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Computer Science by DY > 3 Hardware > Flashcards

3 Hardware Flashcards

1
Q

What is the role of the CPU

A

An integrated circuit which accepts data input into the computer and processes it into information ready for output.

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2
Q

What does a CPU consist of? (3)

A

control unit

Arithmetic and logic unit

reigsters and buses

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3
Q

What is the role of the ALU?

A

responsible for carrying out mathematical calculations or logical operations

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4
Q

What is the role of the control unit? (2)

A

oversees the overall operation of the CPU

Includes initiating each step of the fetch decode execute cycle and managing the ALU

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5
Q

What is a register

A

small area of storage found within the CPU

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6
Q

Why are registers extremely fast to access

A

located directly within the CPU

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7
Q

what is the purpose of the current instruction register

A

CIR stores the current instruction being decoded and executed

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8
Q

what is the purpose of the accumaltor

A

used when carrying out ALU calculations

temporarily stores data during calculations

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9
Q

What is the purpose the memory address reigster

A

MAR stores the address of the RAM currently being read from or written to

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10
Q

What is the purpose of Memory Data Register

A

Register used to temporarily store data that will be written to RAM or data that has just been read from RAM.

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11
Q

What is the function of the program counter

A

PC stores the address where the next instruction to be read can be found

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12
Q

Define buses

A

a connection between major components in a computer that can carry data, addresses, or control signals

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13
Q

Describe the address bus (2)

A

carries addresses throughout the CPU

unidirectional (bits can travel one direction only)

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14
Q

Describe the data bus (2)

A

bidirectional (allows data to be sent in both ways along the bus)

Connects CPU with RAM and input devices with output devices

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15
Q

What are the three types of buses

A

address bus

data bus

control bus

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16
Q

Describe the control bus

A

bidirectional

carries signals from the Control Unit to all other computer components

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17
Q

Explain the fetch decode execute cycle (7)

A

The PC contains address of memory location of the next instruction which is to be fetched

address copied from PC to MAR via address bus

Contents in RAM address stored in MAR copied temporarily to MDR

Contents of MDR copied to CIR

Value of PC incremented by 1 so that it now points to the next instruction which is to be fetched

CU decodes instruction in CIR

instruction sent to ALU to be executed

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18
Q

What are the three main factors that affect the performance of a CPU

A

clock speed

cache

core

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19
Q

What is clock speed (2)

A

determines the number of cycles a cpu can perform each second

higher clock speed generates more heat and uses more energy

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20
Q

Describe the core (2)

A

processor within the CPU

The idea of using more core alleviates the need to increase clock speed

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21
Q

Describe the cache (2)

A

extremely fast memory located within the CPU

used to temporary store copies of the data in the most commonly accessed RAM locations

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22
Q

Define instruction set

A

Listof instructions that a CPU can process

when instructions are in binary it is known as machine code

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23
Q

Define embedded system

A

computer system that performs a dedicated function inside a device or appliance

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24
Q

Examples of where embedded systems can be found

A

Entertainment systems in cars

Domestic appliances, such as washing machines

Security systems, such as automatic lighting and alarms.

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25
Q

What are general purpose computers

A

A computer system designed to perform unlimited different functions.

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26
Q

Benefits of embedded systems (3)

A

small, easy to fit into devices

compared to other systems, relatively low cost to make

consumes very little power

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27
Q

Drawbacks of embedded systems (2)

A

any device that can be accessed over the internet is open to hackers, viruses etc

troubleshooting faults in the device becomes a specialist task

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28
Q

Define input devices

A

used to enter data into a computer for processing

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29
Q

Describe the process when barcode is scanned (4)

A

shine a light at a barcode

light is reflected off the barcode (white reflects light back, black absorbs and reflects less)

reflected light is read by microprocessor

a pattern is created and is converted to digital data

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30
Q

Describe the QR code (2)

A

Consists of square black and white patterns, representing a small number of text characters

As more and more data is added, structure of QR code becomes more complex

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31
Q

Advantages of QR code compared to traditional barcode (4)

A

can hold much more information

easy to transmit QR codes

possible to encrypt QR codes

easy to read (don’t need expensive laser or LED)

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32
Q

What happens when a photograph is taken by a digital camera? (3)

A

Light enters camera, falls onto sensor made up of millions of pixels

each pixel measures light intensity

microprocessor converts these values into digital data, representing colour values

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33
Q

What happens when a key is pressed (4)

A

there is a membrane or circuit board at the base of the keys

CPU determines which key has been pressed

CPU refers to an index file which identifies which character the key pressed represents

Each character on a keyboard has a corresponding ASCII value

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34
Q

What does a microphone do? (2)

A

vibrations caused by soundwaves cause a coil to move around a magnet, resulting in electromagnetic field changes

Tiny charges converted by microprocessor and ADC into digital representation of sound

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35
Q

What are the 3 types of touchscreens (3)

A

Resistive touchscreens

Capacitive touchscreens

infra red touch screens

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36
Q

What is resistive touch screen (3)

A

uses two very thin metal sheets over the screen

when pressure applied, metal sheet make contact, completing electrical circuit

this can be used to detect where the user has pressed

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37
Q

What is capacitive touch screens (3)

A

uses transparent layer over the screen

layer is sensitive to static electrical charge in human body

when user touches screen, charge detected, location of touch detected

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38
Q

What is infra-red touch screen (3)

A

creates a grid of infra-red light over the screen

when user touches screen, light is broken

this can be used to detect location of touch

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39
Q

How do 2D scanners work? (1)

A

shines bright line across a document to measure the levels of reflected light and create digital version of it

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40
Q

Describe 3D scanners (1)

A

shines a laser over the surface of an object to record its geometry and dimensions and create a digital model of it.

41
Q

Why is a microphone required (2)

A

capture any real world sound and store it as digital data

digital sounds can then be modified

42
Q

How does a optical mouse work? (2)

A

uses red LED and sensor to determine the movement of mouse relative to the surface beneath

microprocessor analyses speed and distance of the movement and replicates it on the screen via virtual cursor

43
Q

Advantages of using an opitcal mouse (2)

A

no moving parts (more reliable)

no need for special surfaces (eg: a mouse mat)

44
Q

What are 2D scanners typically used for (2)

A

reading passport at airports

creating digital versions of documents and photographs

45
Q

What are 3D scanners typically used for (2)

A

Creating 3D models

dentistry, product development, research etc

46
Q

What does an actuator do? (2)

A

carries out some sort of a physical movement

often used with motor to translate digital signal into real world physical movement

47
Q

What does a digital light processing (DLP) projector do?

A

use thousands of tiny mirrors to reflect a digital image from a computer onto a screen.

48
Q

Advantages of DLP projectors over LCD projectors (3)

A

smoother video

better suited to dusty or smokey atmospheres

portable

49
Q

What does Liquid crystal display (LCD) projectors do?

A

create an image by projecting light in three colours: red, green and blue. These colours are combined to form a final image on the projector screen.

50
Q

Advantages of LCD projectors over DLP projectors (3)

A

sharper image

better colour reproduction

less expensive

51
Q

What does an inkjet printer do?

A

force tiny droplets of liquid ink through very fine nozzles onto a sheet of paper to replicate a digital document or iamge

52
Q

What does a laser printer do?

A

use a laser to apply a static charge to areas on the paper.

Toner (a powdered ink) is then attracted to the static charge and sticks to the paper in these areas, forming an image.

53
Q

What does LCD screen do? (3)

A

work by sandwiching crystals between two sheets of glass.

A white back light illuminates the screen from behind.

When an electrical current is applied to the crystals in individual pixels, light is passed through and an image forms.

54
Q

What does LED screen do

A

use tiny LEDs to produce a bright image almost instantly without the need for any backlighting

55
Q

advantages of LED screens over LCD screens (2)

A

Better image quality

no need for additional backlighting

56
Q

What does a speaker do?

A

A speaker produces output in the form of sound, by converting electrical signals into vibrations.

57
Q

What does a 3D printer do?

A

deposit layers of materials on top of each other to build 3D object

58
Q

What is 3D printing often used for (3)

A

inexpensive prosthetics

personalised items

rapid prototyping

59
Q

What role does Computer Aided Design (CAD) have in 3D printing

A

allows us to produce real world models of virtual objects

60
Q

Define a sensor

A

A type of input device which measures an aspect of the environment around it

61
Q

What is an acoustic sensor + applications

A

An acoustic sensor detects sound.

One application of an acoustic sensor would be a burglar alarm, which could be used to detect a break-in.

62
Q

What is an accelerometer sensor + applications

A

An accelerometer measures acceleration force

Cars with stability control systems also use accelerometers to measure the car’s situation.

62
Q

What is an flow sensor

A

Flow sensors measure the flow speed of liquids or gases in pipes.

63
Q

What is an gas sensor + applications

A

Gas sensors can detect the presence of different gases.

a gas sensor may be used to detect the presence of toxic gases in a chemical manufacturing plant.

64
Q

What is an Humidity sensor + applications

A

A humidity sensor detects water vapour in the air.

a greenhouse might use a humidity sensor to help a computer determine if the environment is correct for the plants growing there.

65
Q

What is an infra-red sensor + applications

A

An infra-red (IR) sensor is a type of light sensor that detects invisible infra-red light.

an automatic door system might use an infra-red sensor to detect a person walking in front of the door.

66
Q

How to answer sensor question (7)

A

1st mark – naming the sensor
eg: temperature sensor in air conditioner

2nd mark – Signal from the sensor is converted from analogue to digital by the ADC

3rd mark – Microprocessor compares digital value with stored value

4th mark- If its within a range, nothing happens
eg: air conditioner is set at 30 degrees and the room temperature is 30 degrees

5th mark – If its outside the range, a signal is sent to the actuator

6th mark- Does something (according to question)

7th mark- Operates in a continuous loop

67
Q

What are the two types of storage in a computer storage (2)

A

primary storage

secondary storage

68
Q

Define primary storage

A

storage that is accessed directly by the CPU

69
Q

What are the two types of primary storage

A

RAM

ROM

70
Q

Describe Random Access Memory (RAM) (4)

A

used for temporary storage of programs and data that are currently being used

Extremely fast to access

volatile (loses its contents when the power is removed)

Read and Write

71
Q

Describe Read Only Memory (ROM) (3)

A

Read only

contains bootup instructions

non-volatile (data retained even after computer turned off)

72
Q

Define + describe secondary storage (3)

A

type of storage that is not directly accessed by the CPU

non-volatile (permanently stores all of users’ data and programs)

larger capacities than primary storge

73
Q

What are the 3 types of secondary storages (3)

A

magnetic storage

Optical storage

solid-state storage

74
Q

Common example of magnetic storage

A

Hard disk drive

75
Q

How does a magnetic hard disk drive work? (3)

A

inside a hard disk are multiple disks called platters, which spin constantly when the computer is running.

A read/write arm moves in and out across the disk surface,

an electromagnet on the read/write head is used to read and write the data on the disk.

76
Q

How does an optical storage device work?

A

An arm moves the laser across the surface of the disk

The laser used to read the data from the pits and lands

When the laser light hits the point where the pit changes into a land or vice versa the light scatters and is not reflected back as well. This is captured by a sensor and can be interpreted as a change in the binary value

77
Q

Examples of optical storage devices (3)

A

CDs

DVDs

Blu-rays

78
Q

How does an SSD store data (6)

A

uses NAND/NOR technology/flip-flops

stores data by flashing it onto chips

controls flow of electrons using
transistors

electric current reaches control gate

current flows through to floating gate to be stored

when data is stored transistor is converted from 1 to 0

79
Q

Define virutal memory

A

A system that allows a computer’s operating system to use secondary storage as though it were RAM.

80
Q

What is paging out in virtual memory

A

When more RAM is needed than available, chunk of data (pages) moved from RAM to secondary storage, freeing up space

81
Q

What is paging in virtual memory

A

When data needed again, the page must first be copied back from secondary storage to RAM

82
Q

Define local storage

A

Storage devices which are directly connected to a computer system, such as a hard disk or a flash drive. The opposite of cloud storage.

83
Q

Explain how cloud storage works (3)

A

uses servers on the internet

When a user saves data, that data is sent across the internet to a server, where it is stored

When user requires the data again, a request is sent to the server to retrieve the data again

84
Q

What may cloud storages be used for (3)

A

data backup

photo and video uploads

streaming services

85
Q

where are the servers for cloud stroage stored?

A

located in huge data centres that house thousands of servers

86
Q

Benefits of using cloud storage (3)

A

data can be accessed from any device anywhere in the world, if provided with internet access

no need for user to carry external storage with them

offers almost unlimited storage capacity

87
Q

Drawbacks of using cloud storage (3)

A

if user has slow unstable internet connection, they might have problems accessing data

costs can be high if large storage is required

potential failure of the cloud storage company risks the loss of back-up data

88
Q

Purpose of Network Interface Card

A

hardware device that is needed to connect a computer to a network

89
Q

Where is the MAC address usually found in a computer? (physically)

A

Network interface card

90
Q

Explain what is meant by a MAC address (4)

A

hardware identifier that uniquely identifies each device

48 bits long, written in hexadecimal

1st part = manufacture cdode

2nd part = device serial number

91
Q

Define IP address (1)

A

unique address assigned to each computer on a network.

92
Q

What are the two types of IP addresses that can be allocated by a network (2)

A

static IP address

dynamic IP address

93
Q

Explain what is ment by a static IP address

A

given the same address every time it joins the network

94
Q

Explain what is meant by a dynamic IP address

A

it is assigned any available address when it joins the network

95
Q

What are the two types of IP addresses (2)

A

IPv4

IPv6

96
Q

Difference between IPv4 and IPv6 (2)

A

IPv6 128 bits in size while IPv4 only 32 bits

IPv6 is replacing IPv4 because IPv4 is running out

97
Q

Define router

A

a device that that enables data packets to be moved between different networks

98
Q

roles of the router (4)

A

They allow devices to connect to a LAN

They can assign IP addresses to devices joining a local network

They connect a local network to the internet

They send data to the correct destination on a network

Computer Science by DY (10 decks)

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