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Computer Science Yr 10-11 > Unit 3 > Flashcards

Unit 3 Flashcards

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1
Q

what is the purpose of the CPU

A

the Central Processing Unit processes instructions and data that are input into the computer to output the result

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2
Q

what does the CPU consist of

A

control unit(CU)
Arithmetic and Logic Unit(ALU)
registers and buses

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3
Q

what is the ALU

A

arithmetic and logic unit
does the required arithmetic or logic such as operations
computers can have multiple ALU’s

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4
Q

what is a microprocessor

A

a type of integrated circuit on a single microchip

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5
Q

what is the CU

A

control Unit
reads instructions from memory
The control units ensures synchronisation of data flow and program instructions through the computer

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6
Q

what is the system clock

A

used to produce timing signals on the control bus to ensure synchronisation
without it the computer would crash

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7
Q

what is the CIR

A

current instruction register
stores the current instruction being decoded and executed

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8
Q

what is the ACC

A

accumulator
stores data temporarily thats used for the calculations in the ALU

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9
Q

what is the MAR

A

memory address register
stores the address of the memory location currently being read from or written to

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10
Q

what is the MDR

A

memory data register
stores data which has just been read from memory is about to be written to memory

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11
Q

what is the PC

A

program counter
stores the address where the next instruction to be read can be found

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12
Q

what are system buses

A

used in computers as parallel transmission components
address bus, data bus, control bus

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13
Q

whats the address bus used for

A

carries addresses throughout the computer system
it is unidirectional(one direction)

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14
Q

what is the data bus

A

bidirectional
used to carry data from CPU to memory and vice versa
also to and from input and output devices

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15
Q

what is the control bus

A

bidirectional
carries signals from the control unit to all other computer components

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16
Q

what is the fetch - decode - execute cycle

A
  • the PC contains the address of the memory location of the next instruction
  • address is then copied from the PC to the MAR through the address bus
  • the data at the location are then copied temporarily into the MDR
  • the contents of the MDR are then copied and placed into the CIR
  • value in PC is incremented by 1 so it points to the next instruction which has to be found
  • instruction is decoded and executed by sending out signals through the control bus to the various components of the computer system
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17
Q

how can width of buses affect computer performance

A

increasing the width allows more data to flow meaning the CPU works faster

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18
Q

what is overclocking

A

if the clock speed becomes higher than the computer was designed for can cause the computer to be unsynchronised and cause the computer to crash
can lead to overheating and unreliable performance

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19
Q

what are cache memories

A

can also improve CPU performance
located inside the CPU meaning faster access times
stores frequently accessed instructions and datas
larger the cache size the better the CPU performance

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20
Q

how does the use of different number of cores affect performance

A

using more cores can improve computer performance
however increasing the number of cores means the the CPU needs to communicate more with each core so potential performance is reduced

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21
Q

what is instruction sets

A

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

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22
Q

what are embedded systems

A

combination of hardware and software which is designed to carry out a specific set of functions

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23
Q

features of an embedded system

A

they are small
cheap to make
consume little power
can be controlled remotely
reliable due to mass production

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24
Q

what is a barcode

A

a series of dark and light parallel lines of varying thickness

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25
Q

what devices can be found at a checkout in supermarkets

A

keypad(input)
screen/monitor(output)
speaker(output)
printer(output)
card reader (input)
touchscreen(input)

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26
Q

how do capacitive touch screens work

A

when fingers touch the screen, the electrostatic field of the conductive layer is changed and it can calculate where the change took place
there are 2 types, surface and projective

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27
Q

how do surface capacitive screens work

A

sensors are placed at the corner of the screen and the finger draws currents
only works with a bare finger or stylus

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28
Q

how do projective capacitive screens work

A

they create a 3D electrostatic field
when a finger touches the screen it disturbs the electrostatic filed
this system works with gloves and also allows pinching and sliding

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29
Q

advantages of capacitive screens

A

better image clarity than resistive
durable screens
projective allows multitouch

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30
Q

disadvantages of capacitive screens

A

surface capacitive only works with bare fingers
sensitive to electromagnetic radiation

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31
Q

how do infrared touch screens work

A

use a glass screen with an array of sensors and infrared transmitters
when one of the infrared beams is reduced the place where the screen is touched is located

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32
Q

advantages of infrared touch screens

A

allows multi touch facility
has good screen durability
isnt affected by scratched or cracked screen

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33
Q

disadvantages of infrared screens

A

can be sensitive to water or moisture
possible for accidental activation
can be sensitive to light interference

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34
Q

how do resistive screens work

A

there are 2 resistive layers
when the top layer is touched it makes contact with the bottom layer resulting in a flow of electricity
the point of contact is where there is a change in voltage

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35
Q

advantages of resistive screens

A

good resistance to dust and water
can be used with gloves

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36
Q

disadvantages of resistive screens

A

low touch sensitivity
doesnt support multitouch faciliy
poor visibility in strong sunlight
vulnerable to scratches on the screen

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37
Q

what is an actuator used for

A

actuators are used to start and stop machines or open and close valves
is a mechanical device like a solenoid or a motor

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38
Q

how do digital light projectors work

A

they use millions of micro mirrors on a small digital micromirror device to create a dark or light pixel
requires a bright light source to pass over it

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39
Q

what are LCD projectors

A

Liquid crystal display projectors
works by passing a high intensity beam of light through an LCD display and then onto a screen

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40
Q

what are advantages of DLP projector

A

higher contrast ratio
lasts longer
runs quieter and is smaller

41
Q

disadvantages of DLP projector

A

no grey components
saturation of color isnt that good

42
Q

advantages of LCD projector

A

gives sharper image
better color saturation
more efficient in use of energy

43
Q

disadvantages of LCD projector

A

contrast ratios are not as good
have a limited life
tend to degrade over time

44
Q

how do thermal bubble inkjet printers work

A

heat causes the ink to form a tiny bubble and as the bubble expands some of the ink is ejected onto the paper
a vacuum is created causing fresh ink to be drawn

45
Q

how do piezoelectric inkjet printers work

A

a crystal is given an electric charge whcih makes it vibrate and forces ink onto the page

46
Q

how do laser printers work

A

dry ink is used
the paper is negatively charged and attracts the positively charged drum of ink toner causing the toner to stick to the page and print out the text or data

47
Q

when are inkjet printers used

A

used to print when only a few pages of good quality is needed

48
Q

when are laser printers used

A

when high quality quality and high amounts of printouts are required
for fliers or posters

49
Q

what are 3D printers used for

A

used to produce solid objects that can acutally work

50
Q

what is drect 3D printing

A

a printhead moves left adn right and up and down to build up the layers of the object

51
Q

what is binder 3D printing

A

uses 2 passes for each layer
first it sprays dry powder and then secondly, sprays a biner to form a solid layer

52
Q

what can 3D printing be used for

A

making of prosthetic limbs
making parts of items that no longer exist
fashion and art

53
Q

What are LED screens

A

made up of tiny Light Emitting Diodes
the electric current is varied in each diode creating a vast range of colors

54
Q

what are LCD screens

A

Liquid crystal display
they require light to work so usually LED technology is used to provide backlighting for the screen

55
Q

what is OLED

A

Organic light emitting diodes
use organic material between two charged electrodes
when an electric field is applied to the electrodes, they give off light

56
Q

advantages of OLED compared to LED and LCD

A

the layers are thinner, lighter and more flexible
give off a brighter light
do not require backlighting like LCD so uses less power
can be made into thin sheets
large field of view

57
Q

what are loudspeakers

A

output devices that produce sound

58
Q

how do loudspeakers work

A

digital data is passed through a digital to analogue converter where its changed to an electric current
passed through an amplifier which creates a current large enough to drive a loudspeaker
then fed into a loudspeaker

59
Q

what are sensors

A

input devices which read or measure their surroundings

60
Q

what is primary memory

A

directly addressable by the CPU
RAM, ROM, cache memory

61
Q

what is secondary storage

A

not directly addressable by the CPU
all are non volatile devices
can be external or internal
HDD, SSD, DVD, memory stick

62
Q

what is Random access memory

A

when applications are run, data is retrieved from secondary storage and placed temporarily into RAM

63
Q

what are features of RAM

A

can be written to or read from and data can be changed by the user
used to store data, files or part of the operating system currently in use
it is volatile which means memory contents are lost when powering off the computer

64
Q

what happens when the size of the RAM is larger

A

the computer will operate faster

65
Q

what happens when RAM becomes ‘full’

A

it never runs out of memory but becomes slower and slower.
The CPU has to continually access the secondary data storage device to overwrite old data on the RAM with new data

66
Q

what is DRAM

A

dynamic RAM
consists of transistors and capacitors
needs to be constantly refreshed

67
Q

advantages of DRAM

A

less expensive
consume less power
have higher memory capacity

68
Q

what is SRAM

A

Static Ram
doesnt need to be constantly refreshed since it uses flip flops
found in memory caches in the CPU

69
Q

advantages of SRAM

A

doesnt need to be constantly refreshed
has faster data access times

70
Q

features of ROM

A

Read only memory
they are non volatile
contents cannot be changed or written to, only read
used to store data that the computer needs to acess when powering up (BIOS) and start up instructions

71
Q

What is a HDD

A

Hard disk drive is a form of magnetic storage

72
Q

how do HDD’s work

A

data is stored on the magnetic surfaces of the disks
read-write heads are used to read and write data to the disks
data is stored on the surface in sectors and tracks

73
Q

disadvantages of HDD

A

slower access times than RAM and the effects of latency are very significant
over time, the HDD will become fragmented and the performance will keep deteriorating

74
Q

What are SSD’s

A

Solid State Drives
they have no moving parts and data is retrieved quicker
data is stored by controlling the electrons within NAND or NOR chips

75
Q

advantages of SSD over HDD

A

they are more reliable
lighter
lower power consumption
run much cooler than HDD’s
they are thinner
data access is considerably faster than HDD

76
Q

what is the main drawback of SSD

A

the longevity of the technology

77
Q

what are memory sticks

A

use solid state technology and connect through the computer through the USB port
they are small, lightweight devices

78
Q

What are CD/DVDs

A

optical storage devices
laser light is used to read and write data to adn from the surface of the disk

79
Q

where is the data stored on CDs/DVDs

A

stored in pits and lands

80
Q

difference between DVD and CD

A

DVD can store more since they can store data on both sides while CD’s can only use one side

81
Q

what are blu-ray discs

A

also optical storage media
able to store much more data since the pits and lands are much smaller
also come with a secure encryption system

82
Q

why are blu-rays better than DVD

A

able to store much more data and record high definition movies

83
Q

what is virtual memory

A

when the RAM becomes full, data is loaded into memory from HDD or SSD whenever required

84
Q

benefits of virtual memory

A

programs can be larger than physical memory and still be executed
there is no need to waste memory with data this isnt being used
reduces the need to buy more expensive RAM memory

85
Q

what is the problem with virtual memory

A

as more and more data is used, the processing speed of the computer is reduced.
a point is reached where execution of a process comes to a halt since theres so much data being moved
this is known as the thrash point

86
Q

what is cloud storage

A

the method of data storage where data is stored on remote servers

87
Q

what is public cloud

A

the storage environment where the customer and cloud storage provide are different companies

88
Q

what is a private cloud

A

the is storage provided by a dedicated environment behind a company firwall.
customer and client are integrated

89
Q

what is hybrid cloud

A

combination of private and public
some data resides in the private cloud and less sensitive data is stored on a public cloud

90
Q

benefits of cloud storage

A

can be accessed anytime anywhere in the world with internet
there is no need for a customer to carry an external storage device or the computer to retrieve information
allows recovery of data
offers unlimited storage capacity

91
Q

disadvantages of cloud storage

A

if they have a slow internet access they will be unable to access their data
costs can be high
cloud storage company can fail and all data is lost

92
Q

what is NIC

A

network interface card
needed to allow device to connect to a network

93
Q

what is the MAC address

A

made up of 48 bits
Media Access Control
found inside the NIC
cannot be changed

94
Q

What is the IP address

A

when a device connects to a private network, a router assigns a private IP address that is only unique on that network
however, when the device is connected to the internet, the device is given a unique public IP address and no other device will have the same address

95
Q

what is the difference between MAC and IP

A

MAC identifies the physical address of a device on the network and is assigned by the manafacture
IP identifies the global address on the internet and may not be necessarily unique

96
Q

what are static IP addresses

A

they are permanently assigned to a device by the internet and dont change each time a device logs onto the internet

97
Q

what are dynamic IP addressed

A

the IP address could be different everytime a device connects to the internet for greater privacy

98
Q

what are routers

A

enables data packets to be routed between different networks

Computer Science Yr 10-11 (6 decks)

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