03a - input devices - inputs

7/22/2019 03a - Input Devices - Inputs

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GCSE ICT

Input and Output Devices - Inputs


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Input devices

Input devices are used to get data into a

system.

They should be able to do this as

accurately and quickly as possible, and

with the minimum of human intervention.


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Input devices

The most common types of input devices

are:

Keyboards

Point and Click devices (including mouse,

tracker balls, touch sensitive pads, joysticks,

light pens, touch screens, and graphic tablets)


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Input devices


are:

Readers (including magnetic strip readers,

barcode readers, optical character

readers/recognition, magnetic ink character

readers/recognition, and optical mark

readers/recognition) Punched cards and tape (including punched

cards and Kimball tags)


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Input devices


are:

Sound capture devices (including voice

recognition and microphones)

Terminals (including EPOS and EFTPOS

terminals)


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Input devices


are:

Digital imaging devices (including video

digitisers, scanners, digital cameras, and web

cams)

Tonal devices (including touch tone

telephones)


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Input Devices

keyboards,

numeric keypads,

pointing devices (including mouse, touchpad and tracker ball),

remote controls,

joysticks, touch screens,

graphics tablet,


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magnetic stripe readers,

chip readers,

PIN pads, digital cameras,

video cameras,

web cams, scanners,

microphones,


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sensors,

MICR,

OMR, OCR,

barcode readers,

light pens;


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Keyboards

The most common type of keyboard is

the QWERTY keyboard (so called

because the top line of letters are q, w, e,

r, t, and y.


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Concept Keyboard

A concept keyboard is a flat

board that contains a grid of

buttons. Each button can be

programmed to do whatever

you want.

An overlay sheet with

pictures or symbols is placed

on the grid so that the user

can tell what pressing on

different areas will do.


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Concept keyboards are used

when fast input is needed and

are ideally suited to selecting

from a limited range of choices

such as fast food restaurants.Checkout tills such as

McDonalds use symbols to

make ordering faster and

easier. Primary schools often

use them with young children.

The overlay image could be apicture of a farmyard. Pressing

on an animal would cause the

computer to make the right

animal noise.

Concept keyboards are

particularly useful for

people who would find

using an ordinary

keyboard difficult. It isalso very handy in

locations where an

ordinary keyboard might

be damaged e.g. byspillage or dust.


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AdvantagesMuch faster for making non-

text selections such as menu

choices on the till of a fast-food

outlet.

The keyboard is waterproof

which can be useful where

there is dirt or the risk of

splashes

Disadvantages Poor for text or numeric

input - although some

keyboards do include a

numeric keypad so the

operator can enter the

amount sold.

Limited to the options

shown on the keyboard


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Keyboards

Another type of keyboard is the concept

keyboard.

The can be specially designed so that

people with restricted vision can use them

to interface with a computer.

Concept keyboards can also be

programmed to perform common functions

with one keystroke (e.g. a computerised till

in a fast food restaurant).


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Ergonomic KeyboardErgonomic computerkeyboards encourage the user

to adopt an ergonomic typing

posture which minimizes the

exposure to awkward postures

and repetitive stress. The main

concerns are the horizontal

and vertical bending of thewrists, known as ulnar

deviation and pronation

respectively. These deviations

result in the compression of

the nerves in the wrist, causing

disorders such as carpeltunnel syndrome.

carpel tunnel syndrome.
http://www.ergonomics-info.com/carpal-tunnel-ergonomics.htmlhttp://www.ergonomics-info.com/carpal-tunnel-ergonomics.html


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Pin PadNumeric KeypadA small keyboard that only

has numbers.

Used to enter numeric data into

computers such as those in ATMs.

Most computer keyboards have a

numeric keypad on the right side,

and most mobile phones (there

are also computers) have a one

for entering phone numbers, etc.

This is a device with

a numeric keypad used to

enter a personsPersonal

Identity Number (PIN) e.g.

when paying with a credit

card.

PIN pads are also found on

electronic door locksyou

enter a PIN to unlock the door.


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Point and Click devices

Point and Click devices include mouse,

tracker balls, touch sensitive pads,

joysticks, light pens, touch screens, and

graphic tablets.


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Mouse

The mouse translates movement

on the desktop into digital

information.

This information is converted intomovement of the cursor on the

screen.

A mouse will also have one, two, or

three buttons which can be clicked

to help the user to select what

functions they wish to use.


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The mouse is a very important input device. It helps

you to do many things, such as:

controlling the cursor or pointer

opening up menus

selecting items from menus by clicking the mousebutton

opening up software by clicking the mouse button

dragging icons to move them into folders, to save

files.


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Advantages Ideal for use with desktop

computers

Usually supplied as part

of a new computer

system Most computer users are

familiar with them and

require little training

Works well in conjunctionwith a keyboard for data

entry

Disadvantages They need a flat space

close to the computer

The rollers in mice that

use balls can become

clogged with grease and

grime and lose their

accuracy until cleaned.

Overuse can lead to RSI


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Tracker ball

The tracker ball is essentially an

upside down mouse.

Instead of moving the mouse on

the table top, the ball is rotated. This achieves the same result as

using a mouse but takes up far

less room.


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Used as an alternative to a

mouse. To operate it theuser rotates the ball whichmoves the pointer onscreen. They areparticularly easy to use forthose with limitedmovement in their handsand are often used inComputer Aided Design

(CAD) for their increasedprecision over a mouse.


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Touch sensitive pad

These are most

commonly found on

laptop computers.

A stylus or the usersfinger is pressed gently

onto the pad, and as it is

moved the cursor moves

on the screen.


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Joystick / Joypad

These are most commonly used to

interact with computer games,

although they are also used in other

circumstances (e.g. on hospital

scanners). Like the tracker ball, the movement

of the joystick moves the cursor on

the screen,


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Advantages They give a better

gaming experiencefor racing or flying

styles of computer

games

Disadvantages Some people find

joysticks more difficult

to control than atraditional mouse.

Joysticks are not

particularly robust and

can break easily if too

much force is used on

them.


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Light pen

Light pens are usually used

with specialist design

software.

The light pen works by being

touched against the screen.

As the pen is moved on the

screen, the cursor moves.


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Light PenLight Pen A light pen is a computer input device in

the form of a light-sensitive wand used in

conjunction with a computer's CRT TV set ormonitor. It allows the user to point to displayed

objects, or draw on the screen. A light pen is fairly

simple to implement. Just like a light gun, a light

pen works by sensing the sudden small change inbrightness of a point on the screen when the

electron gun refreshes that spot.


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Touch screen

The touch screen is a special type of

screen which is sensitive to touch.

Selections can be made by touching

the screen. These are particularly useful in banks,

building societies, and shops, where

customers who are not used to using a

keyboard can interact with a computer

system.


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Stylus Used on palmtopand tablet

computers where a flat screen

is pressure sensitive and

sends a signal ack to the

computer when it touched by a

plastic stick called a stylus.This is often used

with handwriting

recognition software to allow

the user to enter data. The

software is "taught" the shapesof letter that the user uses and

then as the user writes on the

touch screen the shapes are

interpretted into text.


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Advantages

Easy to use - intuitive,

don't need much training

No extra peripherals such

as a mouse are needed

Software can alter the

screen while it is being

used, making it more

flexible than a conceptkeyboard which has a

permanent overlay.

Disadvantages Not suitable for inputting large

amounts of data

Not very accurate - selecting

detailed objects can be difficultwith fingers

Tiring to use for long periods

More expensive than

alternatives such as a mouse

Not robust - can soon becomefaulty if misused


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Graphics tablet

A graphics tablet allowsthe user to create designsdirectly onto the screen.

A special stylus isconnected to thecomputer via the graphicstablet, and as the userdraws on the tablet with

the stylus the drawingappears on screen.


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This has a flat surface that can sense the

slightest touch.

Artists and designers use it to enter drawings

into a computer system.

By dragging a stylus across the tablet surface

you can draw freehand and the drawing is

entered exactly into the computers memory.


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Advantages It is much more

natural to draw

diagrams with a

pencil typeimplement (the

stylus) rather than

with a mouse

A great level of

accuracy can be

achieved

Disadvantages Not really suitable

for general

selection work

such as pointingand clicking on

menu items

Graphics tabletsare much more

expensive than a

mouse


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Sensors

Sensors are often used as part of afeedback cycle. They collect datacontinuously and are typically linked to

a control programthat specifiesacceptable levels, eg the minimum and

maximum temperature in a greenhouse. The control program decideswhat to do next based on the data it's

fed by the sensors.
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Readers

The most common types of reader usedinclude

magnetic strip readers

barcode readers optical character readers/recognition,

magnetic ink character readers/

recognition optical mark readers/recognition).


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Magnetic stripes are built into

many plastic cards such as debit

or credit cards and personal

identity cards.

The magnetic strip on the back of

the card can hold the personal

details of the card owner and,

with the necessary PIN, will allow

access to secure information, eg

bank account details.

Data stored on the strip is

scanned and input into a computersystem by a magnetic stripe

reader.


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The information printed on the

cheque using MICR is :

A unique number for the

cheque.

A code that identifies the bank

and branch that issued the

cheque.

The number of the account

that the cheque relates to.

MICR readers can only read

one special font which can

represent only numbers and a

few punctuation marks. They

can read characters very

quickly and with 100%accuracy. Information printed

in magnetic ink is also very

secure. It is not possible to

change the information by

writing over it with a pen andthe printed numbers are not

damaged by folding (as often

happens with cheques). Both

the reader used by MICR and

the special ink are expensive.


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Barcode readers

Barcodes are used in

shops, libraries,

luggage handling,

and stock control.

The lines on a

barcode represent

numbers, and can bescanned very quickly

using a laser

scanner.


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Barcodes are printed on nearly every product you buy,

each product has a unique code. When read,

information stored in the shop'sdatabase

is recalled,such as the product name and price. This information

later appears on your receipt. The scanning process

also assists in stock management, reducing the stock by

one each time a product is scanned/sold.

The information normally included on a bar code for a

product is country of origin, manufacturer and item code.

The price is not included in the bar code. A scanner can read a barcode number incorrectly. A check digitis

included in the barcode number to reduce the likelihood of this

happening.
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Scanners

A scanner is a

device that

optically scans

images, printedtext, handwriting,

or an object, and

converts it to a

digital image.


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A scanner works by shining a light at the image beingscanned and measuring how much light is reflected back

using an optical sensor. The amount of light that is

reflected back tells the computer how light or dark the

image is at each point


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:- Image Scanners

(a)Flatbed scanners

(b)Handheld scanners

OCR (Optical Character

recognition) OMR (Optical Mark

Reader)

Bar code Reader

MICR (Magnetic InkCharacter Recognition).

Types of Scanners are


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Flatbed Scanner: You place the image on top of the scanner. Thescanner moves the light and sensor itself and scans the whole image

automatically. Most flatbed scanners are A4 size.Handheld Scanner: You must manually push the light/sensor along theimage. Handheld scanners are usually 5 inches wide.


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Optical Character Recognition (OCR)software can be used to

read printed text from an image that has been scanned and store it

as text rather than an image. You can then edit the text using a

word processoror desktop publisher. OCR software is not yetsophisticated enough to read hand-written text accurately.

Advantages
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Advantages

Flatbed scanners are very accurate and

can produce reasonably high quality

images

Any image which is digitised by thescanner can then be included on electronic

documents

Images once digitised can be enhanced

with a graphics application

Disadvantages

Images can take up a lot of memory

space

Images lose some quality in the

scanning and digitising process

The quality of the final image is

dependent on the quality of the original

image

Optical character


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Optical character

readers/recognition

Optical character recognition is a method ofinputting text using a scanner.

It requires special software to convert thescanned image of each letter into an ASCII(American Standard Code for InformationInterchange) code, and it often confuses similarshaped letters and numbers (e.g. S and 5, B and8).

It is used to convert paper books and documentsinto electronic files. When one scans a paperpage into a computer, it produces just an imagefile, a photo of the page.


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Magnetic ink character


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Magnetic ink character

readers/recognition

Branch codeCheque number Account number


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Magnetic ink characters appear at the bottom of cheques. Banks use

MICR to read the numbers from the bottom of cheques to obtain data

such as account numbers and bank sort codes. A particular fontis used

that makes it easy for the machine to discriminate between characters.

The ink is magnetised, this makes it immune to creases and dirty

marks.
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Optical mark readers/recognition

Optical mark recognition sense marks

made on specially designed forms (e.g.

multiple choice answer sheets, lottery

cards). OMR is a very cheap, easy and quick to

handle system of inputting data, but if a

user makes a mistake they are difficult tocorrect.


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Optical mark readers/recognition


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An OMR reads marks made by pencil on a printed form into the

computer. OMR systems are suited to reading pre-printed forms and

check boxes such as National Lottery number selection sheets and

multiple choice exam papers.

Smart Cards

S d f ll d i d i I f h ll


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Smart cards are often called input devices. In fact they are actually

simple storage devices. A smart card contains a small RAMchip.

When the card is put into a machine data can be read from the card

or written onto it. A smart card can store much more data than amagnetic stripe can. A popular card in use at the moment can store

8k (about 8000 characters) of information.
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Petrol companies and supermarkets use smart

cards to store information about points that

customers earn when they buy goods. Every

time the customer buys something the numberof points stored on the card is increased. The

customer can then spend these points to buy

goods.


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A new generation of smart cards is now

appearing which contain a small

microprocessoras well as memory. These

cards are practically a complete computersystem on a card.
http://www.hollyfield.kingston.sch.uk/gcseit/GCSE/compsys.htmhttp://www.hollyfield.kingston.sch.uk/gcseit/GCSE/compsys.htm


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Punched cards and tape

Punched cards and tape were used by the

first computers to store programs and

data.

They are seldom used today except forclock cards, which records when a person

starts and ends work, and Kimball tags,

which are used for stock control.


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Sound capture devices

Voice recognition software remembersthe way a user speaks, and converts theirspeech into text that appears on screen.

Although voice recognition software hasbecome increasingly sophisticated, manysuch programs have difficulty convertingmore than 90% of common words

accurately.


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Microphone

The sound is detected by the microphone

and an electrical signal is transmitted to the

computer.

Special hardware is used to convert thisanalogue data into digital data so it can be

stored and manipulated.


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Voice Recognition Voice recognition systems listen to what

people are saying and carry out the

instructions given to them when peoplespeak.


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Existing voice recognition systems come in

two different types :

Systems which recognise only a few

words but can understand most peoples

voices. e.g. telephone banking computers.

Systems which recognise a wide

vocabulary but need to be trained to

understand each different voice. e.g.

automatic dictation systems.


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Digital Cameras

Digital camera A digital camera takes pictures and can

usually record video too. The pictures it

takes and the videos it records are storedin files. These files can be copied to a

computer and later edited.


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C S


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WEB CAMS

Webcams are very basic digitalvideo cameras used to capture

images to be sent down networks

for video conferencing.

Webcams do not allow you to savethe images like digital video cameras

do. Video conferencing is where

people can "meet" across a network

using microphones, webcams andmonitors. This lets people meet who

are different countries meet.


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Video Digitiser A video digitiser takes an image from a video

camera or television and converts it so that it

can used by and stored on a computer. Almost

all video digitisers now work in colour. Unlike

scanners video digitisers can capture movingvideo sequencesas well as still images.


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When a video sequence is captured thecomputer stores this as a sequence of still

images called frames. These images aredisplayed quickly one after the other(rather like a flick-book) to create the

illusion of a moving picture.


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When you want to capture a videosequence you must tell the computer :

Size: How big you want the image youcapture to be. e.g. should it take up thewhole screen, 1/2 the screen, 1/8th of the

screen ... ?

Frame Rate: How frequently the framesshould be captured from the video.

T i l


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Terminals

EPOS (Electronic Point Of Sale) andEFTPOS (Electronic Fund Transfer at

Point Of Sale) terminals are connected,

via secure Internet connections, to thecomputers of the main banks and credit

card companies.


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T i l


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Terminals

It also gives the retailer an opportunity tocollect information about their customers,

and to develop individual customer profiles

(i.e. know what an individual customermay want to buy).

This helps to retailer to target individual

customers with special offers etc.

Di it l i i d i


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Digital imaging devices

These include video digitisers, scanners,digital cameras, and web cams.

Vid Di iti


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Video Digitisers

The video digitiser is a combination ofhardware and dedicated software thatconverts an analogue signal into a digital

signal. This is the basis of most set top boxes thatgive access to digital television onstandard television sets.

It can also be used to capture still imagesfrom video.

Di it l


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Digital cameras

Digital cameras convert the analogueimage seen through the cameras lenseinto a digital signal that can be stored.

Each picture is split up into millions of tinysquares (or pixels), each of which is adifferent colour.

Each pixel is stored as a bit of digitalinformation.

W b


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Web cams

Web cameras (web cams for short) aresmall digital cameras which are attached

to computers so that still and motion digital

images can be captured and used. They are often used in conjunction with

the Internet so that people can

videoconference.

T l d i


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Tonal devices

Touch tone telephones are the mostcommon tonal device used to input data.

Customers can use them to interact with

computerised telephone systems so thatthey can respond to choices given to them

by recorded messages.


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03a - input devices - inputs

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