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  1. 1. Chapter 1 <ul><li>How Computers Work </li></ul><ul><li>An Overview </li></ul>Managing and Maintaining Your PC
  2. 2. How Computers Work An Overview <ul><li>Hardware </li></ul><ul><ul><li>Outside the Case </li></ul></ul><ul><ul><ul><li>Input/Output devices: connected through Ports </li></ul></ul></ul><ul><ul><ul><li>Peripherals: monitor, keyboard, mouse, printer </li></ul></ul></ul><ul><ul><li>Inside the Case </li></ul></ul><ul><ul><ul><li>Systemboard or Motherboard </li></ul></ul></ul><ul><ul><ul><li>Memory, such as SIMMs and DIMMs </li></ul></ul></ul><ul><ul><ul><li>Interface Cards for monitors, scanners ... </li></ul></ul></ul><ul><ul><ul><li>Power Supply </li></ul></ul></ul><ul><ul><ul><li>Hard, floppy, and CD-ROM Drives </li></ul></ul></ul>
  3. 3. How Computers Work An Overview <ul><li>Software </li></ul><ul><ul><li>Operating Systems, which consist of: </li></ul></ul><ul><ul><ul><li>Program files controlling Input/Output </li></ul></ul></ul><ul><ul><ul><li>A means of Booting the system </li></ul></ul></ul><ul><ul><ul><li>Interfaces </li></ul></ul></ul><ul><ul><ul><ul><li>Command-driven, such as DOS </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Menu-driven, such as the DOS Shell </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Icon-driven, such Windows and Macintosh </li></ul></ul></ul></ul><ul><ul><ul><li>May be Multitasking </li></ul></ul></ul><ul><ul><ul><li>Examples of Operating environments are </li></ul></ul></ul><ul><ul><ul><ul><li>DOS, Windows, OS/2, Mac OS, UNIX </li></ul></ul></ul></ul>
  4. 4. How Computers Work An Overview <ul><ul><li>Applications Software </li></ul></ul><ul><ul><ul><li>Types: </li></ul></ul></ul><ul><ul><ul><ul><li>Word processors such as Word and WordPerfect </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Spreadsheets such as Excel and Lotus 123 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Database management such as Access </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Graphics </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Communications </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Games </li></ul></ul></ul></ul><ul><ul><ul><li>Installed from Disk or CD-ROM </li></ul></ul></ul>
  5. 5. How Computers Work An Overview <ul><ul><li>Directories </li></ul></ul><ul><ul><ul><li>Root or main directory, created when a hard drive is first formatted </li></ul></ul></ul><ul><ul><ul><li>Subdirectories or folders for program applications and data files </li></ul></ul></ul><ul><ul><ul><li>Paths point to the location of a file folder and a particular file </li></ul></ul></ul>
  6. 6. Hardware - Outside the Case <ul><li>Input/output devices or peripherals </li></ul><ul><ul><li>Monitor </li></ul></ul><ul><ul><ul><li>Primary output device </li></ul></ul></ul><ul><ul><ul><li>Displays images with pixels </li></ul></ul></ul><ul><ul><li>Keyboard </li></ul></ul><ul><ul><ul><li>Primary input device </li></ul></ul></ul><ul><ul><li>Mouse </li></ul></ul><ul><ul><ul><li>Pointing device </li></ul></ul></ul><ul><ul><li>Printer </li></ul></ul><ul><ul><ul><li>Produces paper output called hard copy </li></ul></ul></ul>
  7. 7. Hardware - Outside the Case Figure 1-2 Cables connected to ports
  8. 8. Hardware - Inside the Case Figure 1-3 Inside the computer case
  9. 9. Hardware - Systemboard <ul><li>The most important circuit board, it holds microchips and interface cards: </li></ul><ul><ul><li>CPU or microprocessor </li></ul></ul><ul><ul><ul><li>Does most of the computer’s “thinking” </li></ul></ul></ul><ul><ul><li>Coprocessor </li></ul></ul><ul><ul><ul><li>Speeds up performance of older CPUs </li></ul></ul></ul><ul><ul><li>ROM </li></ul></ul><ul><ul><ul><li>Read-Only Memory, unchanging </li></ul></ul></ul><ul><ul><ul><li>Holds programs or instructions that tell the CPU how to perform many tasks </li></ul></ul></ul>
  10. 10. Hardware - Systemboard <ul><ul><li>RAM </li></ul></ul><ul><ul><ul><li>Random-Access Memory, volatile </li></ul></ul></ul><ul><ul><ul><li>Individual chips or banks of chips such as SIMMs or DIMMs </li></ul></ul></ul><ul><ul><li>System clock </li></ul></ul><ul><ul><ul><li>Times the activities of the chips on the systemboard </li></ul></ul></ul><ul><ul><li>CMOS configuration chip </li></ul></ul><ul><ul><ul><li>System chip that contains setup information such as time and date, and drive size and type </li></ul></ul></ul>
  11. 11. Hardware - Systemboard <ul><ul><li>Bus </li></ul></ul><ul><ul><ul><li>Paths along which data is passed </li></ul></ul></ul><ul><ul><li>Expansion Slots </li></ul></ul><ul><ul><ul><li>Interface cards are plugged into these slots to enhance the computer’s hardware, such as: </li></ul></ul></ul><ul><ul><ul><ul><li>16-bit ISA slots </li></ul></ul></ul></ul><ul><ul><ul><ul><li>32-bit VLB slots </li></ul></ul></ul></ul><ul><ul><ul><ul><li>32-bit and 64-bit PCI slots </li></ul></ul></ul></ul>
  12. 12. Hardware - Systemboard Figure 1-4 Components on a systemboard
  13. 13. Hardware - Memory <ul><li>Conventional memory - used by older XT computers </li></ul><ul><li>Upper memory - used to load drivers </li></ul><ul><li>Extended memory - used by Windows </li></ul>Table 1-1 Divisions of Memory Under DOS
  14. 14. Hardware - Circuit board <ul><li>Plugs into expansion slots </li></ul><ul><li>Some types of circuit boards: </li></ul><ul><ul><li>Video card </li></ul></ul><ul><ul><li>Hard drive controller card </li></ul></ul><ul><ul><li>Multi-input/output controller card </li></ul></ul><ul><ul><li>Internal modems </li></ul></ul><ul><ul><li>Scanner card </li></ul></ul><ul><ul><li>Network Interface Card (NIC) </li></ul></ul>
  15. 15. Hardware - Circuit board Figure 1-5 Circuit boards mounted in expansion slots
  16. 16. Hardware - Expansion Slot Figure 1-6 Expansion card and port
  17. 17. Hardware - Power Supply <ul><li>Converts electricity, reducing it to a voltage the computer can use - either 5 or 12 volts DC </li></ul><ul><li>Runs a cooling fan when the computer is on </li></ul><ul><li>Provides connectors to power the main Systemboard and Floppy, CD, Tape, and Hard drives </li></ul>
  18. 18. Hardware - Power Supply Figure 1-7 Power supply with connections
  19. 19. Hardware - Secondary Storage <ul><li>Hard drive </li></ul><ul><ul><li>Sealed case containing rotating disks and read/write heads </li></ul></ul><ul><li>Floppy disk drives </li></ul><ul><ul><li>5 1/4” disks </li></ul></ul><ul><ul><li>3 1/2” double-density or high density disks </li></ul></ul><ul><li>CD-ROM drives, DVD drives </li></ul><ul><li>Tape drives </li></ul><ul><li>Removable drives </li></ul>
  20. 20. Hardware Figure 1-9 A floppy drive subsystem
  21. 21. Software <ul><li>Programs that instruct the computer to perform specific tasks </li></ul><ul><ul><li>Operating system software </li></ul></ul><ul><ul><ul><li>DOS, Windows, OS/2, Mac OS, UNIX </li></ul></ul></ul><ul><ul><li>Applications software </li></ul></ul><ul><ul><ul><li>Word processor, spreadsheet, database, graphics, communications, games </li></ul></ul></ul>
  22. 22. Software - Operating Systems Figure 1-10 The operating system is stored in files on the hard drive but is executed from memory
  23. 23. Software - Operating Systems <ul><li>DOS </li></ul><ul><ul><li>First Operating System used by IBM PCs </li></ul></ul><ul><ul><li>The most common OS of the 1980’s and early 1990’s </li></ul></ul><ul><ul><li>Command-driven from DOS prompt </li></ul></ul><ul><ul><ul><li>Example: C:> DIR A: </li></ul></ul></ul>
  24. 24. Software - Operating Systems Figure 1-11 An operating system command-driven interface: the C prompt C:>time Current time is 6:12:09.41a Enter new time: C:>ver MS-DOS Version 6.22 C:>copy config.sys config.bak Overwrite CONFIG.BAK (Yes/No/All)?y 1 file(s) copied C:> C prompt
  25. 25. Software - Operating Systems <ul><li>Windows 3.1 </li></ul><ul><ul><li>Menu-driven File Manager </li></ul></ul><ul><ul><ul><li>Choose from a list of options on screen to perform various operations </li></ul></ul></ul><ul><ul><li>Icon-driven Program Manager </li></ul></ul><ul><ul><ul><li>Graphical-User Interface </li></ul></ul></ul><ul><ul><ul><li>Choose operations by selecting or clicking on pictures on screen </li></ul></ul></ul>
  26. 26. Software - Interfaces Figure 1-12 A menu-driven interface: File Manager in Windows 3.1
  27. 27. Software - Interfaces Figure 1-13 An icon-driven interface: Program Manager in Windows 3.1
  28. 28. Software - Operating Systems <ul><li>Windows 95 </li></ul><ul><ul><li>Icon-driven Windows Explorer </li></ul></ul><ul><ul><li>Includes icons for shortcuts to applications software programs </li></ul></ul><ul><ul><li>Icons sit on the “Desktop” - the initial, background screen that appears </li></ul></ul><ul><ul><li>Plug and Play features </li></ul></ul>
  29. 29. Software - Interfaces Figure 1-14 An icon-driven interface: Windows Explorer in Windows 95
  30. 30. Software - Multitasking <ul><li>Multitasking </li></ul><ul><ul><li>Ability of the computer to perform more than one function at a time </li></ul></ul><ul><ul><ul><li>Example: Use a Modem, a Word Processor, and a Spreadsheet at the same time </li></ul></ul></ul><ul><ul><li>Requires newer CPUs, such as a 486 or Pentium </li></ul></ul><ul><ul><li>Requires a special OS, such as Windows 95 or Windows NT </li></ul></ul>
  31. 31. Software - Multitasking Figure 1-15 A multitasking environment allows two or more applications to run simultaneously
  32. 32. Software - Operating Environment <ul><li>Operating environment refers to the overall support that software provides to applications software </li></ul><ul><li>DOS manages its single-tasking environment and relates to hardware in single-task fashion </li></ul><ul><li>Windows 3.x performs some functions of an OS and provides an environment in which applications software works </li></ul>
  33. 33. Software - Operating Systems Table 1-2 Advantages and Disadvantages of DOS
  34. 34. Software - Operating Systems Table 1-3 Advantages and Disadvantages of DOS with Windows 3.x
  35. 35. Software - Operating Systems Table 1-4 Advantages and Disadvantages of Windows 95
  36. 36. Software - Operating Systems Table 1-5 Advantages and Disadvantages of Windows NT
  37. 37. Software - Operating Systems Table 1-6 Advantages and Disadvantages of OS/2
  38. 38. Software - Operating Systems Table 1-7 Advantages and Disadvantages of the Macintosh Operating System
  39. 39. Software - Operating Systems Table 1-8 Advantages and Disadvantages of the UNIX Operating System
  40. 40. Applications Software <ul><li>Applications software falls into six main categories: </li></ul><ul><ul><li>Word processing </li></ul></ul><ul><ul><li>Spreadsheet </li></ul></ul><ul><ul><li>Database management </li></ul></ul><ul><ul><li>Graphics </li></ul></ul><ul><ul><li>Communications </li></ul></ul><ul><ul><li>Games </li></ul></ul>
  41. 41. Applications Software <ul><li>Designed to work on top of a particular OS </li></ul><ul><li>An application written for one OS may not work with another </li></ul><ul><li>Comes on floppy disks or CD-ROMs </li></ul><ul><li>Usually installed on the hard drive </li></ul>
  42. 42. How Software Works <ul><li>In the final stages of startup, the computer passes control to the OS </li></ul><ul><li>When OS completes its startup procedures, control passes to the user </li></ul><ul><ul><li>For DOS users, the C prompt will appear </li></ul></ul><ul><ul><ul><li>Example: C:> </li></ul></ul></ul><ul><ul><li>Files with extensions of .COM, .EXE, and .BAT can be run from the DOS prompt </li></ul></ul>
  43. 43. Software - The Boot Process Figure 1-18 DOS prompt after booting C:>C:WINDOWSSMARTDRIVE.EXE MICROSOFT SMARTDrive Disk Cache version 4.0 Copyright 1991, 1992 Microsoft Corp. Cache size: 761,856 bytes Cache size while running Windows: 0 bytes Disk Caching Status Drive read cache write cache buffering A: yes no no B: yes no no C: yes yes no For help, type &quot;Smartdrv /?&quot; C:>
  44. 44. How DOS Searches for Executable Programs <ul><li>Path - tells DOS where to look for files </li></ul><ul><ul><li>If no path is given, DOS looks in the current directory </li></ul></ul><ul><ul><li>If a path is given in front of the file name, DOS looks in the PATH provided </li></ul></ul><ul><ul><ul><li>Ex: C:DOSCHKDSK </li></ul></ul></ul><ul><ul><li>If the file is not found in the current directory, DOS looks in the path given by the last PATH command </li></ul></ul><ul><ul><ul><li>Ex: Path= C:;C:DOS;C:WINDOWS </li></ul></ul></ul>
  45. 45. Copying Programs into Memory <ul><li>DOS cannot execute a program directly from the hard drive or floppy disks </li></ul><ul><ul><li>DOS copies the program into RAM </li></ul></ul><ul><ul><li>It goes to the first address occupied by the program to receive its first instruction </li></ul></ul><ul><ul><li>DOS manages requested read/write tasks to and from memory </li></ul></ul><ul><ul><li>It performs other requested tasks and returns to the application when done </li></ul></ul>
  46. 46. Software Figure 1-20 Applications software is stored in files but executed from memory
  47. 47. Software - Errors <ul><li>When an error occurs, either </li></ul><ul><ul><li>The applications program detects the error and displays its own error message </li></ul></ul><ul><ul><li>The operating environment software detects the error and displays an error message </li></ul></ul>
  48. 48. Software - Errors Figure 1-21 Disk error in Windows 95
  49. 49. Software - Errors Figure 1-22 Windows error while using Paintbrush
  50. 50. Software - Program Execution <ul><li>Windows 3.x programs can be executed by double-clicking an icon </li></ul><ul><ul><li>To see the command line that executes the program, single-click or select the icon and choose Properties from the File menu of Program Manager </li></ul></ul>
  51. 51. Software - Properties Box Figure 1-23 Properties of a program item in Windows 3.x
  52. 52. Software - Program Execution <ul><li>Applications may also be executed from the File Manager in Windows 3.x </li></ul><ul><li>To execute a program, either </li></ul><ul><ul><li>Double-click the filename in the file list, or </li></ul></ul><ul><ul><li>Use the Run command from the File menu in File Manager </li></ul></ul><ul><ul><ul><li>Select Run from the menu </li></ul></ul></ul><ul><ul><ul><li>Type the command line that executes the program </li></ul></ul></ul>
  53. 53. Software Figure 1-25 Using the Run command from File Manager in Windows 3.x
  54. 54. Software - Program Execution <ul><li>Windows 95 offers 3 ways to execute software </li></ul><ul><ul><li>You may place a shortcut icon on the desktop, then double-click the shortcut </li></ul></ul><ul><ul><li>Use the Start button and select Run or select Programs </li></ul></ul><ul><ul><li>Double-click the filename in Windows Explorer </li></ul></ul>
  55. 55. Software - Shortcuts Figure 1-26 Properties of a shortcut in Windows 95
  56. 56. Software Figure 1-27 Using the Run command from the Start menu in Windows 95
  57. 57. Software Interactions with Hardware <ul><li>The user interacts with the applications program </li></ul><ul><li>The applications program interacts with the OS </li></ul><ul><li>The OS interacts with the hardware, possibly through device drivers </li></ul>
  58. 58. Software Interactions with Hardware Figure 1-28 Layers of software when printing
  59. 59. Chapter Summary <ul><li>Hardware </li></ul><ul><ul><li>The components of a microcomputer </li></ul></ul><ul><ul><ul><li>Monitor, CPU, printer, mouse, keyboard... </li></ul></ul></ul><ul><ul><li>How the components function together </li></ul></ul><ul><li>Software </li></ul><ul><ul><li>Common operating systems </li></ul></ul><ul><ul><ul><li>DOS, Windows, OS/2, Mac OS, UNIX </li></ul></ul></ul><ul><ul><li>Applications programs </li></ul></ul><ul><ul><ul><li>Word processing, database, spreadsheet... </li></ul></ul></ul>