Lecture 2 - OS Basics

Definition of an Operating System

Management layer between user and the hardware.

Objectives of OS:

  • Run user programs
  • Facilitate access to all computer components
  • Handle resources and tasks efficiently

System Components

  • Process management
  • I/O handling
    • Buffer
    • Interface for device drivers
    • Drivers for specific hard ware devices
  • Main memory management
  • Secondary storage management
    • Tracking of free space
    • Space allocation
    • Scheduling of disk I/O queries
  • File management
    • File/directory creation, deletion and manipulation
    • Backup of files on a non-volatile storage media (secondary storage)
  • Networking
    • Management of port and network addresses for applications
    • Management of communication protocols
    • Management of machine addresses
  • Security management
    • Identify authorized and unauthorized accesses
    • Specify the policies to enforce
    • Provide the means to enforce them
  • Command interpretation
  • System calls: interface between process and OS
    • Parameter passing via a table

OS Evolutions

  • Mainframes
    • Resident monitor
    • Grouping tasks with similar needs
    • Automate sequencing of executions
    • Automatic transfer of control from one task to another
  • Batch systems
  • Batch multi-program systems
  • Timesharing systems
  • Personal systems
  • Multi-processor systems
  • Distributes systems