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					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
   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
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
Input: Getting Data from the User to the
Computer
 Keyboard
 Pointing devices
 Source data automation
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
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
    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
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
    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
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
Other Sources

 Voice input
 Digital cameras
 Video input
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
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
   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
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
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
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
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
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
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
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
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
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
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
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
Computer Graphics

 Business graphics
 Video graphics
 Computer-aided design/computer-aided
 manufacturing (CAD/CAM)
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
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
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
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?

				
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