Lecture 1 - Introduction

Overview

• the operating system is the software layer that sits between application programs and the hardware

Roles of the OS

Abstractions

• create abstractions to ease the use of hardware
  • CPU -> threads
  • memory -> address space
  • disk -> file system
  • network card -> sockets

Resource Management

• manage shared hardware resources
  • processor
  • memory
  • disk
  • network
• goals
  • safety
  • efficiency
  • fairness

OS <-> Apps Perspective

• the OS is the main program
  • calls applications as subroutines
  • application runs until it returns control back to OS

History

Single Operator at Console (Synchronous)

• goal: basic functionality
• OS is library of standard services
• one thing happens at a time
  • gain interactivity
  • poor utilization of hardware

Batch Processing

• goal: improve utilization by removing user interaction
• non-interactive: submit job to queue, wait for completion
• OS is library of standard services + batch monitor