COMP 3511: Lecture 1

Date: 2024-09-26 13:41:44

Reviewed:

Topic / Chapter: Basic OS

summary

ā¯“Questions

Notes

Introduction to the Course

  • Introduction

    • learning goals
      • fundamental principles, strategies, and algorithms
        • for design & implementation of operating systems
      • analyze & evaluate OS functions
      • understand basic structure of OS kernel
        • and identify relationship between various subsystems
      • identify typical events / alerts / symptoms
        • indicating potential OS problems
      • design & implement programs for basic OS functions and algorithms
    • course overview
      • overview (4)
        • basic OS concept (2)
        • system architecture (2)
      • process and thread (12)
        • process and thread (4)
        • CPU scheduling (4)
        • synchronization and synchronization example (2)
        • deadlock (2)
      • memory and storage (8)
        • memory management (2)
        • virtual memory (3)
        • secondary storage (1)
        • file systems and implementation (2)
      • protection (1)
        • protection (1)
        • security - optional
Operating System

  • Operating system components

    • users: people, machine, other computers / devices
    • application programs: defining ways how system resources are used
      • to solve user problems
      • e.g. editors, compilers, web browsers, video games, etc.
    • operating system: controls & coordinates use of computing resources
      • among various application & different users
    • hardware: basic computing resources: CPU, memory, IO devices 01_os_levels

  • Operating system introduction

    • OS: a (complex) program working as intermediary between: user-applications and hardware
      • iOS, MS Window, Android, Linux, etc.
    • OS goals:
      • execute user programs & solve user problems easier
      • make computer system: convenient to use
      • manage & use computer hardware efficiently
    • user view:
      • convenience, easy of use, good performance & utility
      • user: doesn't care about resource utilization & efficiency
    • system view:
      • OS: resource allocator & control program
    • no universally accepted definition, but:
      • "everything vendors ships when you order an OS"
    • OS as a resource allocator
      • managing both SW & HW resources
      • decides among conflicting requests: for efficient & fair resource use
    • OS as a control program
      • controls: execution of programs, prevent errors & improper use of computer
    • OS: manages & controls hardware
      • helps to facilitate (user) programs to run

  • OS breakdown

    • kernel: one program always running on computer
      • provides essential functionalities
    • middleware: set of SW frameworks: provide additional services to app dev
      • e.g. DB, multimedia, graphics
      • popular in mobile OS
    • all else:
      • system programs
      • application programs
    • OS includes:
      • always running kernel
      • middleware frameworks: for easy app development & additional feature
      • system programs: aid in managing system while running

  • Operating system tasks

    • depends on: PoV (user vs. system) and target devices
    • shared computers (mainframe, minicomputer)
      • OS: need to keep all users satisfied
      • performance vs. fairness
    • individual systems (e.g. workstations) with dedicate resources
      • performance > fairness; may use shared resource from servers
    • mobile devices: resource constrained
      • target specific user interfaces (touch screen, voice detection)
      • optimized for usability & battery life
    • computers / computing devices w/ little-no UI
      • embedded systems: present within home devices, automobiles, etc.
        • run real-time OS
      • design: run primarily without user intervention
Computer System Organization

  • Computer system organization

    • one or more CPU cores & device controllers: connected through common bus
      • providing access to shared memory
    • goal: concurrent execution of CPUs and devices
      • compete for memory cycles w/ shared bus 02_computer_system_org

  • Von Neumann architecture: composition

    03_von_neumann

    • CPU: contains ALU & processor registers
      • programmer counter (PC)
      • accumulator (AC)
      • memory address register (MAR)
      • memory data register (MDR)
    • control unit: contains
      • instruction register (IR)
      • program counter (PC)
    • memory: w/ data and instructions
      • as well as caches
    • external mass storage / secondary storage for more space
    • input-output mechanism

  • Von Neumann architecture

    • steps
      • fetch instruction
      • decode instruction
      • fetch data
      • execute instruction
      • write back (if any)
    diagrams
    • 04_von_neumann_again
    • 05_instruction_cycle