Input DevicesLO2: HARDWARE AND SOFTWARE

QuestionHow can you give a computer and instructions?

1. We can type them using a keyboard.

2. We can use the mouse.3. We can speak an instruction

into a microphone (i.e. use voice recognition)

By DefinitionAn Input Device is….

This is used to get data into a system. The ideal input devices

would be able to get data into a system as accurately as possible, in the least amount of time and preferably without human intervention.

Keyboard The keyboard is the oldest and most familiar of

all input devices.

Keyboards are intelligent devices and contain their own chips.

Keyboard Basically each key acts as a switch which closes

when the key is pressed.

How computer received instructions:• The microprocessor scans the keyboard

hundreds of times a second to see if a key has been pressed; if it has, a code that depends on which key has been pressed is sent to the processing unit.

• The CPU translates this code into an ASCII code (the code that computers use to represent characters on the computer keyboard), which is then used by the computer program.

A standard keyboard is called a QWERTY keyboard because of the arrangement of the letters of the top row of the alphabet keys.

Concept KeyboardA concept keyboard consists of a flat – bed of contact switches covered by a flexible membrane. Programmers can allocate one or more switches to respond in different ways. Overlays with pictures and symbols are placed over the membrane.

Concept KeyboardA concept keyboard consists of a flat – bed of contact switches covered by a flexible membrane. Programmers can allocate one or more switches to respond in different ways. Overlays with pictures and symbols are placed over the membrane.

Who uses concept Keyboard• In the primary schools - where the overlays are

designed with interesting picture layouts. Children press particular symbols or pictures in response to the activity being done.

• In the restaurant - where the checkout tills use symbols to speed up the data entry.

• Hostile environment - for example, on North Sea oil platforms where the keyboard allows workers to use computer – controlled machinery through the keyboard without it being damaged by salt spray or chemicals on the platform.

Concept KeyboardWho uses concept Keyboard

• Keyboards for disabled – a Braille Keyboard make it easy for blind users to input data into a computer.

Concept KeyboardWho uses concept Keyboard

• Visually – impaired users – who have some vision, there are also keyboards with large coloured keys that are easier to see. Each key is about one inch square.

MouseA mouse is an input device that translates its movements on the desktop into digital information; this is fed to the computer which turns causes the cursor to move on the screen.

Tracker BallA tracker ball is like an upside down mouse. The ball is rotated by the user in this case the ‘mouse’ stays still.

Advantage compared to a mouse• the advantage of a tracker ball compared with a

conventional mouse, is that it takes up much less space, and this is why tracker balls are often seen on laptop computers.

Touch sensitive padTouch sensitive pads or track pads are commonly found on notebook computers.

A track pad is a small flat, square pad below the spacebar. As you move your finger across the track pad’s surface, the pointer moves across the screen.

JoystickA joystick is similar to a tracker ball. Whenever the stick is moved, the cursor moves in a similar direction on the screen.

Joysticks are mainly used for games but you can also see them being used with, for example, scanners in hospitals

Light PenA screen cursor can be moved by touching the screen with a light pen.

Light pens are mainly used for design work and need special software to make them work.

Touch ScreenA touch screen is a special kind of screen which is sensitive to touch. A selection is made from a menu on the screen by touching part of it.

Commonly use in:• These screen are ideal for use in banks and

building socities, where customers whore not used to keyboards can obtain information about the services offered.

• You can also see touch screen in restaurants and bars.

Graphics TabletsGraphics tablets are rather like electronic tracing paper and, like paper, they come in all size from a modest A4 to a very large A0 size which will occupy the best part of a desk.A cursor or puck is used on a graphics tablet to trace over technical drawings put on the screen using a computer aided design package such as AutoCAD.

Magnetic Stripe ReaderMagnetic stripe are thin strips of magnetic tape, often found on the back of plastic credit and debit cards. When the card is used, the stripe passes record and playback heads, similar to a tape recorder, which reads data form from, and writes data to, the stripe.

Commonly use:• To withdraw cash from cash dispenser machine

(called automatic teller machines or ATMs) in the walls of banks, building societies and shopping centres.

Magnetic Stripe ReaderIn a addition to being able to read the magnetic stripe, some devices can also write information onto it. The stripe can carry permanent value, such as an account number or a value that could change, such as the amount of cash you are allowed to get from an ATM or cashpoint.

Barcode ReaderBar code are made up of black and white stripes of different thicknesses. These lines represent numbers and are read with a wand or laser scanner. They are now used on almost all goods sold in shops and supermarkets, and provide a fast and reliable method of entering data even when the surfaces being read are curved or upside down.Bar code hold information

about:• Product, including the country of manufacture, the name of the manufacturer, a product item code, and a check digit. They do no hold information directly for the name, description or price of the product. When the numbers on the bar code are scanned, the data is passed to the computer which returns information about the product.

Barcode ReaderBarcode reader are commonly use in:• Supermarkets

• Library systems• Luggage handling systems at airports and for

warehouse stock control

Optical Character Recognition (OCR)It is a method of inputting text using a scanner

along with a special software to turn the scanned image into standard ASCII code. In other words, the text is no longer treated as a picture, since each individual letter is recognised on its own and can therefore be edited using word processing software.

How it can be used• One application of optical character recognition

is reading postcodes on letters at sorting offices so that letters can be sorted automatically

• OCR software can also be used to scan financial documents such as company accounts directly into spreadsheet, as well as to scan text directly into word processors.

Optical Character Recognition (OCR)

Magnetic Ink Character Recognition (MICR)Magnetic ink characters are the rather strange

looking numbers that you see at the bottom of cheques. The characters are printed using an ink which contains iron and may be magnetised. The magnetic pattern of the numbers is read by a special reader called a magnetic ink character reader.

The difference between OCR and MICR• One difference is that one technology uses

reflected light, while the other uses magnetic field patterns produced by the characters. Another important difference is that OCR systems can recognize handwriting and different types of text, but MICR needs specially shaped characters

Magnetic Ink Character Recognition (MICR)

Optical Mark Reader (OMR)Optical mark readers are able to sense marks made on a special form in certain places.

Commonly use for:• Multiple choice answer sheet marking• Capturing data from questionnaires and

enrolment forms, and the checking of football pools coupons.

Optical Mark Reader (OMR)Advantages:

1. The use of OMR means that details do not have to be typed in; typing could introduce errors and takes time.

2. OMR reduces the cost of inputting large volumes of data because people do not need to type the details.

3. The method is useful when results of tests are needed very quickly, e.g. with an aptitude test for a job.

Disadvantages:1. If the forms are being filled in by the general public

they very clear instructions are needed. A couple of examples should be chosen as an illustration. No matter how clear your instructions are you will find that a high proportion of forms are filled in incorrectly. The rejection rate is found to be around 30%.

2. If the forms are creased or folded then they may be rejected or foul the machine. This will add to time needed to read the forms. Badly damaged forms will need to be rewritten or keyed in manually.

Punch CardPunch cards contain holes in different positions which mean something when they are read by a reader. Before screens and keyboards were widely used.

Punch cards were the main method of entering data into computers.

Kimball TagKimball tag are the small cards with holes punched in them that you see attached to clothing in certain shops.

How it is use:1. When you buy the goods, one of the tags is

removed and sent for processing to a computer centre.

2. A card reader there reads the information contained in the holes suck as stock number, size, colour and etc. This information is used to keep stocks records and to re – order stock.

Voice RecognitionWith the voice recognition you speak directly to the computer. It is particularly useful for handicapped people with limited movement. It is now popular for inputting data into word processing or database packages. A micro – phone is the input device for such systems.

MicrophoneA microphone is used as the input device for a speech recognition system. The voice pattern of the user is then converted into instructions to the operating system or applications software into text on the screen.A microphone may also be used as an input device to a voice mail system. Voice mail uses the internet to send, store and receive voice messages. The system works in a similar way to the e- mail system but instead of a text message being store on disk, the user’s voice is stored instead.

The company providing the connection to the internet, called Internet service provide (ISP) stores the voice message on its server and when the user logs on the system informs them that they have a voice mail message.

MicrophoneHow it works

Voice use internet to send, store and receive messages

The ISP (internet service provider the provides the internet connection will store the message to its server

When the user logs on the system, the ISP server will informs them that they have a voice mail message.

Microphone

Electronic Point of Sale (EPOS)EPOS terminals are the cash registers which also

act as terminals to a main computer system. As well as providing customers with itemised bills, these systems also give useful management information.

Electronic fun transfer at point of sale (EFTPOS)

EFTPOS can be able to transfer funds from your bank account directly to a store’s account using a card called a debit card.

A switch card is an example of a debit card in EFTPOS.

A card that can be use:

Advantage using debit card:To the person it is a faster method of payment.To the store the money can be transferred into its

accounts instantly comparing to cheques.

Disadvantage using debit cards:It can be stolen or forged

Encourage people to spend more money

Electronic fun transfer at point of sale (EFTPOS)

Video DigitiserA video digitiser is a combination of a hardware and software that converts an analogue signal to digital signal in the computer’s memory.

• Each frame from a video is converted, using the video digitiser and it may be played back in any required.

• Taking a video frame and digitiser is often called image grabbing or frame grabbing

• Grabbed video images take up a lot of main memory and when stored use a large amount of disk space.

• Video digitising is used to convert a frame from a video sequence into a picture, which can be printed in isolation in a magazine or document. Digitising is also used to make television adverts and to produce pop video.

How it works

Video Digitiser

ScannerScanners are used to scan text or pictures into a computer’s memory where they can then be manipulated in some way before being printed. The can be cheap hand held ones, or flatbed A4 size or large.Scanners are also used to scan photographs and pictures for use in desktop publishing.

• Main problem of scanning images is the amount of space they take up on the disk.

Main problem:

Digital CamerasDigital cameras look just like traditional cameras except they have no film as such. Instead they have a memory which stores the image and many of them have special memory cards to give extra storage. The memory they have, the greater the number of pictures which can be taken before down – loading. Storage varies widely between cameras from 40 to 100 pictures.The amount of memory taken up by a picture depends on its resolution. The resolution is determined by the number of dots which make the picture; the greater the number of dots, the crisper the image. Higher resolution photographs take up more memory so the camera will store fewer of tem.

Digital Cameras

Web Cameras (web cams)A web cameras is simply a digital camera that is used to capture still images and video images. These images can then be transmitted to a computer where they are stored in a suitable graphics format. If required, pictures can be used on a website.Uses of Webcams:AdvertisingCruise companies place them on ships so that potential customers can see what is going on inside a ship and where the ships is at particular time.

Checking on children in nurseriesAll parents worry about child abuse. When they put their children in nurseries they want to be sure that the children are looked after properly. Some nurseries have web cams so that parents can see their children on a computer while they are at work.

Web Cameras (web cams)Uses of Webcams:Checking on the weather in another pat of the worldThere are web cams just about everywhere. It is possible to see what the weather is like anywhere in the world if you have access to a web cam there.

Touch tone telephonesModern telephones work by having a different tone of each number key pressed. The different tones that the numbers dialled are recognised and routed to the correct telephone. Once connected, a touch tone telephone can be used a s a data entry device.

Example:In some banking systems the customer keys in their identification number using the phone keys. Once connected, the customer can select certain services, such as statement requests, using the same keypad.

Touch tone telephonesModern telephones work by having a different tone of each number key pressed. The different tones that the numbers dialled are recognised and routed to the correct telephone. Once connected, a touch tone telephone can be used a s a data entry device.

Example:In some banking systems the customer keys in their identification number using the phone keys. Once connected, the customer can select certain services, such as statement requests, using the same keypad.

SensorsSensors are used to detect physical quantities outside a computer such as light, temperature and pressure.

They collect data automatically and usually at regular intervals. This data can either be transmitted immediately to the computer or it can be stored for a period of time and a batch of readings sent in one go.

It use a device called ‘Analogue to Digital Converted’ (ADC) to process input from sensors. This device converts the analogue signals from the sensors to digital data that the computer can process.

Sensors

Pressure Sensor

Thermal leak detector

Biometric ScannersFinger print and retinal identification are being used in many places now and even facial recognition systems are starting to be introduced.

Biometric authentication methods can be used to identify you at ATMs to withdraw cash, in computer networks to allow you to log on and many schools are now introducing ‘fingerprint registration’

Activity 1LO2: HARDWARE AND SOFTWARE

Activity 1Answer the following activities in your book.

Questions on page 22Which input device on page 22

Note:Put all your answers in your book. Put the date today and the title of the activity which is ACTIVITY 1: INPUT DEVICE