CHAPTER

1. 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).

6. 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.

7. 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.

8. 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.

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

10. 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.

11. 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.

12. 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.

13. 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

14. 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.

15. 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.

16. 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.

17. 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.

18. 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.

19. 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.

20. 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.

21. 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.

22. 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.

23. 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.

24. 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.

25. 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.

26. 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.

27. 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.

28. 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.

29. 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.

30. 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.

31. 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.

32. 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.

33. 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.

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

35. 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.

36. 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.

37. 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.

38. 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.

39. 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.

40. 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.

41. 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.

42. 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.

43. 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.

44. 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.

45. 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.

46. 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)

47. 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.

48. 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.

49. 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

50. 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.