Chapter 7 Input/Output Technology

1. Chapter 7Input/Output Technology

2. Chapter 7 Systems Architecture Chapter Goals • Describe manual input devices and how they are implemented. • Explain the characteristics and implementation technology of video display devices. • Understand printer characteristics and technology.

3. Chapter 7 Systems Architecture Chapter Goals • Identify the characteristics of audio I/O devices, and explain how they operate.

4. Chapter 7 Systems Architecture Chapter Topics • Describes the concepts, technology and hardware used in communication between people and computers. • Understand the importance of I/O technology.

5. Chapter 7 Systems Architecture Chapter Topics

6. Chapter 7 Systems Architecture Manual Input Devices • Keyboard Input • Pointing Devices

7. Chapter 7 Systems Architecture Manual Input Devices Keyboard Input • Keyboard devices translate keystrokes directly into electrical signals. • A keyboard controller is used to generate bit stream outputs. • The controller generates a bit stream output according to an internal program or lookup table.

8. Chapter 7 Systems Architecture Manual Input Devices Keyboard Input • A keyboard controller generates an output called a scan code. • A scan code is a one or two-byte data element that represents a specific keyboard element.

9. Chapter 7 Systems Architecture Manual Input Devices Pointing Devices • Mouse • Trackball • Joystick • Digitizer Tablet

10. Chapter 7 Systems Architecture Manual Input Devices Pointing Devices Translates the spatial position of a pointer, stylus, or other selection device into numeric values within a system of two-dimensional coordinates.

11. Chapter 7 Systems Architecture Manual Input Devices Mouse – a pointing device that is moved on a flat surface such as a table, desk or rubber pad. Trackball – a mouse with the roller ball on the top. The roller ball is moved by the fingertips, thumb or palm of the hand.

12. Chapter 7 Systems Architecture Manual Input Devices Joystick – used as an input device with computer games. Digitizer Tablet – uses a pen, or stylus, and a digitizing tablet. The tablet is sensitive to the placement of the stylus at any point on its surface.

13. Chapter 7 Systems Architecture Basic Concepts of Print and Display • Matrix-Oriented Image Composition • Fonts • Color • Pixel Content • Image Storage Requirements • Image Description Languages

14. Chapter 7 Systems Architecture Basic Concepts of Print and Display Matrix-Oriented Image Composition • Display surfaces can be divided into rows and columns similar to a large table or matrix. • Each cell in the table represents one component of the image.

15. Chapter 7 Systems Architecture Basic Concepts of Print and Display Matrix-Oriented Image Composition • One of the cells is a pixel. • The resolution of the display is the number of pixels displayed per linear measurement unit. • Resolution is stated in dots per inch(dpi).

16. Chapter 7 Systems Architecture Basic Concepts of Print and Display

17. Chapter 7 Systems Architecture Basic Concepts of Print and Display • Font – a collection of characters of similar style and appearance.

18. Chapter 7 Systems Architecture Basic Concepts of Print and Display

19. Chapter 7 Systems Architecture Basic Concepts of Print and Display

20. Chapter 7 Systems Architecture Basic Concepts of Print and Display Color • For video displays, color is generated directly by the display device. • The video display industry has used red, green and blue as primary colors. • A video display that generates color uses mixtures or these colors.

21. Chapter 7 Systems Architecture Basic Concepts of Print and Display Color • For print, color is light frequency reflected from the paper. • The printing industry generates color using the inverse of the primary video display colors. (subtractive color)

22. Chapter 7 Systems Architecture Basic Concepts of Print and Display Pixel Content • Pixel content must be described numerically. • A stored set of numeric pixel descriptions is called a bit map. • A palette is a table of colors. • Color can also be produced using dithering.

23. Chapter 7 Systems Architecture Basic Concepts of Print and Display

24. Chapter 7 Systems Architecture Basic Concepts of Print and Display Image Storage Requirements • Image storage requirements apply to images stored in primary and secondary storage, and to buffers used in I/O devices. • Image storage requirements can be reduced with image compression techniques.

25. Chapter 7 Systems Architecture Basic Concepts of Print and Display Image Storage Requirements Compression Techniques: • Graphics Interchange Format (GIF) • Joint Photographic Experts Group (JPEG) • Moving Pictures Experts Group (MPEG)

26. Chapter 7 Systems Architecture Basic Concepts of Print and Display Image Description Languages • Use a symbolic language to describe primitive image components. • Can use a vector list . • Describe the image components that are straight-line segments or can be built from segments.

27. Chapter 7 Systems Architecture Basic Concepts of Print and Display

28. Chapter 7 Systems Architecture Technology Focus - Postscript

29. Chapter 7 Systems Architecture Technology Focus - Postscript

30. Chapter 7 Systems Architecture Video Display • Character-Oriented Video Display Terminals • Graphic Video Display Devices • CRTs • Flat Panel Displays

31. Chapter 7 Systems Architecture Video Displays Character-Oriented Video Display Terminals • Commonly used during 1970s and 1980s. • Terminal – consist of an integrated keyboard and television screen. • Used today primarily in systems such as retail checkout counters and factory floor environments.

32. Chapter 7 Systems Architecture Video Display

33. Chapter 7 Systems Architecture Video Display Graphic Video Display Devices • Used for displaying diagrams such as construction blueprints, wireframe models, writing diagrams and to produce mathematical graphs. • By the mid-1980s monitors were manufactured.

34. Chapter 7 Systems Architecture Video Display • Monitors operate as independent devices under control of a video controller attached to the system bus.

35. Chapter 7 Systems Architecture Video Display

36. Chapter 7 Systems Architecture Video Display CRT • Current monitors are implemented using cathode ray tubes. • A CRT is an enclosed tube. • An electron gun in the rear of the tube generates a stream of electrons. • Pixel illumination is controlled by pulsing the electron beam.

37. Chapter 7 Systems Architecture Video Display • The number of times per second that the entire surface is scanned by the electron gun is called the refresh rate.

38. Chapter 7 Systems Architecture Video Display Flat Panel Display • Liquid Crystal Display – is a flat panel matrix that consists of encapsulated liquid crystals sandwiched between two polarizing panels. • Passive Active Matrix Display – shares transistors among rows and columns of pixels.

39. Chapter 7 Systems Architecture Video Display • Electroluminescent Displays – similar to construction of LCDs. Color is generated with three matrices of different colored phosphors.

40. Chapter 7 Systems Architecture Printers and Plotters • Dot Matrix Printers • Ink-Jet Printers • Laser Printers • Plotters

41. Chapter 7 Systems Architecture Printers and Plotters

42. Chapter 7 Systems Architecture Printers and Plotters Dot Matrix Printers • Generate images through mechanical contact with ink and papers. • Character codes received by the print generator are transmitted as a series of control commands to the print head. • Characters are generated one or two vertical rows at a time.

43. Chapter 7 Systems Architecture Printers and Plotters Ink-Jet Printers • Uses a paper movement mechanism similar to that of a dot matrix printer. • The print head of an ink-jet printer consists of an ink cartridge, a set of ink chambers and a set of ink nozzles.

44. Chapter 7 Systems Architecture Printers and Plotters Ink-Jet Printers • Each ink nozzle can print a single pixel and nozzles are arranged in short vertical rows similar to those of a dot matrix printer.

45. Chapter 7 Systems Architecture Printers and Plotters Laser Printers • Operates differently from other types of printers. • No print head or ink ribbon is used. • An internal image of the entire page is stored in an internal buffer as a bit map. • Once filled, the buffer contents are sent to the print driver for generation.

46. Chapter 7 Systems Architecture Printers and Buffers

47. Chapter 7 Systems Architecture Printers and Plotters Plotters • A printer that generates line drawings on wide sheets or rolls of paper. • Paper is mounted within a paper control mechanism that can move the paper up or down precisely. • Can handle paper widths up to 60 inches.

48. Chapter 7 Systems Architecture Optical Input Devices Optical scanning devices can be differentiated by the following criteria: • Input format requirements • Normal and maximum spatial resolution • Normal and maximum chromatic resolution • Embedded processing capacity

49. Chapter 7 Systems Architecture Optical Input Devices Mark Sensors and Bar Code Scanners • Mark Sensors – scans for light or dark marks at specific locations on a page. • The mark sensors uses preprinted bars on the edge of the page to establish reference points.

50. Chapter 7 Systems Architecture Optical Input Devices Mark Sensors and Bar Code Scanners • A scanning laser sweeps a narrow laser beam back and forth across the bar code. • Bars must have precise width and spacing, as well as high contrast for accurate decoding.