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Chapter 1: Introduction

Operating System Concepts – 9^th Edit9on

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Chapter 1: Introduction

What Operating Systems Do
Computer-System Organization
Computer-System Architecture
Operating-System Structure
Operating-System Operations
Process Management
Memory Management
Storage Management
Protection and Security
Kernel Data Structures
Computing Environments
Open-Source Operating Systems

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Objectives

To describe the basic organization of computer systems
To provide a grand tour of the major components of operating systems
To give an overview of the many types of computing environments
To explore several open-source operating systems

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What is an Operating System?

A program that acts as an intermediary between a user of a computer and the computer hardware
Operating system goals:

Execute user programs and make solving user problems easier
Make the computer system convenient to use
Use the computer hardware in an efficient manner

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Computer System Structure

Computer system can be divided into four components:

Hardware – provides basic computing resources

CPU, memory, I/O devices

Operating system

Controls and coordinates use of hardware among various applications and users

Application programs – define the ways in which the system resources are used to solve the computing problems of the users

Word processors, compilers, web browsers, database systems, video games

Users

People, machines, other computers

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Four Components of a Computer System

Figure: A view of operating system services

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Computer System Organization

Computer-system operation

One or more CPUs, device controllers connect through common bus providing access to shared memory
Concurrent execution of CPUs and devices competing for memory cycles

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Computing Environments - Virtualization

Allows operating systems to run applications within other OSes

Vast and growing industry

Emulation used when source CPU type different from target type (i.e. PowerPC to Intel x86)

Generally slowest method
When computer language not compiled to native code – Interpretation

Virtualization – OS natively compiled for CPU, running guest OSes also natively compiled

Consider VMware running WinXP guests, each running applications, all on native WinXP host OS
VMM (virtual machine Manager) provides virtualization services

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Computing Environments - Virtualization

Use cases involve laptops and desktops running multiple OSes for exploration or compatibility

Apple laptop running Mac OS X host, Windows as a guest
Developing apps for multiple OSes without having multiple systems
QA testing applications without having multiple systems
Executing and managing compute environments within data centers

VMM can run natively, in which case they are also the host

There is no general purpose host then (VMware ESX and Citrix XenServer)

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Computing Environments - Virtualization

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Operating System Concepts – 9^th Edition