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Input and Output: The User Connection

Input and Output: The User Connection. Chapter 5. Objectives. Describe the user relationship with computer input and output Explain how data is input to a computer system and differentiate among various input equipment

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Input and Output: The User Connection

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  1. Input and Output:The User Connection Chapter 5

  2. Objectives • Describe the user relationship with computer input and output • Explain how data is input to a computer system and differentiate among various input equipment • Describe how a monitor works and the characteristics that determine quality • List and describe the different methods of computer output • Differentiate among different kinds of printerExplain the function of a computer terminal and describe the types of terminals

  3. Contents • Input and Output • Input • Output • Terminals • Computer Graphics • Ethics and Data

  4. Input and Output Input • Users submit input data Output • Users get processed information

  5. Input • Data from the user to the computer • Converts raw data into electronic form

  6. Diversity of Input Methods • Zebra-striped bar codes on supermarket items • Word commands operate a forklift truck • An order is entered using a pen on a special pad • Time clock generates paycheck • Data on checks are read and used to prepare a monthly bank statement • Charge-card transactions generate customer bills

  7. Keyboard • Traditional • Looks like typewriter with extra keys • Non-traditional • Fast food restaurants • Each key represents a food item rather than a character

  8. Function Keys Give commands Software specific Main Keyboard Typewriter keys Special command keys Keyboard

  9. Keyboard • Numeric Keys • Num Lock – toggle • On – numeric data & math symbols • Off – cursor movement • Cursor Movement Keys

  10. Shift Caps Lock Ctrl Alt Esc Enter Windows Shortcut KeyboardSpecial Keys

  11. Pointing Devices • Position a pointer / cursor on the screen • Controls drawing instruments in graphics applications • Communicate commands to a program

  12. Pointing Devices Mouse • Types • Mechanical • Optical • Wireless • Features • Palm-sized • 1 or 2 buttons • Wheel

  13. Other Pointing Devices • Trackball • Upside-down mouse • Ball on top • Roll ball with hand • Laptop computers • Touchpad • Pressure-sensitive pad • Cursor moves as you slide your finger • Laptop computers

  14. Other Pointing Devices Pointing stick • Pressure-sensitive post • Mounted between G and H keys on keyboard • Apply pressure in a direction to move cursor Joystick • Short lever • Handgrip • Distance and speed of movement control pointer position

  15. Graphics Tablet • Digitizing tablet • Rectangular board • Invisible grid of electronic dots • Write with stylus or puck • Sends locations of electronic dots as stylus moves over them • Creates precise drawings • Architects and engineers

  16. Touch Screens • Human points to a selection on the screen • Types • Edges emit horizontal and vertical beams of light that crisscross the screen • Senses finger pressure • Light pen for pointing

  17. Touch Screens • Kiosks • Self-help stations • Easy to use • Where found • Malls • Disney World • Government offices

  18. Pen-based Computing • Small hand-held devices • Electronic pen (stylus) • Pointer • Handwritten input • Personal Digital Assistants (PDA)

  19. Source Data Automation • Special equipment to collect data at the source • Sent directly to a computer • Avoids need to key data • Related input areas • Magnetic-Ink Character Recognition • Scanners • Optical recognition devices • Voice

  20. MICRMagnetic-Ink Character Recognition • Read characters made of magnetic particles • Numbers on the bottom of checks • MICR inscriber – adds characters to check that show amount cashed

  21. Optical Scanners • Optical recognition • Light beam scans input data • Most common type of source input • Document imaging – converts paper documents to electronic form • Converts snapshots into images • Converts scanned picture into characters – OCR Exact computer-produced replica of original

  22. Types of Scanners • Flatbed • One sheet at a time • Scans bound documents • Sheetfeed • Motorized rollers • Sheet moves across scanning head • Small, convenient size • Less versatile than flatbed • Prone to errors

  23. Types of Scanners • Handheld • Least expensive • Least accurate • Portable • User must move the scanner in a straight line at a fixed rate • Wide document causes problems

  24. Optical Recognition • Optical mark recognition (OMR) • Mark sensing • Exams • Recognizes the location of the marks • Optical character recognition (OCR) • Light source reads special characters • OCR-A is ANSI standard typeface for optical characters

  25. Optical RecognitionWand Reader Retail stores Libraries Hospitals Factories

  26. Optical RecognitionBar Code Reader • Photoelectric device • Reads bar codes • Inexpensive • Reliable • Where Used? • Supermarket – UPC • Federal Express

  27. Optical RecognitionHandwritten Characters Must follow rigid rules • Size • Completeness • Legibility

  28. Voice Input • Speech Recognition • Speech recognition devices • Input via a microphone • Voice converted to binary code • Problems • Speaker-dependent • Voice training

  29. Voice Input • Changing radio frequencies in airplane cockpits • Placing a call on a car phone • Requesting stock-market quotations over the phone • Command from physically disabled users

  30. Voice Input • Discrete work systems • Understand isolated words • Pause between words • Difficult for dictation • Continuous work systems • Normal speaking pattern • Easy to use • Faster and easier to dictate than to key

  31. Digital Cameras • Photos stored in electronic form • No film • Point and shoot • Edit

  32. Output • Information for the user • Types • Screen – soft copy • Printer – hard copy • Voice • Sound • Graphics

  33. Monitor • Data that is entered appears on the screen • Screen is part of the monitor

  34. Monitor Cathode Ray Tube (CRT) Flat panel display Liquid Crystal Display (LCD)

  35. CRT Raster scanning • Sweeping electron beams across the back of the screen • Phosphorous coating on back • Glows when hit by a beam of electrons • Phosphorous loses glow and image fades and flickers • Image must be continually refreshed

  36. CRT Refresh rate / scan rate • Number of times electron beams refreshes the screen • 80-100 times per second adequate for clear screen image • Process also used for television

  37. CRT Interlaced vs. Non-interlaced • Interlaced • Refresh every other line on each pass • Lower refresh rate without flicker • Good for fixed graphics • Causes flutter with animated graphics • Inexpensive • Non-interlaced • Refresh every line on each pass • Typical screen sold today

  38. CRT Color vs. Monochrome • Color • Typical monitor sold today • Monochrome • Green or amber on a contrasting background • Less expensive than color

  39. CRT Resolution • Clarity of image • Pixel (Picture element) • Dot on screen • Is addressable • Can be illuminated • More pixels means higher resolution • Dot pitch • Distance between dots • Smaller distance means better quality image

  40. CRT Graphics Card/Graphics Adapter Board • Plugs into expansion slot on motherboard • Graphics card and monitor must be compatible for high quality image

  41. CRT Size • Measured diagonally • Typical sizes • Office user: 15-17 inch • High-powered graphics user: 19 inch • High-end monitors: 21 inches and up • Larger size • More expensive • More space on desktop • Reduces eye strain

  42. Graphics Standards • PCs • Monitor • Graphics boards • Software Help insure that the products work together

  43. Graphics Standards • SVGA (Super VGA) • Resolution – 800 x 600, 1024 x 768, 1280 x 1024, 1600 x 1200 pixels • 16 million colors • Number of colors displayed simultaneously limited by amount of video memory • XGA (Extended Graphics Array) • High resolution • Supports more simultaneous colors • Allows non-interlaced monitors

  44. Flat-panel Screens • Liquid Crystal Display (LCD) • Primarily on laptops • Moving to desktop • Skinny (depth) regardless of size

  45. Flat-panel Screens • Crisp, brilliant images • Easy on eyes • No flicker • Full dimension is useable • More expensive that CRT monitors

  46. Flat-panel Screens • Active Matrix • Thin-film transistor technology (TFT) • Transistors for each pixel • Brighter image • Viewable from an angle • Passive Matrix • Fewer transistors • Cheaper • Less power

  47. Printer • Produces information on paper • Orientation • Portrait • Landscape • Methods of printing • Impact • Nonimpact

  48. Line printer One line at a time High volume Low quality Dot-matrix printer One character at a time Impact Printers

  49. Nonimpact PrinterLaser Printer

  50. Nonimpact PrinterLaser Printer • Transfers images to paper using a light beam • Prints one page at a time • 600-1200 dpi – High quality • Speed • Personal laser printers: 8-10 ppm • Network laser printers: 35-50 ppm • High-volume laser printers: up to 1000 ppm • Black and white / color

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