Basics Of Operating System, Summaries of Operating Systems

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U U U

WHAT IS AN OPERATING SYSTEM?

An (OS) is an interface between a computer

user and computer hardware.

A software

. which performs all the basic tasks.

. hat enables applications to interact with a computer's

hardware.

The software that contains the core components of the

operating system is called the.

WHAT IS AN OPERATING SYSTEM?

U A program that acts as an intermediary between a

user of a computer and the computer hardware

U 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

FUNCTIONS OF AN OPERATING SYSTEM.

d Memory Management

d Processor Management

d Device Management

d File Management

d Network Management

d Security

d Control over system performance

d Job accounting

d Error detecting aids

d Coordination between other software and users

COMPUTER SYSTEM STRUCTURE

U Computer system can be divided into four components:

. Hardware – provides basic computing resources U CPU, memory, I/O devices . Operating system U 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 U Word processors, compilers, web browsers, database systems, video games . Users U People, machines, other computers

WHAT OPERATING SYSTEMS DO

U Depends on user the point of view U (^) Users want convenience, and

. Don’t care about U (^) But shared computer such as or must keep all users happy U Users of dedicate systems such as have dedicated resources but frequently use shared resources from U Handheld computers are resource poor, optimized for usability and battery life U Some computers have little or no user interface, such as embedded computers in devices and automobiles

OPERATING SYSTEM DEFINITION

U OS is a

. Manages all resources . Decides between conflicting requests for efficient and fair resource use

U OS is a

. Controls execution of programs to prevent errors and improper use of the computer

COMPUTER STARTUP

U is loaded at power-up or reboot

. Typically stored in ROM or EPROM, generally known as . Initializes all aspects of system . Loads operating system kernel and starts execution

COMPUTER SYSTEM ORGANIZATION

U 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

MEMORY LAYOUT FOR MULTIPROGRAMMED SYSTEM