Understanding Computers, Chapter 4

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Chapter 4 Input and Output
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Learning Objectives

• Explain the purpose of a computer keyboard and
  the types of keyboards widely used today.
• List several different pointing devices and
  describe their functions.
• Describe the purposes of scanners and readers and
  list some types of scanners and readers in use
  today.
• Understand how digital cameras differ from
  conventional cameras.
• Explain how audio input is accomplished.
• Describe the characteristics of a display device
  and explain some of the technologies used to
  display images.
• List several types of printers and explain their
  function.
• Understand which hardware devices are used for
  audio output.

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Overview

• This chapter covers
• Different types of keyboards and pointing devices
• Types of scanners, readers, and digital cameras
  and what they are used for
• Audio input devices
• Types of display devices and how they work
• Types of printers and how they work
• Audio output

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Keyboards

• Keyboard An input device containing keys,
  arranged in a typewriter configuration, used to
  input letters, numbers, and other symbols
• Can be wired or wireless
• Most PCs today are designed to be used with a
  keyboard
• Contains
• Standard alphanumeric keys
• Numeric keypad
• Function keys
• Directional keys and special keys

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Keyboards
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Keyboards

• Keyboards are increasingly including alternate
  input tools
• Touch pads
• Scroll wheels
• Some also include built-in display screens
• Portable PCs and mobile devices often use
• Thumbpad
• Slide-out keyboard
• Pen or touch input
• Portable keyboard
• Virtual keyboard is an emerging possibility

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Keyboards
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Pointing Devices

• Pointing device An input device that moves an
  onscreen pointer (arrow or insertion point) to
  allow the user to select objects on the screen
• Usually buttons on the device are used to select
  objects
• Common types of pointing devices
• Mouse
• Electronic pen
• Touch screen

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The Mouse

• Mouse A pointing device the user slides along a
  flat surface to move a pointer around the screen
  and clicks its buttons to make selections
• Older mechanical mice use a ball
• Newer optical or laser mice track movements with
  light
• Can be wireless

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The Electronic Pen and Stylus

• Electronic pen Device used to select objects, as
  well as to draw or write electronically on the
  screen
• Also called tablet pen, digital pen, stylus
• Commonly used with pen-based PCs
• Used to issue commands and input data
• If handwriting recognition is used, written text
  can be converted to editable typed text

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Handwriting Recognition
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The Electronic Pen and Stylus

• Also used with
• Digital writing systems
• Graphics tablets
• Signature capture devices

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Touch Screens

• Touch screen Display device that is touched with
  the finger to issue commands or otherwise
  generate input to the connected PC
• Used with
• Desktop and portable PCs
• Mobile phones and mobile devices
• Interactive whiteboards
• Consumer kiosks

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Touch Screens
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Other Pointing Devices

• Joysticks, gamepads, and other gaming devices
• Trackballs
• Control buttons and wheels
• Touch pads

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Scanners, Readers, and Digital Cameras

• Source documents Documents containing data that
  already exists in physical form (order form,
  photograph, invoice, check, or price label)
• Source data automation Capturing data directly
  from a source document
• Saves time
• Increases accuracy

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Scanners

• Scanner (optical scanner) Input device that
  reads printed text and graphics and transfers
  them to a computer in digital form
• Can scan photos, documents, drawings, (flat
  objects)
• Data is typically input as a single image
• If optical character recognition (OCR) is used,
  text is input as editable, typed text
• Types of scanners
• Flatbed
• Drum

• Handheld
• 3D

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Scanners

• Optical resolution Quality of scanned images
• Measured in number of dots per inch (dpi)
• Can often be specified when image is scanned
• Can be changed when scanned image is edited
• Varies with scanner used
• Pixel Smallest colorable area in an electronic
  image

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Barcode Readers

• Barcode readers Input devices that read barcodes
• Barcode Machine-readable code that represents
  data as a set of bars
• Common types
• Universal Product Code (UPC)
• ISBN
• Code 39
• POSTNET code
• High-capacity color barcode (HCCB)

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Radio FrequencyIdentification Readers

• Radio frequency identification (RFID) Technology
  used to store and transmit data located in RFID
  tags
• RFID tag Contains tiny chips and radio antennas
• Attached to objects for identification purposes
• Read by RFID readers
• Tags only need to be within range of the reader,
  rather than in the line of sight
• Applications
• Tracking inventory and assets
• Electronic tolls
• Electronic payments (Near Field Communication)
• Security

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Radio FrequencyIdentification Readers
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Optical Mark Readers (OMRs)

• Optical Mark Readers (OMRs) Input data from
  special forms to score or tally exams,
  questionnaires, ballots

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Optical Character Recognition Devices

• Optical Character Recognition (OCR) Reads
  optical characters that are designed to be
  identifiable by humans as well as OCR devices
• Most machines today are designed to read several
  standard OCR fonts
• Used to process turnaround documents like monthly
  bills

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Magnetic Ink Character Recognition (MICR) Readers

• Magnetic ink character recognition (MICR)
  readers Read MICR characters
• Used primarily for banking
• MICR readers read the special magnetic characters
  and sort/process checks

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Biometric Readers

• Biometric data Based on unique physiological
  characteristics or personal trait
• Fingerprint
• Hand or face geometry
• Iris of the eye
• Voice or signature
• Biometric readers Used to input biometric data
• Can be stand-alone or built into another piece of
  hardware (keyboard, mouse)
• Also being built into computers and storage
  devices to allow access only by authorized
  individuals
• Most often used for access control and to verify
  transactions

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Biometric Readers
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Digital Cameras

• Digital cameras Record images on digital storage
  medium rather than film
• Can either be still cameras or video cameras
• Typically use flash memory for storage
• Images can be edited, posted to a Web page,
  burned to a CD or DVD disc, etc.
• Digital still cameras
• Available in a wide variety of sizes and
  capabilities
• Photos can be transferred to a PC or printer
• Camera quality is measured in megapixels
• Digital video cameras
• Digital camcorders
• PC video cameras (PC cams, Web cam)

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Digital Cameras
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Audio Input

• Audio input The process of entering audio data
  into the computer
• Voice (narrations, podcasts, etc.)
• Music (from CDs, MIDI keyboards, etc.)
• Voice input systems (speech recognition systems)
• Enable a computer to recognize the human voice
• Consist of a microphone or headset and
  appropriate software
• Can be used to dictate text or commands into a PC

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Voice Input Systems
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Display Devices

• Display device Presents output visually
• Monitor Display device for a desktop PC
• Display screen Screen built into a variety of
  devices
• Notebook and handheld PCs,
• Mobile phones and mobile devices
• E-books readers, digital photo frames, and other
  consumer devices, and many other devices
• Digital signage systems
• E-paper

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Display Devices
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Display Device Characteristics

• Color vs. monochrome displays
• CRT vs. flat-panel display
• Size
• Screen resolution
• Wired vs. wireless
• 2D vs. 3D
• Digital TV and HDTV capabilities
• Touch screen capabilities
• Video card being used determines some of the
  characteristics (bit depth, video RAM,
  connections, etc.)

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Screen Resolution
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Flat-Panel Display Technologies

• Liquid crystal displays (LCDs) Use charged
  liquid crystals between sheets of glass or
  plastic
• Requires backlighting
• LED (Light emitting diode) Used in displays as
  well as a variety of consumer products

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Flat-Panel Display Technologies

• Organic light emitting diode (OLED) displays Use
  emissive organic material to display brighter and
  sharper images
• Do not need backlighting
• Used with consumer devices (portabledigital
  mediaplayers, TVs,etc.)

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Flat-Panel Display Technologies

• Special types of OLEDs
• Flexible OLEDs (FOLEDs)
• Transparent OLEDs (TOLEDs)
• Phosphorescent OLEDs (PHOLEDs)
• Interferometric Modulator Displays (IMOD)
  Essentially a complex mirror that uses external
  light to display images
• Designed initially for mobile phones and portable
  devices
• Images are bright and clear, even in sunlight
• Plasma displays Use layers of gas to display
  images
• Most often used on large displays

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Flat-Panel Display Technologies
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Data and Multimedia Projectors

• Data projector Display device that projects all
  computer output to a wall or projection screen
• Most data projectors today can project video, in
  addition to computer output
• Can be wireless or integrated into devices
• FogScreen systems projects on a thin layer of fog
• Holographic projectors are in development

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Printers

• Printers Produce hard copy
• Printer Characteristics
• Printing technology used
• Impact vs. nonimpact
• Color vs. black and white
• Personal vs. network printers
• Print resolution
• Print speed
• Possible connections
• Multifunction capabilities

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Printers
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Laser Printers

• Laser printer Uses toner powder and technology
  similar to that of a photocopier to produce
  images on paper
• The standard for business documents
• Print one entire page at a time
• Generally faster and have better quality than
  ink-jet printers
• Can be black and white or color
• Common print resolution for laser printers is
  between 600 and 2,400 dpi
• Use toner cartridges

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Laser Printers
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Ink-Jet Printers

• Ink-jet printer Sprays droplets of ink to
  produce images on paper
• Usually print in color
• Often the choice for home use
• Print fairly slowly, one line at a time
• Quality not quite as good as a laser printer
• Use ink-jet cartridges
• Newer printers with full width printheads are
  much faster
• Potential applications for the future
• Dispensing liquid metal, aromas, computer chips
  and other circuitry, printing human tissue

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Ink-Jet Printers
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Special-Purpose Printers

• Photo printers
• Barcode, label, and postage printers
• Portable printers
• Plotters and wide-format ink-jet printers
• 3-D printers

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Audio Output

• Audio output Output in the form of voice or
  music
• Speakers
• Voice output systems
• Headphones and headsets
• Earphones and earbuds

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Summary

• Keyboards
• Pointing Devices
• Scanners, Readers, and Digital Cameras
• Audio Input
• Display Devices
• Printers
• Audio Output