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OBJECTIVES:
After completing this chapter, you will be able to:
1. List characteristics of a keyboard.
2. Summarize how these pointing devices work: trackball, touch pad, pointing stick, joystick, wheel, light pen, touch screen, stylus, and digital pen.
3. Describe other types of input, including voice input; input devices for PDAs, smart phones, and Tablet PCs; digital cameras; video input; scanners and reading devices; terminals; and biometric input.
4. Describe the characteristics of LCD monitors, LCD screens, and CRT monitors.
5. Summarize the various types of printers.
6. Explain the characteristics of speakers and headsets, fax machines and fax modems, multifunction peripherals, and data projectors.
7. Identify input and output options for physically challenged users.
CONTENTS:
WHAT IS INPUT?
KEYBOARD AND POINTING
DEVICES
The Keyboard
Mouse
Trackball
Touchpad
Pointing Stick
Joystick and Wheel
Light Pen
Touch Screen
Pen Input
OTHER TYPES OF INPUT
Voice Input
Input for PDAs, Smart Phones, and Tablet PCs
Digital Cameras
Video Input
Scanners and Reading Devices
Terminals
Biometric Input
WHAT IS OUTPUT?
DISPLAY DEVICES
LCD Monitors and Screens
Plasma Monitors
CRT Monitors
PRINTERS
Producing Printed Output
Nonimpact Printers
Ink-Jet Printers
Photo Printers
Laser Printers
Thermal Printers
Mobile Printers
Plotters and Large-Format Printers
Impact Printers
OTHER OUTPUT DEVICES
Speakers and Headsets
Fax Machines and Fax Modems
Multifunction Peripherals
Data Projectors
PUTTING IT ALL TOGETHER
INPUT AND OUTPUT PHYSICALLY CHAI
CHAPTER SUMMARY
COMPANIES ON THE CUTTING EDGE
Logitech
Hewlett-Packard
TECHNOLOGY TRAILBLAZERS
Douglas Engelbart
Donna Dubinsky
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Input is any data and instructions entered into the memory of a computer. As shown in Figure 5-1, people have a variety of options for entering input into a computer. L. An input device is any hardware component that allows users to enter data and instructions into a computer. The following pages discuss a variety of input devices.
FIGURE 5-1 Users can enter data and instructions into a computer in a variety of ways.
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KEYBOARD AND POINTING DEVICES
Two of the more widely used input devices are the keyboard and the mouse. Most computers include a keyboard or keyboarding capabilities.
The mouse is a pointing device because it allows a user to control a pointer on the screen. In a graphical user interface, a pointer is a small symbol on the screen whose location and shape change as a user moves a pointing device. A pointing device can select text, graphics, and other objects; and click buttons, icons, links, and menu commands.
The following pages discuss the keyboard and a variety of pointing devices.
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Many people use a keyboard as one of their input devices. A keyboard is an input device that contains keys users press to enter data and instructions into a computer (Figure 5-2).
All computer keyboards have a typing area that includes the letters of the alphabet, numbers, punctuation marks, and other basic keys. Many desktop computer keyboards also have a numeric keypad on the right side of the keyboard.
Most of today’s desktop computer keyboards are enhanced keyboards. An enhanced keyboard has twelve function keys along the top and a set of arrow and additional keys between the typing area and the numeric keypad (Figure 5-2). Function keys are special keys programmed to issue commands to a computer. Many keyboards also have a WINDOWS key(s) and an APPLICATION key. When pressed, the WINDOWS key displays the Start menu, and the APPLICATION key displays an item’s shortcut menu.
Newer keyboards also include media control buttons that allow you to access the computer’s CD/DVD drive and adjust speaker volume, and Internet controls that allow you to open an e-mail program, start a Web browser, and search the Internet.
Desktop computer keyboards often attach via a cable to a serial port, a keyboard port, or a USB port on the system unit. Some keyboards, however, do not use wires at all. A wireless keyboard, or cordless keyboard, is a battery-powered device that transmits data using wireless technology, such as radio waves or infrared light waves. Wireless keyboards often communicate with a receiver attached to a port on the system unit.
On notebook and some handheld computers, PDAs, and smart phones, the keyboard is built in the top of the system unit. To fit in these smaller computers, the keyboards usually are smaller and have fewer keys.
Regardless of size, many keyboards have a rectangular shape with the keys aligned in straight, horizontal rows. Users who spend a lot of time typing on these keyboards sometimes experience repetitive strain injuries (RSI) of their wrists and hands. For this reason, some manufacturers offer ergonomic keyboards. An ergonomic keyboard has a design that reduces the chance of wrist and hand injuries.
The goal of ergonomics is to incorporate comfort, efficiency, and safety in the design of the workplace. Employees can be injured or develop disorders of the muscles, nerves, tendons, ligaments, and joints from working in an area that is not ergonomically designed.
Do not rest your wrist on the edge of a desk; use a wrist rest. Keep your forearm and wrist level so your wrist does not bend. Do hand exercises every 15 minutes. Keep your shoulders, arms, hands, and wrists relaxed while you work. Maintain good posture. Keep feet flat on the floor, with one foot slightly in front of the other. For more information, visit scsite.com/ dcf2e/ch5/faq and then click Repetitive Strain Injuries.
FIGURE 5-2: On a desktop computer keyboard, you type using keys in the typing area and on the numeric keypad.
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For more information, visit scsite.com/dcf2e/ ch5/weblink and then click Mouse.
A mouse is a pointing device that fits comfortably under the palm of your hand. With a mouse, users control the movement of the pointer. As you move a mouse, the pointer on the screen also moves. Generally, you use the mouse to move the pointer on the screen to an object such as a button, a menu, an icon, a link, or text. Then, you press a mouse button to perform a certain action associated with that object.
A mechanical mouse has a rubber or metal ball on its underside (Figure 5-3a). When the ball rolls in a certain direction, electronic circuits in the mouse translate the movement of the mouse into signals the computer can process. You should place a mechanical mouse on a mouse pad. A mouse pad is a rectangular rubber or foam pad that provides better traction than the top of a desk.
An optical mouse, by contrast, has no moving mechanical parts inside. Instead, an optical mouse uses devices that emit and sense light to detect the mouse’s movement. Some use optical sensors (Figure 5-3b); others use laser (Figure 5-3c). An optical mouse is more precise than a mechanical mouse and does not require cleaning as does a mechanical mouse, but it also is more expensive.
A mouse connects to a computer in several ways. Many types connect with a cable that attaches to a serial port, mouse port, or USB port on the system unit. A wireless mouse, or cordless mouse, is a battery-powered device that transmits data using wireless technology, such as radio waves or infrared light waves. Read At Issue 5-1 for a related discussion.
FIGURE 5-3 A mechanical mouse contains a small ball. An optical mouse uses an optical sensor or a laser. Many also include buttons to push with your thumb that enable forward and backward navigation through Web pages and a wheel you roll to scroll and zoom.
When you consider the causes of workplace injuries, you might not put clicking a mouse in the same category with lifting a bag of concrete, but perhaps you should. According to the chairman of a National Academy of Sciences panel that investigated workplace injuries, every year one million Americans lose workdays because of repetitive strain injuries. Repetitive strain injuries are caused when muscle groups perform the same actions over and over again. Once, repetitive strain injuries were common among factory workers who performed the same tasks on an assembly line for hours a day. Today, these injuries, which often result from prolonged use of a computer mouse and keyboard, are the largest job-related injury and illness problem in the United States. OSHA proposed standards whereby employers would have to establish pro grams to prevent workplace injuries with respect to computer use. Yet, congress rejected the standards, accepting the argument that the cost to employers would be prohibitive and unfair, because no proof exists that the injuries are caused exclusively by office work. Should the government establish laws regarding computer use? Why or why not? Who is responsible for this type of workplace injury? Why?
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Similar to a mechanical mouse that has a ball on the bottom, a trackball is a stationary pointing device with a ball on its top or side (Figure 5-4).
To move the pointer using a trackball, you rotate the ball with your thumb, fingers, or the palm of your hand. In addition to the ball, a trackball usually has one or more buttons that work just like mouse buttons.
A touchpad is a small, flat, rectangular pointing device that is sensitive to pressure and motion (Figure 5-5). To move the pointer using a touchpad, slide your fingertip across the surface of the pad. Some touchpads have one or more buttons around the edge of the pad that work like mouse buttons. On most touchpads, you also can tap the pad’s surface to imitate mouse operations such as clicking. Touchpads are found most often on notebook computers.
A pointing stick is a pressure-sensitive pointing device shaped like a pencil eraser that is positioned between keys on a keyboard (Figure 5-6). To move the pointer using a pointing stick, you push the pointing stick with a finger. The pointer on the screen moves in the direction you push the pointing stick. By pressing buttons below the keyboard, users can click and per form other mouse-type operations with a pointing stick.
IBM developed the pointing stick for its notebook computers.
FIGURE 5.4 A trackball is like an upside-down mouse.
FIGURE 5.5 Most notebook computers have a touchpad that allows users to control the movement of the pointer.
FIGURE 5.6 Some notebook computers include a pointing stick to allow a user to control the movement of the pointer.
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Users running game software or flight and driving simulation software often use a joystick or wheel as a pointing device (Figure 5-7). A joystick is a vertical lever mounted on a base. You move the lever in different directions to control the actions of the simulated vehicle or player. The lever usually includes buttons called triggers that you press to activate certain events.
A wheel is a steering-wheel-type input device. Users turn the wheel to simulate driving a car, truck, or other vehicle. Most wheels also include foot pedals for braking and acceleration actions.
A light pen is a handheld input device that can detect the presence of light. Some light pens require a specially designed monitor, while others work with a standard monitor (Figure 5-8). To select objects on the screen, a user presses the light pen against the surface of the screen or points the light pen at the screen and then presses a button on the pen.
A touch screen is a touch-sensitive display device. Users can interact with these devices by touching areas of the screen. Because touch screens require a lot of arm movements, you do not enter large amounts of data using a touch screen. Instead, users touch words, pictures, numbers, letters, or locations identified on the screen. Kiosks, which are freestanding computers, often have touch screens (Figure 5-9).
FIGURE 5-7 Joysticks and wheels help a user control the actions of players and vehicles in game and simulation software.
FIGURE 5.8 To use a light pen, you press the pen against the screen or press a button on the pen while pointing the pen toward an object on the screen.
FIGURE 5-9 A voter uses a kiosk touch screen to cast ballots in an election.
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Mobile users often enter data and instructions with a pen-type device. With pen input, users write, draw, and tap on a flat surface to enter input. The surface may be a monitor, a screen, or a special type of paper. Two devices used for pen input are the stylus and digital pen. A stylus is a small metal or plastic device that looks like a tiny ink pen but uses pressure instead of ink. A digital pen, which is slightly larger than a stylus, is available in two forms: some are pressure-sensitive; others have built-in digital cameras.
Some mobile computers and nearly all mobile devices have touch screens. Instead of using a finger to enter data and instructions, most of these devices include a pressure-sensitive digital pen or stylus. You write, draw, or make selections on the computer screen by touching the screen with the pen or stylus. For example, Tablet PCs use a pressure-sensitive digital pen (Figure 5-10) and PDAs use a stylus. Pressure-sensitive digital pens, often simply called pens, typically provide more functionality than a stylus, featuring electronic erasers and programmable buttons.
Pen input is possible on computers without touch screens by attaching a graphics tablet to the computer. A graphics tablet is a flat, rectangular, electronic, plastic board. Architects, mapmakers, designers, artists, and home users create drawings and sketches by using a pressure-sensitive pen on a graphics tablet (Figure 5-11).
Digital pens that have built-in digital cameras work differently from pressure-sensitive digital pens. These pens look very much like a ballpoint pen and typically do not contain any additional buttons. As you write or draw on special digital paper with the pen, it captures every handwritten mark and then stores the images in the pen’s memory. You then can transfer the images from the pen to a computer (Figure 5-12) or mobile device, such as a smart phone.
FIGURE 5-10 Tablet PCs use a pressure-sensitive pen.
FIGURE 5-1 1 Artist using a pen.
FIGURE 5-12 Some digital pens have built-in digital cameras that store handwritten marks and allow you to transfer your handwriting to a computer.
For more information, visit scsite.com/dcf2e/ ch5/weblink and then click Pen Input.
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Test your knowledge of pages 166 through 172 in Quiz Yourself 5-1.
Instructions: Find the true statement below. Then, rewrite the remaining false statements so they are true.
1. A keyboard is an output device that contains keys users press to enter data and instructions into a computer.
2. A trackball is a small, flat, rectangular pointing device commonly found on notebook computers.
3. Input is any data and instructions entered into the memory of a computer.
4. An optical mouse has moving mechanical parts inside.
5. PDAs use a pressure-sensitive digital pen, and Tablet PC5 use a stylus.
Quiz Yourself Online: To further check your knowledge of the keyboard, the mouse, and other pointing devices, visit scsite.com/dcf2e/ch5/quiz and then click Objectives 1 — 2.
In addition to the keyboard, mouse, and pointing devices just discussed, users have a variety of other options available to enter data and instructions into a computer. These include voice input; input for PDAs, smart phones, and Tablet PCs; digital cameras; video input; scanners and reading devices; terminals; and biometric input. Read Looking Ahead 5-1 for a look at the next generation of input devices.
Voice input is the process of entering input by speaking into a microphone. Voice recognition, also called speech recognition, is the computer’s capability of distinguishing spoken words. Voice recognition programs recognize a vocabulary of preprogrammed words. The vocabulary of voice recognition programs can range from two words to millions of words. Some business software, such as word processing and spreadsheet, includes voice recognition as part of the program. For example, users can dictate memos and letters into a word processing pro gram instead of typing them.
Frodo, the hero in the Lord of the Rings trilogy, wears a durable, inconspicuous tunic that saves his life. You, too, may one day wear a garment that saves your life by detecting health problems and summoning emergency help. Researchers in Germany have developed undergarments with sensors that monitor heartbeats and then alert medical experts when an abnormal heart rhythm is detected.
While this clothing is practical, other researchers are creating the newest fashions and accessories ouffitted with computers. For example, a cellular telephone could connect wirelessly to a calorie counter monitor on your wrist and then order food when it detects you are hungry. Other wearable computers can change color depending upon weather conditions, deliver e-mail messages, and improve a golf swing. For more information, visit scsite.com/dcf2e/ch5/looking and then click Wearable Computers.
FIGURE 5-13 An electronic piano keyboard is an external MIDI device that allows users to record music, which can be stored in the computer.
AUDIO INPUT
Voice input is part of a larger category of input called audio input. Audio input is the process of entering any sound into the computer such as speech, music, and sound effects. To enter high-quality sound into a personal computer, the computer must have a sound card. Users enter sound into a computer via devices such as micro phones, tape players, CD/DVD players, or radios, each of which plugs in a port on the sound card.
Some users also enter music and other sound effects using external MIDI devices such as an electronic piano keyboard (Figure 5-13). MIDI (musical instrument digital interface) is the electronic music industry’s standard that defines how digital musical devices represent sounds electronically. Software that conforms to the MIDI standard allows users to compose and edit music and many other sounds.
For more information, visit scsite.com/dcf2e/ ch5/weblink and then click Voice Input.
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Mobile devices, such as the PDA and smart phone, and mobile computers, such as the Tablet PC, offer convenience for the mobile user. A variety of alternatives for entering data and instructions is available for these devices and computers.
A user enters data and instructions into a PDA in many ways (Figure 5-14). PDAs ship with a basic stylus, which is the primary input device. With the stylus, you enter data in two ways: using an on-screen keyboard or using handwriting recognition software. With a specialized pen and data reader, you also can transfer notes as you write them on a pad of paper.
For users who prefer typing to handwriting, some PDAs have a built-in mini keyboard. For PDAs without a keyboard, users can purchase a keyboard that snaps on the bottom of the device. Other users type on a desktop computer or notebook computer keyboard and transfer the data to the PDA. To take photographs and view them on a PDA, simply attach a digital camera directly to the PDA.
FIGURE 5-14 Users input data into a FDA using a variety of techniques.
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SMART PHONES
Voice is the traditional method of input for smart phones. That is, a user speaks into the phone. Today, however, text messaging, instant messaging, and picture messaging have become popular means of entering data and instructions into a smart phone. With text messaging, you type and send a short message to another smart phone by pressing buttons on the telephone’s keypad. Some wireless Internet service providers (WISPs) partner with TM (instant messaging) services so you can use your smart phone to communicate via text with other smart phone or computer users with the same TM service. Users can send graphics, pictures, video clips, and sound files, as well as short text messages with picture messaging, to another smart phone with a compatible picture messaging service. Most smart phones include PDA capabilities. Thus, input devices used with PDAs typically also are available for smart phones.
TABLET PCs
The primary input device for a Tablet PC is a pressure-sensitive digital pen, which allows users to write on the device’s screen. Both the slate and convertible designs of Tablet PC provide a means for keyboard input. To access peripherals at their home or office, users can slide their Tablet PC in a docking station. A docking station, which is an external device that attaches to a mobile computer, contains a power connection and provides connections to peripherals (Figure 5-15). The design of docking stations varies depending on the type of mobile computer or device to which they attach.
A digital camera allows users to take pictures and store the photographed images digitally, instead of on traditional film (Figure 5-16). Some digital cameras use internal flash memory to store images. Others store images on mobile storage media, including a flash memory card, memory stick, and mini-CD/DVD.
Digital cameras typically allow users to review, and sometimes edit, images while they are in the camera. Some digital cameras can connect to or communicate wirelessly with a printer or television, allowing users to print or view images directly from the camera.
Often users prefer to download, or transfer a copy of, the images from the digital camera to the computer’s hard disk, where the images are available for editing with photo editing software, printing, faxing, sending via e-mail, including in another document, or posting to a Web site or photo community for everyone to see.
A digital camera often features flash, zoom, automatic focus, and special effects. Some allow users to record short audio narrations for photographed images. Others even record short video clips in addition to still images.
One factor that affects the quality of a digital camera is its resolution. Resolution is the number of horizontal and vertical pixels in a display device. A digital camera’s resolution is defined in pixels. A pixel (short for picture element) is the smallest element in an electronic image. The greater the number of pixels the ca...
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