Operating System

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Operating System

  1. 1. OperatingSystem<br />11/09/2009<br />Operating System<br />
  2. 2. ?<br />11/09/2009<br />Operating System<br />What is Operating System…?<br />
  3. 3. <ul><li> Operating system is a System Software
  4. 4. Act as interface b/w User and the Hardware
  5. 5. Organized set of programs
  6. 6. Controls & manage computer resources(H/W, S/W)
  7. 7. Schedules task, manage storage</li></ul>11/09/2009<br />Operating System<br />What is Operating System…?<br />
  8. 8. Application<br />Operating System<br />Keyboard<br />Printer<br />Hardware<br />RAM<br />Drives<br />Monitor<br />Operating System in a Hierarchy<br />11/09/2009<br />Operating System<br />
  9. 9. <ul><li>Making a computer system convenient to use.
  10. 10. Managing the resources.</li></ul>11/09/2009<br />Operating System<br />Primary objectives of Operating System<br />
  11. 11. Characteristics of operating System<br />Is a Program<br />Executes at all time<br />Act as Platform<br />Act as police<br />Provides Services<br />11/09/2009<br />Operating System<br />
  12. 12. Functions of Operating System<br />Process Management<br />Memory Management<br />File Management<br />Security<br />Command Interpretation<br />Device Management<br />11/09/2009<br />Operating System<br />
  13. 13. <ul><li>Process is a program in execution.
  14. 14. OS manages creation & deletion of processes.
  15. 15. Methods for process management are:-
  16. 16. Manual loading mechanism
  17. 17. Batch processing
  18. 18. Multiprogramming
  19. 19. Multiprocessing</li></ul>11/09/2009<br />Operating System<br />Process Management<br />
  20. 20. <ul><li> Programmer writes the program.
  21. 21. Programs are then punched on punch card.
  22. 22. Cards are submitted to computer centre.
  23. 23. Cards & data were manually loaded.
  24. 24. Result of execution of the job was printed on</li></ul> the punch cards.<br />11/09/2009<br />Operating System<br />Process of Management in Early Systems<br />
  25. 25. <ul><li>Takes care of main memory
  26. 26. Deals with part of memory in use & the memory part which is not in use
  27. 27. Allocates memory to processes & de-allocate</li></ul> when they are done<br />11/09/2009<br />Operating System<br />Memory Management<br />
  28. 28. <ul><li> File is a collection of related info.
  29. 29. Manages file stored on the disk.
  30. 30. Provides functions to delete, copy, move, rename and view files.
  31. 31. Backup of files on stable(non volatile) storage.
  32. 32. File access methods :-
  33. 33. Sequential Access Files
  34. 34. Random Access Files</li></ul>11/09/2009<br />Operating System<br />File Management<br />
  35. 35. <ul><li>Protect resources and information against destruction & unauthorized access
  36. 36. Types of Security:-
  37. 37. External Security
  38. 38. Adequate back-up data
  39. 39. Excess of sensitive information only
  40. 40. Internal Security
  41. 41. User authentication
  42. 42. Access control</li></ul>11/09/2009<br />Operating System<br />Security<br />
  43. 43. <ul><li> Manages the peripheral devices.
  44. 44. Accepts input from the user and give corresponding output.
  45. 45. Consist of policies and procedures for handling I/O devices.</li></ul>11/09/2009<br />Operating System<br />Device Management<br />
  46. 46. <ul><li> Act as primary interface between the user & the rest of the system.
  47. 47. Understands & executes commands entered by human beings.</li></ul>11/09/2009<br />Command Interpretation<br />Operating System<br />Operating System<br />
  48. 48. Batch processing<br />Multi-tasking<br />Types of Operating System<br />Multi-programming<br />Time-sharing<br />Multi- processor<br />Distributed OS<br />Network OS<br />On-line & Real time OS<br />11/09/2009<br />Operating System<br />
  49. 49. <ul><li> Effective form of processing.
  50. 50. Programs are prepared Offline.
  51. 51. Groups of programs are collected together & are processed one by one.
  52. 52. Advantage:-Reduces computer idle time.
  53. 53. Disadvantage:- Large turn around time.</li></ul>11/09/2009<br />Operating System<br />Batch processing<br />
  54. 54. <ul><li> Programmer prepares their programs and data on deck of cards.
  55. 55. Operator periodically collect the submitted programs and would batch them together.
  56. 56. Batched programs were loaded into input device.
  57. 57. Operator gives command to start executing the jobs.
  58. 58. Jobs automatically loads from the input device.
  59. 59. After process, operator separates and keep the printed output.</li></ul>11/09/2009<br />Operating System<br />Steps in Batch Processing<br />
  60. 60. <ul><li> How the computer separates one job from another from a batch of jobs for automatic job-to-job transaction ?
  61. 61. How does the system know which complier or what hardware devices are to be used by a particular job when there is no operator interventions ?
  62. 62. Ans:- Control Statements and Job Control Statement(JCLs)</li></ul>11/09/2009<br />Operating System<br />Some questions…….?<br />
  63. 63. <ul><li>CS and JCL are used by the operating system to identify a new job and to determine resource need.
  64. 64. Control cards are indentified by a special character or pattern on the card.
  65. 65. JCL tells the OS things such as :-
  66. 66. the name of the job
  67. 67. the user’s name
  68. 68. the I/O devices used during processing.
  69. 69. the complier or the assembler to be used.</li></ul>11/09/2009<br />Operating System<br />Job Control Statements<br />
  70. 70. 11/09/2009<br />Operating System<br />Uniprogramming System<br />Main Memory<br />Operating System<br />OS area<br />User Job<br />User<br />Program<br />area<br />Execution in<br />progress<br />CPU<br />A Uniprogramming system model in which only one job is processed by the system at a time and all the system resources are exclusively available for the job until it completes.<br />
  71. 71. <ul><li> Is a interleaved execution of two or more programs by the same computer.
  72. 72. One or more programs are executed at the same time.
  73. 73. Different scheduling techniques are:-
  74. 74. First come first serve
  75. 75. Round robin (RR)
  76. 76. Shortest job first (SJF)</li></ul>11/09/2009<br />Operating System<br />Multiprogramming System<br />
  77. 77. 11/09/2009<br />Operating System<br />Multiprogramming System<br />Main Memory<br />Operating System<br />Writing O/P data<br />Job A<br />Secondary Disk Storage<br />Job B<br />Job C<br />(Writing for CPU)<br />CPU<br />Execution in Progress<br />
  78. 78. 11/09/2009<br />Operating System<br />Multiprogramming System<br />Job is allocated the <br />CPU for execution<br />Ready<br />Running<br />New<br />Job<br />Job processing completed<br />I/O completed<br />Job must wait for I/O completion<br />Blocked<br />Three different stages of Job<br />
  79. 79. <ul><li> It is the system capability to concurrently work on more than one task.
  80. 80. Same as multiprogramming.
  81. 81. Multitasking is referred in context to single user.</li></ul>11/09/2009<br />Operating System<br />Multitasking System<br />
  82. 82. <ul><li> Multiprocessing system is a integrated system.
  83. 83. Two or more CPU is present.
  84. 84. Simultaneously execute several programs.</li></ul>11/09/2009<br />Operating System<br />Multiprocessing System<br />I/O Units<br />I/O Units<br />I/O Processor<br />CPU<br />Architecture of a computer system showing its CPU, memory & I/O processors<br />
  85. 85. <ul><li> Multiprocessing systems are of two types:-
  86. 86. Tightly coupled systems
  87. 87. Loosely coupled systems.</li></ul>11/09/2009<br />Operating System<br />Multiprocessing System<br />CPU -1<br />Main memory<br />CPU-2<br />I/O processors<br />I/O processors<br />I/O Units<br />I/O Units<br />Basic Org. of a physical multiprocessing System.<br />
  88. 88. <ul><li> Is a mechanism to provide simultaneous interactive use of computer system.
  89. 89. There are many terminals connected to the same computer.
  90. 90. CPU scheduling algorithm is used.
  91. 91. Concept of Time Slice is used.</li></ul>11/09/2009<br />Operating System<br />Time Sharing System<br />
  92. 92. 11/09/2009<br />Operating System<br />Time Sharing System<br />Job is allocated the <br />CPU for execution<br />Ready<br />Running<br />New<br />Job<br />Job processing completed<br />Allocated time slice is over<br />I/O completed<br />Job must wait for I/O completion<br />Blocked<br />The process state diagram for a time-sharing system<br />
  93. 93. <ul><li>Consists of entering transaction data and viewing the results immediately.
  94. 94. Airline reservation, Railway reservation, & banking are some of the examples.
  95. 95. These OS cannot be modified as it support single application.</li></ul>11/09/2009<br />Operating System<br />Online Operating System<br />
  96. 96. Thanks for your keen interest...<br />11/09/2009<br />Operating System<br />

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