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igcse computer science > topic 5 - input & output device > Flashcards

topic 5 - input & output device Flashcards

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1
Q

Input Device =

A

A device that allows data to be entered into a system

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2
Q

Output Device=

A

A device that allows the user to see/hear data

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3
Q

how does a 2D Scanner work (5)

A
  1. Paper placed on a glass panel
  2. Bright light illuminates the document (modern scanners use a xenon light)
  3. Scan head moves across the document
  4. Lens focuses on the document image
  5. Scanned image turned into electric form by the CCD
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4
Q

application of 2D scanner (2)

A
  • At airports to read passports

- OCR software used to read text

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5
Q

application of 3D scanner (2)

A
  • CT Scanners

- MRI Scanners

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6
Q

how does a barcode Scanner work (6)

A
  1. Red laser shone at barcode
  2. Light is reflected back
  3. Sensors detect the light back
  4. Pattern converted to digital
  5. Microprocessor interprets the data
  6. Each digit made up of 2 dark and 2 white lines
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7
Q

advantage of using a barcode scanner to the company (3)

A
  • Easy to change prices on stock items
  • No need to price every item on the shelf
  • Allow for automatic stock control
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8
Q

advantage of using a barcode scanner to the customers (3)

A
  • Faster checkout
  • Reduces errors
  • Itemized bills
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9
Q

how does a QR code Scanner work (8)

A
  1. QR Code scanned by camera
  2. Light reflected back
  3. Black squares reflect less than white squares
  4. Three large squares used to define alignment
  5. Squares data is decoded – each square has a binary value
  6. Processed by an app
  7. Links to website or document
  8. QR code can be saved and used again
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10
Q

QR Code v Barcode (4)

A
  • Barcode 1D QR is 2D
  • QR code can contain more data
  • QR code can be read from any angle
  • QR codes faster to scan than bar codes
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11
Q

Benefits Concept Keyboard (3)

A
  • Fewer typing errors because one button is pressed to order an item
  • Speeds up time to order because fewer buttons pressed
  • May require less training
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12
Q

how does a microphone work (2)

A
  • A diaphragm vibrates producing an electric signal

- Signal goes to a sound card and is converted into digital values

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13
Q

how does Voice recognition system work (4)

A
  1. Users voice converted into digital signal
  2. Spoken words produce a digital pattern
  3. Software compares wave pattern to patterns stored in memory
  4. If they match person is identified
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14
Q

speech recognition=

A

Spoken words recognized and shown on screen

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15
Q

problems of speech recognition (2)

A
  • The software needs to be trained

- Some dialects and accents can cause problems

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16
Q

application of speech recognition (2)

A
  • Cars

- Siri

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17
Q

how does resistive touch screen work? (2)

A
  1. Uses multiple layers of material that transmit electric current
  2. When top layer is touched into the lower layer current changes and location is found
18
Q

advantage of resistive touch screen (2)

A
  • Cheap to make

- Can use when wearing a glove

19
Q

how does Capacitive touch screen work (4)

A
  1. Conductive layer
  2. Current flows from 4 corners – electric field created
  3. Sensors monitor field
  4. When screen is touched charge transferred to finger - current changes and location is calculated
20
Q

disadvantage of resistive touch screen (3)

A
  • Poor in sunlight
  • Easily scratched
  • Doesn’t allow multi touch
21
Q

advantage of capacitive touch screen (3)

A
  • Good in sunlight
  • Durable
  • Allows multi touch
22
Q

disadvantage of capacitive touch screen (2)

A
  • Screen can crack on impact

- Can’t use while wearing gloves

23
Q

how does infra red work? (2)

A
  1. Invisible grid of infra-red beams on screen

2. When screen is touched beam is broken and location is calculated

24
Q

advantage of infra red (3)

A
  • Durable
  • Allows multi touch
  • Can use with gloves
25
Q

disadvantage of infra red (3)

A
  • Expensive to make
  • Screen can crack on impact
  • Sensitive to dirt
26
Q

types of sensors (6)

A 
1. Temperature
Aircon, central heating
2. Motion
Detects if an infra-red beam has been broken and sends a signal to the microprocessor
3. Pressure
Detects a change in pressure and receives current if a circuit is created sending a signal to the microprocessor
4. pH
5. Light
6. Magnetic fields
7.Anti-lock brakes on a car
27
Q

examples of Monitoring Applications (3)

A
  • Burglar Alarm
  • Street Lights
  • ABS Brakes
28
Q

Control Systems Process (7)

A
  1. Sensor detects input (Name the sensor)
  2. Analogue data converted to digital
  3. Signal sent to microprocessor
  4. Microprocessor compares signal to stored value
  5. If value outside range signal sent to device
  6. Actuator used to operate device
  7. Process is in a continuous loop
29
Q

Printers (2)

A
  • Interrupt - Signal sent to computer about no paper

- Buffer – Area of memory used to temporarily store data being sent to the printer

30
Q

Types of Printer (3)

A
  • Laser
  • Inkjet
  • 3D
31
Q

Inkjet (8)

A
  • Used for low quantities of documents
  • Used for photographs
    - Uses liquid ink cartridges
    - Uses thermal bubble
    - Rollers used to move the paper
    - Uses a moving print head
    - Sprays ink onto the paper
    - Different colour inks are mixed to create required colours
32
Q

Laser (5)

A
  • Used for high volume quality output
    • User toner cartridges
    • Uses charged print drum
    • Uses static electric charges
    • Toner is fused to the paper
33
Q

3D(4)

A
  • Used to make physical model from blueprint
  • Used to create physical model from CAD
  • Uses resin
  • Solid is built up in thin layers
  • Uses inkjet technology with a moving head
34
Q

Binder 3D printing (3)

A
  • Similar to direct but uses two passes
  • 1st pass sprays dry powder
  • 2nd pass sprays a binder (type of glue)
35
Q

2D & 3D Cutters(1)

A

-Very complex designs can be made as the cutters are controlled by computers

36
Q

Speakers & Headphones(3)

A
  • Sound produced by passing digital data through a digital to analogue converter (DAC) then through an amplifier
  • Sound produced by voltage differences vibrating a cone
  • Rate with which DAC can translate the digital signals is know as sampling rate
37
Q

LCD & LED Screens Advantages over CRT(5)

A
  • Brighter image
  • Higher resolution
  • Thinner screen
  • Uses less power
  • Last longer
38
Q

OLED advantages(6)

A
  • Organic layers are thinner, lighter and more flexible
  • OLED layers can be made from plastic so are lighter
  • Brighter than LED
  • No backlighting required so use less power
  • Can be made into large thin sheets for advertising boards
  • Very large field of view
39
Q

DLP projectors (4)

A
  • Uses millions of micro mirrors on a DLP chip
  • Micro mirrors can switch on/off thousands of times a second
  • Bright white light passes through colour filter on its way to the DLP chip
  • Light split into primary colours RGB
40
Q

LCD projectors (6)

A
  • Older technology than DLP
  • Beam of light generated by a bulb
  • Light sent to group of chromatic-coated mirrors that reflect the light back at different wavelengths corresponding to RGB
  • Three different light components pass through three LCD screens
  • Images are then combined using a prism to create full colour image
  • Finally image passes through projector lens onto a screen

igcse computer science (8 decks)

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