Understanding Input and Output Hardware in Information Technology

1. Using Information Technology Chapter 5 Hardware--Input & Output

2. Hardware--Input & Output Taking Charge of Computing & Communications • 5.1 Input & Output • 5.2 Input Hardware • 5.3 Output Hardware

3. 5.1 Input & Output • Input hardware - devices that translate data into a form the computer can process • Output hardware - devices that translate information processed by the computer into a form that humans can understand

4. 5.2 Input Hardware • Keyboard - a device that converts letters, numbers, and other characters into electrical signals that can be read by the computer’s processor • Traditional keyboards… Braille keyboard One-handed keyboard

5. Keyboards • Specialty keyboards and terminals: • Dumb terminal, VDT, display & keyboard, but no processing • Intelligent terminal • Internet terminal Dumb terminal

6. Examples of intelligent terminals: Automatic teller machine (ATM) Point-of-sale (POS) terminal Keyboards • Specialty keyboards and terminals: • Dumb terminal • Intelligent terminal Has own memory & processor • Internet terminal

7. Keyboards • Specialty keyboards and terminals: • Dumb terminal • Intelligent terminal • Internet terminal: • Web terminal • Network computer • Online game player • PC/TV • PDA PDA (Internet terminal)

8. Pointing Devices • Pointing devices - control the position of the cursor or pointer on the screen • Mouse • Trackball • Pointing stick • Touchpad Mouse for right-handed user

9. Pointing Devices Touch pad • The mouse and its variants: • Mouse • Trackball • Pointing stick • Touchpad Ergonomic trackball Pointing stick

10. Pointing Devices • Touch screen - a video display screen that has been sensitized to receive input from the touch of a finger Touch screen

11. Pointing Devices Pen input: • Pen-based computer system - allows users to enter handwriting and marks onto a computer screen by means of a penlike stylus rather than by typing on a keyboard • Light pen - a light-sensitive penlike device connected by a wire to the computer terminal

12. Pointing Devices Pen input: • Digitizer - converts drawings and photos to digital data using a mouselike device called a puck • Digitizing tablet - electronic plastic board on which each specific location corresponds to a location on the screen Digitizing tablet

13. Source Data-Entry Devices Scanning devices - imaging systems: • Scanners - devices that use light-sensing equipment to translate images of text, drawings, photos, and the like into digital form

14. Source Data-Entry Devices Scanning devices – bar-code readers: • Bar codes - vertical zebra-striped marks you see on most manufactured retail products • Bar-code readers - optical scanners that translate the symbols in the bar code into digital code

15. Source Data-Entry Devices Scanning devices - mark- & character-recognition: • MICR - Magnetic-ink character recognition. Reads the strange-looking numbers printed at the bottom of checks • OMR • OCR

16. Source Data-Entry Devices Scanning devices - mark- & character-recognition: • MICR • OMR - Optical mark recognition. Uses a device that reads pencil marks and converts them into computer-usable form • OCR

17. Source Data-Entry Devices Scanning devices:mark- & character-recognition: • MICR • OMR • OCR - Optical character recognition. Uses a device that reads preprinted characters in a particular font and converts them to digital code

18. Source Data-Entry Devices • Scanning devices - fax machines… • Types of fax machines: • Dedicated fax machine • Fax modem Dedicated fax machine Fax modem

19. Other Source Data-Entry Devices • Audio-input devices • Webcams and video-input cards • Digital cameras • Voice-recognition systems

20. Other Source Data-Entry Devices • Audio-input devices • Webcams and video-input cards • Digital cameras • Voice-recognition systems • Human-biology input devices (biometrics)

21. 5.3 Output Hardware • Softcopy - data that is shown on a display screen or is in audio or voice form • Hardcopy - printed output

22. Softcopy Output: Display Screens • Display screens - output devices that show programming instructions and data as they are being input and information after it is processed

23. Softcopy Output: Display Screens • Screen clarity… • Pixel (picture element) - the smallest unit on the screen that can be turned on and off or made different shades

24. Softcopy Output: Display Screens • Screen clarity… • Dot pitch (dp) - the amount of space between the centers of adjacent pixels; the closer the dots, the crisper the image

25. Screen clarity… Resolution - the image sharpness of a display screen; the more pixels there are per square inch, the finer the level of detail dpi = dots per inch Standard resolutions (horizontal x vertical) 640 x 480 800 x 600 1024 x 768 1280 x 1024 1600 x 1200 1920 x 1440 Softcopy Output: Display Screens

26. Softcopy Output: Display Screens • Screen clarity… • Refresh rate - the number of times per second that the pixels are recharged so that their glow remains bright • The higher the refresh rate, the more solid the image looks (less flicker).

27. Softcopy Output: Display Screens Two types of monitors: • CRT - a vacuum tube used as a display screen in a computer or video display terminal • Flat-panel display - made up of two plates of glass separated by a layer of a substance in which light is manipulated

28. Softcopy Output: Display Screens Active-matrix versus passive-matrix flat-panel displays: • Active-matrix - each pixel on the screen is controlled by its own transistor (brighter & sharper, but more expensive) • Passive-matrix - a transistor controls a whole row or column of pixels (provides sharper image for single color screens but more subdued for color)

29. Softcopy Output: Display Screens Color & resolution standards: • SVGA – Super video graphics array (most common w/ 15” monitors) • XGA – Extended graphics array (17-19” monitors) • SXGA – Super extended graphics array (19”-21” monitors) • UXGA - Ultra extended graphics array (popular w/ design & graphic artists

30. Hardcopy Output: Printers • Printer - an output device that prints characters, symbols, and perhaps graphics on paper or another hardcopy medium • Dpi (dots per inch) - resolution measure for printers. Specifies the number of dots that are printed in a linear inch

31. Hardcopy Output: Printers • Impact printer- forms characters or images by striking a mechanism such as a print hammer or wheel against an inked ribbon, leaving an image on paper (dot matrix printer) • Non-impact printer - forms characters and images without direct physical contact between the printing mechanism and paper • Laser printer - creates images on a drum which are treated with a magnetically charged toner, & then transferred from drum to paper • Ink-jet printers - spray small, electrically charged droplets of ink from four nozzles through holes in a matrix at high speed onto paper • Thermal printers - use colored waxes and heat to produce high quality images by burning dots onto special paper

32. Hardcopy Output: Printers • Multifunction printer - output device that combines several capabilities, such as printing, scanning, copying, and faxing

33. Other Output • Sound output - devices which produce digitized sounds, ranging from beeps and chirps to music • Voice output - devices which convert digital data into speech-like sounds • Video output - photographic images which are played at 15-29 frames per second to give the appearance of full motion

34. Concept Check • Which type of scanning technology reads the special characters printed at the bottom of checks? • Magnetic-ink character recognition (MICR)

35. Concept Check • What is the smallest unit on the screen that can be turned on and off or made different shades? • Pixel (short for picture element)

36. Concept Check • What is the measure specifying the number of times per second that screen pixels are recharged? • Refresh rate

37. Concept Check • How is screen resolution specified--vertical x horizontal, or horizontal x vertical? • Horizontal x vertical

38. Concept Check • What is the measure of resolution for printers? • Dots per inch (dpi)

39. Concept Check • What is the amount of space between the centers of adjacent pixels? • Dot pitch (dp)

40. Concept Check • What type of scanning technology is used to read pencil marks, such as those made by students on examination forms? • OMR (Optical mark recognition)

41. Concept Check • What is an example of an impact printer? • Dot-matrix printer

42. Concept Check • Which type of printer produces the very highest-quality color output? • Thermal printer

43. Concept Check • What type of input device consists of a small, flat surface over which you slide your finger, using the same movements as you would with a mouse? • Touchpad

44. Concept Check • What is the term for printed output? • Hardcopy

45. Concept Check • Does a very crisp image require a small dot pitch or a large dot pitch? • A small dot pitch (the closer the dots, the crisper the image)