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COMP SCI > IGCSE > Flashcards

IGCSE Flashcards

1
Q

6.2 robotics

A

branch of computer science that incorporates the design, construction and operation of robots
(e.g. factory equipment, domestic robots, drones)

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2
Q

6.2 Characteristics of a robot

A

mechanical structure of framework, electrical components (e.g. sensors, mp, actuators), programmable

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3
Q

6.3 AI

A

artificial intelligence
: branch of computer science dealing with the simulation of intelligent behaviours by computers

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4
Q

1.2 Resolution

A

number of pixels wide by number of pixels high

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5
Q

1.2 colour depth

A

number of bits used to represent each colour

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6
Q

1.2 image

A

series of pixels that are converted to binary, which is processed by a computer

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7
Q

2.1 structure of a packet

A

packet header, payload, trailer

header –> destination address, packet number, originator’s address

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8
Q

2.1 process of packet switching

A

data broken down into packets
each packet could take a different route
router controls the route a packet takes
packets may arrive out of order
once the last packet has arrived, packets are reordered

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9
Q

Serial data transmission

A

one bit at a time // using a single wire

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10
Q

parallel

A

several bits transmitted at the same time // down a several wires

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11
Q

simplex

A

data sent in one direction only

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12
Q

half-duplex

A

sent in both directions // only one direction at a time

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13
Q

full-duplex / duplex

A

data transmitted in both directions at the same time

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14
Q

3.1 Microprocessor

A

type of integrated circuit on a single chip

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15
Q

3.4 Computer needs a ____ to access a network

A

NIC (network interface card)

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16
Q

3.4 Role of router in a network

A

sends data to a specific destination on a network, assign IP addresses, connect a local network to the internet

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17
Q

5.1 URL

A

uniform resource locator.

text-based address for a web page; can contain the protocol, domain name, web page/file name

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18
Q

5.1 purpose of a web browser

A

display webpages
by rendering hypertext markup language (HTML)

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19
Q

5.1 functions of a web browser

A

− Convert HTML code
− Display web pages
− Check if a website is secure
− Request web pages from a web server
− Send URL/domain name
− Runs active script
− Store history/favourites/bookmarks
− Create tabs

storing bookmarks/favourites, recording user history, allowing use of multiple tabs, providing an address bar, providing navigation tools, send URL to DNS, managing protocols

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20
Q

1.3 Data storage units

A

bit - nibble - byte - kibibyte - mebibyte - gibibyte - tebibyte - pebibyte - exbibyte

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21
Q

impact of data compression

A

less bandwidth required, less storage space required, shorter transmission time

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22
Q

Sample rate

A

number of samples taken in a second

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23
Q

sample resolution

A

number of bits per sample

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24
Q

Increasing sample rate & resolution would..

A

increase the accuracy of recording and file size

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25
Q

byte = _ bit

A

8

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26
Q

Increasing the resolution & colour depth will..

A

increase the file size & quality of image

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27
Q

How are files compressed using lossy

A

compression algorithm used
redundant data removed
reduce colour depth, image resolution, sample rate, sample resolution, frame rate

reduces sample rate, sample resolution

reduces file size by permanently removing data

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28
Q

how are files compressed using lossless
for images and text

A

reduces file size without permanent loss of data
original file can be restored
compression algorithm used
example : run length encoding - RLE

repeating frames/pixels identified // collated/indexed // no data is permanently removed // just records the changes between frames

repeated words identified // are indexed // replaced with their index // their positions are stored // number of occurrences stored

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29
Q

Role of CPU

A

process instructions and data that are input into the computer so that the result can be output

processes data // processes instructions // carries out calculations // carries out logical operations // fetch ,decode, execute

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30
Q

Process of the fetch-decode-execute cycle

A

PC holds address of next instruction to be fetched// address sent to MAR // using address bus // PC is incremented // instruction is sent from address in memory to MDR // instruction is transferred using data bus // instruction sent to CIR

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31
Q

Instruction set

A

list of all the commands that can be processed by a CPU and the commands are machine code

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32
Q

What is meant by a MAC address?

A

Media access control

UNIQUE address // used to identify a device // does not change // set by a manufacturer // first part : manufacturer ID // second part : serial number

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33
Q

uses of hexadecimal

A

error messages, IP(v6) address, assembly language, HTML colour codes, URL, ASCII.Unicode

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34
Q

DDoS attack. and it’s method of prevention

A

attacker encourages people to download malware onto their computer
turn each computer into a bot creating a network called a bot net

multiple computers are used as bots // designed to deny people access to a website // large number of requests sent to a server // all at the same time // server is unable to respond // the server fails

prevent - Firewall OR proxy server

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35
Q

characteristics of IP address

A

unique address // can be static or dynamic // can be public or private // can be IPv6 // can be IPv4

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36
Q

network component that uses IP address to send data only to its correct destination

A

router

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37
Q

purpose of CU

A

send control signals // that manage the transfer/flow of data & instructions within the CPU

decodes an instruction // using an instruction set // manages the execution of instructions in CPU

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38
Q

purpose of core in a CPU

A

process an instruction // carry out a fetch-execute cycle

increasing core may increase perforance, because more instructions can be processed simulaneously

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39
Q

Advantages of high-level language

A

easier.quicker to read/write/understand - less chance of mistakes

greater range of languages

easier to maintain

easier to debug
-> can find and correct errors in less time

code is portable

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40
Q

disadvantages of high-level language

A

not able to directly manipulate the hardware // may need to wait for translation before running // program may be less efficient

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41
Q

IDE (integrated development environment) , and it’s functions

A

software that provides useful functions for a programmer writing a computer program

code editor, run-time environment, translators, error diagnostics, auto-completion, auto-correction, prettyprint

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42
Q

character set

A

all the characters and symbols that can be represented by a computer system // each character & symbol assigned a unique value

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43
Q

secure socket layer (SSL)

A

is a security protocol // encrypts any data that is sent // uses digital certificates // which are sent to user’s browser // that contains the ___’s public key // that can be used to authenticate the ____ // once the certificate is authenticated, the transaction will begin

− Uses (digital) certificates
− ….requested from web server by browser/client // browser/client asks web
server to identify itself
− Server send SSL/digital signature to browser/client
− Client and server agree on encryption method to use
− … that contains the server’s public key
− Browser checks authenticity of certificate…
− … then session key is generated
− … the transaction will begin // sends signal to server to start transmission

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44
Q

what is meant by ROM

A

read only memory// non-volatile memory // primary storage // holds firmware // cannot be written to

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45
Q

phishing

A

legitimate looking emails sent // encourages user to click link // redirects to a fake website // aim is to obtain personal details

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46
Q

pharming

A

malicious code is downloaded without user’s knowledge // that will re-direct user to fake website // encourages to enter personal details into a fake website

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47
Q

brute-force attack

A

Trial and error to guess a password //
Combinations are repeatedly entered // until correct password is found //
Can be carried out manually or automatically by software

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48
Q

hacking

A

gaining UNAUTHORISED ACCESS to the computer
steal data file that contains personal details

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49
Q

malware (include types of malware)

A

virus, worm, trojan horse, spyware, adware, ransomware

email sent to user to encourage them to click link/download attachment // triggers download of malware/virus

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50
Q

social engineering

A

Manipulating / deceiving / tricking people ///// to obtain data // to force them to make an error

e.g. phishing

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51
Q

how does encryption improve data security

A

encrypted text is meaningless// need the key to decrypt the text

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52
Q

what is meant by interrupt

A

signal sent from a device // requests processor time // interrupts have different priorities

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53
Q

benefits of touch screen

A

does not require peripherals // less chance of input error // number of possible inputs limited

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54
Q

what is meant by HTML structure & presentation
and examples of it

A

structure : layout of the web page ,
e.g. placement of text, margins, line break, padding, heading, subheading

presentation : formatting of the web page ,
e.g. font colour, font style, font size, image size, background colour

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55
Q

why are structure & presentation often separated

A

FORMATTING of the page can be edited WITHOUT NEEDING TO ALTER THE STRUCTURE // so they can make regular updates without needing to check the structure

FORMATTING document can be used again for a different website // if further content are added to website, necessary formatting can be easily applied // this can save time when developing a website

can easily change the style of webpage
can add new content and apply same style easily
can re-use presentation for other websites

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56
Q

browser

A

SOFTWARE/APPLICATION that allows users to view webpages / render HTML

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57
Q

ISP internet service provider

A

company that provides a user with a connection to the internet

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58
Q

HTTP // HTTPS

A

hypertext transfer protocol secure —— secure protocol that is used to send data for web pages across the internet // set of rules for data transmission // combines HTTP and SSL to transmit data // encrypts data for transmission

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59
Q

cookie

A

small text FILEs // stored by the browser // that contains data about a USER’S BROWSING HABITS/DETAILS/PREFERENCES

sent between web SERVER and BROWSER when user visits the website.

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60
Q

firewalls

A

set criteria // such as a whitelist/blacklist // firewall examine the INCOMING & OUTGOING traffic // check whether traffic meets criteria // if data is sent that is not on the list, it will be blocked.rejected

prevents hacking

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61
Q

What is meant by a high-level language

A

uses English-like statements , close to human language // needs to be converted to MACHINE CODE // using a translator // it is portable // one line of code can perform multiple commands

machine independent,

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62
Q

examples of data damage and it’s prevention method

A

software failure – enable automatic updates

hardware failure – correct care & maintenance of hardware

fire – keep device in a fireproof box when not in use

water – don’t have water near the device

data accidentally deleted – add verification method for data deletion

back data up, use surge protection, don’t drink liquids near a computer

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63
Q

examples of optical data storage

A

CD, DVD, blu-ray

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64
Q

what is meant by HTML

A

hypertext mark-up language

used to create webpages

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65
Q

uses / functions of cookies

A

saving personal details –> no need to be re-entered // tracking user preferences -> can send adverts that match their preferences // holding items in an online shopping cart // storing login details

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66
Q

role of arithmetic logic unit

A

carries out calculations // carries out logical operations // holds temporary values during calculations // temporarily store data // in a register called the accumulator

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67
Q

functions of operating system

A

managing files // interrupt handling // managing user accounts // managing peripherals // multitasking // providing an interface // installs software // memory management

68
Q

how are data encrypted

A

encryption algorithm is used // to scramble data // original data called plain text // key is used to encrypt the data // key applied to plain text // plaint text encrypted into cypher text

key is transmitted separately // key is used to decrypt the cypher text

69
Q

spyware

A

The user receives an email with an attachment/link containing the spyware // user clicks a link on an untrusted website // spyware downloaded onto the user’s computer // spyware records all the key logs from the user’s keyboard // recorded key logs sent back to the creator of the spyware // key logs analysed // A common pattern/word in the key logs allows a password to be identified

70
Q

what is meant by primary storage

A

memory directly accessed by the CPU // example : RAM,ROM // RAM stores data&programs that are currently in use, ROM permanently stores boot-up instructions // RAM : volatile, ROM : non-volatile

71
Q

what is meant by secondary storage

A

storage that is not directly accessed by CPU // example : HDD,SDD // stores data,files that can be accessed at a later stage // non-volatile

72
Q

how does compiler translate a computer program and report errors

A

translates high-level language into machine code // translates all at once before executing // produces an executable file

creates an error report after trying to compile // displaying all errors // require correction before execution can take place

73
Q

how does interpreter translate a computer program

A

translates high-level language to machine code // translates line by line // stops execution when an error is found // will only continue when error is fixed

74
Q

what is an assembly language

A

form of low-level language that uses mnemonics.
assembler is needed to translate an assembly language program into machine code.

75
Q

what is meant by https

A

hypertext transfer protocol secure // means the website uses SSL // means data sent is encrypted

76
Q

proxy server

A

acts as a firewall // monitor/examines incoming AND outgoing traffic // rules for traffic can be set // blacklist/whitelist set // blocks any traffic that does not meet criteria // can send a warning message to the user // stop the website failing in a Dos attack

prevents direct access to the WEBSERVER // if an attack is launched it hits the proxy server instead // used to direct invalid traffic away from the webserver // filter traffic // if traffic is valid, data will be obtained by the user // if traffic is invalid, request to obtain data is declined // can block requests from certain IP addresses

limits the number of requests to the website // preventing too many requests that could overwhelm the server // block multiple requests from the same IP within a timeframe

help prevent ddos, act as a firewall, reduce the number of requests server needs to process, allow faster response time for requests

77
Q

examples of robotics

A

factory equipment, domestic robots, drones

78
Q

role of web browser in requesting&displaying web pages for the website

A

sends request to webserver // receives web pages back from webserver // converts HTML to display web page // manages protocols

79
Q

purpose of RAM

A

store data currently in use

80
Q

purpose of ROM

A

permanently store the boot up instructions

81
Q

purpose of HDD

A

store the database / software

82
Q

virus

A

software that can replicate itself // cause the computer to crash // could delete,damage files // could fill up the storage space // could spread to other devices on the network

83
Q

how does a browser check that a website is secure

A

requests web server to identify SSL certificate // receives a copy of a certificate, sent from the web server // checks if certificate is authentic // sends signal back to webserver that it is authentic // starts to transmit data once connection is established as secure

84
Q

symmetric encryption

A

data is ENCRYPTED and DECRYPTED using the SAME key// if hacker gains access to the key, they can decrypt intercepted information

data before encryption : plain text
data after encryption : cypher text
key is sent to a receiver

85
Q

asymmetric encryption

A

uses public & private key . both keys are needed to encrypt and decrypt

86
Q

IP address

A

internet protocol .

UNIQUE address // used to identify and locate devices on the internet // can be static or dynamic // IPv4 has four groups of digits // IPv6 has eight groups of digits // can be public or private

87
Q

what is meant by low-level language

A

close to language processed by computers // may use mnemonics // example : assembly language, machine code

machine dependent, have direct access to memory locations, may need an assembler to be translated, one line of code represents a single instruction

88
Q

advantages of low-level language

A

quicker to execute // can directly manipulate the hardware –> more efficient control // program will be more memory efficient // no requirement for a compiler.interpreter // allows the use of specialised hardware

89
Q

concept of digital currency

A

ONLY exists electronically // decentralised // volatile // example : bitcoin

can be a decentralised system // can be a centralised system // usually encrypted

90
Q

definition of digital currency

A

currency that exists only in electronic form

91
Q

process of blockchain

A

acts as a ledger // by tracking each transaction // keeps a series of time-stamped records // that cannot be altered

92
Q

difference between application software & system software

A

system - provides services that the computer requires (operating system, utility software)

application - provides services that the user requires

93
Q

How captured images are converted to digital photo files

A

– Image is converted from analogue to digital (using ADC)
– Image is turned into pixels
– Each pixel is given a binary value
– Pixels form a grid (to create the image)
– Each pixel has a colour
– Pixels are stored in sequence (in a file)
– Meta data is stored (to describe the dimensions/resolution of the image) // It stores the dimensions/colour
depth .etc.
– An example of a suitable photo file format e.g. JPEG

94
Q

checksum

A

– checksum value is calculated FROM THE data
–using an algorithm
- value appended to the data
– (checksum/calculated) value transmitted with data
– receiver recalculates the checksum value
- value compared to the transmitted checksum after transmission
– If they are the same then no error-successful transmission, otherwise an error has occurred

95
Q

ARQ

A

– uses positive/negative acknowledgment and timeout
– sender starts a timer when data (packet) is transmitted
– receiving device checks data packet for errors
– once they know the packet is error free it sends an acknowledgement back to the sending device
– next packet is sent

– A request is sent with data to acknowledge all data is received
– Acknowledgement sent back to say all data is received
– if no error detected, positive acknowledgement is returned to sender
– if error detected, negative returned to sender
– triggers the data to be resent
– If no acknowledgement is received in a time frame data TINMEOUT OCCURS, data packet is automatically resent.
– until an acknowledgement is received

96
Q

optical storage - how is laser used to store and read data from the disk?

A

 Laser is shone at the disk
 An (arm/head) moves the laser across the surface of the disk
 The laser burns pits onto the surface of the disk
 The laser is used to read the pits and lands on the surface of the disk
 The reflected light from the laser shining on the disk is captured (by a sensor)

97
Q

advantages of SSD

A

small in size, low power consumption, fast access speed, runs quietly, runs at cool temp, high capacity

98
Q

why computer can only process binary data

A

 Computer consist of transistors / logic circuits/gates …
 … that can only store/process data in two states / high-low / on-off / 1 and 0

99
Q

benefits of USB

A

− universal standard
− can’t be inserted the wrong way around/incorrectly
− Supports different transmission speeds
− Automatically detects device
– fast transmission speed
– backward compatible
–

100
Q

Role of program counter

A

holds the address of the NEXT/CURRENT INSTRUCTION to be processed

101
Q

role of MAR

A

holds the address of the data that needs to be fetched / address where the data needs to be stored

102
Q

role of MDR

A

TEMPORARILY store // address of next instructions required // stores address that is to be collected by the address bus

stores data THAT IS IN USE // from address in MAR

103
Q

role of CIR

A

stores the instruction of CPU currently decoding or executing

104
Q

role of accumulator

A

built into ALU, temporary holds the result of interim calculation

105
Q

drawback of using LOSSY compression

A

reduced quality, original file cannot be reconstructed

106
Q

drawback of using LOSSLESS

A

takes more time to transmit file // larger file size -> takes up more storage space // data usage would be increased // uses more bandwidth -> could be more expensive

107
Q

what is stored in primary storage

A

BIOS // start-up instructions // programs currently in use // data currently in use // parts of OS currently in use

108
Q

why are both checksum & ARQ used

A

checksum used to detect errors // using a calculated value
ARQ checks if data is received // uses acknowledgement and timeout
requests data be sent again if checksum detects error

109
Q

how are webpages requested and displayed

A

Brower sends URL to DNS // using HTTP(S) // DNS finds matching IP addresses for URL // DNS returns IP address to the browser // browser sends request to web server // web server sends web pages back to browser // browser RENDERS HTML to display webpages // security certificates exchanged // encrypting any data sent

110
Q

why might a error not be detected using parity check

A

transposition of bits // does not check the order of bits // even number of bits change // incorrect bits still add up to correct parity

111
Q

disadv of parallel data transmission

A

bits may arrive skewed // more expensive to setup // limited distance // more prone to error

112
Q

adv of using hexadeciaml

A

easier to understand // easier to debug // takes up less screen space,display // less chance of making an error

113
Q

operation of USB flash memory

A

data flashed onto chips // uses NAD/NOR technology // uses transistors // to control the flow of electrons // type of EEPROM tech // when data stored, transistor is converted from 1 to 0 // writes sequentially

114
Q

how are cookies used

A

webserver sends cookie file to user’s browser // user’s data (payment details) stored in encrypted text file // cookie file is stored by browser // when revisit website, webserver requests cookie file // and broswer sends cookie file back to webserver

115
Q

concerns of cookies

A

user does not see what info is stored // feel privacy is affected

profile could be built about the user // lead to identity theft

sensitive info stored could be intercepted in transmission // other websites could gain access to stored cookies // so payment info could be stolen and used by a third party

116
Q

operation of HDD

A

− It has platters
− Platters/disk divided into tracks
− Platter/disk is spun
− Has a read/write arm that moves across storage media
− Read/writes data using electromagnets
− Uses magnetic fields to control magnetic dots of data
− Magnetic field determines binary value

117
Q

parity check

A

odd or even parity is SET for the data
number of 1s/0s counted
parity bit is added to each byte before transmission
to make the sum of the bits in each byte odd/even
after transmission, if the number is __ no error detected
after transmission, if the number is ___ error is detected

118
Q

why are lossy > lossless

A

decreases file size more
quicker to upload.download
takes up less bandwidth to upload
less lag
uses less data allowance

119
Q

three types of bus

A

Address = unidirectional

data = bidirectional

control = bidirectional

120
Q

components of expert system

A

knowledge base, rule base, inference engine, interface

121
Q

operation of expert system

A

has an interface // used to input data // has a knowledge base // has a rule base // has an inference engine // applies rule base to provide output // decides what to ask next based on the data input

122
Q

how is text converted to binary to be processed by the computer

A

character set is used
such as ASCII/unicode
each character has a unique binary value

123
Q

what is meant by cloud storage

A

A collection of servers // that store data in a remote location // that allows data to be accessed remotely // that are (normally) accessed using an internet connection

124
Q

disadvantages of storing in cloud storage

A

May be less secure // May lose access to them if internet connection lost // Reliant on a third party maintaining the hardware // Could incur an extra/ongoing fee/cost

125
Q

network interface card definition

A

this is a component in a device that enables it to connect to a network

126
Q

router definition

A

device that forwards packets to their correct destinations in a network

127
Q

how to avoid pharming

A

 Checking the spelling and tone of the email/website
 Checking the URL attached to a link
 Scanning a download with anti-malware
 Only downloading data / software from trusted sources
 Never providing personal details online
 Install a firewall to check if the website is valid

128
Q

access levels

A

 Providing users with different permission for the data
 Limiting access to reading data limiting the data that can be viewed
 Limiting access to editing data // limiting the data that can be deleted / changed
 Normally linked to a username

129
Q

advantages of serial data transmission, not parallel

A

More accurate/reliable/efficient over long distances
− Less chance of interference / cross talk
− …that will skew / distort the data // less likely to get errors
− Data will arrive in order
− Serial is cheaper to purchase/install/maintain

130
Q

why are interrupts needed

A

− To identify that the processor’s attention is required // to stop the current
process/task
− To allow multitasking
− To allow for efficient processing // prioritising actions
− To allow for efficient use of hardware
− To allow time-sensitive requests to be dealt with
− To avoid the need to poll devices

131
Q

how digital image file is stored

A
  • Image is made of pixels
  • Each pixel stores one colour
  • Image has a set number of pixels wide by pixels high
  • Each colour has a unique binary value // Each colour has a unique colour code
  • The colour/binary value of each pixel is stored in sequence
  • File contains metadata to identify how the file should be displayed
  • … metadata can be the colour depth / resolution
132
Q

how parity bit is used

A

parity can be set to odd or even // sender and receiver agree on parity to use // data is split into bytes // sender counts the number of 1s/0s in each byte // each byte is assigned a parity bit to match the parity // receiving device recounts the number of 1s in each byte // and compares to parity used, AND if it doesn’t match, an error is reported

133
Q

how check digit can be used

A

data is input with check digit // calculation is performed on the data // calculated digit is compared to a stored value // if it matches, the data entered is correct // if it does not match, the data entered is correct

134
Q

TLS protocol

A

− Client/browser requests secure connection to server
− Client/browser requests the server to identify itself
− Server provides a digital certificate
− Client/browser validates the certificate
− Client/browser send signal back to server (to begin transmission)
− Session caching can be used
− A session key is generated
− Encryption method is agreed // data is encrypted

135
Q

two layers of TLS

A

handshake, record

136
Q

Difference between compiler and interpreter

A

− An interpreter translates and executes the code line by line
− … whereas a compiler translates and executes the whole code all in one go
− An interpreter stops translating and reports an error as it finds one
− … whereas a compiler produces an error report at the end of translation
− An interpreter does not produce an executable file
− … but a compiler does produce an executable file
− An interpreter will execute the code until it finds an error
− … whereas a compiler will not execute any code if there are errors present
− An interpreter allows correction of errors in real-time
− … whereas a compiler needs to retranslate the code each time after errors are found and corrected

137
Q

when an interrupt signal could be generated

A

− A peripheral is connected/disconnected
− A key on a keyboard is pressed
− A mouse button click
− A phone/video call is received
− A buffer requires more data
− A printer has a paper jam
− A printer runs out of paper
− A printer runs out of ink
− When switching from one application to another

138
Q

what would happen if interrupt signals were not used in computer

A

− The computer would only start a new task when it had finished processing the current task // by example
− Computer will not be able to multitask
− Errors may not be dealt with
− Computer would become impossible to use

139
Q

role of an interrupt in generating a message on the comp that the paper has jammed

A

− Printer generates interrupt
− Interrupt is given a priority
− Interrupt is queued
− Interrupt stops CPU from processing current task
− CPU will service interrupt // Interrupt handler services interrupt …
− … generating an output message to state there is a paper jam

139
Q

why lossless .> lossy

A

maintains quality // original file is retained, data not permanently lost // significant reduction in file size not required

139
Q

why would you write a software in assembly language

A

can directly access the hardware // can use special machine-dependent instructions // no need for program to be portable // smaller file size // more efficient use of memory // programs will be more time efficient when running

139
Q

drawbacks of using assembly language

A

programs are not portable // complex to learn // difficult to debug

139
Q

hoow secure connection is created

A
  • Web browser sends request to web server
  • … to view the digital certificate
  • Web server sends the digital certificate to the web browser
  • Web browser checks the certificate for authenticity
  • If certificate is authentic a secure connection is created
  • Any data sent is encrypted
  • If certificate is not authentic the connection is rejected
  • Uses a protocol such as SSL/TLS
140
Q

preventing accidental data loss

A

create a back-up // data can be restored
add verification // get the user to confirm they want to delete the data
set access rights // she cannot delete any files

141
Q

how the interrupt signal is processed

A

__ generates interrupt // interrupt given priority // interrupt signal sent to the CPU // interrupt is placed in a queue // CPU stops the task it is currently processing, to check the queue // to service the interrupt // using an interrupt service routine // if __ is highest priority the interrupt is processed // once the interrupt is serviced, a message is displayed to notify the user

142
Q

how analogue sound is recorded and converted to digital

A

recorded using microphone
sound wave is sampled
measuring the amplitude
each amplitude has a unique binary value
sample rate is et
= number of samples taken per sec
sample resolution is set
= number of bits used for each sample
each sample taken is converted to binary

143
Q

purpose of the operating system

A

PERFORMS the basic functions of a computer // manages the hardware // provides a platform to run software // provides user interface // performs tasks such as ____

144
Q

why might an error occur when data is transmitted

A

interference

145
Q

advantages of storing data in cloud storage

A

data can be accessed from any location
-> can work from anywhere with a connection

Hardware is owned/maintained by a third party
-> aren’t responsible for its security

can increase storage needed easily
-> without needing to buy new hardware

cloud system will back up the data
-> does not need to do this cuz it does it for you

146
Q

disadvantages of storing data in cloud storage

A

INTERNET connection is needed
-> if not available, data cannot be accessed

employees could be pressured to work outside of hours
-> as they can access the data from any location

147
Q

machine learning capabilities

A

form of artificial intelligence // means it can adapt // can edit its own data // can be trained .// this can be supervised // meanng it can learn with human interaction // analyses patterns and stores SUCCESSFUL results // to influence future decisions // supervised means a user tells the system the input and output

148
Q

differences between primary storage and secondary storage -

A

P : directly accessible by CPU, S : not directly accessible by CPU

P : stores data currently in use, S : stores USER’S files

P : SOME PARTS are volatile, S : non-volatile

P : SOME PARTS cannot be changed, S : can be changed

P : faster access speeds to data, S : slower access speeds to data

149
Q

similarities and differences between proxy-servers and firewalls

A

Similarities : check incoming and outgoing signals // store whitelist // block incoming,outgoing signals // both block unauthorised access // keep a log of traffic // both can be hardware or software or both

differences :
P can hid user’s IP address, F does not hide
P protects a server, F protects individual computer
P PROCESSES client-side requests whereas firewall FILTERS packets
P transmits website data to the user, F does not
P can hide internal network from internet, F cannot

150
Q

data commonly stored in RAM

A

currently running data // currently running software //currently running instructions // currently running parts of OS // currently running utility software

151
Q

purpose of secondary storage \

A

for non-volatile storage of data
to store data that is not currently required by the CPU
to store data to transfer it to another computer

152
Q

what is a pixel

A

ONE square of ONE colour

153
Q

how does program use AI

A

use MACHINE LEARNING algorithms
collects data about where it has been
collect data about obstacles
store successful actions
stores unsuccessful actions
identify patterns
to make sure it does not repeat the same incorrect route
so it knows how to react to obstacles next time

154
Q

why biometrics

A

adds extra level of security // requires properties unique to individual // don’t need to remember password

155
Q

similarities between check digit and checksum

A

both calculate a value from the data // both append the calculated value to the data // both recalculate the value // both report an error if they don’t match

156
Q

keylogging

A

keylogger downloaded without knowledge // keylogger records key presses // data is relayed back to third party // data is analysed // details can then be used to log into account

157
Q

how a browser checks that the website is secure

A

requests web server to identify itself (request to view the SSL certificate // receives a copy of SSL certificate, sent from the webserver // checks if SSL certificate is authentic // sends signal back to webserver that the certificate is authentic

158
Q

how SSL connection is established

A
  • Browser / client sends request to webserver to request identification
  • Web server sends its digital / security certificate
  • Browser authenticates certificate
    «
    *
    « if authentic connection, is established
  • Any data sent is encrypted
    «
    *
    « using public and private keys
159
Q

how image is represented

A

image made up of pixels
each pixels stores one colour
image has set number of pixels wide by pixels high
each colour has unique binary value
binary value of pixel stored in sequence

160
Q

characteristics of von neuman architecture

A

both data & instructions sotred in same memory unit
single arithmetic & logic unit
single control unit
uses FDE cycle to execute instructions serially

161
Q

clock speed

A

max number if FDE cycles a CPU can perform

162
Q

cache

A

type of storage that stores frequently used data // to speed up access as it;s faster to access than RAM

163
Q

AI

A

branch of computer science dealing with the simulation of intelligent behaviours by computers

collect data, store rules for using data, ability to learn, by adapting what it does by changing i’ts own rules, by changing its down data, find patterns

COMP SCI (2 decks)

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