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IGCSEs > Computers πŸ’» | I/O Devices | 3.2 > Flashcards

Computers πŸ’» | I/O Devices | 3.2 Flashcards

1
Q

Define input device

A

A hardware component that allows users to input data or instructions into a computer

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2
Q

Define output device

A

A hardware component that displays or outputs information from a computer, such as a monitor or a printer

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3
Q

Define barcode

A

A series of dark and light line of varying thickness used to represent data

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4
Q

What is the purpose of a barcode scanner?

A

To read and convert the analogue data in a barcode to understandable digital data

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5
Q

Where may a barcode reader be used?

A
  • In checkout at supermarkets
  • Libraries
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6
Q

What are the advantages of using barcodes in supermarkets?

A

For the management:
- Easier and faster to change prices on stock
- More upto date sales information
- No need to price every stock item
- Auto stock control
For the customer:
- Faster checkout queues
- Errorrs in charging customers reduced
- Itemised bill given
- Better track of sell-by dates; fresher food

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7
Q

Define QR code

A

QR (Quick Response) codes are a matrix of dark and light squares which represent data.

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8
Q

What is used to read a QR code?

A

A phone camera

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9
Q

What are some uses of QR codes?

A
  • Advertising products
  • Giving automatic access to a website / telephone number
  • Storing boarding passes electronically at airports / train stations
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10
Q

What are the advantages of QR codes opposed to traditional barcodes?

A
  • Holds more information
  • Fewer errors: built in error checking
  • Easier to read
  • Encryptable
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11
Q

What are the disadvantages of QR codes opposed to traditional barcodes?

A
  • More than one format available
  • Can transmit malicious code
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12
Q

How do frame QR codes differ from traditional QR codes?

A

An image can be displayed in the centre for marketing

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13
Q

What is a digital camera?

A

A camera that does not need film, producing digital images

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14
Q

What automatic tasks can a digital camera carry out?

A
  • Adjusting shutter speed
  • Focusing image
  • Operating flash
  • Changing aperture
  • Adjusting size
  • Removing red eye
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15
Q

Define ADC

A

Analouge to Digital Converter
A device which converts analogue data to a form understood by the computer

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16
Q

Define DAC

A

A device which converts digital data into electrical currents that can drive actuators

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17
Q

What is the purpose of keyboards?

A

To enter text on computers, tablets, phones…

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18
Q

A keyboard can be either ___

A

Virtual or physical

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19
Q

Define virtual keyboard

A

An onscreen keyboard which uses the featres of the touchscreen to emulate a physical keyboard

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20
Q

Each keyboard character has a …

A

Corresponding ASCII value

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21
Q

What is the purpose of a microphone?

A

To convert sound waves to an electric current

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22
Q

What may microphones be used for?

A

Videocalling, recording music, singing, etc.

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23
Q

Define optical mouse

A

A pointing device that uses a red LED to track the movement of an onscreen cursor or allows for onscreen selection by clicking a button on the device

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24
Q

What are the benefits of optical mice over mechanical mice?

A
  • No moving parts
  • Dirt cant get trapped
  • No need for special surfaces
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25
Q

What are the two types of scanners?

A

2D scanners and 3D scanners

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26
Q

What is the purpose of a 2D scanner?

A

To input hard copy (paper) documents into electronic form in a computer

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27
Q

Define OCR

A

Optical character recognition:
Technology that can convert hard copy text and images to digital format stored in a computer

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28
Q

Define OMR

A

Optical mark recognition:
Technology that can recognise marks on a hard copy and store the counts in digital format on a computer

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29
Q

What is the purpose of 3D scanners?

A

To scan solid objects and produce a 3D image

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30
Q

Define CAD

And what does it stand for?

A

Computer Aided Design
Software used to create drawings. 3D scanned images are often used in it.

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31
Q

What could some of the uses of 3D scanners be?

A
  • CAD design
  • 3D printing
  • CT scanning
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32
Q

How can 2D scanning be used in airports?

A
  • Reading passports
  • Using OCR to represent passport pages in ASCII
  • Storing passport faces for facial recognition
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33
Q

Define touch screen

A

A screen which allows the user to select or manipulate a screen image using the touch of a finger or stylus

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34
Q

What are the 3 types of touch screens?

A

Resistive, Capacitive, and Infrared

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35
Q

Where are touch screens often found?

A
  • Mobile phones
  • Tablets
  • Fast food selectors
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36
Q

Define capacitive touch screen

A

A type of touch screen that uses the change in the screen’s capacitance when it is touched by a finger or stylus

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37
Q

Define resistive touch screen

A

A type of touch screen that uses two conductive layers which make contuct where the screen is touched

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38
Q

Define infrared touch screen

A

A type of touch screen that uses infrared beams and sensors to detect where the screen is touched

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39
Q

What are the advantages of capacitive touch screens?

A
  • Better image clarity than resistive screens
  • Very durable
  • Projective touch screens allows for multi touch
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40
Q

What are the disadvantages of capacitive touch screens?

A
  • Surface capacitive touch screens only work with bare fingers or a stylus
  • Sensitive to EM radiation
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41
Q

What are the advantages of infrared touch screens?

A
  • Allows for multi touch
  • Good durability of screen
  • Operability not affected by scratched or broken screen
42
Q

What are the disadvantages of infrared touch screens?

A
  • The screen can be water or moisture sensitive
  • Possible for accidental activationt o take place
  • Sensitive to light interference
43
Q

What are the advantages of resistive touch screens?

A
  • Good resistance to dust and water
  • Can be used with bare fingers, stylus and gloved hand
44
Q

What are the disadvantages of resistive touch screens?

A
  • Low touch sensitivity (sometimes have to press down harder)
  • Doesn’t support multi-touch facility
  • Poor visibility in strong sunlight
  • Vulnerable to scratches on the screen (made of polymer)
45
Q

What are the disadvantages of resistive touch screens?

A
  • Low touch sensitivity
  • Doesnt support multi touch
  • Poor visibility in strong sunlight
  • Vulnerable to screen scratches
46
Q

Define actuator

A

An output device which converts electrical energy to mechanical movement

47
Q

Define DLP projector

A

Digital Light Projector
A projector making use of micromirrors that tilt towards a light source in differing ways

48
Q

Define LCD projector

A

Aprojector making use of a high intensity beam of light that passes through an LCD display

49
Q

What are the advantages of DLP projectors?

A
  • Higher contrast ratios
  • Higher reliability
  • Quieter running
  • Smaller and lighter than LCD projectors
50
Q

What are the disadvantages of DLP projectors?

A
  • Image tends to suffer from β€˜shadows’ when showing movement
  • No grey components in image
  • Color definitition not as good as LCD projectors due to lower color saturation
51
Q

What are the advantages of LCD projectors?

A
  • Gives a sharper image
  • Better color saturation
  • More efficient in energy use
52
Q

What are the disadvantages of LCD projectors?

A
  • Contrast ratios not as good as DLPs
  • Limited lifespan
  • More organic so they degrade over time
53
Q

What are the two types of printers?

A

Inkjet printers and laser printers

54
Q

When are inkjet printers used?

A

For printing one off photos where only a few pages of good quality, color printing is needed

55
Q

When are laser printers used?

A

When high quality fast prints inn high voolume are needed

56
Q

What are 3D printers used for?

A

To produce solid objects that actually work, created using materials

57
Q

What are some uses of 3D printing?

A
  • Covering prosthetic limbs to exactly fit the limb
  • Making items to allow precision reconstructive surgery
  • Making lightweight wings in aerospace
  • Fashion and art
  • Making parts for items no longer in production
58
Q

What is an LED screen?

A

A screen made up of tiny Light Emitting Diodes, each LED being either red, green, or blue

59
Q

What is an LCD screen?

A

A screen made up of tiny liquid crystals that make up an array of pixels, backlit by a ligh source

60
Q

An LCD screen can be backlit by either a … or a …

A

LED screen, or a CCFL

61
Q

Where are LED screens often used?

A

In large outdoor displays due to brilliance of colours.

62
Q

What does OLED stand for?

A

Organic Light Emitting Diodes

63
Q

How does OLED differ from LED in functionality?

A

They do not require a backlight as it is a self contained system

64
Q

What are CCFLs made up of?

A

Two fluorescent tubes behind the LCD screen

65
Q

What are the advantages of LEDs?

A
  • Reach max brightness almost immediately
  • Give of a white light rather than yellowish light in CCFL
  • Monitors can be thin
  • Lasts indefinitely
  • Consume little power
66
Q

What are the advantages of OLEDs?

A
  • Lighter
  • Gives off brighter light
  • No need of backlighting
  • Allows for β€˜blacker blacks’
67
Q

What is a speaker?

A

An output device that converts electrical currents into sound produced

68
Q

Define sensor

A

Input devices which read or measure physical properties from their surroundings

69
Q

Why does a sensor’s data have to pass through an ADC?

A

Sensors measure physical quantities in analogue form, which cannot be understood by a computer and has to be converted into digital form.

70
Q

Purpose

Temperature sensor

A

Measure temperatuure of the surroundings

71
Q

Example applications

Temperature sensor

A
  • Control of a central heating system
  • Controlling a chemical process
  • Monitoring temperatures in greenhouse
72
Q

Purpose

Moisture sensor

A

Measures water level in a substance

73
Q

Example applications

Moisture sensor

A
  • Controlling moisture levels of soil in greenhouse
  • Monitoring moisture levels in food processing factory
74
Q

Purpose

Humidity sensor

A

Measures amount of water vapor in a sample

75
Q

Example applications

Humidity sensor

A
  • Monitor humidity levels in building
  • Monitor humidity levels in microchip factory
  • Monitor humidity levels in greenhouse air
76
Q

Purpose

Light sensor

A

Using photoelectric cells to produce an output depending on the brightness of light

77
Q

Example applications

Light sensor

A
  • Switching street lights on and off depending on light levels
  • Switching on car headlights automatically when dark
78
Q

What are the two types of infrared sensors?

A

Active and passive

79
Q

Purpose

Infrared (active) sensor

A

Monitoring whether invisible beam of infrared radiation is broken

80
Q

Example applications

Infrared (active) sensor

A
  • Security alarm systems
  • Turning on car windscreen wipers automatically
81
Q

Purpose

Infrared (passive) sensor

A

Measures the heat radiation given off by an object

82
Q

Example applications

Infrared (passive) sensor

A
  • Security alarm system
  • Monitoring temperature inside industrial freezer
83
Q

Purpose

Pressure sensor

A

Generating different electric currents depending on pressure applied

84
Q

Example applications

Pressure sensor

A
  • Weighing of lorries at weighing station
  • Measuring gas pressure in nuclear reactor
85
Q

Purpose

Acoustic / sound sensor

A

Converting detected sound into electrical signals

86
Q

Example applications

Acoustic / sound sensor

A
  • Picking up noise of footsteps in a security system
  • Detecting sound of liquids dripping at a faulty pipe joint
87
Q

Purpose

Gas sensor

A

Detecting gas and producing output depending on level of said gas

88
Q

Example applications

Gas sensor

A
  • Monitor pollution levels in air in airport
  • Monitoring oxygen and carbon dioxide levels in greenhouse
  • Monitoring oxygen levels in car exhaust
89
Q

Purpose

pH sensor

A

Measuring acidity through changes in voltage

90
Q

Example applications

pH sensor

A
  • Monitoring acidity levels of soil in greenhouse
  • Controlling acidity levels in chemical process
91
Q

Purpose

Magnetic field sensor

A

Measuring changes in magnetic fields

92
Q

Example applications

Magnetic field sensor

A
  • Detecting magnetic field changes in mobile phones and CD players
  • Used in anti-lock braking systems in cars
93
Q

Purpose

Accelerometer

A

Measuring acceleration and motion of an application

94
Q

Example applications

Accelerometer

A
  • Measuring rapid deceleration and applying air bags in cars
  • Changing between portrait and landscape mode in mobile phones
95
Q

Purpose

Proximity sensor

A

Detecting the presence of a nearby object

96
Q

Example application

Proximity sensor

A
  • Burglar alarm system
  • Detecting when face or ear is close to mobile phone
97
Q

Purpose

Flow (rate) sensor

A

Measuring the flow rate of moving liquid or gas and producing an output based on the amount of liquid or gas passing over the sensor

98
Q

Example applications

Flow (rate) sensor

A
  • Respiratory devices and inhalers in hospitals
  • Measuring gas flows in pipes
99
Q

Purpose

Level sensor

A

Using ultrasonics or conductivity to measure changing liquid levels

100
Q

Example applications

Level sensor

A
  • Monitoring petrol tank levels in car
  • In pharmaceutical process where powder levels in tablet production is monitored
  • Leak detection in refridgeran (AC)

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