Operating System Notes

Table of Contents
  1. 1. Introduction
    1. 1.1. What Operating Systems Do
    2. 1.2. Computer-system Organization
    3. 1.3. Computer-system Architechture
    4. 1.4. Operating-system Structure
    5. 1.5. Operating-system Operations
    6. 1.6. Process Management

Introduction

What Operating Systems Do

  • A computer system can be divided into: hardware, operating system, application programs, users
  • An operating system performs no useful function by itself, but provides an environment within which other programs can do useful work.

    Computer-system Organization

  • Bootstrap program in ROM
  • interrupt vector is an array of pointers to interrupt routines.
  • I/O and storage

    Computer-system Architechture

  • Multicore systems are multiprocessor, not all multiprocessor are multicore
  • Blade servers : each processor boots independently and runs its own OS.
  • Clustered System: Individual systems are joined via LAN to provide high availability (service will continue even one fails)

    Operating-system Structure

  • Multiprogramming: Run multiple programs to increase the utilization of the CPU.
  • Time Sharing: is a logical extension of multiprogramming that CPU executes multiple jobs by switching fast.
  • To ensure reasonable response time, use swapping or virtual memory.

    Operating-system Operations

  • A trap is a software-generated interrupt caused either by an error or request
  • Use a mode bit to indicate in user mode or kernel mode to avoid user programs to crash OS.
  • A Timer is used to detect possible infinite loops in user programs.

    Process Management

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