Chapter 1 Introduction to Operating System

Chapter 1 Introduction to Operating System

1. Operating System

   • A program that controls the execution of application programs
   • An interface between application and hardware
   • Main objectives of an OS
     • convenience
       • An OS makes a computer more convenient to use
     • efficiency
       • An OS allows the computer system resources to be used in an efficient manner
     • ability to evolve
       • An OS should be constructed in such a way as to permit the effective development testing and introduction of new functions without interfering with service
   • An intermediary between computer user and computer

2. The Role of an OS

   • The OS is responsible for managing these resources
     • movement
     • storage
     • processing of data

3. Evolution of Operating System

   • Reason of evolve
     • hardware upgrades
     • new types of hardware
     • new services
     • Fixes
   • Stage
     • Serial Processing
     • Simple Batch System
     • Multiprogrammed Batch System
     • Time Sharing System

4. Characteristics of Real Time Systems

   • Determinism
   • Responsiveness
   • User control
   • Reliability
   • Fail-soft operation

5. Soft real-time task

   • has an associated deadline that is desirable but not mandatory

6. Hard real-time task

   • one that must meet its deadline

7. Asymmetric Multiprocessing (AMP)

   • Several processes can run in parallel
   • all processors can perform the same functions
   • Peer-to-peer relationship between processors

8. Distributed Systems

   • Loosely coupled system
     • each processor has its own local memory
     • processors communicate with one another through various communications lines
   • Advantages
     • Resources Sharing
     • Computation speed up
     • Reliability
     • Communications requires networking infrastructure

9. Symmetric Multiprocessing (SMP)

   • Master-slave relationship among the processors
   • Each processor is assigned a specific task
     • Master processor
     • Slave processor

10. Parallel Systems

    • Multiprocessor System
    • Tightly coupled system
      • processors share memory and a clock
      • communication usually takes place through the shared memory
    • Advantages
      • Increased throughput
      • Economical
      • increased reliability
        • graceful degradation
        • fail-soft systems