Computers: Tools for an Information Age

1. Computers:Tools for an Information Age Chapter 5 Input and Output: The User Connection

2. 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

3. 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

4. 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

5. Instant Reaction • Items scanned at supermarket • Produce item name and price at counter • Forklift operator speaks to computer • Forklift obeys operator’s commands • Sales rep enters an order on a pad • 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

6. Input and Output Separated • Data on checks input into bank computer • Computer processes entries once a month to prepare statements • Charge-card transactions provide input • Processed monthly to produce customer bills • Water samples collected and input into computer • Used to produce reports that show patterns of water quality

7. Input: Getting Data from the User to the Computer • Keyboard • Pointing devices • Source data automation

8. Keyboard • Similar to typewriter keyboard • May be part of a personal computer • May be part of a terminal connected to a computer in another location • Can be unique to an industry • Keys on McDonald’s keyboards represent Big Mac or large fries • Ergonomic keyboards

9. Ergonomic Keyboards • Designed to reduce or minimize repetitive strain injury of wrists • Provide more natural, comfortable position of wrists, arms, and hands

10. 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

11. 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.

12. 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

13. 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

14. 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

15. Other Pointing Devices • Graphics tablet • User moves stylus or puck across board • Used to create or trace precise drawings • Touch screen • 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

16. 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

17. 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

18. 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

19. Common Uses • Scanners at supermarkets • Document imaging - converts paper documents to electronic versions • Documents stored on disk • Can be edited or processed by software

20. Scanners • Flatbed scanner • Typically scans one page at a time • Can be used to scan large bound documents • Sheetfed scanner • Motorized rollers feed sheet across scanner head • Handheld scanner • Smallest and least accurate • Optical character recognition (OCR) software required to convert picture into characters

21. Other Optical Recognition Methods • Optical Mark Recognition • Machine senses marks on piece of paper • Optical character recognition • 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

22. Other Sources • Voice input • Digital cameras • Video input

23. Voice Input • User speaks to computer • Speech recognition devices convert spoken words into binary digits • Most are speaker-dependent • System “learns” user’s voice • Types of systems • Discrete word systems - user must pause between words • Continuous word systems - user can speak normally

24. 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

25. 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

26. Output: Information for the User • Computer screens • Printers • Voice output • Music output • Microform

27. 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

28. 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

29. Factors Affecting Performance • Scan rate • The frequency with which the image is refreshed • Resolution (clarity) of screen • Measured in pixels (picture elements) • The more pixels, the higher the resolution • Graphics standards • Dot pitch • The amount of space between dots • The smaller the dot pitch, the sharper the image • Video memory • A high-speed form of RAM installed on graphics card

30. Graphic Standards • Agree on resolutions, colors, other issues related to displaying graphics • Super Video Graphics Adapter (SVGA) is most common standard • Provides 800 (horizontal) x 600 (vertical) pixels on the display • Other varieties of SVGA exist • Support 16 million colors • The number of colors that can be displayed depends on amount of video memory

31. Flat-Panel Screens • Liquid crystal display (LCD) • Originally used for laptops, but making their way to desktop computers • Very thin (only a few inches) • Produce sharper text images than CRTs • Easier on eyes than CRTs • Different flat-panel technologies

32. LCD Technologies • Active-matrix • Uses many thin-film transistors (TFT) • Produces brighter image and can be viewed from wider angles • Passive-matrix • Uses fewer transistors • Cheaper and uses less power • Gas plasma • Supports very large displays • Has brilliant color display • Viewable at very wide angles

33. Smart Displays • Based on flat-panel technology • Each contains its own processor • Wireless transmitter-receiver allows user to control desktop from anywhere in the house

34. Printers • Produce information on paper output • Printed output known as hard copy • Orientation settings • Portrait - vertical alignment • Landscape - horizontal alignment • Two ways of printing • Impact printer • Non-impact printer

35. Impact Printers • Physical contact with paper required to produce image • Line printer • Prints an entire line of a program at once • Typically used with mainframe computers printing lengthy reports • Dot-matrix printer • Has print head consisting of one or more columns of pins • Pins form characters and images as pattern of dots

36. Non-impact Printers • Places an image on a page without physically touching the page • Laser printer • Uses light beam to help transfer images to paper • Produces high-quality output at very fast speeds • Ink-jet printer • Sprays dots of ink from jet nozzles • Can print in both black and white and color • Requires high-quality paper so ink does not smear • Less expensive than laser printers

37. Voice Output • Voice synthesizers convert data to vocalized sounds • Two approaches • Synthesis by analysis - analyzes actual human voice, records and plays back as needed • Synthesis by rule - uses linguistic rules to create artificial speech • Used in automated telephone-based customer service applications • Useful when an inquiry would be followed by a short reply, such as a balance inquiry

38. Music Output • Multimedia clips, games, videos include sight and sound • Speakers placed on side of monitor • Powered sub-woofers produce low-frequency sounds • Musical Instrument Digital Interface (MIDI) • Rules for connecting musical instruments, synthesizers, and computers • Allows users to set up home studios that rival capabilities of professional recording studios

39. Computer Output Microform (COM) • Output of photographically reduced images on microfilm or microfiche • Microfilm - images stored on continuous roll of film • Microfiche - images stored in rows and columns on a card • Needs special reader • Common uses • Libraries store back issues of periodicals • Businesses store large volumes of historical records

40. Terminals • Combine input and output capabilities • Dumb terminal • Keyboard for input and monitor for output • No processing capability • Intelligent terminal • Has limited memory and a processor • Point-of-sale (POS) terminal • Captures retail sales data when transaction takes place

41. Computer Graphics • Business graphics • Video graphics • Computer-aided design/computer-aided manufacturing (CAD/CAM)

42. Business Graphics • A powerful way to impart information • Colorful graphics, maps, and charts help managers compare data, spot trends, and make quicker decisions • As underlying data changes, charts and graphs are instantly updated

43. Video Graphics • A series of video images • Displayed rapidly to give the impression of motion • Used extensively in television • Also used in computer and arcade video games

44. Computer-Aided Design/Computer-Aided Manufacturing • Creates two- and three-dimensional designs • Performs engineering tests such as stress tests • Serves as bridge between design and manufacturing

45. Ethics and Data • Once data is in computer, there are many ways it can be used • Ethical issues to ponder • Is it ethical to use a computer to alter photographs? • Is it ethical to erase e-mail messages that may be of interest to a party in a lawsuit? • Is it ethical to use someone else’s data for your purposes?