Input and Output

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5
CHAPTER
Input and Output
2
Objectives

• To understand that input and output devices are
  essentially translators.
• To understand that input devices translate
  symbols that people understand, into symbols that
  computers can process.
• To understand that output devices translate
  machine output to output people can comprehend.

3
Input

• Input is any data or instructions that are used
  by a computer.
• It can come directly from the user or from other
  sources.
• You can enter data and issue commands using your
  keyboard, voice, by pointing to items, and by
  writing on special devices.

4
Input

• Input devices are hardware devices that convert
  people-readable data into machine-readable form.
• Common input devices are the keyboard to enter
  text and a mouse to issue commands.
• Other input devices are scanning, image
  capturing, digitizing, and audio-input devices.

5
Input

• Input devices must translate human language to
  machine language.
• The computer can only understand machine
  language, which is represented by a binary system
  of electronic signals (0s and 1s).

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KEYBOARD ENTRY

• The keyboard is a common way to input data.
• The keyboard combines a typewriter keyboard with
  a numeric keypad and special keys.
• The keyboard converts numbers, letters, and
  special characters into electrical signals.
• Traditional, ergonomic, and folding are types of
  keyboards.

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Keyboards

• Numeric Keypad - Enters numbers, arithmetic
  symbols, controls cursor or insertion point.
• Function Keys - Shortcut for specific tasks such
  as F1 for online Help.
• Escape Key - Typically cancels a selection or a
  procedure.
• Windows Key - Displays the Start menu.

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Keyboards

• Spacebar - Enters blank spaces between
  characters.
• Navigation Keys - Control the cursor or insertion
  point on the screen.
• Toggle Keys - Keys that turn a feature on or off
  Caps Lock, Num Lock, Scroll Lock.
• Combination Keys - Keys that perform an action
  when held down in combination with another key
  Ctrl, Alt, Shift.

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Keyboards

• Special Keys - Keys above arrow keys to the right
  of keyboard.

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POINTING DEVICES

• Pointing devices provide a comfortable interface
  with the system unit, by accepting point gestures
  and converting them into machine-readable input.
• Use of pointing devices reduces human errors that
  may occur during keyboard entry.
• Direct entry includes pointing, scanning, and
  voice-input devices.

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Pointing Devices

• The pointing devices used in direct entry include
  the following
• Mouse a device that controls the cursor or
  pointer displayed on the monitor.
• Touch Screen a special kind of monitor screen
  covered with a plastic layer.
• Light Pen a light-sensitive pen like device.

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Types of Mouse Devices

• Mechanical Mouse
• Has a ball on the bottom and is attached to the
  system unit with cable.
• Controls the pointer when rolled on a tabletop.
• Optical Mouse
• Does not require a flat surface.
• Has no moving parts.
• Emits and senses light to detect movement.
• Can be used on any surface, is more precise.

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Types of Mouse Devices

• Cordless Mouse
• Typically, part of a portable computer.
• Battery-powered device that uses radio waves or
  infrared light waves.
• Wireless, eliminates cord, frees up desk space

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Types of Mouse Devices

• Joystick
• The most popular input device for computer games.
• Controls game actions by varying pressure, speed,
  and direction of the joystick.
• Can use buttons and triggers to specify commands
  or initiate specific actions.

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Types of Mouse Devices

• Related Devices
• Trackball (roller ball) control the pointer by
  rotating a ball with your thumb
• Touch surfaces control the pointer by moving
  and tapping your finger on the surface of a pad
• Point stick - controls the pointer by directing
  the stick with your finger. Located in the
  middle of the keyboard.

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Types of Mouse Devices

• Touch Screen Features
• Behind the plastic layer of the touch screen are
  crisscrossed invisible beams of infrared light.
• Touching the screen with a finger can activate
  actions or commands.
• Touch screens are often used in ATMs, information
  centers, restaurants, and or stores.
• Light Pen Features
• When the light pen is placed against the monitor,
  it closes a photoelectric circuit.
• The photoelectric circuit identifies the spot for
  entering or modifying data.

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SCANNING DEVICES

• Scanners copy or reproduce text as well as
  images.
• Scanned data can be a written document, an
  inventory tag, a price tag, a graphic image, or
  even a photograph.
• A scanner device reads the data or information
  and then converts it into a form that the system
  unit can process.

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Optical Scanners

• An optical scanner copies or reproduces text as
  well as images.
• These devices record the light and dark areas as
  well as color of the scanned document.
• After the image has been scanned, it can be
  displayed, printed on paper, and stored for later
  uses.
• There are two basic types of scanners.

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Optical Scanners

• Flatbed scanner is much like a copy machine.
  The image is placed on a glass surface. The
  scanner records the image from below.
• Portable scanner a handheld device that the
  user slides across the image, making direct
  contact.

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Bar-Code Reader

• Bar code readers identify the product and search
  for a match in a computer database.
• Supermarkets use bar-code reader systems called
  the Universal Product Code (UPC).
• A point-of-sale terminal will display the price
  and name of the product.

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Character and Mark Recognition Device Features

• Can be used by mainframe computers or powerful
  microcomputers.
• There are three kinds of character and mark
  recognition devices
• Magnetic-ink character recognition (MICR)
• Reads numbers on the bottom of checks.
• Optical-character recognition (OCR)
• Reads special preprinted characters, such as
  those on utility and telephone bills. Example
  Wand readers
• Optical-mark recognition (OMR)
• Reads marks on tests also called mark sensing.

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IMAGE CAPTURING DEVICES

• create or capture original images
• include digital cameras and digital video cameras
• Digital Camera Features
• Images are recorded in the cameras memory rather
  than on film.
• You can take a picture and view it immediately.
• Prices are typically higher than regular cameras.
• Popular with real estate agents to capture
  pictures of homes for Web pages.

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IMAGE CAPTURING DEVICES

• Digital Video Camera Features
• Record motion digitally on a disk or in the
  cameras memory.
• The image quality is better and the price is
  higher than traditional video cameras.
• Webcams are specialized digital video cameras
  that capture images and send them to a computer
  for broadcast over the Internet.

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Digitizing Devices

• Convert a sketch or figure into a form that can
  be processed by a computer.
• These devices have some type of flat surface and
  a writing device.
• As the user moves the writing device across the
  surface, the digitizing device records the
  movement as a series of points and sends this
  information to the computer.
• Two widely used digitizing devices are graphic
  tablets and digital notebooks.

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Graphic Tablets

• The item to be copied is placed on a flat
  digitizing tablet.
• A special stylus connected to a computer is used
  to trace the item.
• The computer records the position of the item on
  the digitizing tablet.
• After the item is traced, its image can be
  displayed on the screen, and printed or stored in
  the computer.
• Graphic tablets are often used by designers,
  architects, and engineers.

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Digital Notebook Features

• Uses a special pen to write on a regular notepad
  positioned on top of an electronic pad or tablet.
• A signal from pen is sent to and stored in the
  underlying electronic pad.
• Notes can be transferred to a microcomputer to be
  viewed, edited or printed.

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AUDIO-INPUT DEVICES

• Audio-input devices convert speech into a digital
  code.
• The most widely used audio-input device is the
  microphone.
• A microphone, sound card, and software form a
  voice recognition system.

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Voice Recognition System Features

• Voice recognition systems can be used to operate
  microcomputers or create documents.
• Some voice recognition systems must be trained
  to the particular users voice.
• Training is done by matching the users spoken
  words to previously stored patterns.
• Advanced systems can recognize the same word
  spoken by many different people.
• Some systems can translate from one language to
  another.

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Voice Recognition System Features

• Portable systems can connect to a computer system
  through system unit serial ports.
• There are two types of voice recognition systems
  
• Discrete Speech directly converts the spoken
  word into printed material.
• Continuous Speech able to accept dictation as
  well as spoken commands.

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Discrete-Speech Recognition Features

• Common in business in preparing memos and other
  written documents.
• Widely used in legal and medical professions.
• Audio signal is converted to a digital signal
  then analyzed using a special program.
• Program recognizes individual words based on
  their sound and stores them in a file.
• The system cannot distinguish between such
  distinctions as theyre, their, and there.
  Captured dictation must be reviewed to make
  corrections.
• File can be retrieved, edited, and printed using
  a standard word-processing program.

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Continuous-Speech Recognition Features

• Key technology of the twenty-first century.
• More natural and conversational than discrete
  word systems.
• Able to recognize individual words and phrases in
  content.
• Able to distinguish between same-sounding words
  such as there, their, and theyre.
• Can be used to accept commands to operate
  applications such as Word and Excel.
• Two well-known systems are NaturallySpeaking from
  Dragon Systems and ViaVoice from IBM.

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Output

• Output is people-readable information.
• Input (data) is processed inside the computers
  CPU into meaningful output (information).
• INPUT ? PROCESSING ? INFORMATION
• Output devices are any hardware used to provide
  or to create output from the computer.
• Output devices translate the machine-readable
  information into people-readable information.

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Ouput

• The three most widely used output devices for
  microcomputers include
• Monitors - output images formed on a screen.
• Printers - output images formed on paper.
• Audio system - output in form of sounds.

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MONITORS

• Some monitors are used on the desktop others are
  portable.
• Two important characteristics of a monitor are
  size and clarity.

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Monitor Size

• A monitors size is indicated by the diagonal
  length of its viewing area.
• Common sizes for monitors are 15, 17, 19, and 21
  inches.
• Larger monitors can display more information at
  one time.
• Larger monitors are more expensive.

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Monitor Clarity

• A monitors clarity is indicated by its
  resolution.
• Resolution is measured in pixels.
• Pixels are individual dots of picture elements
  that form images on a monitor.
• The greater the resolution (more pixels), the
  better the clarity of the image.

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Monitor Standards

• Standards have been created to indicate a
  monitors color and resolution capabilities.
• The four most common monitor standards today are
• SVGA (Super Video Graphics Array)
• Has a minimum resolution of 800 by 600 pixels.
• Primarily used with 15-inch monitors.
• XGA (Extended Graphic Array)
• Has a resolution of 1024 by 768 pixels.
• Popular today with 17-inch and 19-inch monitors.

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Monitor Standards

• SXGA (Super Extended Graphics Array)
• Has a resolution of 1280 by 1024 pixels.
• Popular with 19-inch and 21-inch monitors.
• UXGA (Ultra Extended Graphics Array)
• The newest and highest standard.
• Popularity expected to increase with 21-inch
  monitor use.
• Primarily used for high end engineering design
  and graphics arts.

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Desktop Monitor - The Cathode-Ray Tube (CRT)

• The Cathode-Ray Tube (CRT) is the most common
  type of monitor for home and office.
• It is typically placed directly on the system
  unit or desktop.
• It is similar in size and technology to
  televisions.
• The advantages of CRTs are low cost and excellent
  resolution.
• The disadvantage of CRTs is size.
• Figure 5-19, page 127 shows a picture of a CRT
  monitor.

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Flat Panel Monitors

• Also known as liquid crystal display (LCD)
  monitors.
• Uses a technology that involves liquid crystals.
• Are much thinner than CRTs.
• Have been used for portable computers.

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Flat Panel Monitors

• Passive-matrix (dual-scan monitor)
• Creates images by scanning the entire screen.
• Requires very little power.
• Clarity of image is not as sharp as
  active-matrix.
• Active-matrix
• Does not scan down the screen to form images.
• Each pixel is independently activated to form
  images.
• More colors with better clarity can be displayed.
• Are more expensive and require more power.

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Other Monitors

• E-books are handheld, book-sized devices that
  display text and graphics.
• The device uses special cartridges or the Web to
  download content such as newspapers, magazines
  and entire books.
• The cost of producing and distributing e-book
  content is less than publishing and delivering
  traditional print media.
• Many experts predict that e-books will soon
  become as commonplace as todays traditional
  books.

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Other Monitors

• Data Projectors
• Data projectors are specialized devices similar
  to slide projectors.
• These devices connect to microcomputers and
  project computer output just as it would appear
  on a traditional monitor.
• Data projectors are frequently used for to
  deliver presentations created from presentation
  graphics programs like PowerPoint.

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Other Monitors

• HDTV is all-digital high-definition television
  (HDTV).
• HDTV delivers a clearer and more detailed
  wide-screen picture.
• Digital output enables users to freeze video
  sequence to create still images.
• Frozen images can be digitized and output as
  artwork or stored on disks.
• This technology is useful to graphic artists,
  publishers, and educators.

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PRINTERS

• Three popular kinds of printers used with
  microcomputers are
• Ink-Jet the most widely used printer.
• Sprays small droplets of ink at high speed onto
  the surface of the paper.
• Produces a letter-quality image.
• Permits printing in a variety of colors.
• Reliable, quiet, and inexpensive.

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PRINTERS

• Laser used in applications requiring
  high-quality output.
• Uses a technology similar to that used in
  photocopying machines (laser beam).
• Produces images with excellent letter and
  graphics quality.
• More expensive than ink-jet printers.
• There are two categories of laser printers
• Personal inexpensive and used by many single
  users. (4-6 pages a minute)
• Shared more expensive and shared by a group of
  users. (over 30 pages a minute)

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PRINTERS

• Thermal widely used to produce very high
  quality color artwork and text.
• Uses heat elements to produce images on
  heat-sensitive paper.
• Not as popular because of cost and requirement of
  specially treated paper.
• Produces near-photographic output.

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Other types of printers

• Dot Matrix
• Was once the most widely used microcomputer
  printer.
• Forms characters or images using a series of
  small pins on a print head.
• Are inexpensive and reliable, but noisy.
• Often used for draft documents or documents that
  will not be shown to customers.

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Printers

• Chain
• Designed to serve minicomputers, mainframes, and
  communications networks.
• Expensive, high-speed machines
• Plotters
• Special-purpose output devices
• Used to produce charts, maps, architectural
  drawings, and 3-D illustrations
• Produce high-quality multicolor documents or
  larger size documents

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AUDIO-OUTPUT DEVICES

• Audio-output devices translate audio information
  from the computer into sounds that people can
  recognize and understand.
• Audio-output devices use prerecorded vocalized
  sounds to produce output.
• Most widely used audio-output devices are stereo
  speakers and headphones.
• Devices are connected to a sound card in the
  system unit.
• Sound card is used to capture sound as well as
  play it back.
• Voice output is not as difficult to create as
  voice input.
• The computer speaks synthesized words.

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AUDIO-OUTPUT DEVICES

• Examples of voice output uses
• Soft-drink machines, the telephone, and in cars.
• Voice output can be used as a tool for learning.
• Can help students study a foreign language
• Used in supermarkets at the checkout counter to
  confirm purchases
• Most powerful capability is to assist the
  physically challenged

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COMBINATION INPUT AND OUTPUT DEVICES

• Fax Machine Features
• Fax machines are also called facsimile
  transmission machines.
• In transmission, the sending fax converts the
  image to a format for telephone lines.
• The receiving fax then converts the telephone
  format back to its original image.
• Dedicated fax machines are stand-alone devices
  for sending and receiving images over telephone
  lines.
• Most computers systems now have fax/modem boards
  that provide fax and modem capabilities.

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COMBINATION INPUT AND OUTPUT DEVICES

• Multifunctional devices
• Multifunctional devices have input and output
  capabilities such as scanner, fax, and copying
  machine.
• These devices offer a cost and space advantage.
• Disadvantage of these systems is the quality and
  functionality is not quite as good as separate
  function devices.
• Multifunctional devices are widely used in home
  and small business offices.

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COMBINATION INPUT AND OUTPUT DEVICES

• Internet Telephone
• Internet telephony, also known as telephony, uses
  the Internet to connect two or more people via
  telephone.
• This requires the Internet, a special service
  provider, a sound card, and special software.
• This service is not available in all locations
  but is gaining in popularity.

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COMBINATION INPUT AND OUTPUT DEVICES

• Terminals
• A terminal is an input and output device that
  connects you to a mainframe called a host
  computer or server.
• There are four kinds of terminals Dumb,
  Intelligent, Network and Internet.

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COMBINATION INPUT AND OUTPUT DEVICES

• Dumb Terminal
• Used to input and receive data only.
• It cannot process data independently.
• A terminal used by an airline reservation clerk
  to access a mainframe computer for flight
  information is an example of a dumb terminal.

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COMBINATION INPUT AND OUTPUT DEVICES

• Intelligent Terminal
• Includes a processing unit, memory, and secondary
  storage.
• It uses communications software and a telephone
  hookup or other communications link.
• A microcomputer connected to a larger computer by
  a modem or network link is an example of an
  intelligent terminal.
• An increasingly popular type is the Net PC.
  These low-cost and limited microcomputers
  typically have only one type of secondary
  storage, a sealed system unit, and no expansion
  slots.

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COMBINATION INPUT AND OUTPUT DEVICES

• Network Terminal
• Also known as a thin client or network computer.
  
• It is a low cost alternative to an intelligent
  terminal.
• Most network terminals do not have a hard drive.
  
• This type of terminal relies on a host computer
  or server for application or system software.

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COMBINATION INPUT AND OUTPUT DEVICES

• Internet Terminal
• Is also known as a Web terminal or Web appliance.
  
• It provides access to the Internet and displays
  Web pages on a standard television set.
• It is used almost exclusively in the home.