Computers Tools for an Information Age Chapter 5 Input and Output The User Connection Objectives Describe the user relationship with computer input and output Explain how data is input into a computer system and differentiate among various input equipment Describe how a monitor works and the characteristics that determine quality List and describe the different methods of computer output Objectives Differentiate among different kinds of printers Explain the function of a computer terminal and describe the types of terminals Describe the ethical considerations involved in handling computer data How Users See Input and Output Users submit data input to the computer to get processed information output Output can be instant reaction to input Also can be separated by time distance or both Instant Reaction Items scanned at supermarket Forklift operator speaks to computer Forklift obeys operator s commands Sales rep enters an order on a pad Produce item name and price at counter Characters displayed as typed text and stored in pad Factory workers punch a time clock as they go from task to task Produce weekly paychecks and management reports Input and Output Separated Data on checks input into bank computer Charge card transactions provide input Computer processes entries once a month to prepare statements Processed monthly to produce customer bills Water samples collected and input into computer Used to produce reports that show patterns of water quality Input Getting Data from the User to the Computer Keyboard Pointing devices Source data automation Keyboard Similar to typewriter keyboard Can be unique to an industry May be part of a personal computer May be part of a terminal connected to a computer in another location Keys on McDonald s keyboards represent Big Mac or large fries Ergonomic keyboards Ergonomic Keyboards Designed to reduce or minimize repetitive strain injury of wrists Provide more natural comfortable position of wrists arms and hands Anatomy of a Keyboard Pointing Devices Used to position a pointer on the screen Communicate commands to operating system by clicking a button Common devices Mouse Devices used for games Devices used in laptops Others The First Mouse Invented by Doug Englebart at SRI 1963 4 Doug Engelbart invented the computer mouse in 1963 64 as part of an experiment to find better ways to point and click on a display screen It was made in a shop at SRI The casing was carved out of wood The mouse had only one button that was all there was room for Mouse The most common pointing device Movement on flat surface causes movement of pointer on screen Several types Mechanical small ball on underside rolls as mouse is moved Optical uses a light beam to monitor mouse movement Cordless uses either infrared or radio waves rather than a cord to connect to computer Trackball and Joystick Trackball Variation on mechanical mouse User rolls the ball directly Often built into laptop computers Joystick Short lever with handgrip Distance and speed of movement controls pointer s position Pressing trigger causes actions to take place Touchpad and Pointing Stick Touchpad Rectangular pressure sensitive pad Sliding finger across pad moves pointer Tapping with finger recognized as click Pointing stick Small pressure sensitive post mounted in center of keyboard Pushing post in any direction moves pointer Other Pointing Devices Graphics tablet Touch screen User moves stylus or puck across board Used to create or trace precise drawings Allow user to touch items on screen Position of finger on screen determines item to be input into system Used at kiosks in public places such as malls Pen based computing Use pen like stylus to input data Often used in PDAs or pocket PCs Source Data Automation Use of special equipment to collect data at the source Primary areas Magnetic ink character recognition MICR Optical recognition devices Other sources MICR Uses a machine to read characters made of magnetized particles Banking industry is predominant user Characters preprinted on lower left hand side of check Amount added by MICR inscriber when check is cashed Optical Recognition Uses a light beam to scan data and convert to electrical signals Common uses Scanners are the most common form Other optical recognition methods Common Uses Scanners at supermarkets Document imaging converts paper documents to electronic versions Documents stored on disk Can be edited or processed by software Scanners Flatbed scanner Sheetfed scanner Motorized rollers feed sheet across scanner head Handheld scanner Typically scans one page at a time Can be used to scan large bound documents Smallest and least accurate Optical character recognition OCR software required to convert picture into characters Other Optical Recognition Methods Optical Mark Recognition Optical character recognition Machine senses marks on piece of paper Wand reader reads characters in special typeface Bar Codes A series of vertical marks Represents a unique code Universal Product Code UPC used as standard in supermarkets Other Sources Voice input Digital cameras Video input Voice Input User speaks to computer Most are speaker dependent Speech recognition devices convert spoken words into binary digits System learns user s voice Types of systems Discrete word systems user must pause between words Continuous word systems user can speak normally Digital Camera User takes photo that is stored on a chip Photo can be downloaded to computer Use photo editing software to enhance Store permanently on CDs or DVDs Photos composed of many pixels of color Photos stored on removable memory card Video Input Digital video consists of series of still frames Displayed rapidly enough to give illusion of motion Web cam used to transmit video over the Internet Can capture video from analog sources with video capture card Output Information for the User Computer screens Printers Voice output Music output Microform Computer Screen Technology Screen is part of computer s monitor Screen output known as soft copy Intangible and temporary Common forms Cathode ray tube CRT Flat panel screens Smart displays CRT Screens Display text and graphics Most are in color Some monochrome monitors are used in applications that have no need for color or graphics Graphics card converts signals from the control unit into the image the user sees Factors Affecting Performance Scan rate Resolution clarity of screen Measured in pixels picture elements The more pixels the higher the