Chapter 5: Input

1
Chapter 5 Input Output

• Objectives
• Explain how data is input into a computer
• 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

2
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

3
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

4
Input Keyboard

• Similar to typewriter keyboard
• Can be unique to an industry
• Keys on McDonalds keyboards represent Big Mac or
  large fries

5
Ergonomic Keyboard

• Designed to reduce or minimize repetitive strain
  injury of wrists
• Provides more natural, comfortable position of
  wrists, arms, and hands

6
Pointing Devices

• Used to position a pointer on the screen
• Communicate commands to the operating system by
  clicking a button
• Mouse most common pointing device

7
Mouse

• Mouse Types
• Mechanical - small ball on underside rolls as
  mouse is moved
• Optical - uses a light beam to detect mouse
  movement
• Cordless - uses either infrared or radio waves to
  connect to computer

8
Trackball

• Trackball
• Variation on mechanical mouse
• User rolls the ball directly
• Often built into laptop computers

9
Touchpad and Pointing Stick

• Touchpad
• Rectangular pressure-sensitive pad
• Sliding finger across pad moves pointer
• Tapping with finger recognized as click
• Common on laptop / notebook computers

10
Pointing Stick

• Pointing stick
• Small pressure-sensitive post mounted in center
  of keyboard
• Pushing post in any direction moves pointer

11
Other Pointing Devices

• 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

12
Source Data Automation

• The use of special equipment to collect data at
  the source
• Primary areas
• Magnetic-ink character recognition (MICR)
• Optical recognition devices

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MICR Magnetic Ink Character Recognition

• Uses a machine to read characters made of
  magnetized particles
• Banking industry is predominant user

14
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

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Common Uses

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

16
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

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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

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Voice Input

• User speaks to computer
• Speech recognition devices convert spoken words
  into binary digits
• Most are speaker-dependent
• System learns users voice
• Only work for user its trained for
• Speaker-independent systems
• Work for almost any user
• Have limited vocabulary

19
Digital Camera

• Photos stored on a chips or memory cards
• Photos can be downloaded to computer, emailed,
  edited, etc
• No film

20
Video Input

• Digital video consists of series of still frames
• Web cam used to transmit video over the Internet
• Can capture video from analog sources with video
  capture card

21
Output Information for the User

• Computer screens
• Printers
• Voice output
• Music output

22
Computer Screen Technology

• Screen is part of computers monitor
• Screen output known as soft copy
• The display is temporary
• Common forms
• Cathode ray tube (CRT)
• Flat-panel screens

23
CRT Screens

• Display text and graphics
• Most are in color (uses red, green, blue)
• 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

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Monitor Quality and Performance

• Scan rate (refresh rate)
• The frequency with which the image is refreshed
• The number of times per second the entire screen
  is redrawn
• Resolution (clarity) of screen
• Measured in pixels (picture elements)
• The more pixels, the higher the resolution
• Dot pitch
• The amount of space between dots
• The smaller the dot pitch, the sharper the image

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Graphics Standards

• Resolution, colors, etc. related to displaying
  graphics
• Super Video Graphics Adapter (SVGA) is most
  common standard
• Provides 800 (horizontal) x 600 (vertical) pixels
  on the display
• Support 16 million colors
• The number of colors that can actually be
  displayed depends on amount of video memory

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Flat-Panel Screens

• Liquid crystal display (LCD)
• Originally used for laptops
• Now available for desktop computers
• Very thin
• Produce sharper text images than CRTs
• Easier on eyes than CRTs

27
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

28
Printers

• Produce information on paper
• Printed output known as hard copy
• Orientation settings
• Portrait - vertical alignment
• Landscape - horizontal alignment

29
Impact Printers

• Physical contact with paper required to produce
  image
• Dot-matrix printer
• Has print head consisting of one or more columns
  of pins
• Pins form characters and images as pattern of dots

30
Nonimpact 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
• Similar technology in photocopiers

31
Nonimpact Printers

• 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
• Slower than laser printers

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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

33
Sounds and Music

• Multimedia clips, games, videos include 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

34
Terminals

• Combine input and output capabilities
• Dumb terminal
• Keyboard for input and monitor for output
• No processing capability
• Requires a host computer to store data and
  perform processing

35
Terminals

• Intelligent terminal
• Has limited memory and a processor
• Requires a host computer
• Point-of-sale (POS) terminal
• Captures retail sales data when transaction takes
  place
• Cash registers in most stores
• Requires a host computer

36
Business Graphics

• A powerful way to impart information
• Colorful graphics, maps, and charts help managers
  compare data, spot trends, and make quicker
  decisions
• Charts and graphs can be quickly updated

37
Video Output

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

38
Computer-Aided Design/Computer-Aided
Manufacturing

• Specialized software
• Allows the user to create 2-dimensional and
  3-dimensional designs
• Performs engineering tests such as stress tests
• Serves as bridge between design and manufacturing

39
Ethics and Data

• 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 elses data for your
  purposes?