Year 10 · ICT · Autumn 1 · Computer systems, devices and storage; document production

Input and output devices

TheoryPresent ▶

What this lesson covers

2.1 Input devices

Cambridge IGCSE ICT 0417 · Topic 2: Input and output devices · Paper 1

2.2 Direct data entry devices

Cambridge IGCSE ICT 0417 · Topic 2: Input and output devices · Paper 1

2.3 Output devices

Cambridge IGCSE ICT 0417 · Topic 2: Input and output devices · Paper 1

You will learn to

Describe the use of common input and output devices.
Give an advantage and a disadvantage of each device.
Explain what direct data entry is, with examples such as barcode and RFID readers.
Choose a suitable device for a given scenario and justify the choice.

Success criteria

I can give a scenario, an advantage and a disadvantage for twenty devices.
I can explain why a supermarket uses barcode readers, not keyboards, at the till.
I can answer a past-paper 'which device' question with a justified choice.

The syllabus points for these sections

Describe the use of each input device in the syllabus.
Give an advantage and a disadvantage of each.
Choose a suitable input device for a given situation and justify the choice.
Name the right sensor for a measurement.
Explain what direct data entry (DDE) means and why it is used.
Describe magnetic stripe readers, chip and PIN readers and RFID readers.
Describe OMR, OCR, barcode readers and QR code scanners.
Give an advantage and a disadvantage of each DDE device.
Describe the use of each output device in the syllabus.
Compare laser, inkjet and dot matrix printers.
Explain uses of plotters and 3D printers.
Describe how actuators are used in control systems.

Key words

Say each word, then read what it means. Every one is in the glossary too.

Input device: Hardware that sends data or instructions into a computer.
Output device: Hardware that shows, prints, plays or does the result of processing.
Direct data entry (DDE): Reading data straight from its source with no manual typing.
Sensor: An input device that measures a physical quantity such as temperature.
Actuator: An output device, such as a motor or valve, that makes something move or happen.
OMR: Optical mark recognition: reads shaded marks in set positions on a form.
OCR: Optical character recognition: turns a scanned image of text into editable text.
RFID: Radio frequency identification: reads a tag using radio waves, without contact.
Barcode: A pattern of lines that stands for a number, read by a light beam.
QR code: A square pattern of black and white squares that holds more data than a barcode.
Chip and PIN: A bank card chip read by a terminal; the user types a PIN to prove identity.
Impact printer: A printer that strikes the paper through an inked ribbon, such as dot matrix.
Plotter: An output device that draws very large, accurate drawings.
3D printer: A device that builds a solid object layer by layer.
Trackerball: A pointing device where you roll a ball; the device stays still.

The explanation

Read it here, or open the study page below to go one step at a time with things to try.

2.1 Input devices

What an input device does

An input device lets data or instructions go into a computer.

Some are manual: a person operates them, like a keyboard. Others capture data automatically, like a sensor.

When you answer an exam question, name the device, say what it is used for, then give a reason linked to the situation.

e.g.Example

Weak answer: "A barcode reader is fast." Strong answer: "A barcode reader is faster than typing the product code, because the code is read in one scan, so the queue moves quickly."

Keyboards and numeric keypads

A keyboard is used to type text and commands. Most use the QWERTY layout.

A concept keyboard has flat keys with pictures or words. Fast-food tills use them.

A numeric keypad has only numbers and a few keys. It is on ATMs, chip and PIN terminals, phones and the side of large keyboards.

Device	Use	Advantage	Disadvantage
Keyboard	Typing documents, emails, data into forms	Fast, accurate entry of text for a trained typist; familiar to most users	Slow for people who cannot type; long use can cause RSI; takes up desk space
Numeric keypad	Entering PINs at an ATM, prices at a till, phone numbers	Faster than a full keyboard for numbers; small, so fits on a card terminal	Keys are small and can be hard to press; PIN can be seen by shoulder surfing

Pointing devices

A pointing device moves a pointer (cursor) on a screen and selects things.

A mouse is moved on a desk. A touchpad is a flat pad on a laptop: you move a finger on it. A trackerball is like an upside-down mouse: you roll the ball and the device stays still.

Device	Use	Advantage	Disadvantage
Mouse	Selecting icons and menus in a GUI; drawing	Faster to select options than using keyboard shortcuts; easy to use	Needs a flat surface; can cause RSI with long use
Touchpad	Pointing on a laptop	Built in, so no extra device to carry; works where there is no desk	Harder to control precisely than a mouse, e.g. for drawing
Trackerball	People with limited hand movement; control rooms; some medical equipment	Does not move, so needs less space and less wrist movement; easier for some disabilities	Not as fast as a mouse for most users; costs more

Remote controls, joysticks and driving wheels

A remote control sends infrared or radio signals to a TV, projector or air conditioner from a distance.

A joystick controls movement in games and flight simulators. A driving wheel controls steering in driving games and car simulators.

Device	Use	Advantage	Disadvantage
Remote control	Changing TV channel; controlling a projector or a multimedia system	Can be used from a distance, so the user does not need to move	Infrared needs a clear line of sight; small buttons hard for some people; easy to lose
Joystick	Games; flight simulators; controlling robot arms	Easier to control movement in any direction than with keys; feels realistic	Harder to use for selecting menus or typing
Driving wheel	Driving games and training simulators	More realistic than a keyboard, so training is more useful	Expensive; takes up space; only useful for one kind of task

Touch screens and light pens

A touch screen is a screen you touch to select options. It is used on phones, tablets, ATMs, information kiosks and self-service tills.

A light pen is a pen with a light sensor. You point it at a screen to draw or select. It is rare now and is used in some design and medical work.

Device	Use	Advantage	Disadvantage
Touch screen	Phones, ATMs, kiosks, self-service checkouts	Fast and intuitive, no training needed; no keyboard or mouse, so saves space	Screen gets dirty and scratched; limited options per screen; hard for some disabilities
Light pen	Drawing directly on screen; selecting on medical or design screens	More precise than a finger; no desk space needed	Can be tiring to hold up against a screen; not suitable for all screen types

Scanners, digital cameras and microphones

A scanner turns a paper document or photo into a digital image.

A digital camera takes photos and videos and stores them on a memory card.

A microphone turns sound into an electrical signal. Uses: video calls, voice recognition, recording.

Device	Use	Advantage	Disadvantage
Scanner	Digitising old photos and documents; with OCR, turning print into editable text	Faster than retyping or redrawing; makes a digital backup of paper	Quality depends on the original; large image files
Digital camera	Photos for websites, ID cards, reports	Images can be checked at once and deleted; easy to transfer to a computer	High-quality images use a lot of storage; good cameras are expensive
Microphone	Voice recognition, video calls, voice notes	Faster than typing for many users; hands-free	Background noise affects quality; voice recognition makes errors

Sensors

A sensor measures a physical quantity, such as temperature, and sends the reading to a computer. The data is usually analogue, so an ADC converts it.

Sensors take readings automatically and continuously, day and night. A person does not need to be there.

Sensor	Measures	Example use
Temperature	How hot or cold	Central heating, greenhouses, ovens
Light	Light level	Street lights turning on at dusk; phone screen brightness
Pressure	Force or weight	Burglar alarm mats; car airbags; checking tyre pressure
Moisture / humidity	Water in soil or air	Watering plants in a greenhouse; museums
Infrared / motion	Movement or heat from a body	Security lights; automatic doors
Sound (acoustic)	Noise level	Burglar alarms detecting breaking glass
pH	Acidity	Fish tanks; checking river pollution
Gas (e.g. CO2, oxygen)	Gas levels	Greenhouses; carbon monoxide alarms

?Why?

Advantage: readings are more accurate and more frequent than a person could take, and work in dangerous places. Disadvantage: a faulty sensor gives wrong data, and sensors cost money to install and maintain.

!Watch out

A sensor does not "control" anything. It only measures. The microprocessor decides and an actuator acts.

2.2 Direct data entry devices

What direct data entry means

Direct data entry (DDE) devices read data straight from its source, such as a card, tag, form or label. Nobody types it in.

This makes entry faster and more accurate, because there are no typing errors.

Try the sorter below. Some devices are input, some output and some DDE. Tap a device card, then tap the bin it belongs in. Press Check when you are done.

!Watch out

DDE devices are still input devices. Cambridge lists them separately because they need no manual typing.

There is something to try for this step in the IGCSE library.

Card readers: magnetic stripe, chip and PIN, RFID

A magnetic stripe reader reads the dark stripe on the back of a card when it is swiped. Uses: hotel key cards, some ID and loyalty cards.

A chip and PIN reader reads the small chip on a bank card. The customer types a PIN (personal identification number) to prove it is their card.

An RFID reader (radio frequency identification) reads a tiny tag using radio waves, without touching it. Uses: metro cards like the Madrid Tarjeta Transporte Público, contactless cards, library books, tracking parcels and animals.

Device	Advantage	Disadvantage
Magnetic stripe reader	Fast: one swipe; stripe is cheap to make	Stripe is damaged by magnets and wear; easy to copy (card cloning), so less secure
Chip and PIN reader	More secure than a stripe, because the chip is hard to copy and a PIN is needed	PIN can be seen by shoulder surfing; slower than contactless; forgotten PIN stops payment
RFID reader	No contact and no line of sight needed; reads many tags at once; very fast	Tags can be read by criminals with their own reader; more expensive than barcodes; signal can be blocked by metal

OMR and OCR

Optical mark recognition (OMR) reads marks made in set positions on a form, such as shaded boxes. Uses: multiple-choice exam answer sheets, lottery tickets, school registers, surveys.

Optical character recognition (OCR) is software that turns a scanned image of text into editable text. Uses: scanning passports at airports, reading car number plates, digitising printed books.

Device	Advantage	Disadvantage
OMR	Thousands of forms read quickly and accurately; no typing errors	Forms must be designed and printed carefully; marks outside the box or crossed out are misread; only for set choices, not free text
OCR	Much faster than retyping a document; text can then be edited and searched	Makes errors with handwriting or poor print, so text must be checked; cannot always read unusual fonts

!Watch out

OMR reads marks (where you shaded). OCR reads characters (letters and numbers). Do not swap them.

Barcode readers and QR code scanners

A barcode is a pattern of black and white lines that stands for a number. A barcode reader shines a light and reads the pattern. Supermarket tills and libraries use them.

A QR code (quick response code) is a square pattern of black and white squares. It holds much more data, such as a website address, a ticket or a payment. A phone camera can scan it.

Device	Advantage	Disadvantage
Barcode reader	Faster and more accurate than typing a product number; links to automatic stock control	Damaged or dirty barcodes cannot be read; item must be in line of sight of the reader
QR code scanner	Holds more data than a barcode (e.g. a full URL); can be read from any angle; any smartphone can scan it	A fake QR code can lead to a malicious website; needs a camera and app

e.g.Example

Supermarket checkout: the barcode 8 410000 810004 is scanned. The till looks up the number in the stock database. It finds the name and price, adds them to the bill and takes 1 off the stock level.

2.3 Output devices

Monitors, touch screens and projectors

LCD (liquid crystal display) monitors need a backlight. Modern ones use LED (light-emitting diode) backlighting, so most screens today are LED screens.

A touch screen is also an output device, because it displays the result.

A multimedia projector shows a computer image on a large screen or wall, for a class or audience.

Device	Use	Advantage	Disadvantage
LCD / LED monitor	Showing output on desktops, laptops, TVs	LED-backlit screens are thin, light, bright and use less power than old CRT screens	Viewing angle can be limited; can cause eye strain with long use
Touch screen (as output)	Phones, kiosks, ATMs	One device does input and output, saving space	Fingerprints and glare make the screen harder to read
Multimedia projector	Classrooms, presentations, home cinema	Very large image, so a whole audience can see	Image fades in bright rooms; bulbs are expensive and get hot; fan can be noisy

Laser, inkjet and dot matrix printers

A laser printer uses toner (powder) and a laser to print a whole page at once. Good for large volumes, such as a school office.

An inkjet printer sprays tiny drops of liquid ink. Good for small numbers of high-quality colour photos at home.

A dot matrix printer is an impact printer: pins hit an inked ribbon onto the paper. It can print multi-part (carbon copy) forms and works in dirty or damp places, such as a factory or warehouse.

	Laser	Inkjet	Dot matrix
Speed	Fast, many pages per minute	Slower	Slow
Quality	High, sharp text	High, very good for photos	Low
Noise	Quiet	Quiet	Very noisy
Cost of printer	Higher	Low	Low to medium
Cost per page	Low; toner lasts many pages	High; cartridges run out quickly	Very low
Best for	High-volume printing, e.g. school reports	Low-volume, high-quality colour, e.g. home photos	Multi-part forms, invoices, harsh environments

!Watch out

"Laser printers are better" earns nothing. Say "a laser printer is faster than an inkjet, so 600 school reports print in less time".

Plotters and 3D printers

A plotter draws on very large paper using pens or ink. Uses: architects' building plans, maps, engineering drawings, large posters.

A 3D printer builds a solid object layer by layer from plastic, resin, metal or even living cells. It reads a design made with CAD (computer-aided design) software.

Device	Use	Advantage	Disadvantage
Plotter	Building plans, maps, large banners	Very large, very accurate drawings	Slow; expensive; takes a lot of space
3D printer	Prototypes, prosthetic limbs, spare parts, models of organs	One-off custom items made cheaply; complex shapes possible	Slow for large items; materials can be expensive; could be used to make dangerous items

Speakers and actuators

A speaker turns digital sound data into sound. A DAC changes the digital data to an analogue signal first. Uses: music, alarms, screen readers for blind users.

An actuator is a motor, valve, pump, heater or buzzer that makes something physically happen when a computer sends a signal. It is the output part of a control system.

Device	Use	Advantage	Disadvantage
Speaker	Music, video, alarms, reading text aloud	Can reach many people at once; helps visually impaired users	Disturbs others in an office; sound quality varies
Actuator	Opening a greenhouse window; turning on a heater; moving a robot arm	Lets a computer control real equipment automatically, 24 hours a day	Expensive; needs maintenance; a failure can stop the whole system

e.g.Example

Greenhouse control: Temperature sensor reads 31 °C (input). Microprocessor compares with the set value of 26 °C. It is too hot. Actuator: a motor opens the window (output). The loop repeats.

Study it

Open the study page and go one step at a time.

ICT topic 1

Check yourself

One question at a time. The reason shows after each answer.

Saved on this device.

Input and output devices

What this lesson covers

You will learn to

Success criteria

Key words

The explanation

What an input device does

Keyboards and numeric keypads

Pointing devices

Remote controls, joysticks and driving wheels

Touch screens and light pens

Scanners, digital cameras and microphones

Sensors

What direct data entry means

Card readers: magnetic stripe, chip and PIN, RFID

OMR and OCR

Barcode readers and QR code scanners

Monitors, touch screens and projectors

Laser, inkjet and dot matrix printers

Plotters and 3D printers

Speakers and actuators

Study it

Types and components of computer systems

Input and output devices

Storage devices and media

File management

Document production

What a computer is

Check yourself