Lecture 1 Introduction

Operating Systems

Short definition: A software to manage hardware resources.

Provider of a virtual execution environment on top of hardware that is more convenient than the raw hardware interface.

Abstractions

Resource Abstraction
CPU Process
Disk File
Screen Window
Network Socket

Goals

User goals & System goals

Mechanisms and Policies

Policy: what one wants to implememt

Mechanism: how it is implemented

System Implementation

Traditionally written in assembly.

Most current OSs are written in high level languages (C language).

OS Design Principles

Dependability & Performance