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5. CHAPTER. Input and Output. 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.

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slide1

5

CHAPTER

Input and Output

objectives
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.
input
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.
input4
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.
input5
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).
keyboard entry
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.
keyboards
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.
keyboards8
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.
keyboards9
Keyboards
  • Special Keys - Keys above arrow keys to the right of keyboard.
pointing devices
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.
pointing devices11
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.
types of mouse devices
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.
types of mouse devices13
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
types of mouse devices14
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.
types of mouse devices15
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.

types of mouse devices16
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.
scanning devices
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.
optical scanners
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.
optical scanners19
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.
bar code reader
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.
character and mark recognition device features
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.
image capturing devices
IMAGE CAPTURING DEVICES
  • create or capture original images
  • include digital cameras and digital video cameras
  • Digital Camera Features
    • Images are recorded in the camera’s 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.
image capturing devices23
IMAGE CAPTURING DEVICES
  • Digital Video Camera Features
    • Record motion digitally on a disk or in the camera’s 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.
digitizing devices
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.
graphic tablets
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.
digital notebook features
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.
audio input devices
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.
voice recognition system features
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 user’s voice.
  • Training is done by matching the user’s 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.
voice recognition system features29
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.
discrete speech recognition features
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 they’re, their, and there. Captured dictation must be reviewed to make corrections.
  • File can be retrieved, edited, and printed using a standard word-processing program.
continuous speech recognition features
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 they’re.
  • 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.
output
Output
  • Output is people-readable information.
  • Input (data) is processed inside the computer’s 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.
ouput
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.
monitors
MONITORS
  • Some monitors are used on the desktop; others are portable.
  • Two important characteristics of a monitor are size and clarity.
monitor size
Monitor Size
  • A monitor’s 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.
monitor clarity
Monitor Clarity
  • A monitor’s 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.
monitor standards
Monitor Standards
  • Standards have been created to indicate a monitor’s 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.
monitor standards38
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.
desktop monitor the cathode ray tube crt
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.
flat panel monitors
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.
flat panel monitors41
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.
other monitors
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 today’s traditional books.
other monitors43
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.
other monitors44
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.
printers
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.
printers46
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)
printers47
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.
other types of printers
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.
printers49
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
audio output devices
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.
audio output devices51
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
combination input and output devices
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.
combination input and output devices53
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.
combination input and output devices54
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.
combination input and output devices55
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.
combination input and output devices56
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.
combination input and output devices57
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.
combination input and output devices58
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.
combination input and output devices59
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.