03a - Input and Output Devices - Inputs

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GCSE ICT:

GCSE ICT Input and Output Devices - Inputs

Input devices:

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.

Input devices:

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)

Input devices:

Input devices The most common types of 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)

Input devices:

Input devices The most common types of input devices are: Sound capture devices (including voice recognition and microphones) Terminals (including EPOS and EFTPOS terminals)

Input devices:

Input devices The most common types of input devices are: Digital imaging devices (including video digitisers, scanners, digital cameras, and web cams) Tonal devices (including touch tone telephones)

Input Devices:

Input Devices keyboards, numeric keypads, pointing devices (including mouse, touch pad 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;

Keyboards:

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.

Concept Keyboard:

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 a picture 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 is also very handy in locations where an ordinary keyboard might be damaged e.g. by spillage or dust.

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Advantages Much 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

Keyboards:

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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Advantages Much 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.

Ergonomic Keyboard:

Ergonomic Keyboard Ergonomic computer keyboards 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 the wrists, known as ulnar deviation and pronation respectively. These deviations result in the compression of the nerves in the wrist, causing disorders such as carpel tunnel syndrome. carpel tunnel syndrome .

Pin Pad:

Pin Pad Numeric Keypad A 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 person’s Personal Identity Number (PIN) e.g. when paying with a credit card. PIN pads are also found on electronic door locks – you enter a PIN to unlock the door.

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Advantages Most computers come with a keyboard supplied People are used to using keyboards to enter data, they need very little training A skilled typist can enter data very quickly Specialist keyboards are available e.g. ergonomic, gaming keyboards Disadvantages It is easy to make mistakes when typing in data If you can't touch type, it can be time consuming to enter data Keyboards are not suitable for creating diagrams Disabled people often find keyboards difficult to use Excessive use can lead to R.S.I.

Point and Click devices:

Point and Click devices Point and Click devices include mouse, tracker balls, touch sensitive pads, joysticks, light pens, touch screens, and graphic tablets.

Mouse:

Mouse The mouse translates movement on the desktop into digital information. This information is converted into movement 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 mouse button • 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 conjunction with 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

Tracker ball:

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 the user rotates the ball which moves the pointer on screen. They are particularly easy to use for those with limited movement in their hands and are often used in Computer Aided Design (CAD) for their increased precision over a mouse.

Touch sensitive pad:

Touch sensitive pad These are most commonly found on laptop computers. A stylus or the user’s finger is pressed gently onto the pad, and as it is moved the cursor moves on the screen.

Joystick / Joypad:

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 experience for racing or flying styles of computer games Disadvantages Some people find joysticks more difficult to control than a traditional mouse. Joysticks are not particularly robust and can break easily if too much force is used on them.

Light pen:

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 Pen : Light 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 or monitor. 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 in brightness of a point on the screen when the electron gun refreshes that spot. Light Pen

Touch screen:

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 palmtop and 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 shapes of 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 concept keyboard which has a permanent overlay. Disadvantages Not suitable for inputting large amounts of data Not very accurate - selecting detailed objects can be difficult with fingers Tiring to use for long periods More expensive than alternatives such as a mouse Not robust - can soon become faulty if misused

Graphics tablet:

Graphics tablet A graphics tablet allows the user to create designs directly onto the screen. A special stylus is connected to the computer via the graphics tablet, and as the user ‘draws’ on the tablet with the stylus the drawing appears 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 computer’s memory.

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Advantages It is much more natural to draw diagrams with a pencil type implement (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 pointing and clicking on menu items Graphics tablets are much more expensive than a mouse

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Automatic Input Devices

Sensors:

Sensors Sensors are often used as part of a feedback cycle . They collect data continuously and are typically linked to a control program that specifies acceptable levels, eg the minimum and maximum temperature in a green house . The control program decides what to do next based on the data it's fed by the sensors.

Readers:

Readers The most common types of reader used include magnetic strip readers barcode readers optical character readers/recognition, magnetic ink character readers/ recognition optical mark readers/recognition).

Magnetic strip readers:

Magnetic strip readers The most common magnetic tape readers are those used at electronic points of sale (EPOS). These ‘read’ the personal data stored on the magnetic strip of a credit or debit card.

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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 computer system 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 and the printed numbers are not damaged by folding (as often happens with cheques). Both the reader used by MICR and the special ink are expensive.

Barcode readers:

Barcode readers Barcodes are used in shops, libraries, luggage handling, and stock control. The lines on a barcode represent numbers, and can be scanned 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's database 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 digit is included in the barcode number to reduce the likelihood of this happening .

Scanners:

Scanners A scanner is a device that optically scans images, printed text, 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 being scanned 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 Ink Character Recognition). Types of Scanners are

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Flatbed Scanner : You place the image on top of the scanner. The scanner 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 the image. 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 processor or desktop publisher . OCR software is not yet sophisticated enough to read hand-written text accurately.

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Advantages Flatbed scanners are very accurate and can produce reasonably high quality images Any image which is digitised by the scanner 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 readers/recognition:

Optical character readers/recognition Optical character recognition is a method of inputting text using a scanner. It requires special software to convert the scanned image of each letter into an ASCII (American Standard Code for Information Interchange) code, and it often confuses similar shaped letters and numbers (e.g. S and 5, B and 8). It is used to convert paper books and documents into electronic files. When one scans a paper page into a computer, it produces just an image file, a photo of the page.

Magnetic ink character readers/recognition:

Magnetic ink character readers/recognition Magnetic ink characters are printed at the bottom of cheques. They are used by banks to identify the bank a customer banks with, the individual branch where their account is held, and the customer’s bank account number.

Magnetic ink character readers/recognition:

Magnetic ink character readers/recognition Branch code Cheque 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 font is 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.

Optical mark readers/recognition:

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 to correct.

Optical mark readers/recognition:

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.

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Smart Cards Smart cards are often called input devices. In fact they are actually simple storage devices . A smart card contains a small RAM chip. 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 a magnetic 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 number of points stored on the card is increased. The customer can then spend these points to buy goods.

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Satellite television companies also use smart cards in their receivers. The smart card stores a code which is needed to let the receiver decode and display the pictures coming from the satellite. The government is currently considering introducing an identity card which could be based on a smart card. Many people are worried about this as people would not be able to tell what information was stored about them.

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A new generation of smart cards is now appearing which contain a small microprocessor as well as memory. These cards are practically a complete computer system on a card.

Punched cards and tape:

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 for clock cards, which records when a person starts and ends work, and Kimball tags, which are used for stock control.

Sound capture devices:

Sound capture devices The most common use of sound capture devices involves the use of voice recognition software and microphones.

Sound capture devices:

Sound capture devices Voice recognition software ‘remembers’ the way a user speaks, and converts their speech into text that appears on screen. Although voice recognition software has become increasingly sophisticated, many such programs have difficulty converting more than 90% of common words accurately.

Microphone:

Microphone The sound is detected by the microphone and an electrical signal is transmitted to the computer. Special hardware is used to convert this analogue 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 people speak.

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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.

Digital Cameras:

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 stored in files. These files can be copied to a computer and later edited.

WEB CAMS:

WEB CAMS Webcams: are very basic digital video cameras used to capture images to be sent down networks for video conferencing . Webcams do not allow you to save the images like digital video cameras do. Video conferencing is where people can "meet" across a network using microphones, webcams and monitors. This lets people meet who are different countries meet.

Video Digitiser :

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 moving video sequences as well as still images.

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When a video sequence is captured the computer stores this as a sequence of still images called frames . These images are displayed 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 video sequence you must tell the computer : Size : How big you want the image you capture to be. e.g. should it take up the whole screen, 1/2 the screen, 1/8th of the screen ... ? Frame Rate : How frequently the frames should be captured from the video.

Terminals:

Terminals EPOS (Electronic Point Of Sale) and EFTPOS (Electronic Fund Transfer at Point Of Sale) terminals are connected, via secure Internet connections, to the computers of the main banks and credit card companies.

Terminals:

Terminals EPOS and EFTPOS allow a retailer to transfer the cost of what they have sold to a customer from the customer’s credit card or bank account to their own bank account. This is much faster than accepting payment by cheque, and more secure than accepting payment in cash.

Terminals:

Terminals It also gives the retailer an opportunity to collect information about their customers, and to develop individual customer profiles (i.e. know what an individual customer may want to buy). This helps to retailer to ‘target’ individual customers with special offers etc.

Digital imaging devices:

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

Video Digitisers:

Video Digitisers The video digitiser is a combination of hardware and dedicated software that converts an analogue signal into a digital signal. This is the basis of most set top boxes that give access to digital television on standard television sets. It can also be used to ‘capture’ still images from video.

Digital cameras:

Digital cameras Digital cameras convert the analogue image seen through the camera’s lense into a digital signal that can be stored. Each picture is split up into millions of tiny squares (or pixels), each of which is a different colour. Each pixel is stored as a ‘bit’ of digital information.

Web cams:

Web cams Web cameras (web cams for short) are small 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.

Tonal devices:

Tonal devices Touch tone telephones are the most common tonal device used to input data. Customers can use them to interact with computerised telephone systems so that they can respond to choices given to them by recorded messages.

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