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Chapter 5: Input

| Overview | Expand Your Knowledge | Checkpoint | Practice Test |


 

Overview

  1. Describe the two types of input
  2. List the characteristics of a keyboard
  3. Identify various types of keyboards
  4. Identify various types of pointing devices
  5. Explain how a mouse works
  6. Describe different mouse types
  7. Explain how voice recognition works
  1. Understand how to input data into a handheld computer
  2. Identify the uses of a digital camera
  3. Describe the various techniques used for video input
  4. Describe the uses of PC video cameras and web cams
  5. Explain how scanners and other reading devices work
  6. Identify alternative input devices for physically challenged users

In this chapter, you learn what is input and what are input devices. The keyboard is presented and different keyboard types are described. You are introduced to various pointing devices, such as the mouse, trackball, touchpad, pointing stick, joystick, touchscreen, and pen input. Scanners and reading devices, including optical scanners, optical readers, magnetic ink character recognition readers, and data collection devices are explained. You learn about digital cameras, audio input, speech recognition, video input, and videoconferencing. Finally, input devices for physically challenged users are explored.

    Describe the two types of input

Input is any data or instructions entered into the memory of a computer. Two types of input are data and instructions. Data is a collection of unorganized items that can include words, numbers, pictures, sounds, and video. A computer processes data into information, which is organized, meaningful, and useful. Instructions can be in the form of programs, commands, or user responses. A program is a series of instructions that tells a computer how to perform the tasks necessary to process data into information. A command is an instruction given to a computer program. A user response is an instruction you issue to the computer by responding to a question posed by a computer program. Any hardware component that allows you to enter data, programs, commands, and user responses into a computer is an input device.

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    List the characteristics of a keyboard

The keyboard is an input device that contains keys you press to enter data into a computer. Desktop computer keyboards usually have from 101 to 105 keys, while keyboards for smaller computers contain fewer keys. All keyboards have a typing area used to type letters of the alphabet, numbers, punctuation marks, and other basic characters. Many desktop computer keyboards also have a numeric keypad designed to make it easier to enter numbers, function keys programmed to issue commands and accomplish certain tasks, arrow keys used to move the insertion point (a symbol on the screen that indicates where the next typed character will display), and toggle keys that can be switched between two different states.

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    Identify various types of keyboards

A standard computer keyboard sometimes is called a QWERTY keyboard because of the layout of its typing area. An enhanced keyboard has 12 function keys along the top row, 2 ctrl keys, 2 alt keys, and a set of arrow and additional keys between the typing area and the numeric keypad. Cordless keyboards transmit data via infrared light waves. Keyboards for notebook and handheld computers usually have smaller and fewer keys than desktop computers. A portable keyboard is a full-sized keyboard you can attach to and remove from a handheld computer. Some manufacturers have designed ergonomic keyboards to reduce the chance of workplace injuries. The goal of ergonomics is to incorporate comfort, efficiency, and safety into the design of workplace items.

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    Identify various types of pointing devices

In a graphical user interface, the pointer is a small symbol on the screen. A pointing device is an input device that allows you to control the pointer. Common pointing devices include the mouse, trackball, touchpad, pointing stick, joystick, touch screen, light pen, and a stylus. A mouse is a pointing device, designed to fit comfortably under the palm of your hand, that is moved across a flat surface. A trackball is a stationary pointing device with a ball mechanism on its top. A touchpad is a flat, rectangular pointing device that is sensitive to pressure and motion. A pointing-stick is a pressure-sensitive pointing device shaped like a pencil eraser that is positioned between keys on the keyboard. A joystick is a vertical lever mounted on a base. A light pen is a handheld device that contains a light source or can detect light. A touch screen is a touch-sensitive display on the screen. A stylus looks like a ballpoint pen but uses pressure, instead of ink, to write text and draw lines. An electronic pen can be used on a graphics tablet, which consists of a flat, rectangular, electronic plastic board used to input graphical data.

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    Explain how a mouse works

As you move a mouse across a flat surface, the movement is translated into signals that are sent to the computer, and the pointer on the screen also moves. When you move the mouse to the right, the pointer moves to the right on the screen. For Windows users, the top of a mouse has at least two buttons and sometimes also a wheel. Generally, you use a mouse to move the pointer on the screen to an object and then press a button, or click, to perform a certain action on that object. Other operations you can perform using a mouse include right-click, double-click, drag, right-drag, rotate wheel, and press wheel button.

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    Describe different mouse types

A mechanical mouse has a rubber or metal ball on its underside. When the ball rolls in a certain direction, electronic circuits in the mouse translate the movement into signals that are sent to the computer. For better traction, you should place a mechanical mouse on a mouse pad. An optical mouse has no moving parts; instead it uses devices that emit and sense light to detect the mouse’s movement. An optical mouse can be used on nearly all surfaces, is more precise than a mechanical mouse, and does not require cleaning. A cordless mouse, or wireless mouse, is a battery powered device that transmits data using wireless technology, such as radio waves or infrared light waves. A cordless mouse uses technology very similar to that of a cordless keyboard.

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    Explain how voice recognition works

Voice input is the process of entering data by speaking into a microphone that is attached to the sound card on a computer. Voice recognition is the computer’s capability of distinguishing spoken words. The first voice recognition programs were speaker dependent. With speaker-dependent software, the computer makes a profile of your voice, which means you have to train the computer to recognize your voice. Today, most voice recognition programs use speaker-independent software, which has a built-in set of word patterns and does not have to be trained to recognize your voice. Some voice recognition software requires discrete speech, meaning that you have to speak slowly and separate each word with a short pause. Most voice recognition products, however, support continuous speech, allowing you to speak in a flowing conversational tone.

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    Understand how to input data into a handheld computer

To satisfy the input needs of many different types of users, handheld computers provide many different ways to input data. A handheld computer typically includes a basic stylus. With the stylus, you can enter data using an on-screen keyboard or using handwriting recognition software that translates handwritten letters and characters into symbols the computer understands. Other input alternatives available with some handheld computers include attaching a full-sized keyboard, transferring data from a desktop computer, using voice input, and attaching a digital camera.

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    Identify the uses of a digital camera

A digital camera is used to take pictures and store the photographed images digitally instead of on traditional film. Pictures are stored on a storage medium, such as a floppy disk, SuperDisk, Clik! disk, PC Card, compact flash card, memory stick, mini-CD, or microdrive. Many digital cameras allow you to review and edit the images while they are in the camera. You also can download, or transfer a copy of, the stored image to a computer. Once on a computer, the pictures can be edited with photo-editing software, printed, faxed, sent via electronic mail, included in another document, or posted to a Web site. There are three basic types of digital cameras. A studio camera is a stationary digital camera used for professional studio work. A field camera is a portable camera, often used by photojournalists, that has many lenses and other attachments. A point-and-shoot camera is more affordable and lightweight and provides acceptable quality photographic images for the home or small business user.

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    Describe the various techniques used for video input

Video input, or video capture, is the process of entering a full-motion recording into a computer and storing the video on a storage medium. Many video devices use analog video signals. To input video from these devices, the device is plugged into a video capture card, an expansion card that converts the analog signal into a digital signal the computer can understand. A digital video (DV) camera is a new generation of video camera that records video as digital signals, instead of using analog signals, and therefore does not require a video capture card. Video files can demand huge amounts of storage space. Video compression reduces the size of video files by recognizing that only a small portion of an image changes from frame to frame. Instead of storing every frame in its entirety, a video compression program might store an initial frame and then store only the changes from one frame to the next. A video decoder is a card that decompresses video. A video digitizer can be used to capture an individual frame from a video and save the still picture in a file.

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    Describe the uses of PC video cameras and Web cams

A PC camera is a DV camera that allows home users to record, edit, capture video and still images, and make video telephone calls on the Internet. During a video telephone call, both parties can see each other as they talk. Although usually placed on top of the monitor and attached to a computer’s USB port, some PC cameras are portable and can be used anywhere. A Web cam is a video camera whose output displays on a Web page. Some Web sites have live Web cams that display still pictures and update the displayed images at specified time intervals.

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    Explain how scanners and other reading devices work

Scanners and optical readers can capture data from a source document, which is the original form of the data. A scanner is a light-sensing input device that reads printed text and graphics and then translates the results into a form a computer can use. One of the more popular scanners is a flatbed scanner, which works similarly to a copy machine except it creates a file of the document in memory instead of a paper copy. Many scanners include OCR software, which converts a scanned image into a text file that can be edited. An optical reader uses a light source to read characters, marks, and codes and converts them into digital data that a computer can process. Three types of optical readers are optical character recognition, optical mark recognition, and bar code scanner. Optical character recognition (OCR) is a technology that reads typewritten, computer printed, or handwritten characters from ordinary documents and translates the images into a form that the computer can understand. Optical mark recognition (OMR) devices read hand-drawn marks such as circles or rectangles. A bar code scanner uses laser beams to read bar codes, which are identification codes consisting of vertical lines and spaces of different widths. Another type of reader, called a magnetic-ink character recognition (MICR) reader, reads text printed with magnetized ink and is used almost exclusively by the banking industry.

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    Identify alternative input devices for physically challenged users

Whether at work or at home, it may be necessary to obtain input devices that address physical limitations. Voice recognition is ideal for blind or visually impaired users, but several other input devices also are available. A keyguard, which is placed over the keyboard, allows people with limited hand mobility to rest their hands on the keyboard and guides a finger or pointing device so that only one key is pressed. Keyboards with larger keys and on-screen keyboards on which keys are pressed using a pointing device also can help. Pointing devices such as small trackballs controlled with a thumb or one finger and head-mounted pointers also are available for users with motor disabilities. Two new developments are gesture recognition and computerized implant devices. With gesture recognition the computer will be able to detect human motions. Computerized devices implanted in the brain will allow paralyzed individuals to transmit signals to the computer.

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Expand Your Knowledge
  1. Input
  2. The keyboard
  3. Keyboard Types
  4. Pointing devices
  5. Using a mouse
  6. Mouse types
  7. Voice recognition
  1. Handheld computer input
  2. Digital cameras
  3. Video input
  4. PC video cameras and web cams
  5. Scanners and reading devices
  6. Input devices for physically challenged users

Here you will find additional information that will expand and enhance your knowledge beyond that contained in your textbook. Compare this information to what may be provided in a traditional classroom by your instructor or peers.

    Input

Of the four operations in the information processing cycle – input, process, output, and storage – input is the operation to which computer users are most closely linked and on which each subsequent action depends.

Typed commands use keywords – specific words, phrases, or codes that a program recognizes as instructions. Keywords are an essential element of command-driven programs, such as DOS. The problem with keywords is that: 

This makes command-driven programs difficult to use. Menu-driven programs and graphical user interfaces eliminate the problems of having to memorize and correctly type keywords.

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    The Keyboard

Data entered through the keyboard averages about one error for every 300 characters, while data entered more directly, such as with a scanning device, averages only one error for every 3 million characters. Nevertheless, the keyboard continues to be the most popular input device. Some special keys – alt, ctrl, and shift – almost always are used in combination with other keys. Desktop computer keyboards generally have two ways to enter numbers – the numeric keypad and the row of number keys above the alphabetic keys. Think of situations in which both would be used. The numeric keypad also contains arrow keys, but these keys are active only when the keypad is turned off. Although the purpose of function keys varies, some developers have tried to standardize certain keys (such as using f1 to access online Help). In addition to the num  lock key, other toggle keys are the caps lock key and the insert key. Unlike the caps lock key on a typewriter, the caps lock key on a computer keyboard cannot be used to print the special characters on the keys in the number row.

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    Keyboard Types

Keyboards are used primarily to enter alphanumeric data. Not surprisingly, keyboards for oriental languages are significantly more complex than the keyboard shown in Figure 5-3. The QWERTY keyboard was devised in 1867 by Christopher Sholes, inventor of the first practical commercial typewriter. Ironically, Sholes’ intent when designing the keyboard was to slow typists down; if typists worked too quickly, keys had a tendency to jam. Many feel the QWERTY keyboard is an anachronism, and its continued use is counterproductive. A more recent design, called the Dvorak keyboard (named for August Dvorak, American educator, 1895-1975) places the most frequently used keys in the middle of the typing area. Studies have shown that trained typists using the Dvorak keyboard are up to 20 times faster than trained QWERTY typists. Despite this, the Dvorak keyboard rarely is used. Repetitive stress injury (RSI) afflicts more than 1.8 million people in the United States. A debilitating repetitive stress injury that plagues some keyboard users is carpal tunnel syndrome. This painful wrist injury affects sufferers not only when working at the keyboard, but when performing other tasks as well. The wrist rest on the keyboard in Figure 5-3 is designed to reduce wrist strain.

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    Pointing Devices

The original mouse was a one-button, cigarette-pack shaped device invented by Doug Engelbart in 1964. Today, many software manufacturers have made the mouse (or a related pointing device) an essential part of their applications. When the screen is cluttered or pointer targets are small, however, some experienced users still prefer keyboard commands if they are offered.

Some people feel that a touchpad is the most difficult pointing device to use. To satisfy divergent preferences, several laptop computers include both a pointing stick and a touchpad.

Although trackballs, touchpads, and pointing stick devices require less space than a mouse (making them popular for portable computers), most people find them harder to use. Because of this a smaller mouse, called Mouse2Go, has been developed for use on a small pad that clips to the side of a portable computer.

Joystick concepts evolved from actual use in jet fighter airplanes, where joysticks allowed pilots to control an aircraft’s movement quickly and precisely.

Although touch screen users touch a symbol on the screen, it is the location where the touch occurred, not the symbol contacted, that is important. Because they are so user-friendly, even people unfamiliar with computers are comfortable with touch screens.

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    Using a Mouse

The major advantage of a mouse is that it is easy to use. The disadvantages are twofold: first, the mouse requires additional desk space, making it difficult to use in cramped locations; and second, mouse use demands that a hand be taken from the keyboard (unlike a pointing stick, which can be used without removing a hand from the keyboard). When a mouse has two buttons, one is the primary mouse button and the other is the secondary mouse button. To reverse the functions of these buttons or change other mouse options in Windows 98, point to Settings on the Start menu, click Control Panel on the Settings submenu, then double-click the Mouse icon in the Control Panel window. In the Mouse Properties dialog box that displays, the Basics tab allows you to change pointer speed, button selection, and double-click speed.

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    Mouse Types

Since its introduction in 1965, the mouse has gone through several transformations. Microsoft’s “green eye” mouse, an early mouse with two buttons, was released in 1983 and now is a collector’s item. Other interesting mouse variations include Spectrum’s RingMouse (which uses infrared to point), Interlink’s wireless mouse (often used for presentations), and Interlink’s DuraPoint PC mouse (an incredibly durable mouse that gained the Pentagon’s interest). A new mouse from Immersion Corporation provides tactile sensations, with an internal motor that allows users to “feel” the desktop. The mouse – which senses cursor position, identifies screen objects, and sends pulses to a motor beneath the surface of the mouse – lets users feel icons, sense Web links, or bump through menu commands.

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    Voice Recognition

Some experts believe voice input eventually will be the most common way to operate a computer. Speech recognition is particularly welcome to people with certain disabilities. Although speech recognition continues to improve, developers admit that advertisements touting high accuracy rates generally assume a standard vocabulary. Specialized words, regional accents, and local dialects reduce accuracy. Even a 95 percent accuracy rate, meaning that on average 1 out of every 20 words is wrong, may not inspire confidence. (Imagine if, in conversation, every 20th word spoken was misinterpreted.) Nevertheless, voice recognition systems are gaining in popularity.

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    Handheld Computer Input

Instead of using a keyboard, with most handheld computers you write or make selections on the computer screen with a stylus. Although a handheld computer typically includes a basic stylus, you can buy more elaborate models that have a ballpoint pen at one end and a stylus at the other.

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    Digital Cameras

Some manufacturers use dots per inch to represent a digital camera’s resolution, or the sharpness and clarity of the image it produces. Dots per inch (DPI) is the number of pixels in an inch of screen display. A pixel is a single point in an electronic image. Digital cameras for the consumer range from 640 x 480 dpi to 1,792 to 1,200 dpi. The actual photographed resolution is called the optical resolution. Some manufacturers also state enhanced resolution, which uses a special formula to add pixels between those generated by the optical resolution. With the price of digital cameras decreasing, will the era of film-based cameras soon come to an end? Why or why not?

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    Video Input

Video input is used in a variety of ways, from developing training films to creating presentation enhancements. Video input also has been used in the workplace to record (sometimes secretly) office or assembly-line workers in an effort to find possible quality or efficiency problems. Do you think this secret recording is ethical? Why or why not?

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    PC Video Cameras and Web Cams

Estimates suggest that currently more than 9,000 Web sites use Web cams. Web cams are used to put everything from college dorm rooms to taxi cabs on the Web. The first personal Web page to use a Web cam was the JenniCam, which showed the daily life of a college co-ed. The site started in 1996 as a project for a computer class and still receives more than 4.5 million hits a day. Web cams also have more practical uses. Recently, some day-care centers have installed Web cams so parents can use the center’s Web page to check on their children. This use of Web cams, however, has not been without controversy. Due to the usually slower speeds of Web cam videos, it can be difficult for parents to tell the difference between a day care worker’s loving pat on the head and a rap on the noggin.

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    Scanners and Reading Devices

In general, scanners and reading devices increase input accuracy and efficiency by reducing the role of the weak link in the input process – the human operator. Optical readers are highly specialized. Devices that read one set of codes, marks, or characters may not be able to read another.

An optical mark reader identifies the position, not the shape, of a mark. You may be familiar with optical marks from tests in which you use a pencil to fill in ovals or rectangles that represent the answers.

Bar codes minimize input errors, keep inventories up to date, help to track sales trends, and eliminate the need to price individual items. The identifying numbers on a UPC code can be entered if the scanner fails. This number is not the item’s cost – prices are obtained from a database when the item is scanned. Some consumer groups, however, claim price databases not always are accurate, and that the absence of individual item pricing makes comparing costs difficult.

The MICR font, adopted by the American Banking Association in the 1950s, is standard throughout the banking industry. The special shapes of MICR characters make them easier for a machine to read. MICR readers can interpret magnetic characters even if someone has written over them. If the magnetic ink on a check is damaged, however, the data must be typed into the system. The importance of MICR readers to the banking industry is staggering – half of the U.S. population would be needed to process checks if it were done manually.

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    Input Devices for Physically Challenged Users

Some input aids for physically challenged people are relatively simple (such as keyguards), while others are much more sophisticated (such as head-mounted pointers). Chin-operated joysticks also are available. Another input system, called Eyegaze or ERICA (Eyegaze Response Interface Computer Aid), was developed by Thomas Hutchinson of the University of Virginia, who as a boy was paralyzed temporarily by an accident. With a camera mounted on the computer and directed at a user’s eye, the Eyegaze system can determine to within a ¼ inch where on the screen a user is looking. By staring at the spot for about ¼ second, a user can activate a choice. Adaptive technology has given many people their best opportunity to communicate, work, and play. As a six-year-old victim of cerebral palsy said in her first message, “It’s about time.”

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