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REAL TIME OPERATING SYSTEM<br />VIVEK  JAISWAL<br />0813331103<br />EC VI B<br />
Operating System<br /><ul><li>Collection of system calls (functions)</li></ul>Provides a set of basic services to interact...
Basic Structure of Operating System<br />
Real Time Operating System<br /><ul><li>Completes its task and deliver services on time
Deterministic – guarantees task completion at a set deadline
Operates in constrained environment where computer memory and processing power is limited
Provides services in definite amount of time
Multitasking or multi-threading</li></li></ul><li>Features<br /><ul><li>Fast
Small and occupy very little memory
Consume fewer resources
Mission-critical
Response times are highly predictable
Unpredictable environment
Life risking applications</li></li></ul><li>Applications of RTOS<br /><ul><li>Air Traffic Control Systems
Networked Multimedia Systems
Command Control Systems
Internet Telephony
Anti-lock Brake Systems
Heart Pacemaker</li></li></ul><li>Types of RTOS<br /><ul><li>Hard Real-Time Systems</li></ul>Meets deadlines with zero deg...
Example of Hard Real-Time Systems<br /><ul><li>Weapons defense system
Missile guidance system</li></ul>Weapons Defense System<br />
Example of Soft Real-Time Systems<br /><ul><li>Networked Multimedia System
DVD or multimedia players
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Real Time Operating System

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Real Time Operating System

  1. 1. REAL TIME OPERATING SYSTEM<br />VIVEK JAISWAL<br />0813331103<br />EC VI B<br />
  2. 2. Operating System<br /><ul><li>Collection of system calls (functions)</li></ul>Provides a set of basic services to interact with the hardware<br /><ul><li>Core of the OS is Kernel</li></ul>Basic structural unit of OS<br />Typically a library or set of libraries<br /> A bridge between applications and the actual data processing done <br />at the hardware level<br />
  3. 3. Basic Structure of Operating System<br />
  4. 4. Real Time Operating System<br /><ul><li>Completes its task and deliver services on time
  5. 5. Deterministic – guarantees task completion at a set deadline
  6. 6. Operates in constrained environment where computer memory and processing power is limited
  7. 7. Provides services in definite amount of time
  8. 8. Multitasking or multi-threading</li></li></ul><li>Features<br /><ul><li>Fast
  9. 9. Small and occupy very little memory
  10. 10. Consume fewer resources
  11. 11. Mission-critical
  12. 12. Response times are highly predictable
  13. 13. Unpredictable environment
  14. 14. Life risking applications</li></li></ul><li>Applications of RTOS<br /><ul><li>Air Traffic Control Systems
  15. 15. Networked Multimedia Systems
  16. 16. Command Control Systems
  17. 17. Internet Telephony
  18. 18. Anti-lock Brake Systems
  19. 19. Heart Pacemaker</li></li></ul><li>Types of RTOS<br /><ul><li>Hard Real-Time Systems</li></ul>Meets deadlines with zero degree of flexibility<br /> Missed deadlines cause catastrophe<br /> Cost of catastrophe is high<br /><ul><li>Soft Real-Time Systems</li></ul>Meets deadlines with some degree of flexibility<br /> Missed deadline does not cause catastrophe<br /> Costs rise in proportion to the delay<br />
  20. 20. Example of Hard Real-Time Systems<br /><ul><li>Weapons defense system
  21. 21. Missile guidance system</li></ul>Weapons Defense System<br />
  22. 22. Example of Soft Real-Time Systems<br /><ul><li>Networked Multimedia System
  23. 23. DVD or multimedia players
  24. 24. Internet telephony</li></ul>Tele-seminars<br />
  25. 25. Tasks<br /><ul><li>Group of instructions performing a function of a system
  26. 26. An independent thread of execution
  27. 27. It is schedulable
  28. 28. Characterized by associated name, unique ID, priority, task control block (TCB), stack & taskroutine
  29. 29. Each task moves from one state to another using finite state machine (FSM)</li></li></ul><li>Task States<br /><ul><li>Executing Actually running
  30. 30. Ready Ready to be dispatched
  31. 31. Blocked Blocked by another task or resource
  32. 32. Waiting Blocked by time</li></li></ul><li>Scheduler<br /><ul><li>Maintains ranked list of tasks based on priority
  33. 33. Makes sure that all tasks meet their timing constraints
  34. 34. It is not a task but a function call [schedule()]
  35. 35. Called at various scheduling points likewise end of ISR, when tasks go to sleep or when they are ready to run
  36. 36. Types of algorithms</li></ul>Preemptive priority based scheduling algorithm<br />Round Robin scheduling algorithm<br />
  37. 37. Preemptive priority based scheduling algorithm<br /><ul><li>Each task has a priority and highest-priority task runs first</li></li></ul><li>Round Robin scheduling algorithm<br /><ul><li>Each task of same priority uses time slice to achieve equal share of CPU execution time</li></li></ul><li>Semaphores<br /><ul><li>A kernel object that one or more threads of execution can acquire or release for the purposes of synchronization or mutual exclusion.
  38. 38. Acts like a key
  39. 39. Allows a task to carry out some operation or to access a resource
  40. 40. Types</li></ul>Binary Semaphore<br />Counting Semaphore<br />Mutual Exclusion Semaphore<br />
  41. 41. Semaphores (Contd.)<br /><ul><li>Binary Semaphore
  42. 42. Counting Semaphore
  43. 43. Mutual Exclusion Semaphore</li></li></ul><li>Message Queues<br /><ul><li>It is like a pipeline through which tasks & ISRs communicate and synchronize with data.</li></li></ul><li><ul><li>Non-interlinked </li></ul> one-way data communication<br /><ul><li>Interlocked</li></ul> one-way data communication<br /><ul><li>Interlocked</li></ul> two-way data communication<br /><ul><li>Broadcast Communication</li></ul>Ways to use Message Queues<br />
  44. 44. Exceptions & Interrupts<br /><ul><li>Exception is any event that disrupts the normal execution of the processor and forces the processor into execution of special instructions
  45. 45. Types </li></ul>Synchronous Exceptions Raised by internal events like processor instructions<br /> “An arithmetic operation that results in a division by zero” <br />Asynchronous Exceptions Associated with hardware signals from external hardware devices<br /> Also called as INTERRUPTS<br />“Pushing the reset button on the embedded board”<br />
  46. 46. I/O Subsystem<br /><ul><li>Hides the device-specific information from the kernel as well as from the application developer and to provide a uniform access method to the peripheral I/O devices of the system.
  47. 47. Defines the standard set of functions called API.</li></li></ul><li>Communication<br /><ul><li>Transfer of data from one task to another task.
  48. 48. Signal the occurrences of events from one task to another task
  49. 49. Control the execution of tasks by other task
  50. 50. Synchronize activities
  51. 51. Implement additional synchronization protocols for resource sharing</li></li></ul><li>RTOS Distributions<br /><ul><li>RTLinux
  52. 52. VxWorks
  53. 53. QNX Neutrino
  54. 54. Windows CE
  55. 55. OSE
  56. 56. freeRTOS</li></li></ul><li>Thank You<br />

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