OPERATING SYSTEM INTRODUCTION. OBJECTIVES o o To define the term Operating System. o o Computer System layers. o o Types of Operating Systems. o o Interpret

OPERATING SYSTEMOPERATING SYSTEM

INTRODUCTIONINTRODUCTION

OBJECTIVESOBJECTIVES

o To define the term Operating System.o Computer System layers.o Types of Operating Systems.o Interpret the basic functions of

Operating System.

GOALS OF GOALS OF AN OPERATING AN OPERATING

SYSTEMSYSTEMo To make the computer system

convenient to use.

o To use the computer hardware in an efficient manner.

PURPOSE OF AN PURPOSE OF AN OPERATING SYSTEMOPERATING SYSTEM

The purpose of an operating system is

to provide an environment in which a

user may execute programs.

Users

Application Programs

Operating system

Computer Hardware

Abstract view of the components ofAbstract view of the components ofa computer systema computer system

WHAT IS AN OPERATING WHAT IS AN OPERATING SYSTEM?SYSTEM?

An Operating System is an interface between user and hardware of a computer system.


An Operating System is a system software which may be viewed as an organized collection of software consisting of procedures for operating a computer and providing an environment for execution of programs.

OTHER DEFINITIONSOTHER DEFINITIONS

o An Operating System is a control

program.

o An Operating System is similar to a

Government.

o An Operating System can be defined as a

Resource Manager.



program.


Government.


Resource Manager.

This program controls the execution This program controls the execution of user programs to prevent errors of user programs to prevent errors and improper use of the computer.and improper use of the computer.



program.


Government.


Resource Manager.

As a resource manager and allocator, the As a resource manager and allocator, the OS will resolve the confliting request for OS will resolve the confliting request for computer resources(CPU time, memory computer resources(CPU time, memory space, files storage space, input/output space, files storage space, input/output devices, etc) from various users or devices, etc) from various users or programs.programs.

COMPUTER COMPUTER HARDWARE & SOFTWAREHARDWARE & SOFTWARE

o H/w - Physical Components of a

Computer.

o S/w – Set of Computer Programs.

COMPUTER SOFTWARECOMPUTER SOFTWARE

Application ProgramsApplication ProgramsSystem ProgramsSystem Programs

o Which manages Which manages the operations of the operations of the computerthe computer

o Which manages Which manages the operations of the operations of the computerthe computer

o Which solve Which solve problems for problems for their userstheir users

o Which solve Which solve problems for problems for their userstheir users


o It is the most fundamental of all the system programs, which controls all the computer’s resources and provides the base upon which the application programs can be written.

o It is a layer of s/w on the top of the bare h/w, which will shield programmers from the complexity of the h/w.

COMPUTER SYSTEMCOMPUTER SYSTEM

Physical DevicesPhysical Devices

MicroprogrammingMicroprogramming

Machine LanguageMachine Language

Operating SystemOperating System

CompilersCompilers

Banking Banking SystemSystem

Airline Airline SystemSystem

EditorsEditorsCommand Command

InterpreterInterpreter

Application ProgramsApplication Programs

System ProgramsSystem Programs

HardwareHardware

A Computer system consists of Hardware, System Programs and A Computer system consists of Hardware, System Programs and Application ProgramsApplication Programs






CompliersCompliers






Integrated circuit chips, Integrated circuit chips, wires, power suppliers, wires, power suppliers, cathode ray tube, etc.cathode ray tube, etc.






CompliersCompliers






Directly controls the Directly controls the physical devices and physical devices and provides a cleaner provides a cleaner interface to the next interface to the next layer. It interprets the layer. It interprets the instructions from the instructions from the above layer and carry above layer and carry out them.out them.






CompliersCompliers






Instructions for moving Instructions for moving data around the machine, data around the machine, doing arithmetic and doing arithmetic and comparing values. I/O comparing values. I/O devices are controlled by devices are controlled by loading values into loading values into specified device specified device registers.registers.






CompliersCompliers






Major function is to hide Major function is to hide all h/w complexity and all h/w complexity and give the programmer a give the programmer a more convenient set of more convenient set of instructions to work instructions to work with.with.






CompliersCompliers






The OS runs in kernel The OS runs in kernel mode but the compilers mode but the compilers and editors run in user and editors run in user mode. If a user does not mode. If a user does not like a particular like a particular complier, the user is free complier, the user is free to write his own but he to write his own but he is not free to write his is not free to write his own disk interrupt own disk interrupt handler, which is part of handler, which is part of the OS.the OS.






CompliersCompliers






These programs are These programs are written by the users to written by the users to solve their particular solve their particular problems, such as problems, such as commercial data commercial data processing, engineering processing, engineering calculations, or game calculations, or game playing.playing.

A computer’s Operating system is a group of A computer’s Operating system is a group of programs designed to serve two basic programs designed to serve two basic purposes:purposes:

To control the allocation and use of the To control the allocation and use of the computing system’s resources among the computing system’s resources among the various users and tasks.various users and tasks.

To provide an interface between the To provide an interface between the computer hardware and the programmer.computer hardware and the programmer.

PURPOSE OF AN PURPOSE OF AN OPERATING SYSTEMOPERATING SYSTEM

Distinguished by the nature of interaction Distinguished by the nature of interaction that takes place between the computer that takes place between the computer user and his/her program during its user and his/her program during its processing.processing.

Batch Operating SystemBatch Operating System

Time-Sharing Operating SystemTime-Sharing Operating System

Real-Time Operating SystemReal-Time Operating System

TYPES OF OPERATING TYPES OF OPERATING SYSTEMSYSTEM






Users submit jobs to a central place where these jobs are collected Users submit jobs to a central place where these jobs are collected into a batch, and subsequently placed on an input queue at the into a batch, and subsequently placed on an input queue at the computer where they will be run. The user has no interaction with computer where they will be run. The user has no interaction with the job during its processing. The computer’s response time is the the job during its processing. The computer’s response time is the turnaround time- the time from submission of the job until turnaround time- the time from submission of the job until execution is complete, and the results are ready for return to the execution is complete, and the results are ready for return to the person who submitted the job.person who submitted the job.






Computer provides computing services to several or Computer provides computing services to several or many users concurrently on-line. Various users are many users concurrently on-line. Various users are sharing the central processor, the memory and other sharing the central processor, the memory and other resources of the computer system. The user has full resources of the computer system. The user has full interaction with the program during its execution.interaction with the program during its execution.






A RTOS is designed to support execution of tasks A RTOS is designed to support execution of tasks within specific wall clock time constraints. Use of within specific wall clock time constraints. Use of RTOS is mostly limited to dedicated applications such RTOS is mostly limited to dedicated applications such as industrial control systems, weapon systems and as industrial control systems, weapon systems and computer-controlled products. RTOS is managing the computer-controlled products. RTOS is managing the resources so that a particular operation executes in resources so that a particular operation executes in precisely the same amount of time every time it occurs.precisely the same amount of time every time it occurs.

Buffering and Spooling:Buffering and Spooling:

More ways to overlap CPU with More ways to overlap CPU with slower operations.slower operations.

BufferingBuffering:- overlap computing with :- overlap computing with

I/O for same job.I/O for same job.

SpoolingSpooling:- overlap computing with :- overlap computing with

I/O for different jobs.I/O for different jobs.

Buffering & SpoolingBuffering & Spooling

SpoolingSpooling

A multiprogramming operating system is A multiprogramming operating system is a system that allows more than one a system that allows more than one active user program to be stored in active user program to be stored in main memory simultaneously.main memory simultaneously.

Time-sharing systems are Time-sharing systems are multiprogramming systems.multiprogramming systems.

MULTI PROGRAMMINGMULTI PROGRAMMING

Multiprogramming:Multiprogramming:• Multiprogramming was used as a Multiprogramming was used as a

technique to enhance the throughput technique to enhance the throughput efficiency.efficiency.

• More than one job is “ready” at the More than one job is “ready” at the same time.same time.

MULTI PROGRAMMINGMULTI PROGRAMMING

Different types of Different types of Multiprogramming Operating Multiprogramming Operating SystemSystem

• Multitasking operating systemMultitasking operating system• Multiprocessing operating systemMultiprocessing operating system• Multi-user operating systemMulti-user operating system



More than one active user programs to be stored in the More than one active user programs to be stored in the main memory.main memory.



A computer hardware configuration that includes more A computer hardware configuration that includes more than one independent processing unit.than one independent processing unit.

NETWORK OPERATING NETWORK OPERATING SYSTEMSYSTEM

The Software that enhances a basic The Software that enhances a basic Operating System by adding Networking Operating System by adding Networking Features.Features.

Examples:Examples: Novell Netware,Novell Netware,

WINDOWS NTWINDOWS NT

• A networked computing system is a A networked computing system is a collection of physical interconnected collection of physical interconnected computers.computers.

• The OS of each of the interconnected The OS of each of the interconnected computers must contain provisions for computers must contain provisions for handling communication and transfer handling communication and transfer of program and data among the other of program and data among the other computers, in addition to its own stand-computers, in addition to its own stand-alone functionality.alone functionality.

Networking Operating SystemNetworking Operating System

A distributed computing system consists A distributed computing system consists

of a number of computers that are of a number of computers that are

connected and managed so that they connected and managed so that they

automatically share the job processing automatically share the job processing

load among the constituent computers, or load among the constituent computers, or

separate the job load as appropriate separate the job load as appropriate

particularly configured processors.particularly configured processors.

Distributed Operating SystemDistributed Operating System

DISTRIBUTED OPERATING DISTRIBUTED OPERATING SYTEMSYTEM

Distributed operating system is one that Distributed operating system is one that

looks to its users like an ordinarily looks to its users like an ordinarily

centralized operating system but runs on centralized operating system but runs on

multiple independent CPU’s. Key concept multiple independent CPU’s. Key concept

is TRANSPARENCY.is TRANSPARENCY.

In n/w os, the users are aware of the existence In n/w os, the users are aware of the existence

of multiple computers and can log in to remote of multiple computers and can log in to remote

machines and can copy files from one machine machines and can copy files from one machine

to another ……to another ……

D.os appears to its users as a traditional uni-D.os appears to its users as a traditional uni-

processor system, even though it is actually processor system, even though it is actually

composed of multiple processor..composed of multiple processor..

Transparency- users should not be aware of Transparency- users should not be aware of

where their programs are being run or where where their programs are being run or where

their files are located ….their files are located ….

Networked vs. DistributedNetworked vs. Distributed

FUNCTIONS OF FUNCTIONS OF OPERATING SYSTEMOPERATING SYSTEM

o Memory managementMemory managemento Process managementProcess managemento Device managementDevice managemento Information managementInformation managemento Protection Protection o Error HandlingError Handling



The o/s keeps track of the memory, what parts are in use and by whom.



The o/s keeps track of processors The o/s keeps track of processors and the status of processes. It and the status of processes. It decides who will have a chance decides who will have a chance to use the processor.to use the processor.



The o/s keeps track of the devices, channels, control units and decides what is an efficient way to allocate the device.



O/S keeps track of the information, its location, use, status etc. and decides who gets use of the resources, enforce protection requirements



An o/s is to protect the user from An o/s is to protect the user from unauthorized access of his files or unauthorized access of his files or data. And also it should protect itself data. And also it should protect itself from usersfrom users



An o/s must respond to errors by An o/s must respond to errors by taking the appropriate actions.-*taking the appropriate actions.-*

FILE CONCEPTFILE CONCEPT

o File is a collection of related information. File is a collection of related information.

o It is named and is referred by its name. It is named and is referred by its name.

o Files are organized into directories for easy Files are organized into directories for easy access.access.

DIRECTORY STRUCTUREDIRECTORY STRUCTURE

ROOT D0

F1

D3D2

D21 D31

F311

F31F21

D1

D311

o Operating system is an essential Operating system is an essential component of system software component of system software which consists of procedures for which consists of procedures for managing computer resources. managing computer resources.

o Operating system functions Operating system functions primarily includes Memory, primarily includes Memory, Process, Device and File Process, Device and File management.management.

SUMMARY: SUMMARY:

Thank YouThank You

Murugan R. MCA, M.Phil, DRDBMSMurugan R. MCA, M.Phil, DRDBMSSenior LecturerSenior Lecturer

Dept. of Computer ApplicationsDept. of Computer ApplicationsMES College MarampallyMES College Marampally

[email protected]@[email protected]@gmail.com

Documents

OPERATING SYSTEM INTRODUCTION. OBJECTIVES o o To define the term Operating System. o o Computer System layers. o o Types of Operating Systems. o o Interpret