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Revision > Computer science > Flashcards

Computer science Flashcards

1
Q

What is the purpose of an operating system

A

To manage hardware and run software

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2
Q

What are the functions of an operating system

A

communicate with input and output devices through drivers
provides a user interface
manage system security and user accounts
organise CPU and its processing tasks

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3
Q

What are some ethical issues of technology

A

some people don’t have enough money to buy smartphone- barred from opportunities

each country has a different level of tech- people in countries of lower tech will be barred from some opportunities

internet grants anonymity-causes anti-social behaviour

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4
Q

What are some legal issues of the internet

A

malware can be used to steal info from users and then sell that info without there permission

identity theft is more common

Pirating

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5
Q

What are the pros of using compilers

A

translates the whole source code and the creates an executable file
only needed once to create an executable file

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6
Q

what are the cons of using a compiler

A

compiling takes a long time

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7
Q

What are the pro’s of using a interpreter

A

will return first error it finds- good for debugging

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8
Q

What are the cons of using an interpreter

A

needed every time you want to run the program

program will run more slowly-code being translated as program is running

doesn’t create an executable file after one use-translates and runs code one line at a time

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9
Q

What are the pros of using high-level language

A

easier for humans to write and understand

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10
Q

what are the cons of high level language

A

it has to be translated into machine code for computer to understand

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11
Q

What are the pros of low level language

A

easier for machines to understand

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12
Q

what are the cons of low level language

A

harder for humans to understand

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13
Q

What is an SMTP

A

simple mail transfer protocol- used to send and transfer emails

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14
Q

What is a HTTPS

A

a version of HTTP that secures data

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15
Q

what is HTTP

A

hyper text transfer protocol-used by web browsers to access websites and communicate with websites

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16
Q

What is FTP

A

File transfer protocol- access edit and move files to another server/device

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17
Q

What is a relational database

A

a database with multiple tables that are linked.
Reduces the amount of times data repeats and data that don’t match

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18
Q

What are some examples of data compression methods

A

Run length encoding
Huffman coding

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19
Q

What is White box penetration

A

To simulate an attack from a malicious insider, who have knowledge of basic credentials example username and password.

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20
Q

What is a penetration test

A

A penetration test is a simulated cyberattack carried by ethical hackers to find vulnerabilities in a system, website, mobile application, or network

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21
Q

What does wan stand for

A

Wide area network

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22
Q

What does WAN stand for

A

Wide area network

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23
Q

What does LAN stand for

A

Local area network

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24
Q

What does PAN stand for

A

Personal area network

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25
Q

What is in a PAN network

A

blue tooth devices

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26
Q

What is Rom

A

ROM is a non volatile primary storage

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27
Q

What does non volatile mean

A

when the computer is turned off the stored items will still be kept

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28
Q

What is ROM used for

A

to store instructions and data that the computer needs to run

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29
Q

What is cloud storage

A

remotely accessed storage which is accessed through the internet

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30
Q

Adv of cloud storage

A

you can access your files from any location that has connection to the internet

reduced need to make backups as the cloud already makes backups

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31
Q

Disadv of cloud storage

A

cloud storage hosts could be targeted by hackers

people have less control over their data

access to data is only possible with an internet connection - no connection means no access to data

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32
Q

What is the formula for calculating pixels

A

resolution X colour depth

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33
Q

what is the formula for calculating sounds

A

length X sample rate X bytes

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34
Q

What is sample resolution

A

the number of bits per sample

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35
Q

What is Abstraction

A

a technique that removes the unnecessary details so that you can focus on the important parts of a question

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36
Q

What is decomposition

A

When you break down a large problem into smaller manageable steps

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37
Q

What is selection

A

Selection is where a piece of code is only run if a condition is met

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38
Q

What is Iteration

A

Iteration is the repeated execution of a section of code when a program is running.

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39
Q

What is algorithmic thinking

A

a way of solving problems by producing algorithms

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40
Q

What are sort algorithms

A

a set of instructions used to arrange a data set into a particular order

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41
Q

What does Boolean represent

A

True or false

basically just one of two values

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42
Q

What are the factors that affect CPU speed

A

clock speed
Cache size
Cache type
how many cores the CPU has

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43
Q

What is Secondary storage

A

Storage that is directly connected to the CPU

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44
Q

Why is Secondary storage needed

A

Needed so there is long term storage is available

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45
Q

How is data stored in an optical disk

A

Binary data is stored as variations of height on the disks surface

46
Q

How is data read on Optical storage

A

Light is shined on the disk and is reflected back differently when it either hits a flat piece of the disk (land) or a divot in the disk.
The way the light reflects back decides if the value will either be read as a one or a zero

47
Q

What are the pros of optical storage

A

it is fairly reliable and durable

and has good portability

48
Q

What are the cons of optical storage

A

can be easily damaged through scratches

Has a small capacity usually less than a GB

49
Q

How does magnetic storage work

A

As the disk is spinning, a read/write head containing electro magnets moves across its surface. To write data, the head magnetizes or demagnetizes a section of the disk that is spinning under it. To read data, the head makes a note of whether the section is magnetized or not.

parts of the surface is either magnetized (1) or demagnetized (0) the heads control this and read what state they are in

50
Q

What are the pros of magnetic storage

A

Large capacity
Cheap

51
Q

What are the cons of Magnetic storage

A

Not that durable

Generally not that portable

can be noisy and generate heat

52
Q

What is solid state storage

A

Solid state storage is a special type of storage made from silicon microchips. It can be written to and overwritten like RAM. However, unlike RAM, it is non-volatile, which means that when the computer’s power is switched off, solid state storage will retain its contents.

53
Q

What are the cons of SSD’s

A

Expensive
Generally have a smaller capacity than magnetic

54
Q

What are the pros of SSD’s

A

Very fast storage- because the data is stored electrically in silicon chips called cells.

Very reliable as they’re non-mechanical

Don’t need defragmentation

Are silent

55
Q

What is an Embedded system

A

A special purpose computer encapsulated in a larger computer

56
Q

What are the qualities of embedded systems

A

Can only perform a specific task

Can not be easily programmed

57
Q

What are some examples of embedded systems

A

Cockpits in a plane

Systems such as braking systems in a car

Embedded systems in hospital devices

58
Q

What is a bus

A

a collection of wires through data is transmitted

59
Q

Why is the width of a bus important

A

The the width of a bus is how many bits it can transfer at a time

60
Q

What is the purpose of the address bus

A

Sends a memory address along the CPU to the main memory.

To fetch/write data the CPU needs

to tell the ram where the Data is through the address of the data

61
Q

What is the purpose of the data bus

A

A data bus sends the actual data to and from the memory

62
Q

What is the purpose of the control bus

A

Control bus carries commands from the CPU and status messages from other hardware devices.

63
Q

What is the ALU

A

The circuit that performs the operations on the data

64
Q

What is the control unit

A

The circuits coordinating the activities of the CPU

65
Q

What are registers

A

Quick small stores of data within the cpu

66
Q

what is the purpose of the control unit

A

The control unit controls the flow of data. It also keeps track of memory addresses of the instruction each cycle

67
Q

What is the purpose of the ALU

A

The ALU gets data from the registers and CU, performs an operation on it, and sends the output back to the registers

68
Q

What is the purpose of the registers

A

The registers hold any data, instructions and memory addresses that are about to be used by the CPU. There are specific registers for different tasks, E.G. one that holds data that is about to be used by the CPU

69
Q

What is the purpose of the clock

A

The clock sends out a signal that constantly cycles between one and zero - which is used to synchronize when instructions will be carried out

70
Q

What is cache

A

Very fast memory in the CPU. It’s slower than the registers but faster than Ram

The bigger its cache, the less time a processor has to wait for instructions to be fetched.

71
Q

What is the purpose of Cache

A

Stores regularly used data so that the CPU can access it quickly the next time its needed

72
Q

What is the Purpose of ROM

A

The purpose of ROM is to hold the instructions needed for a computer to properly boot up

73
Q

What does the CPU do with the ROM when the computer boots up

A

The CPU reads instructions from the ROM telling it to perform self checks and setup the computer

74
Q

What is the purpose of RAM

A

Ram is where all data, Files and programs are stored while there being used - for example when a computer boots up the operating system is moved from secondary storage to RAM as its quicker.

75
Q

What are graphical user interfaces

A

GUIs feature a desktop where everything is displayed. Applications run in Windows, and all objects (apps, hardware and files) are represented by icons.

Application features are accessible through the use of menus.

Users interact with the interface by using a mouse and on-screen pointer.

76
Q

What are the pros of graphical user interfaces

A

GUIs are powerful and easy to use

77
Q

What are the cons of graphical user interfaces

A

require a lot of processing power.

78
Q

What are mobile user interfaces

A

Mobile UIs are similar in many ways to GUIs, except that they respond to touch.

79
Q

What are command-line interfaces

A

Command line interfaces are text-based. Users control the computer by typing in commands.

80
Q

What are the pros of command line interfaces

A

CLIs require little processing power and are extremely powerful

81
Q

What are the cons of command line interfaces

A

they are difficult to use

82
Q

What does multi tasking mean

A

Multitasking means to be able to run more than one program simultaneously

83
Q

What must a computer have to be able to multi- task

A

the operating system can support multitasking

the computer has enough memory to hold more than one program in primary memory at the same time

84
Q

What are device drivers

A

Software that controls and communicates with peripherals

85
Q

What are the advantages of device drivers

A

any device can be used with the operating system, as long as a driver is available for it

drivers can be updated, usually to give better performance or to remove a bug

86
Q

What are cores in a CPU

A

A processing unit within a CPU is known as a core. Each core is capable of fetching, decoding and executing its own instructions.

The more cores a CPU has, the greater the number of instructions it can process in a given space of time.

87
Q

What is clock speed

A

Clock speed is the number of pulses the central processing unit’s (CPU) clock generates per second. It is measured in hertz.

88
Q

What is over clocking

A

CPU clocks can sometimes be sped up slightly by the user. This process is known as overclocking.

The more pulses per second, the more fetch-decode-execute cycles that can be performed and the more instructions that are processed in a given space of time.

89
Q

What are the cons of over clocking

A

Overclocking can cause long term damage to the CPU as it is working harder and producing more heat.

90
Q

What are the key elements of von-Neuman architecture

A

data and instructions are both stored as binary.

data and instructions are both stored in main memory.

instructions are fetched from memory one at a time and in order - serially.

the processor decodes and executes an instruction, before cycling around to fetch the next instruction.

the cycle continues until no more instructions are available.

91
Q

What is von-Neuman architecture

A

A description of the processing architecture that all CPUs use. John von Neumann invented the processor architecture which stores a program in memory as instructions and executes them sequentially using the ALU, control unit and registers. This is known as the stored program concept.

92
Q

What five registers does a processor based on von-Neuman architecture have

A

Program counter (PC) - holds the memory address of the next instruction to be fetched from main memory.

Memory address register (MAR) - holds the address of the current instruction that is to be fetched from memory, or the address in memory to which data is to be transferred.

Memory buffer register (MBR) - holds the contents found at the address held in the MAR, or data which is to be transferred to main memory. It is also referred to as the memory data register (MDR).

Current instruction register (CIR) - holds the instruction that is currently being decoded and executed.

Accumulator (ACC) - holds the data being processed and the results of processing.

93
Q

What is a network topology

A

A network’s topology is the arrangement, or pattern, in which all nodes on a network are connected together.

94
Q

What are the most common topologies

A

bus topologies

star topologies

95
Q

What are bus topologies

A

A network layout where all nodes are connected along a linear link/backbone known as a bus.

96
Q

What are star topologies

A

A network where each node is connected to a central switch.

97
Q

What is a node

A

Any device connected to a network.

98
Q

disadvantages of using a bus topology

A

the whole network fails if the backbone cable is broken

terminators must be installed at each end of the backbone

having one backbone increases the chances of data collision

99
Q

Advantages of using a bus topology

A

it is easy to connect nodes to the network

less cabling is needed compared to a star topology, making it cheaper to install

100
Q

Advantages of using a star topology

A

each node is separately connected, therefore a failure of one node or its link - transmission media - does not affect any other nodes

new nodes can be added to the network simply by connecting them to the switch

star networks tend to have higher performance as a message is passed on to its intended node only

101
Q

Disadvantages of using a star topology

A

the whole network fails if the switch fails as no node can communicate

a wired star topology requires plenty of cable - in a large network this can be expensive

102
Q

What are the four layers in an network

A

Application layer

Transport layer

Network layer

Data link layer

103
Q

What operates at the application layer

A

applications such as web browsers and email programs operate at this layer. Protocols such as HTTP, HTTPS, SMTP, IMAP and FTP operate at this layer.

104
Q

What operates happens at the transport layer

A

this breaks down the message into small chunks (packets). Each packet is given a packet number and the total number of packets. This layer sets up the communication between hosts, using protocols such as TCP and UDP.

105
Q

What happens at the network layer

A

this adds the sender’s and recipient’s IP addresses to the packet, and packages the data to make it ready for transmission. The network layer also routes the packets across the network.

106
Q

What is at the data link layer

A

the network interface card/controller (NIC) and operating system drivers are at this layer.

107
Q

Advantages of using networks

A

file sharing - users can share files with other users

hardware sharing - users can share hardware, such as a printer

communication - users can communicate via email, chat, or by video

roaming access - users can sign in to any computer on the network and be able to access their files

centralised maintenance and updates - network managers can apply software updates across a network, removing the need for a user to worry about having to do so

centralised security - anti-virus software and firewalls can be implemented across a network, helping to protect user files from risks

user monitoring - network managers can monitor what users do on a network

levels of access - different users can be given different access rights, and this gives network managers the ability to generally restrict user access to certain files, while granting permission to specific users

108
Q

Disadvantages of networks

A

cost - additional equipment is needed to allow computers to communicate

management - networks require management by technical staff such as a network manager

spread of malware - viruses and other forms of malware can easily spread across an improperly secured network

hacking - once a device is connected to another device, it is possible that data may be accessed without the device owner’s permission

109
Q

What is LAN

A

A local area network (LAN) is a network that is geographically confined to one building or site. Examples include networks employed by small businesses, small organizations, schools, colleges, universities and in homes.

110
Q

What are WAN’s

A

A wide area network (WAN) is a network that is spread over a wide geographical area. It can cover more than one site, or be spread across a country, or even the world.

111
Q

What are PAN’s

A

A personal area network (PAN) is a network that is spread over a very small area. It often covers no more than a few metres and is used to connect personal devices such as a smartphone and wireless headphones or a laptop.

Revision (18 decks)

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