Chapter 2: Input and Output Devices - ICT PDF

Chapter 2–Input and output devices ICT Learning Objectives Explain what is meant by input devices and how they are used. Understand that manual input devices need a person to enter the data but direct data-entry systems do not need a human to enter data. Explain what is...

Chapter 2–Input and output devices ICT Learning Objectives Explain what is meant by input devices and how they are used. Understand that manual input devices need a person to enter the data but direct data-entry systems do not need a human to enter data. Explain what is meant by output devices and how they are used. Describe the advantages and disadvantages of input and output devices.  2.01 Input devices Input devices are used to enter data into a computer. There are two different categories of input device. Manual input devices – Which are the devices used by people to enter data into a computer themselves Direct data entry (DDE) devices – Which enable data to be entered directly, without a human having to input it manually.  2.01 Input devices and their uses Examples of manual input devices Examples of Direct Data Entry devices  Pointing devices Mice A mouse is a pointing device that is used with a computer with a graphical user interface. By moving the mouse on a flat surface, you can move the pointer on the screen.  Computer Mice Advantages: They provide a fast method of input. They are intuitive to use because they simply involve pointing at things. A computer mouse Disadvantages: Mice can be easily damaged or vandalised. An optical mouse Overuse of a mouse can lead to repetitive strain injury Mice need a flat surface to be moved. A wireless mouse  Pointing devices Touchpads Laptops come with a variation on a mouse for a pointing device. It is called a touchpad and is a flat area next to the keyboard. A touchpad Touchpads allow you to swipe, use one, two or more fingers for different functions. An optical trackpad  Pointing Devices Trackerballs Advantages: A trackerball is stationary and does not need a surface to be moved around on. It can be built into a computer. It can also be used by disabled people who may not have the freedom of movement necessary to use other pointing devices. Disadvantages: Trackerballs can be difficult to use for some applications which need fine control.  Remote controls A remote control is a small, handheld device that can be used to operate equipment such as TV or stereo. Advantage: Convenience – do not need to stand up to change the TV channel. Disadvantages: The signal can interfere with other equipment Can be blocked by objects between the remote control and the equipment it controls  Joysticks A joystick can carry out the same tasks as a mouse. It consists of a stick that pivots on a base and the top of the stick can be moved in any directions. Advantage: They give the user the impression of being in control when playing games. Disadvantages: It is more difficult to control the fine movement of the pointer on the screen than with a mouse.  Driving Wheel A driving wheel is designed for use in racing video games and driving simulators. Advantages: Allows users to control movement far more accurately than a mouse or joystick. Force feedback can also be added to provide simulated road resistance. Disadvantages: Can only be used for one purpose - playing racing games. Adding mechanical elements, such as force feedback and gear levers, increases manufacturing costs.  Touch screens Advantage: They are intuitive and easy to use. A user merely taps an image on a screen. Space-saving as input and output devices are the same. Cost effective for shops and restaurants as fewer staff are needed if customers can order and serve themselves. Disadvantages: Not suitable for inputting large amounts of data. Not very accurate for selecting very small areas. Hygiene problems with lots of people touching the screen.  Touch screens A touch screen can determine where on the screen the user has touched and sends that information to the processor. Types of touch screens: Resistive, which means it is sensitive to pressure from fingers or other object pressed onto the screen. Capacitive, which means that the screen is sensitive to static electricity on an exposed finger.  Scanners Scanners are used to convert text, diagrams and images into digital data so that they can be manipulated by a computer. Advantage: Scanners can produce high quality images. Hard-copy material can be changed into form that can be edited or stored on the computer system. Scanned images can be imported into graphics applications and changed as needed. Disadvantages: There may be a reduction in the quality of the image and scanned diagrams can sometimes appear distorted. Scanned images can take up a lot of space in storage.  Cameras Digital cameras capture digital photographs that can be stored on a memory card or a hard disk and displayed on a screen. Advantage: The picture can be seen immediately and erased if it is not good. Digital images can be manipulated more readily than those on film. A digital camera The image can be used in other electronic documents. Disadvantages: The storage device may become full so that images are not saved. The memory card may become corrupted The camera battery may run out so that photographs cannot be A film camera taken.  Cameras Webcams are special category of video camera that have no storage capacity but are connected directly to a computer. Advantages: Can provide live video pictures when chatting with other people using applications. Can be used to do a video-conference. A webcam The live images provided by a webcam can be uploaded to a website so that people can see what is happening at a given site in real time.  Microphones Microphones can be used to input sounds into a computer by converting sound waves into digital data. Advantage: Can be used by disabled people to input data when using a more common input device is not possible for them. Disadvantage: A microphone Cheap microphones do not give a true representation of the input sounds.. A dynamic microphone  Inputting sound and music Microphones Microphones can be used to allow a computer to convert sounds into data that it can handle.  Sensors Temperature sensors read the temperature of their surroundings and send the readings to the processor. A temperature sensor Pressure sensors measure pressures and send the results to the processor where the decision is taken as to what to do. A pressure sensor Light sensors measure the amount of light falling on them. A light sensor  Sensors A sensor is a device that detects and responds to some type on input from the environment, e.g., light, temperature, motion, pressure. Advantages: More reliable than a human being because a human may forget to A light sensor take readings. Readings are more accurate than those taken by humans. It can measure the input to where human can not go. A temperature sensor Disadvantage: Digital sensors are active sensors and need a power source. If there is a power cut or their battery dies, they will stop working. If the sensors are left at a remote location and malfunction, then their users will not know. A pressure sensor  Sensors Definition – A device which automatically inputs data into a computer system, where the data is constantly changing and can be measured. KEY WORDS Smartphone sensor: a sensor in a smartphone for measuring such things as movement and rotation, pressure and light intensity pressure sensor: a device that measures pressures and sends the data to a processor Light sensor: a device that measures light intensity and sends the data to a processor light pen: a specialized pen that works with a CRT monitor CRT monitor: a monitor with a cathode ray tube; CRT was used in the traditional TV sets and monitors  Sensors Types of sensors Sensors application in greenhouse  An Example Control System An Automated Greenhouse A computer-controlled greenhouse might have a number of sensors and actuators : – A light sensors to detect how much light the plants are getting – A temperature sensor to see how cold/hot the greenhouse is – A moisture sensor to see how wet/dry the soil is – Lights to illuminate the plants if it gets too dark – A heater to warm up the greenhouse if it gets too cold – A water pump for the watering system – A motor to open the window if it gets too warm inside  Light pen Light pen were light sensitive input devices that were used before the development of touch screens. A man using a light pen on a CRT monitor KEY WORDS Graphics tablet: an input device consisting of a flat pad which the user ‘draws’ on or points at with a special light pen or stylus Stylus: a pen-shaped instrument whose tip position on a touch screen or tablet can be detected  Inputting sound and music MIDI keyboards It needs to be connected to the computer system using a MIDI interface, to translate the signal coming from the keyboard into electronic data.  Inputting sound and music MIDI keyboards It needs to be connected to the computer system using a MIDI interface, to translate the signal coming from the keyboard into electronic data.  2.2 Direct data entry and associated devices Direct data entry methods, used when large amounts of similar data need to be entered, often in commercial or business applications. The DDE devices discussed here: – Magnetic stripe readers – Chip and PIN readers – RFID readers – OCR and OMR – Barcode readers – QR scanners  Magnetic stripe readers a device used to read a magnetic stripe of a card, which contains data or to write to the stripe. A magnetic stripe reader  Magnetic stripe readers Advantages: Simple for people to use – no training needed. Inexpensive Entering data is fast – just swipe the card. No errors on inputting data – it’s all stored on the card. Data on the card can be altered if necessary. Disadvantages: Very small storage capacity A magnetic stripe Data can be destroyed by magnetic field. reader Insecure – criminals can easily obtain card readers and writers.  Chip and PIN readers device used to read data stored in the silicon chip of a debit card to verify the personal identification number (PIN) entered using a numeric keypad. A chip and PIN reader  Chip and PIN readers Advantages: The information held is more secure than just the magnetic stripe because the chip is difficult to read and chips are harder to clone. The computer chip can hold more information than the magnetic stripe can hold. A debit card with chip Chip and PIN readers can be wireless, which means they can be brought to you when you’re in a shop or restaurant. Disadvantages: People tend to be careless when entering their PIN and people watching can see it. You can forget your PIN, meaning you can’t make A chip and PIN reader payments with that card until you get a new one.  RFID readers Device use to read data stored on RFID tags. KEY WORDS RFID (radio-frequency identification: an RFID reader uses radio waves to identify and track special tags attached to objects RFID tag: radio-frequency identification tag. Contains digital data that can be interrogated by and send the A chip and PIN reader data to a reader device using radio waves Unique identifier: a characteristic of element that is found only on one particular item  RFID readers Advantages: The chips do not need to be positioned precisely on the scanner like a barcode RFID devices work within a few metres of the scanner. At a supermarket, all of the items in a trolley could be read at once. You can write data to RFID tags as well as being able to read them. Disadvantages: The tags can be read without authentication and so hackers could be able to read any sensitive information or even clone them. RFID scanning can be affected by other electrical devices in the vicinity. A chip and PIN reader The range of RFID is limited to about three metres.  OCR (Optical Character Recognition) An OCR is an optical character recognition scans a typewritten or printed document and translates the images of the characters into digital text that can be used on the computer. The scanner is used to scan text on a document or piece of paper into the computer. The OCR software then examines the page and changes the letters into a form that can be edited or processed by a normal word processing package.  OCR (Optical Character Recognition) Advantages: It can be a really fast way of entering hard copy. It can avoid typing errors. It is much cheaper than employing someone to input hard-copy if a high level of accuracy isn’t an issue. Disadvantages: An OCR pen The text produced is not always reliable. This can lead to incorrect information being stored. The text produced need to be checked for errors, which is time consuming and costly.  OMR (Optical Mark Reading) An optical mark recognition device, enables data marked by a human, by making marks to select options to be captured for processing by a computer x  OMR (Optical Mark Reading) A scanner can be used to scan a sheet of paper and identify any marks on it. The software can then use the positions of these marks to obtain information. For example, the position would show which option has been selected as the answer to a multiple-choice exam question.  OMR (Optical Mark Reading) Advantages: It is extremely fast to input data. It is more accurate more than using humans to check the paper. Disadvantages: The sheets will not be read accurately unless they are properly lined up and the marks are in the correct position. Dirty marks on the paper might be misinterpreted by the system as marks to be input. Can only read the marks. Paper jams can occur.  Bar code readers A device to read a set of parallel lines in contrasting color often black and white, that stand for the digits 0 to 9. Barcode readers shine a laser at them and then read the reflection to tell how thick the lines are.  Bar code readers Advantages: Saves time when product prices change as only the price data in the database will need updating once for each product. Quick and easy to get data into the system. Updates stock control automatically so saves time. Very accurate. Disadvantages: A barcode reader reading The technology is expensive. a barcode Bar code must be undamaged.  Input devices and their uses Advantage and disadvantages of a supermarket using a bar code reader and an RFID reader Advantages : – Easier to scan – The RFID chips do not need to be positioned precisely – Additional advantages are in table page 28 Disadvantages : ▪ Expensive ▪ The chips can clash ▪ The price of item is not in the bar code  QR scanners (Quick Response Scanners) Advantages: Very versatile. Can contain different types of data. Codes can be easily read by multiple devices, including smartphones. Anyone can create QR code using software. Quick to read. Stores 100 times more information than a bar code. Disadvantages: A device is needed to scan the code. Relies on the QR code being correct. A QR code reader Some people do not know what they represent or how to read them.  2.3 Output devices and their uses Monitor – Main types CRT LCD Touchscreen  2.3 Output devices and their uses Monitor – Resolution  2.3 Output devices and their uses Monitor – Resolution Resolution Name Quality 3840 x 2160 2160p 4K 2560 x 1440 1440p 2K 1920 x 1080 1080p Full HD maximum resolution 1280 x 720 720p HD minimum resolution 854 x 480 480p Standard definition 640 x 360 360p Normal website resolution 426 x 240 240p YouTube minimum video size  Multimedia projectors A multimedia projector is a device that can project an image from a computer onto as large a surface as is necessary, often used in presentations  Printers and Plotters Impact Printers – An impact printer makes contact with the paper. It usually forms the print image by pressing an inked ribbon against the paper using a hammer or pins. – Examples Dot Matrix Printers This type of printer use continuous paper form  Printers and Plotters Impact Printers – An impact printer makes contact with the paper. It usually forms the print image by pressing an inked ribbon against the paper using a hammer or pins. – Examples Line Printers  Printers and Plotters Impact Printers – An impact printer makes contact with the paper. It usually forms the print image by pressing an inked ribbon against the paper using a hammer or pins. – Examples Daisy Wheel Printers  Examples of Impact Printers Dot matrix Daisy Wheel Line printer  Printers and Plotters Non-Impact Printers – Non-impact printers do not use a striking device to produce characters on the paper; and because these printers do not hammer against the paper they are much quieter. – Examples Ink Jet Printers  Printers and Plotters Non-Impact Printers – Non-impact printers do not use a striking device to produce characters on the paper; and because these printers do not hammer against the paper they are much quieter. – Examples Laser Printers Laser printers use a toner cartridge (filled with fine powder).  Examples of Non-Impact Printers Ink Jet Plotter Laser printer  Examples of Non-Impact Printers 3D Printer Thermal Printer  A printer that can be used to make physical models.  A printer that prints layer by layer.  Advantages & disadvantages Laser printer advantages – Fast output – Relatively quiet – Cheap to buy compared to dot matrix printer Laser printer disadvantages – More expensive running costs than dot matrix – The reproduction of colour is not always as precise as it is with an inkjet printer  Advantages & disadvantages Inkjet printer advantages – Faster output than dot matrix printer – Relatively quiet compared with dot matrix printer – Cheap to buy Inkjet printer disadvantages – Ink more expensive than dot matrix – Ink needs changing regularly on long print runs – Difficult to print a sealed secure payslip  Advantages & disadvantages Dot matrix printer advantages – Cheaper running costs – Continuous paper feed available – Can print multi part forms – Can produce carbon copies – High quality is not needed when printing payslips Dot matrix printer disadvantages – More expensive to buy – Noisy – Relatively slow – They have a poor-quality output – There are very limited colour capabilities  Actuator An actuator is a device that moves or controls some mechanics. An actuator responds to a control signal from the computer and produces a mechanical action. For example, an electric motor The motors and hydraulic system that control robots are actuators. Examples; the motor that control the movement of a lens in a digital camera, the motors that control the opening and closing of automatic doors or the barriers in car part system.  Sensors and actuators in a washing machine Sensors: Actuator: Pressure Motor – (switch & door closed) Pump Water level/pressure Heater Temperature Led Drum speed Buzzer/bell Balance  Actuators Actuators are items that cause movement or a response in control systems. A sensor measures a change in the environment an in response the computer sends a signal to an actuator to cause a response to the change – for example, to open and close the windows in a greenhouse by switching on motors.  Control devices Control devices are used to change some physical value in response to a command from a computer.  Control devices Heaters – Can be controlled by actuators. Motors – Can be used by a computer system to control elements of many household devices Buzzers (beeper) – Make a single sound and are often used to inform a user that a particular thing has happened Examples of Control devices Uses of control devices  Exercise Name three examples of control devices and Explain what are they ? Name three components to make up a Control Application. Explain the use of the motors and name three household devices where you can find motors. What is buzzer and where is it often used on? (two examples)  Review There are two different categories of input device, which are manual input device and direct data entry (DDE) devices. A sensor is a device which automatically inputs data into a computer system, where the data is constantly changing and can be measured.