Computer Input and Output

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Computer Input and Output

• Introduction to Information Technology

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Objectives

• Describe the user relationship with computer
  input and output
• Explain how data is input to 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
• Differentiate among different kinds of
  printerExplain the function of a computer
  terminal and describe the types of terminals

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Contents

• Input and Output
• Input
• Output
• Terminals
• Computer Graphics
• Ethics and Data

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Input and Output

• Input
• Users submit input data
• Output
• Users get processed information

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Input

• Data from the user to the computer
• Converts raw data into electronic form

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Diversity of Input Methods

• Zebra-striped bar codes on supermarket items
• Word commands operate a forklift truck
• An order is entered using a pen on a special pad
• Time clock generates paycheck
• Data on checks are read and used to prepare a
  monthly bank statement
• Charge-card transactions generate customer bills

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Keyboard

• Traditional
• Looks like typewriter with extra keys
• Non-traditional
• Fast food restaurants
• Each key represents a food item rather than a
  character

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Keyboard

• Function Keys
• Give commands
• Software specific

• Main Keyboard
• Typewriter keys
• Special command keys

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Keyboard

• Numeric Keys
• Num Lock toggle
• On numeric data math symbols
• Off cursor movement
• Cursor Movement Keys

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KeyboardSpecial Keys
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Pointing Devices

• Position a pointer / cursor on the screen
• Controls drawing instruments in graphics
  applications
• Communicate commands to a program

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Pointing Devices Mouse

• Types
• Mechanical
• Optical
• Wireless
• Features
• Palm-sized
• 1 or 2 buttons
• Wheel

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Other Pointing Devices

• Trackball
• Upside-down mouse
• Ball on top
• Roll ball with hand
• Laptop computers
• Touchpad
• Pressure-sensitive pad
• Cursor moves as you slide your finger
• Laptop computers

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Other Pointing Devices

• Pointing stick
• Pressure-sensitive post
• Mounted between G and H keys on keyboard
• Apply pressure in a direction to move cursor
• Joystick
• Short lever
• Handgrip
• Distance and speed of movement control pointer
  position

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Graphics Tablet

• Digitizing tablet
• Rectangular board
• Invisible grid of electronic dots
• Write with stylus or puck
• Sends locations of electronic dots as stylus
  moves over them
• Creates precise drawings
• Architects and engineers

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Touch Screens

• Human points to a selection on the screen
• Types
• Edges emit horizontal and vertical beams of light
  that crisscross the screen
• Senses finger pressure
• Light pen for pointing

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Touch Screens

• Kiosks
• Self-help stations
• Easy to use
• Where found
• Malls
• Disney World
• Government offices

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Pen-based Computing

• Small hand-held devices
• Electronic pen (stylus)
• Pointer
• Handwritten input
• Personal Digital Assistants (PDA)

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Source Data Automation

• Special equipment to collect data at the source
• Sent directly to a computer
• Avoids need to key data
• Related input areas
• Magnetic-Ink Character Recognition
• Scanners
• Optical recognition devices
• Voice

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MICRMagnetic-Ink Character Recognition

• Read characters made of magnetic particles
• Numbers on the bottom of checks
• MICR inscriber adds characters to check that
  show amount cashed

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Optical Scanners

• Optical recognition
• Light beam scans input data
• Most common type of source input
• Document imaging converts paper documents to
  electronic form
• Converts snapshots into images
• Converts scanned picture into characters OCR

Exact computer-produced replica of original
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Types of Scanners

• Flatbed
• One sheet at a time
• Scans bound documents
• Sheetfeed
• Motorized rollers
• Sheet moves across scanning head
• Small, convenient size
• Less versatile than flatbed
• Prone to errors

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Types of Scanners

• Handheld
• Least expensive
• Least accurate
• Portable
• User must move the scanner in a straight line at
  a fixed rate
• Wide document causes problems

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Optical Recognition

• Optical mark recognition (OMR)
• Mark sensing
• Exams
• Recognizes the location of the marks
• Optical character recognition (OCR)
• Light source reads special characters
• OCR-A is ANSI standard typeface for optical
  characters

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Optical Recognition Wand Reader

• Retail stores
• Libraries
• Hospitals
• Factories

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Optical RecognitionBar Code Reader

• Photoelectric device
• Reads bar codes
• Inexpensive
• Reliable
• Where Used?
• Supermarket UPC
• Federal Express

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Optical RecognitionHandwritten Characters

• Must follow rigid rules
• Size
• Completeness
• Legibility

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Voice Input

• Speech Recognition
• Speech recognition devices
• Input via a microphone
• Voice converted to binary code
• Problems
• Speaker-dependent
• Voice training

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Voice Input

• Changing radio frequencies in airplane cockpits
• Placing a call on a car phone
• Requesting stock-market quotations over the phone
• Command from physically disabled users

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Voice Input

• Discrete work systems
• Understand isolated words
• Pause between words
• Difficult for dictation
• Continuous work systems
• Normal speaking pattern
• Easy to use
• Faster and easier to dictate than to key

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Digital Cameras

• Photos stored in electronic form
• No film
• Point and shoot
• Edit

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Output

• Information for the user
• Types
• Screen soft copy
• Printer hard copy
• Voice
• Sound
• Graphics

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Monitor

• Data that is entered appears on the screen
• Screen is part of the monitor

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Monitor

• Cathode Ray Tube (CRT)
• Flat panel display
• Liquid Crystal Display (LCD)

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CRT

• Raster scanning
• Sweeping electron beams across the back of the
  screen
• Phosphorous coating on back
• Glows when hit by a beam of electrons
• Phosphorous loses glow and image fades and
  flickers
• Image must be continually refreshed

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CRT

• Refresh rate / scan rate
• Number of times electron beams refreshes the
  screen
• 80-100 times per second adequate for clear screen
  image
• Process also used for television

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CRT

• Interlaced vs. Non-interlaced
• Interlaced
• Refresh every other line on each pass
• Lower refresh rate without flicker
• Good for fixed graphics
• Causes flutter with animated graphics
• Inexpensive
• Non-interlaced
• Refresh every line on each pass
• Typical screen sold today

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CRT

• Color vs. Monochrome
• Color
• Typical monitor sold today
• Monochrome
• Green or amber on a contrasting background
• Less expensive than color

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CRT

• Resolution
• Clarity of image
• Pixel (Picture element)
• Dot on screen
• Is addressable
• Can be illuminated
• More pixels means higher resolution
• Dot pitch
• Distance between dots
• Smaller distance means better quality image

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CRT

• Graphics Card/Graphics Adapter Board
• Plugs into expansion slot on motherboard
• Graphics card and monitor must be compatible for
  high quality image

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CRT

• Size
• Measured diagonally
• Typical sizes
• Office user 15-17 inch
• High-powered graphics user 19 inch
• High-end monitors 21 inches and up
• Larger size
• More expensive
• More space on desktop
• Reduces eye strain

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Graphics Standards
Help insure that the products work together

• PCs
• Monitor
• Graphics boards
• Software

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Graphics Standards

• SVGA (Super VGA)
• Resolution 800 x 600, 1024 x 768, 1280 x 1024,
  1600 x 1200 pixels
• 16 million colors
• Number of colors displayed simultaneously limited
  by amount of video memory
• XGA (Extended Graphics Array)
• High resolution
• Supports more simultaneous colors
• Allows non-interlaced monitors

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Flat-panel Screens

• Liquid Crystal Display (LCD)
• Primarily on laptops
• Moving to desktop
• Skinny (depth) regardless of size

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Flat-panel Screens

• Crisp, brilliant images
• Easy on eyes
• No flicker
• Full dimension is useable
• More expensive that CRT monitors

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Flat-panel Screens

• Active Matrix
• Thin-film transistor technology (TFT)
• Transistors for each pixel
• Brighter image
• Viewable from an angle
• Passive Matrix
• Fewer transistors
• Cheaper
• Less power

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Printer

• Produces information on paper
• Orientation
• Portrait
• Landscape
• Methods of printing
• Impact
• Nonimpact

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Impact Printers

• Line printer
• One line at a time
• High volume
• Low quality

• Dot-matrix printer
• One character
• at a time

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Nonimpact PrinterLaser Printer
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Nonimpact PrinterLaser Printer

• Transfers images to paper using a light beam
• Prints one page at a time
• 600-1200 dpi High quality
• Speed
• Personal laser printers 8-10 ppm
• Network laser printers 35-50 ppm
• High-volume laser printers up to 1000 ppm
• Black and white / color

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Nonimpact PrinterInk-jet Printer

• Spray ink at paper
• Black and white / color
• Excellent graphics
• Good quality
• Slower than laser

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Nonimpact Printer

• Choose based upon
• Speed
• Quality
• Black and white vs. color
• Price

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Sound

• Creates multimedia output
• Multiple sight and sound effects
• Speakers
• Sound card

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Voice OutputSpeech Synthesis

• Enables machines to talk to people
• Types
• Voice synthesizers
• Voice output devices
• Audio-response units
• Convert data in storage to vocalized sounds
• Synthesis by analysis human sounds are stored
  and reproduced as needed
• Synthesis by rule creates artificial speech

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Voice OutputSpeech synthesis

• Uses
• Automobiles
• Telephone surveys
• Catalog order is ready
• Your payment is late reminder

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Music and Other Sounds

• MIDI (Musical Instrument Digital Interface)
• Communicates between MIDI devices and computer
• Rules that produce and process digital music
  signals
• MIDI information tells synthesizer
• When to start and stop playing a note
• Volume
• Modulation
• Software is available for composing and editing
  per MIDI standard

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Terminals

• Device that provides input and output
  capabilities
• Dumb terminal
• Keyboard and monitor
• Connects to host for processing
• Intelligent terminal
• Keyboard, monitor, memory, and processor
• Connects with host
• Point-of-sale terminal (POS)
• Input and output device
• Captures retail data

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Computer Graphics

• Business
• Education
• Science
• Sports
• Computer art
• Entertainment

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Business Graphics

• Types
• Maps
• Charts
• Help
• Compare data
• Spot trends
• Make decisions quickly
• Attention-getting
• Updated instantaneously
• Rendered quickly

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Video Graphics

• Animated graphics
• Prepared one frame at a time
• Examples
• Cartoons
• Commercials without humans
• Television networks logo
• Arcade games

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CAD/CAMComputer-Aided DesignComputer-Aided
Manufacturing

• CAD
• Software creates 2-D and 3-D designs
• CAM
• Controls production equipment
• CIM (Computer Integrated Manufacturing)
• Bridge between design and manufacturing
• CAD/CAM integrated into manufacturing process
• Provides balanced, efficient production process

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Ethics and Data

• Computer data can be
• Used
• Sold
• Altered
• What is legal?