Input & output devices

Input & Output Devices

An input device captures data and sends it to a computer system.

Input devices convert physical movement, such as key pressing, or environmental data, such as temperature, sound or light into electrical signals.

Input Devices

There are two types of input device: manual andautomatic.

Manual Input Devices

A manual input device requires a human hand tocontrol it…

Mouse

Scanner

Camera

Keyboard

Computer Hardware Servicing

Function Keys

Alphanumeric key

Numeric Key Pad

Arrow Keys

Back

Internal External

Back Next

Back

Types of Keyboard

Types of Scanners

Back


Tracker ball

Joystick Graphics tablet

A manual input device requires a human hand tocontrol it…


Keyboard

The most common input device

You press keys to input data into the computer

The most common type of keyboard is the QWERTY keyboard

People are familiar with keyboards, so they don’t need to be trained

Skilled typists can work very quickly

A lot of different keyboards are available, e.g. ergonomic

They are very reliable and cheap

Incorrect use or over-use can cause RSI

Many people cannot type and look at the screen at the same time, so typing can be time consuming

Uses Advantages DisadvantagesDevice


GraphicsTablet

A graphics tablet consists of a pad and a special pen

The image is instantly converted to digital data

User can get much more control, similar to the natural way of drawing

The user can zoom in to an area of the drawing for higher accuracy

Large models are very expensive

Need a large desk area

Holding a pen for a long time is more tiring than holding a mouse



Mouse

Most common pointing device

Used to point and click on icons or menus

Combines well with a keyboard

Fast and accurate

Most people are skilled at using a mouse, so no training is needed

Prolonged use can lead to RSI

Need a flat surface to use them

For an optical mouse, the laser does not work wellon all surfaces

Tracker ball

A tracker ball is basically an upside down ball mouse.

The user runs their thumb over the ball to control the on-screen pointer

User can get great pointing accuracy, without moving the hand

Useful where desk space is limited

Some people find that the thumb gets painful with prolonged use

Ball can get greasy and dirty


Manual Input DevicesUses Advantages DisadvantagesDevice

Scanner

Used to convert printed images or text into a file of digital data

There are two types: handheld and flatbed

Even cheap scanners produce quality images

Any printed image can be inserted into a document

Images can be edited before use

The quality of the final image is dependent on the original image

Joystick Originally designed forpilots to control aeroplanes

Used to control wheelchairs and for playing games

They give a more realistic gaming experience when playing games such as flight simulators

Many different types available

Some people find them difficult to operate,


Digital Camera

Used for taking still images which can be uploaded to a computer for permanent storage

You can preview the image before pressing the shutter button

No film needed or

Unwanted images can be deleted

When the drive is full, images need to be uploaded to a computer or deleted

Touchpador

Fingerpad

A pointing device, built into a laptop for convenience

Portable - built into the laptop

Don’t need to carry extra equipment around

Small movements needed to move the cursor

Takes practice to master

Some people find them very fiddly

Fingers need to be clean and free of grease


Automatic Input Devices

An automatic input device inputs data without the need for human intervention (once the device has been set up), e.g. MICR, OMR, barcode reader, webcam, microphone, sensor.

Microphone

Webcam

Barcode reader


MICR

MagneticInk

Character Recognition

Banks print important data on the bottom of cheques using magnetic ink

This ink is then read by a computer

Very quick and accurate processing of data – very low error rate. Humans could not achieve the same accuracy

Very secure as any attempt to change the numbers on a cheque will be ignored as the reader only recognises magnetic ink in the same font

Banks are the main user – very few other applications



OMROpticalMark

Recognition

Used when youmark the numbers with a pencil ona lottery ticket

Very fast method of reading data, which reduces queuing time for lottery tickets

More accurate than humandata entry

Sometimes incomplete marks are not read correctly


OCR Optical

CharacterRecognition

Uses a scanner to scan text, then software converts the text into a word processor file

Quicker than typing in the text

Reduces the cost of posting a letter

Sometimes it is not very accurate


Barcode Readers

Used to identify products in shops

The code is read by a barcode scanner which identifies the product name, manufacturer and country of origin

Very quick and accurate way to enter data – suits busy shops

All barcodes need to be programmed into the computer in advance

The reader maynot be able to readthe barcode on wrinkled packaging


Magnetic Stripe

Reader

Found on the back of bank cards and store loyalty cards

The stripe holds information, suchas the account number and the PIN

Simple, cheap and effective

The data on the card can be altered if needed

Magnetic stripe can get scratched Not much data can be storedThieves can read data on cards then use the cards themselves


Microphone

Used to input sound into the computer

Very cheap piece of equipment

Helpful for people with additional needs or for busy people who need very quick letters

Computer can misread voice instructions due to natural variations in people’s voices

Generally, the sound quality from a PC microphone is poor


Webcam Used to input moving images into the computer for use in online communication

Very cheap piece of equipment

Enables people to see each other whilst they chat

The image quality from most webcams is poor

The moving picture tends to flicker due to current limitations in data transfer

Output Devices

Output Devices

An output device is used to display or use information that comes out of a computer system.

Output devices convert electrical signals from a computer system into…

Sound (speakers or headphones) Images & Text (screen or printer) Movement (actuator, electric motor)

Output Devices

Monitor Speakers

Plotter

Headphones

Printer

Output Devices

TFT Monitor

Thin Film Transistor monitors are more commonly known as flat screens or LCD screens

Take up very little space

Run very quietly and produce little heat

Use about a third of the energy ofa CRT monitor

Easy to damage

Colour contrast on cheaper models is not as good as CRT monitors


CRT Monitor

Cathode Ray Tube is very old technology.Almost completely replaced by flat screen monitors

Robust and difficult to damage

Reliable

Last for a very long time

Large, bulky

Can be heavy

Produce a lot of heat

Old technology

Output Devices

Speakers&

Headphones

When connected to a computer through a sound card, music can be played

Can help blind people use the computer

A presentation can be more powerful with sound

Games are a lot more involving and realisticwith sound

Speakers are not useful in a network room, as everyone would disturb each other

Headphones can be uncomfortable with extended use


Plotter These are specialist printers that can produce high quality printoutson large piecesof paper

Very high quality printouts

Almost any size paper can be used

Slower than normal printers

Expensive to purchase and run

Printers

There are 3 main types of printer…

Dot Matrix

Laser

Inkjet

Uses Advantages DisadvantagesDeviceGeneral purposeuse for family orhome office

Cheap to buy

Latest modelscan be very fast

Ink cartridges can be very expensive

Print quality not always very good

Business use for letters,stationery and images

Quality printing

Good for large areas of colour

Quiet & Quick

More expensive to buy than inkjets

Toner cartridges are expensive

Business usefor duplicatedocuments

Can make a carbon copyCan print on continuousrolls of paper

Noisy and rather old-fashioned technology

Poor quality and only prints in black ink

Drag the input and output devices to the correct side...

Input & Output Devices

Keyword Activity

Drag the missing words to the correct place in the sentences…

Devices & Hardware

Input & output devices