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Cambridge IGCSE0417

Input devices and their uses

Information Communication Technology 0417 Chapter Notes

What this chapter covers

Input devices and their usesDirect data entry and associated devicesOutput devices and their uses
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In this chapter

  1. 1Keyboards, keypads and pointing devices
  2. 2Microphones
  3. 3Cameras and gesture input
  4. 4Scanners and OCR
  5. 5Sensors
  6. 6Remote controls, joysticks and light pens
  7. 7What direct data entry is
  8. 8Magnetic stripe and chip and PIN readers
  9. 9RFID readers
  10. 10OMR and OCR
  11. 11Bar code readers and QR scanners
  12. 12Monitors and touch screens
  13. 13Multimedia projectors
  14. 14Printers and hard copy
  15. 15Dot matrix and laser printers compared
  16. 16Plotters
  17. 173D printers
  18. 18Speakers
  19. 19Actuators

1. Keyboards, keypads and pointing devices

The syllabus lists the keyboard, the numeric keypad and pointing devices, such as a mouse, as input devices. Continuous use of a keyboard, or continuously clicking a mouse button, can cause RSI.

A touch screen is an input device as well as a screen. Compared with a monitor, keyboard and mouse it has a smaller footprint, and fewer peripherals are needed.

RSI can be an issue with a touch screen as well as a keyboard, so it is not an advantage of either. An advantage must be a comparison with the other device.

Examiner insight

“Some candidates mentioned RSI as being a possible answer but RSI can be an issue with touch screens as well as ordinary keyboards.” “Some candidates correctly wrote that the touch screen would have a smaller footprint and fewer peripherals were needed.”

Worked example 14 marks

A cafe replaces the monitor, keyboard and mouse at its till with one touch screen. Describe two advantages of the touch screen compared with the monitor, keyboard and mouse.

  1. 1

    The touch screen has a smaller footprint than the monitor, keyboard and mouse [1]

  2. 2

    so more of the counter at the till is left free [1]

  3. 3

    Fewer peripherals are needed [1]

  4. 4

    because the touch screen is the input device as well as the screen, so the cafe does not need a separate keyboard and mouse [1]

2. Microphones

A microphone captures sound, such as a voice. The sound is analogue data, so it must be converted before a computer can store it.

The analogue signal goes to an ADC (analogue to digital converter) or sound card. This converts it to digital data. The computer then reads and stores the data as an audio file.

Examiner insight

“Some candidates did not go into enough detail about how the voice could be recorded on the computer.” “A few candidates reworded the question in their answer.”

Worked example 13 marks

A student is making a recording of his voice for a podcast. Explain how the student's voice could be recorded on a computer.

  1. 1

    The student speaks into a microphone, which captures the voice [1]

  2. 2

    The analogue sound is sent to an ADC / sound card [1]

  3. 3

    It is converted to digital data, which the computer reads and stores (for example as an MP3 file) [1]

3. Cameras and gesture input

A digital camera is an input device. It is more portable than a scanner, but light can affect the image.

A camera can also input the commands for a gesture based interface. It captures the movement of the user. Software uses computer vision to track the movement, identify specific gestures and compare them to known movements.

A gesture system is hands free. The commands have to be learnt and acted exactly, and the light level in the room and the distance from the camera can affect it.

Examiner insight

“Many of the correct answers came from the fact that the camera was more portable, and that light could affect the image in a digital camera.” “Many candidates repeated the question in that they wrote ‘to convert the hard copy photographs into digital format’.”

Worked example 13 marks

The gesture based user interface will use a camera to input the commands. Describe how the camera is used with this system.

  1. 1

    The camera captures the movement of the user [1]

  2. 2

    Software uses computer vision to track and analyse the movement and identify specific gestures [1]

  3. 3

    The software compares the gestures to known movements [1]

4. Scanners and OCR

A scanner converts a paper document or a hard copy photograph into digital format. OCR software lets the user edit the text in a scanned document.

OCR gives faster data input with no need to type the data in, and more accurate data entry. Users still need to check the entered text, which takes more time.

OCR can confuse letters and cannot read accurately if the characters are unclear. It reads any mark on the paper and interprets it as a character. Fonts have to be consistent to be read correctly.

Examiner insight

“Most candidates gave a very vague description of OCR.” “Scanners were frequently mentioned, but again vaguely.”

Worked example 14 marks

A student has scanned a paper document into a computer. OCR software is used to allow the student to edit the text in the document. Discuss the benefits and drawbacks of using OCR software.

  1. 1

    Benefit: faster data input, as there is no need to type the data in [1]

  2. 2

    Benefit: more accurate data entry [1]

  3. 3

    Drawback: OCR can confuse letters and cannot read characters that are unclear [1]

  4. 4

    Drawback: users must check the entered text, which takes more time [1]

5. Sensors

A sensor is an input device used in measurement, for example of temperature or light level. Sensors collect data automatically and continuously without human intervention.

The sensor does not do the processing or make decisions. It sends data to the microprocessor, which compares the data with a pre-set value and sends a signal to an actuator when needed.

The drawbacks are over reliance on the technology and the environment affecting the readings.

Examiner insight

“Several candidates still seem to think that sensors do the computer processing required.” “Some candidates thought that the light sensors were able to make decisions as to when to send data to the microprocessor or to operate the barrier.”

Worked example 14 marks

A greenhouse uses a temperature sensor to switch a heater on. Describe how the sensor is used to keep the greenhouse warm.

  1. 1

    The sensor measures the temperature and sends the data to the microprocessor [1]

  2. 2

    The microprocessor compares the data with a pre-set value [1]

  3. 3

    If the temperature is lower than the pre-set value, the microprocessor sends a signal to an actuator to switch the heater on [1]

  4. 4

    The sensor keeps sending data, so the system runs continuously [1]

6. Remote controls, joysticks and light pens

The syllabus also lists the remote control, the joystick or driving wheel and the light pen as input devices.

When a question asks for a suitable device, think of the input devices and link each one back to the scenario. A mouse is an input device, but it does not fit every scenario. Do not mix up input devices with output devices.

Examiner insight

“For example; for part (a) a mouse is an input device, but does not fit into this scenario whereas a bar code scanner would.” “Some candidates mixed up input devices with output devices.”

Worked example 12 marks

A games arcade has a car racing game. Name a suitable input device and give a reason for your choice.

  1. 1

    A driving wheel [1]

  2. 2

    The player steers the car in the game by turning the wheel, so the device fits the scenario [1]

Recap

  • Input devices put data into a computer. Output devices, such as speakers and printers, do not.
  • A touch screen has a smaller footprint and needs fewer peripherals than a monitor, keyboard and mouse.
  • A microphone captures analogue sound. An ADC converts it to digital data.
  • A camera captures the movement of a user. Computer vision tracks it and identifies gestures.
  • A scanner with OCR gives faster data input, but OCR reads any mark as a character and the text must be checked.
  • A sensor sends data. The microprocessor compares it with a pre-set value and signals an actuator.
  • Choose the device that fits the scenario.

7. What direct data entry is

The direct data entry devices in the syllabus are the magnetic stripe reader, chip and PIN reader, RFID reader, OMR, OCR, bar code reader and QR scanner.

A keyboard and a mouse are input devices, but they are not direct data entry devices. Neither is a sensor or a DVD reader. A printer is an output device.

Examiner insight

“Some candidates gave output devices, most candidates gave input devices, but some of those selected incorrect input devices.”

Worked example 12 marks

Circle two direct data entry devices.

Actuator · DVD reader · Keyboard · Mouse · OMR · Printer · RFID · Sensor

  1. 1

    OMR [1]

  2. 2

    RFID [1]

8. Magnetic stripe and chip and PIN readers

A magnetic stripe reader and a chip and PIN reader both read a card. A comparison of the two must be about the readers, not only the cards, and must give similarities as well as differences.

A magnetic stripe card is not contactless, and it does have security. Writing that a chip and PIN card is more secure earns no mark until the answer explains why.

A chip reader does not have to be contactless. An RFID reader is the device for a contactless card.

Examiner insight

“The question asked for contactless, and a chip reader does not have to be contactless.” “Many believed that magnetic stripe cards were contactless or that they had no security.”

Worked example 12 marks

A customer makes a contactless payment by holding a card near a reader. State which direct data entry device reads the card. Give one reason why a chip reader is not the answer.

  1. 1

    RFID reader [1]

  2. 2

    a chip reader does not have to be contactless [1]

9. RFID readers

An RFID reader reads a tag or microchip with radio waves. The reader sends radio waves to the microchip, which is activated by the reader. The microchip then emits radio waves and the data is read by the reader.

The tag does not need to be seen by the reader. A microchip is less likely to be damaged or lost, and it lasts longer due to a lack of wear and tear.

A contactless card is held near the reader. It is not inserted, and no PIN is entered, so a stolen card could be used without a PIN.

Examiner insight

“Some candidates answered this question relating it to searching/comparing the database but the question was about reading the data.” “Many candidates again explained that the data was being read without any mention of why using RFID technology is used and others said it is faster without any explanation of why that is an advantage.”

Worked example 16 marks

Pets must be fitted with a microchip. A veterinary surgeon can use RFID to read and display information about the pet.

(a) Describe how the pet’s information on the microchip is read by RFID. [3]

(b) Describe the benefits of using microchip technology in this way. [3]

  1. 1

    (a) the RFID reader sends radio waves to the microchip, which is activated by the reader [1]

  2. 2

    the microchip emits radio waves [1]

  3. 3

    the data is then read by the RFID reader [1]

  4. 4

    (b) less likely to be damaged / less likely for the microchip to be lost [1]

  5. 5

    lasts longer due to a lack of wear and tear [1]

  6. 6

    easier / faster to read the details about the pet [1]

10. OMR and OCR

Optical Mark Recognition (OMR) reads marks. Optical Character Recognition (OCR) reads characters.

In a car park, a photograph is taken of the number plate as the car enters. OCR reads each character, and each character is then stored. The photograph is not what is stored.

The number plate must be seen by the reader. OCR can fail if the plate is damaged, or if people or objects obscure it.

Examiner insight

“Some candidates understood that OCR read characters and OMR read marks but struggled to convey this answer to show understanding of the topic.” “Answers were frequently in the vein of ‘scanner reads the marks and adds up the score’.”

Worked example 13 marks

A car park takes a photograph of each number plate as a car enters. Describe how OCR is used.

  1. 1

    a photograph of the number plate is taken [1]

  2. 2

    OCR reads each character on the number plate [1]

  3. 3

    each character is stored [1]

11. Bar code readers and QR scanners

A bar code reader reads a bar code and a QR scanner reads a QR code. A QR code can hold information about a product, and it saves space on the packaging.

A QR code can redirect the user to a website. The user scans it with a device with a camera.

A ticket can be sent electronically to a smartphone and displayed as a QR code. This reduces the cost of printing and sending tickets.

Examiner insight

“Most candidates knew that a QR code would redirect a user to a website, however fewer candidates could describe how this could happen by writing ‘with my phone’ rather than with a ‘device with a camera’.” “For example; for part (a) a mouse is an input device, but does not fit into this scenario whereas a bar code scanner would.”

Worked example 12 marks

A QR code is printed on the packaging of a product. Describe how a customer could use it to reach the maker’s website.

  1. 1

    the customer scans the QR code with a device with a camera [1]

  2. 2

    the QR code redirects the customer to the website [1]

Recap

  • Direct data entry devices: magnetic stripe reader, chip and PIN reader, RFID reader, OMR, OCR, bar code reader, QR scanner.
  • Keyboards, mice, sensors and DVD readers are not direct data entry devices.
  • Contactless card: RFID reader. A chip reader does not have to be contactless.
  • RFID: the reader sends radio waves, the microchip is activated and emits radio waves, and the reader reads the data.
  • OMR reads marks. OCR reads characters.
  • QR code: read with a device with a camera. It can redirect the user to a website.
  • A comparison needs similarities and differences, and a reason for each advantage.

12. Monitors and touch screens

A monitor is an output device that displays results on screen. Results are produced faster on a monitor than on a printer.

A touch screen can be an output device too. Compared with a separate monitor, keyboard and mouse, it has a smaller footprint and fewer peripherals are needed.

Long use of a monitor brings health problems. Reduce them by lowering the brightness and taking regular breaks.

Examiner insight

“Some candidates mentioned RSI as being a possible answer but RSI can be an issue with touch screens as well as ordinary keyboards.” “Others described the health issues in great detail without going on to detail what they could do to prevent or reduce these from occurring.”

Worked example 12 marks

A museum replaces the monitor, keyboard and mouse at an information point with one touch screen. Describe two advantages of this change.

  1. 1

    The touch screen has a smaller footprint: it takes the place of three devices, so less space is used [1]

  2. 2

    Fewer peripherals are needed: there is no separate keyboard or mouse to connect [1]

13. Multimedia projectors

A multimedia projector displays a presentation for an audience in a room.

It carries a health risk: the projector uses a strong, bright light, which can cause eye problems and headaches.

It carries safety risks too: the projector falling and hurting someone, or tripping over loose cables.

Examiner insight

“The types of answers that the Examiners were looking for included eye problems and headaches as the projector uses a strong, bright light.” “The Examiners allowed answers like ‘the projector falling and hurting someone’ or ‘tripping over lose cables’.”

Worked example 14 marks

A teacher uses a multimedia projector in a classroom. Describe one health risk and one safety risk of using the projector. Give a reason for each.

  1. 1

    Health risk: eye problems / headaches [1]

  2. 2

    Reason: the projector uses a strong, bright light [1]

  3. 3

    Safety risk: the projector falling [1]

  4. 4

    Reason: it could hurt someone [1]

14. Printers and hard copy

A laser printer and an inkjet printer produce a hard copy of the data.

A hard copy can be used as reference, taken away, annotated with a pen and analysed at a later date. A printout can be lost or damaged. Printing needs consumables, so it costs more than a monitor and takes longer.

Examiner insight

“However, some candidates ticked more than one box and this meant that the mark could not be awarded.” “Detail is needed in the description of these types of answer in order to achieve full marks.”

Worked example 16 marks

A school has a computerised weather station. The weather station outputs its data using both a monitor and a printer. Discuss the advantages and disadvantages of the system only using a printer for its output rather than only using a monitor.

  1. 1

    Advantage: there is a hard copy of the data which can be used as reference [1]

  2. 2

    Advantage: results can be analysed at a later date [1]

  3. 3

    Advantage: it is often easier to print off results and use a pen to annotate them [1]

  4. 4

    Disadvantage: the results are produced faster using a monitor [1]

  5. 5

    Disadvantage: printouts could be more easily lost or damaged [1]

  6. 6

    Disadvantage: more expensive to produce the output due to consumables [1]

15. Dot matrix and laser printers compared

A comparison must name the other device. Say "a laser printer is faster than a dot matrix printer", not just "faster".

A laser printer gives better quality printouts and is quieter to print. A dot matrix printer can be used in harsher conditions, such as a dirty environment.

Cost is relative, so "cheaper" earns no mark on its own.

Examiner insight

“Many candidates wrote about the cost of the devices and their consumables when cost is relative.” “A comparison could name the other device or clearly state it was faster or quieter to print.”

Worked example 14 marks

A company prints invoices in a dirty workshop and in an office. Compare the use of a dot matrix printer with a laser printer.

  1. 1

    A dot matrix printer can be used in harsher conditions / a dirty environment than a laser printer [1]

  2. 2

    A laser printer is quieter to print than a dot matrix printer [1]

  3. 3

    A laser printer gives better quality printouts than a dot matrix printer [1]

  4. 4

    A laser printer is faster to print than a dot matrix printer [1]

16. Plotters

A plotter is used to produce architectural drawings. It is not a 3D printer.

It is noisy and has a large footprint.

Examiner insight

“Some candidates wrote about a plotter producing graphs rather than architectural drawings.” “Some candidates split the question lines in two therefore splitting the positives from the negatives, this type of format does not allow candidates to gain the higher marks.”

Worked example 13 marks

An architect's office uses a plotter. State what the plotter is used to produce and give two disadvantages of using it.

  1. 1

    Used to produce architectural drawings [1]

  2. 2

    Disadvantage: it is noisy [1]

  3. 3

    Disadvantage: it has a large footprint [1]

17. 3D printers

A 3D printer builds a model layer by layer. It needs a design or model, based on a scan or measurements. Software slices the 3D model into layers. The layers are printed in resin or plastic, which binds together.

Uses include prosthetics, drug creation and tissue engineering. Drawbacks: it is expensive to buy, it can be used illegally, and it can breach copyright. It works with only some materials. A fault in the program or a power outage may go unnoticed.

Examiner insight

“The best responses described the software slicing the 3-D model into layers; the layers are then printed layer by layer in resin which then binds together.” “There was a misconception that 3D printers produced perfect models but did not add that it depended on the program.”

Worked example 14 marks

A hospital makes a prosthetic hand for a patient with a 3D printer. Describe how the hand is made.

  1. 1

    A design / model of the hand is created, based on a scan or measurements [1]

  2. 2

    Software slices the 3D model into layers [1]

  3. 3

    The 3D printer prints the model layer by layer [1]

  4. 4

    It prints in resin / plastic, which binds together [1]

18. Speakers

A speaker outputs sound. The computer reads the audio file and sends a digital signal to a DAC / sound card. The digital data is converted into analogue data, which is sent to the speakers.

A speaker is not suitable for displaying weather data.

Examiner insight

“Some candidates did not go into enough detail about the processes that could enable the student to listen to the recording.” “Some candidates answered with speaker but this was not appropriate for displaying the weather data.”

Worked example 13 marks

A student is making a recording of his voice for a podcast. When his voice has been recorded, the student wishes to listen to it. Explain the computer processes that enable the student to listen to the recording of his voice.

  1. 1

    The computer reads the audio file [1]

  2. 2

    It sends a digital signal to a DAC / sound card, which converts the digital data into analogue data / sound [1]

  3. 3

    The signal is sent to the speakers [1]

19. Actuators

An actuator is an output device. It is an external device. In a control system the microprocessor compares the sensor data with a pre-set value. It then sends a signal to the actuator.

The actuator does the work. Actuators open windows. A motor or actuator raises a barrier. The microprocessor does not.

Examiner insight

“Some candidates need to understand that an actuator is an external device.” “Other candidates thought the windows opened rather than actuators opening the windows.”

Worked example 13 marks

A car park barrier is controlled by a microprocessor. Describe what happens after the sensor data reaches the microprocessor so that the barrier is raised.

  1. 1

    The microprocessor compares the data with the pre-set value [1]

  2. 2

    It sends a signal to the actuator [1]

  3. 3

    The actuator raises the barrier [1]

Recap

  • Monitor: results are produced faster than on a printer. Reduce health problems by lowering brightness and taking regular breaks.
  • Touch screen: smaller footprint, fewer peripherals needed.
  • Multimedia projector: strong, bright light gives eye problems and headaches. Loose cables and a falling projector are safety risks.
  • Laser and inkjet printers give a hard copy. Printouts can be lost or damaged and consumables cost money.
  • Compare printers by name: laser is better quality and quieter; dot matrix works in harsher conditions.
  • Plotter: architectural drawings, noisy, large footprint. 3D printer: sliced model printed layer by layer.
  • Speaker: digital data goes to a DAC / sound card and becomes analogue sound. Actuator: external device that a microprocessor signals.

End-of-chapter exercise

Test yourself on the whole chapter. Work through these before moving on.

  1. Name two input devices from this list: monitor, microphone, speaker, scanner, printer.2 marks
  2. A door entry system has a keypad. A question asks for two other input devices the system could use. A candidate writes ‘keypad’ and ‘speaker’. Give the reason each answer earns no mark.2 marks
  3. A museum puts touch screens in its hall instead of a monitor, keyboard and mouse. State two advantages of the touch screens.2 marks
  4. A microphone captures a voice for a computer. State what the sound is converted to and what converts it.2 marks
  5. An estate agent takes photographs of houses with a digital camera instead of scanning printed photographs. State one advantage of the camera compared with a scanner, and one drawback of the camera.2 marks
  6. A clerk scans a letter and uses OCR software to edit the text. Explain why the clerk must check the text.2 marks
  7. An automatic street light has a light sensor and a microprocessor. Describe how the light is switched on when it gets dark.3 marks
  8. A fitness game uses a camera to read the movements of the player. (a) Describe how the camera is used. (b) State one thing in the room that could stop the game reading a movement correctly.4 marks
  9. A clinic keeps medicines in a fridge. A temperature sensor and a microprocessor sound an alarm if the fridge gets too warm. Before this, a nurse read a thermometer twice a day. A student writes: ‘The sensor checks if the temperature is too high and then it turns the alarm on.’ (a) Give two mistakes in the student's answer. (b) Describe what really happens, from the sensor to the alarm. (c) Give one benefit of the sensor compared with the nurse's readings.6 marks
  10. A library has 2000 old index cards to put into a database. The cards are typed in several different fonts. Some are faded and some have ink stains. The library can pay a clerk to type the cards in on a keyboard, or scan them and use OCR software. Discuss which method the library should use. Refer to the cards in your answer.6 marks
  11. Write down the two direct data entry devices in this list. Keyboard · QR scanner · Mouse · RFID reader · Printer2 marks
  12. State what OMR reads and what OCR reads.2 marks
  13. A customer makes a contactless payment for a coffee by holding a card near a reader. Name the direct data entry device that reads the card.1 mark
  14. Every item at a supermarket checkout has a bar code. Name the direct data entry device that fits this scenario.1 mark
  15. A school uses a machine to read multiple-choice answer sheets. Name the direct data entry device and state what it reads from each sheet.2 marks
  16. A car park takes a photograph of each number plate as a car enters. A student writes: ‘The number plate is then stored.’ Describe what really happens after the photograph is taken.2 marks
  17. A farmer fits each cow with a microchip that is read by RFID. Describe two benefits of using a microchip.2 marks
  18. A question asks for a comparison of a magnetic stripe reader and a chip and PIN reader. A student writes: ‘A chip and PIN card is more secure. A magnetic stripe card is contactless and has no security.’ Give three reasons why this answer would lose marks.3 marks
  19. Each runner in a race wears an RFID tag. An RFID reader is placed at the finish line. (a) Describe how the data on a runner’s tag is read at the finish line. [3] (b) The organiser could instead photograph the number printed on each runner’s shirt and read it with OCR. Explain one drawback of OCR here that RFID does not have. [2]5 marks
  20. A music festival emails each visitor a ticket, which is displayed on a smartphone as a QR code. At the gate the visitor is given a contactless wristband. The wristband has money stored on it and is used to pay for food. (a) Name the direct data entry device that reads (i) the ticket and (ii) the wristband. [2] (b) A visitor says: ‘To pay, I insert the wristband and type in my PIN.’ State two mistakes in this description. [2] (c) Describe one disadvantage to the visitor of paying with the wristband. [2]6 marks
  21. A list holds a webcam, a laser printer, an actuator and a speaker. State which one is not an output device.1 mark
  22. A shop uses one touch screen at its till instead of a monitor, a keyboard and a mouse. Give two advantages of the touch screen.2 marks
  23. A clerk looks at a monitor all day. State two ways to reduce the health problems of using a monitor.2 marks
  24. A weather station needs to display its readings. Name two output devices that are suitable.2 marks
  25. A student writes: "A plotter prints graphs." State what a plotter is used to produce and give two disadvantages of a plotter.3 marks
  26. Compare a laser printer with a dot matrix printer. Name both printers in each point.3 marks
  27. A user plays a music file stored on a computer. Explain how the computer makes the sound.3 marks
  28. A dentist scans a patient's tooth and makes a replacement with a 3D printer. Describe how the 3D printer makes the replacement tooth.4 marks
  29. A factory makes door handles by hand. It plans to make them with 3D printers that run all night with no staff present. The manager says: "It is cheaper and every handle will be perfect." Discuss the advantages and disadvantages of using the 3D printers.6 marks
  30. A river station has a water-level sensor, a microprocessor, an actuator on a flood gate, a speaker and a printer. When the river is too high the gate must close and a stored voice warning must play. (a) Describe how the system closes the gate. [4] (b) Explain how the stored warning is played. [2] (c) Readings are output only on the printer, not on a monitor. Give one advantage and one disadvantage. [2]8 marks

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