Input Devices - BH

8/13/2019 Input Devices - BH

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GCSE Information TechnologyGCSE Information Technology

Input Devices

Manual input devices – data entered by

hand

Direct input devices – these handle large

amounts of data

These are used to put data or

instructions into the computer



GCSE Information Technology

Keyboard

Most common type of input device.

QWERTY - the first row of letters.

Function keys

Hot key combinations

Other types of keyboard – supermarket tills

Ergonomic keyboards – split board




How a keyboard works

Keys have electric current passing through

Pressing and releasing keys causes changes in theamount of electric current

A processor in the keyboard detects the change incurrent

Each key has a unique set of codes

When a key is pressed, the processor sends that code toBIOS

The BIOS interprets the key code using ASCII (binary)and sends it to the program requesting it.




Keyboard used by

Advantages/Disadvantages Good for manual text entry.

Special keys for special

functions

Hot key combinations to

simplify tasks

Familiar device

Mistakes easily made

Large footprint

Slow data entry for

most

No real use for drawing

RSI

Widespread use at home and in the workplace




Pointing devices

Pointing device.

Next most common type of input device Developed with GUI

Touch pads and trackballs on portable

computers.

Upside down mice




Mouse and pointing devices used by

Advantages/Disadvantages

Enable drawings and pictures to be done

Pointing device used in Portable computers

Allows different data to be

put at any point directly on

the screen Good for selecting items

from menus

Small

Difficult coordination

at first

Need a flat space

Dust interferes with

use




Joystick

Used to control movement from side-to-side, up-

and-down and diagonally.

One button on it to make something happen - a

character in a game jumping or firing a gun.




Joystick used by


Computer games

Flight simulation

VR and robot control

Better simulation

Specialised use Limited use




Touch screen &How it Works

Detect exactly where on its surface it has beentouched.

Criss-crossed with infra-red beams

Touching the screen at set points interrupts the

beam and sends a message to the processor




Touch screen used by


fast food chains and restaurants - easy to keep clean

and re-program if changes need to be made to the

menu.

Used in public places like shopping malls - most direct

data entry

No training or practice

needed – instinctive use

Need specialist coated

screens

limited but specialised

use




Digital camera

• Storage - can store more pictures than an ordinarycamera – memory stick.

• Different resolutions

• software to manipulate the image or to put the pictures

into albums and give slide shows.• Video input




How a digital camera works

• converts light passing through the lens – It gives

a value to each particle of light

• Pictures are stored inside its memory• transferred to a computer by connecting the

camera to it.




Digital camera used by


widespread use to send photos electronically – web albums,

attachments

Used in screen presentations

No need to scan pictures to

get them into computer

No developing time or costs

Images can easily be edited

expensive – up to £1000

Different expertise to learn

Need specialist paper to get

good print Take up a lot of computer

space




Scanner

used to input pictures and text into a computer . two main types of scanner;

hand- held

flat-bed. Most common

A4 size but can get A3 image software to let you manipulate the images –

crop, rotate, add special effects etc




How a scanner works

A laser beam passes over the surface and detects

the light intensity of every spot on the paper.

It gives a value (digital) to every spot.

value is transferred to the screen where the image

is recreated.

Resolution depends on dpi

other accessories - facility to copy slides.




Scanner used by


offices to incorporate images into promotional literature.

Growing use in home

in schools for teachers to produce illustrated worksheets

saved hand drawing images

to illustrate typed text

Scanned images are more

appropriate than clipart.

Difficult to learn how to use.

Some image formats can take

up a lot of space

Can be difficult to connect

takes up desktop space




OCR & How it Works

special software associated with a scanner.

converts a digital image of scanned text

into real text so it can be edited on thescreen.

The text is scanned in as a bitmapped

image and software recognises font

patterns.




OCR is used by

Widely used in offices to save a lot of copy typing

Passports and ID cards

Advantages and disadvantages

Saves a lot of time on

typing

Difficult to interpret pages

with complex layout; need

more expensive OCRsoftware.

need to check to see if you

need to correct everything




Concept keyboard

a flat board with a grid of programmable keys on its

surface. Software allows you to change the instructions for

each key.

A single key or a group of keys can be set up to carry out a

task.

Paper overlays are placed on top of the keyboard with

pictures drawn on them to represent what will happen if thekeys are pressed.




Concept keyboard used by


used with young children in primary schools who can’t use

an ordinary keyboard

Restaurants

simpler than a normal

keyboard = fewer things to

click on and less likely tomake a mistake.

Can program them with

pictures as well as words

Need reprogramming a lot

New overlays to be

designed or bought




Graphics Tablet

When the special pen touches the surface of the graphicstablet, data about its position is sent to the computer .

Produces an exact copy of what is being drawn

a flat surface and a pen, or

stylus, used to produce

freehand drawings or trace

around shapes.

How a Graphics Tablet works




Graphics tablet used by


Architects and people who do detailed design

Computer artists who feel more comfortable inputting into a

flat surface than to a screen

more precise input for

drawings

More natural to people who

paint or draw using a

pen/pencil

Takes up room on

the desk Can’t be used for

text




Microphone

used to input sound into a computer system.

used for voice recognition systems - convert sounds made

by a user into commands that the computer can carry out.

As computers become more powerful in the future, voicerecognition will be a much more common input method forall computer users.




Microphone used by


Far faster and more

direct.

Any sound can bestored

Growing use in offices as software improves.

Handicapped people

Internet and telephony

Need voice recognition software.

‘training’ to recognise your voice.

speech is full of inconsistencies

and false starts etc need for muchediting after entry.

Background noise

Sometimes our voice is affected by

things like colds.




Light Pen

Connected to the computer

Electronic beam, controlled by the computer –

this builds up the image on the screen

Cost up to £200

How a light pen works

Connected to the computer by cable. As the pen touches the

screen at different points, signals are sent to the computer by an electron beam and a picture is built up.




Light pen used by


popular with Tablet PCs

Surgeons

More natural feel

Good for inputting

drawings

Response time can be slow

Depends on handwritingrecognition for text




Video Camera

Like ordinary video cameras except images stored digitally

Captures still and moving images

Images can be stored and edited on a computerImages stored on memory stick or mini DVD

UsesHome and commercial




Web Cam

A video camera connected to a computer A live cam continually provides new images that are transmitted

(streaming video)

several thousand sites with cams

Captures still and moving images

Allows video conferencing in business Home use systems

Uses

Coffee machines

Advertising – Travel promotion -cruise ships use them to show potentialcustomers what is going on and where ship is

Childcare centres – so parents can keep a watch on children

Weather checks – check anywhere in world to see what weather is like

Traffic information

Visualisation of on-going events




MIDI

Data is input through a piano-type keyboard or by

sensors that respond when struck.

A variety of sounds generated from one keyboard.

'real' sounds recorded into the system through a

microphone and then sequenced to produce musical

effects.

The music industry uses MIDI systems

Schools.

Uses

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Remote ControlThese use infra-red signals to give instructions to devices

they control

TV, DVD and video

Computer input devices

Uses




Direct input devicesDirect Input devices involve the use of machines to speed

data input

Optical Mark Recognition (OMR)

Magnetic Ink Character Recognition (MICR)

Bar Codes

Magnetic Stripe Readers Sensors and Data Logging

Others




Optical Mark

Recognition

Uses special sheets and a machine - a Reader

Detects marks made in special places on the paper

How it works – light from pencil mark is different level

from rest of paper

expensive, need specialmachine and paper

Uses

With Data Capture Forms toenter results of questionnairesand surveys

lottery,

MC exams,

food ordering

very fast 1/100th of a secondto mark an exam





Magnetic Ink Character

Recognition (MICR) Needs a special machine – Reader + the use of

special magnetic ink .

How it works – Uses a special font - only 14characters (0-9 + 4 special characters). Thecharacters are passed through a magnetic field

Advantages/ Disadvantages

speed (cheques cleared very

quickly): reliable (will read even

if cheque is crumpled)

expensive and specialised font

Uses

numbers at bottom of

cheques




Bar Codes

A set of lines of different thicknesses that represent a

number..

How it works – Light shone on the lines and t reflected

back is detected and generates a code to the computer; thisgives information about the product – price, size,

manufacturer.

Can be a read with a light pen or a laser beam

Uses

Supermarkets, libraries

Advantages/ Disadvantages speed (60 per minute), can give detailed

information (supermarket till receipts); can

design your own

– specialised use and need time to set up the

codes




Magnetic

Stripe Readers

A magnetic strip like a tape which contains coded

information. This is read by a machine

How it works – a code is read and interpreted

don’t have to carry money around

Development of Smart cards EFT (Electronic Funds Transfer) using

a debit or credit card, ATM

– cards – a chip can hold more

information

– security – need a PIN number

(fraud); only limited amount of

information)

Uses Advantages/ Disadvantages




Chip readers and PIN pads

Research




Sensors and Data Logging

A way of collecting data over a long period of time without people. data transferred using communication links to acomputer and interpreted. (Period of logging and time interval

are important) How it works - Uses different sensors to measure things like

temperature, light, pressure, movement. May need converterto convert from analogue to digital

accurate readings,

data can be logged over a long period oftime,

can be placed in areas where it is difficult

for humans (dangerous, inaccessible,monotonous).

burglar alarms,

weather forecasting,

scientific experiments,

hospitals,

traffic movement.

Uses Advantages/ Disadvantages




Video Digitiser

Moving pictures captured by a computer using a video

digitiser .

by the TV industry to edit TV programmes.

Video clips for multimedia CDs

digital video cameras in shops, editing of videos through

computers will become commonplace.

Uses

Documents

Input Devices - BH