carries data
17
Q
What is an address bus?
A
The part of a bus that
carries identification about where the data’s being sent
18
Q
What is a control bus?
A
A bus that carries command and control signals to and from every component of a computer
19
Q
What is the Fetch-Decode-Execute cycle?
A
The complete process of recieving an instruction from store, decoding it and carrying it out
20
Q
What is the instruction cycle?
A
Another name for the FDE cycle
21
Q
What is the CPU?
A
the main part of a computer: contains registers, ALU+CU
22
Q
What is clock speed?
A
the frequency at which the internal clock generates pulse. higher clock speed, faster computer.
the clock is the component that synchronises other components by generating regular pulses
23
Q
What is clock speed measured in?
A
Hertz
24
Q
What are cores?
A
A part of a multi-core processor (single components with at least independant CPUs)
25
What is Von Neumann architecture?
Traditional computer architecture where one CU manages program control flow following a linear sequence of FDE
26
what are embedded systems?
A small computer-hard and software- part of a larger device
allows users to interact w/ the device
27
Give some examples of embedded systems
Central heating systems, dishwashers, washing machines, engine management systems in cars
28
What is RAM?
fast, volatile main memory.
When used as main memory, RAM typically can be thought of as containing the OS, programs in use, and data used by those programs
29
What does RAM stand for?
Random Access Memory
30
What are the contents of RAM?
The OS
current instructions / data
any open files / software
31
What is ROM?
Memory where the contents can be read but not changed.
Software is fixed during manufacturing.
Typically holds system boot up instructions.
32
Can ROM be written to?
No, but more modern versions- *(PROM, EPROM and EAROM) *can
33
What does ROM stand for?
Read Only Memory
34
What is stored in the ROM?
POST and BIOS (power on self test and basic input output system)
35
What is virtual memory?
where part of secondary storage is allocated to be used as if it were main memory when RAM is full.
very slow, so the software will attempt to use RAM if possible
36
What is Flash Memory?
A type of very fast-access non-volatile memory
37
What does POST stand for, and what does it do?
Power On Self Test- detirmines if all components are connected and running correctly
38
What does BIOS stand for?
Basic Input and Output System
39
What does volatile mean?
Memory that loses its contents when the computer is turned off
40
What is a bootstrap loader?
first program loaded to RAM when the device turns on
41
What does speed refer to? (storage)
The relative speed at which data can be accessed by each type of device
42
What is magnetic storage?
Uses surfaces coated with a layer of mag material
data stored by setting arrangement of the mag. material.
with electromag r/wr heads
43
What is flash storage?
A collection of memory chips controlled by their own software to make the chips act like a hard drive
44
What is optical storage?
Storage medium using plastic discs to store data in pits + lans
45
What is a lan? (not LAN)
A "bump" in optical storage, as opposed to a pit. also called a fall
46
What is capacity?
The amount of data a device can store
47
What is capacity measured in?
Bytes
48
What is robustness?
The amount of physical damage a device can take before it breaks
49
How do you measure how expensieve a storage device is?
In cost per gigabit
50
What do you call the way to compare how much physical damage a device can take?
robustness
51
What is a sector?
A subdivision of the magnetic disk
52
What is a platter?
A circular disk on which magnetic data is stored. They spin quickly so the read head can recieve the data
53
What is a track?
a circular path on the surface of the disk where data is stored
54
what is speed(referring to different storage devices)
the relative access speed of each device
55
What are the different ways of measuring the effectiveness of different storage devices?
Capacity, durability, robustenss, speed, cost per gigabit, portability
56
What does HDD stand for?
Hard Disk Drive (magnetic)
57
What does SSD stand for?
Solid State Drive , uses flash memory
58
What is an SD card?
Small, portable devices that use flash memory to store data, used in phones, cameras, etc
59
What is a data pen/stick?
A small device that uses flash memory to store data
60
What type of memory do data sticks use?
flash memory
61
What does DVD stand for?
Digital Versatile Disk
62
What type of storage is a DVD?
optical
63
What does CD stand for?
Compact Disk
64
What type of storage do CDs use?
optical
65
what type of storage do blu-rays use?
optical
66
what is a bit?
a single unit of data; a 1 or a 0
67
what is a byte?
8 bits of data
68
what is a nibble?
4 bits of data, or half a byte
69
how many bytes are there in a kilobyte?
1,000 or 10 ^3
70
how many bytes are there in a terabyte?
1,000,000,000,000 or 10^12
71
how many bytes are there in a gigabyte?
1,000,000,000 or 10^9
72
how many bytes are there in a petabyte?
1,000,000,000,000,000 or 10^15
73
how many bytes are there in a megabyte?
1,000,000 or 10^6
74
what is the order of the standard form prefixes, going up in 10^3s?
kilo,mega,giga,tera,peta
75
what is a number base?
the positional number system
using unique digits to display quantities,
digits are resused and their position represents higher or lower values
76
what is denary?
base 10
77
what is binary?
base 2- 0 and 1
78
what is hexadecimal?
base 16, uses denary and A,B,C,D,E to represent 10-15
79
what is a left shift?
By shifting a binary number to the left and placing a zero in the least significant column. this doubles the number (as a left shift in denary would multiply the number by 10)
80
what is a right shift?
the reverse process of a left shift, divides the number by 2
81
what is a character set?
the collection of letters, symbols and digits that a computer can represent
82
what does ASCII stand for?
American Standard for Information Interchange
83
How many bits does ASCII use?
7/8 (uses 7, stored as 8)
84
What is an uppercase A in ASCII?
65
85
What is a lowercase a in ASCII?
97
86
What does pixel stand for?
Picture Element
87
What is metadata?
the information at the beginning of a file, usually the length and height, colour depth, type of file, etc
88
what is colour depth?
the number of colours used in an image
*(3 bit = 2^3 = 8 colours)*
89
how many colours would you get in 6 bit colour depth?
2^6 or 64 colours
90
What is resolution?
the number of dots per inch used in the image file
91
what is sampling rate?
how many times the computer records the amplitude of the sound per second, eg X times per second
92
what is sampling?
a computer records the amplitude of a sound at certain intervals and stored as binary
*(Frequency is taken from the amplitude)*
93
What is bit depth?
The number of bits avaible for each sample (again, 3 bit = 2x2x2 =2^3 = 8 values)
94
what does analogue mean?
a value that can take any value between an upper and lower limit
95
what does digital mean? (referring to storage)
Values that have to stick to certain numbers
96
what does compression mean?
reducing file size
97
what does lossy mean?
reducing the file size with permenant loss of data
98
what does lossless mean?
reducing a file size without losing any data
99
what is a dictionary file?
used to store common words/phrases from the compressed file (eg the "i have a dream" example mr white showed us)
100
what is run length?
a technique used to find repeated data and code it
101
what is a LAN?
A Local Area Network- two or more connected computers in one geographical site, using owned infrastructure
102
what is a WAN?
A Wide Area Network- two or more connected computers, on more than one geographical site and using someone else's infrastructure, eg phone lines
103
what is latency?
how long data takes to reach its destination
104
what is error rate?
how many transmission errors occur in a set amount of time
105
what is bandwidth?
the rate at which data can be trasnmitted in a network, measured in Gigabytes per second
106
what does peer-to-peer mean?
a network where all devices have equal status
107
what does client-server mean?
a type of network in which one computer, the server, has overall control
108
what do "peer to peer" and "client-server" refer to?
networks
109
What is a wireless access point?
Also called a wireless router,
sends/recieves WiFi transmissions from devices & the network
110
what is a router?
connects a network to the interne
by sending/receving data packets
to/from other routers on other networks
using IP addresses.
111
What is a switch?
device that sends data packets to/from their destination on a network using MAC addresses
112
What is a hub?
Broadcasts data to all other devices connected to the hub
113
What is a domain name server?
servers containing all URLs and corresponding IPs
users type URLs to find the target computer w/ the website
114
What is transmission media?
the physical connection between devices- copper wire, wifi, fibre optic
115
what does wifi stand for?
Wireless Fidelity
116
what does DNS stand for?
Domain Name Server
117
what is hosting?
allowing a website space on a computer and remote users to access that data
118
what is the Cloud?
a collection of computers you can rent space on, usually in a server farm
119
what is a virtual network?
a sub-network using the same infrastructure but reserved for a few members
120
What is a network interface card?
A device that provides a device with a MAC address so it can connect to a network
121
What is an ethernet cable?
copper wire, also called a twisted pair
122
What does IaaS stand for?
Infrastructure as a Service
123
What does SaaS stand for?
Software as a Service
124
What is infrastructure as a service?
providing hardware resources for rent
*eg HDD space*
125
what is software as a service?
providing applications for users to use online, eg onedrive
126
what is the internet?
A collection of devices networked together to provide the network of networks
127
what does WWW stand for?
World Wide Web
128
what is the world wide web?
the web pages that sit upon the internet and can be accessed by remote users
129
What is an IP address?
the address that identifies a computer on a network
*if the network is the internet, the address is unique in the world.
if the network is behind a router, it is unique in that network*
130
what does URL stand for?
Universal Resource Locator
131
What is a url?
the web address of a webpage, eg ecosia.org
132
What is an MAC address?
a unique identifier for a machine connecting to a network
built into the hardware and can't be changed.
*each manufacturer is assigned a group of MAC addresses to be used for their devices.*
*they come in the form of 1A:7C:2F:3A:9B:12*
133
what does MAC stand for?
media access control
134
what does SID stand for?
Service Set Identifier
135
what is an SID?
uniquely identifies a wireless LAN- usually you need a password to connect to WiFi
136
what does wired mean?
devices connected with copper/optic cables
137
what does wireless mean?
devices connected via electromagnetic signals
138
what type of waves does wifi use?
microwaves
139
how does bluetooth work and what type of wave does it use?
transmits/recieves data using radiowaves
140
What is encryption?
disguising data so it can only be read with the key
141
what is an IP address?
a number assigned to a device by a network so it can connected to a network
*each IP address on a network is unique, and computers can have different IP addresses on different networks*
142
what are standards?
rules set out so computers can communicate
143
what does IP stand for?
Internet Protocol Address
144
What is TCP/IP?
a set of protocols that allow for communication on the internet
145
what is https?
encrypted transmission of webpages
*(hypertext transfer protocol secure)*
146
what is http?
hypertext transfer protocol- used for transmitting and recieving webpages
147
what is FTP?
file transfer protocol- for transmitting large files across computers
148
what is POP?
post office protocol- takes a copy of emails from the webserver and deletes any files on the webserver
149
what is IMAP?
creates a copy of emails on the webserver on the local machine
*(internet message access protocol)*
150
what is SMTP?
simple mail transfer protocol-
used to send emails
151
What are layers?
Using protocols in layers so they can be replaced/edited without affecting other layers
152
what is malware?
hostile or intrusive software that may change, monitor or delete data without permission
153
what is phishing?
a technique used to try and gather personal details under false pretences,
a form of social engineering
154
What is social engineering?
using hmuan weakness or gullibility to obtain data
155
what is shoulder surfing?
(literally) looking over someone's shoulder as they read their password
156
what are brute force attacks?
trying every possible combination to work out a password
157
what is a DDOS attack?
Intentionally paralysing a network by flooding it with many individual users' data
158
what is data interception?
stealing data from an organisation
159
what is an SQL injection?
uses structured query language, *written at the end of a URL, *to change the state of a database
160
what is a virus?
software designed to harm data or a computer, can usually replicate itself
161
what is a worm?
malware that can replicate without being part of another piece of software
162
what is a zombie?
software that allows someone to remotely use a computer without permission
163
what do keyloggers do?
record the keys pressed on a computer and send them back to the owner to try and learn a password/account details
164
what is ransomware?
encrypts the data on a computer and charges a fee for the key
165
what is a trojan?
malware that disguises itself as another type of software, for instance a musical file
166
what is eavesdropping?
intercepting data packets
167
what is a network policy?
rules an organisation creates to govern how people use their system, usually there is an Acceptable Use Policy
168
What is network forensics?
using audit trails to find wrongdoing on a network
168
What is penetration testing?
Asking white hat hackers to try access your network "without" permission to try to find vulnerabilities
169
what is anti-malware software?
software that looks for malware
can warn about/disable
software/files identified as dangerous
170
what is a password?
a way of restricting access to a system with usernames and an associated code
171
what are firewalls?
combination of soft and hardware that inspect packets as they leave/enter to prevent unauthorised access
172
what are user access levels do?
determine the rights a user has on a computer/network,
*usually:read only, r/wr, full and administrative access*
173
what is encryption?
a method of disguising data so it can only be read with the key
174
what are white hat hackers?
Hackers that access a system with permission to help with it security
175
What are black hat hackers?
hackers that access systems without permission
176
what are grey hat hackers?
Hackers who find vulnerabilities in an organisation's system without permission to report to them
177
What is black box testing?
asking someone to test a system's vulnerabilities knowing no more info than a hacker would
178
What is white box testing?
To ask someone to test a system's vulnerabilities, giving themthe information an insider might have
179
what is ethical hacking?
Hackers put their expertise into finding vulnerabilities in an organisation's system without permission to report it to the organisation
180
what are audit trails?
A log of activity on a network
181
what is a proxy server?
acts as an intermediatry between web browser and internet, blocking or allowing data packets
182
what does an OS do?
manages the general running of a computer,
so a user can interact w/ it
183
what is a user interface?
provides a method for the computer & user to share information
184
what is memory management?
the OS manages how much memory is being used by any running process
185
what is multitasking?
a computer's ability to run several processes simultanesouly or to simulate concurrent processing
186
what is a peripheral?
a device that is plugged into a computer, eg printer
187
what are drivers?
software that allows computers to run and interact with a peripheral device
188
what is user management?
the allocation of usernames, files and permissions for the user
189
what is file management?
the control of
names,
structure
and permissions
allowed on files
190
what is a buffer?
a system of transferring & temporarily storing data
when fast and slow devices communicate
191
what are access rights?
the type of access that a user has to data, usually read only, read and write or full control
192
what is file structure?
the way in which files are linked to each other?
193
what is a kernel?
the program at the core of the computer
allows the OS full control
194
what is a platform?
the combination of OS and hardware that allows the computer to run apps
195
what is utility software?
used to analyse, manage, configure and maintain a computer system
196
what is encryption software?
software that encrypts data so it can only be read with the key
197
What does defragmentation software do?
organises data on an HDD so it's contiguous
198
what is compression?
reducing file size
199
What are ethics?
the moral code agreed by an organisation
200
what is legislation?
the legal framework
201
what is privacy?
keeping one's data / actions to oneself
202
what is the data protection act/DPA?
protects people from unreasonable use of their personal data
203
When was the DPA?
1998
204
What are the three levels of the CMA?
-Access without permission
-access without permission with intent to change
-access and change without permission
205
What is the CMA?
defines electronic vandalism,
unathorised access to computer systems
&information theft
206
What is the CDPA?
Legislation to give creators the right to control how their artistic works are used
207
What does CDPA stand for?
Copyright Design and Patents Act
208
What does RIPA stand for?
The Regulation of Investigatory Powers Acts
209
When was the CMA?
1990
210
When was the CDPA?
1988
211
When was the RIPA?
2000
212
What is the RIPA?
Legislation to regulate the powers of public bodies to carry out surveillance/investigation
covers interception of communications
213
give some examples of ethical issues surrounding computing
losing jobs to automation
unequal IT access (digital divide)
invasion of privacy
irresponsible internet content
214
give some examples of legal issues surrounding computing
digital content ownership and copyright
different laws in different countries
*(crime may be comitted in a certain country but the people may be physically living in another country)* hacking
piracy
215
give some examples of environmental issues surrounding computing
manufacturers use fossil fuels,
non-renewable resources eg gold,
data centers use 2% of global energy,
computers contain hazardous materials which are shipped to other countries for disposal
216
give some examples of cultural issues surrounding computing
censorship to provide political unrest and preserve culture,
a country's geography/economy affects access network/power access
increased mobile technology impacts communication,
cyberbullying
217
what does open source mean?
Software that users can modify/distribute
support provided by the community.
users have access to source code
may not be fully tested
218
what does proprietary mean?
users can't modify the software
copyright protected, usually paid for
licensed per user/computer
users can't access source code
fully tested&supported by devs
219
what is computational thinking?
the thought processes involved in formulating a problem and expressing its solutions in a way that a computer- human or machine- can carry them out
220
what word do you use when describing whether files are next to each other (related to defragmentation)
contiguous
221
what are the words for encrypted/non encrypted text
cipher/plain text
222
What is the first network layer?
passes data as electrical signals over the physical network
223
What is the second network layer?
Involves making connections between networks and directing data
224
What is the third network layer?
Involves splitting data into packets and checking data is sent (tcp is an example of this)
225
What is the fourth network layer?
turns data into apps / websites and vice-versa
226
What is Transmission Control Protocol?
Sets rules for how devices connect on the network.
Splits data into packets+reassembles them.
Checks data is sent+delivered
