#operatingsystemtutorials

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Operating System And Its Functions

Operating System And Its Functions - Operating System Provides Interaction Between User And Hardware.

HARDWARE

CPU - CPU Is Called As Brain Of The System. I/O Devices  - Keyboard, Mouse, Printer, Scanner Etc Are Some Of The I/O Devices. RAM - It Is Called As Main Memory. Hard Disk - It Is Called As Secondary Memory. User Accesses The Hardware Through Operating System. Operating System Works As The Interface Between User And Hardware.

Why There Is A Need Of Operating System?

What Happens If There Is Not Operating System?

If There Is No Operating System And If User Wants To Access The Hardware. The User Need To Write Program To Access Hardware. Through Programs User Accesses Hardware. Repeatedly(Everytime) User Should Write Programs For Different Hardware Devices To Access Those Devices. Example If User Wants To Print A Document, At That Time User Should Write A Program For Printer To Understand It And To Invoke The Printer To Give Print. Like That For CPU, If User Wants To Execute A Job. User Should Write A Program, User Should Give Instruction To The CPU In The Form Of Program. If User Writes Too Many Programs For Too Many Devices For Too Many Times. The Communication Between User And Hardware Becomes Very Complex(Very Tough). Example If User 1 Is Accessing A Hardware Device, The User 2 Cannot Access The Same Device Until The User 1 Releases It. Like That There Are Lot Of Reasons To Use Operating System. The Functions Of Operating System Are The Reasons Why User Needs Operating System To Use Hardware.   Majority Of The People Uses Windows Operating System. The Major Goal Or The Primary Goal Of The Operating System Is To Provide Convenience To The User. This Is Why The Reason Windows Operating System For Many Years It Acquired In Market. 95% Of The Users Used Windows Operating System At Some Point Of Time. Day By Day The Problems Solved By The Operating System Increasing Gradually. User Wants To Solve His Problems Very Fastly.   Throughput - Throughput Means Number Of Tasks Executed Per Unit Time. The Number Of Tasks Done By Operating System Are Increasing At A Particular Amount Of Time. The Through Put Also Increases. So User Need A Operating System Which Has More Convenience And More Throughput. Throughput Is Used Mostly In Linux Operating System. But It Doesn't Mean That Linux Operating System Is Not Providing Convenience. Windows Acquired 95% In The Market Because Of Convenience. In 2018 The Windows Operating System Usage World Wide Is 82%, The Acquisition Of Windows As Decreased As Compared To The Last Years. Linux Acquisition Was 1% Before But Today It Increased Because Of Throughput. Apple (Mac Os) Is Also Good Today In Market But That Is Different. Major Goal Of OS Is Convenience And Throughput.  

Functionalities Of Operating System

First Functionality And Major Functionality Of Operating System Is Resource Management Example - If Multiple Users Are Accessing(Using) Resources(Hardware). Operating System Allocates Hardware Devices Based On The Requirement. It Takes Hardware From One User And Allocates To Another User. In Simple Words, The Operating System Manages The Resources (Hardware). If User Opens 'Task Manager' In The System, User Can See How Much 'CPU' Is Used And How Much The RAM Is Used, All Those Values(Percentage Used) Managed By Operating System. Process Should Not Take More CPU Or Less CPU, Operating System Loading Percentage. Resources Are Used Properly With Operating System. Specially In Parallel Processing. This Management Is Used Where Multiple Users Tries To Access One Device At The Same Time.   Process Management Processes Are Managed By Operating System. Processes Are Executed By Operating System. Example User Using MS Word And At The Same Time User Uses Windows Media Player And Also User Using A Gaming App. Which Means User Is Using Multiple Processes. How All These Processes Should Be Executed. That Is Also Done By Operating System. This Is Done Using CPU Scheduling. To Do This Various CPU Scheduling Algorithms Are Used. CPU Scheduling Means To Execute A Process, User Writes A Simple C Program And That C Program Is Saved With .C(Extention) Now The Program Have To Be Executed Means The 'Program' Becomes 'Process'. This Process Is Executed In 'CPU' So How To Execute That Process In CPU? That Is Done By The CPU Scheduling.   There Are Different Types Of Scheduling Are Used. To Use CPU In Proper And Efficient Way, To Access CPU , To Execute Processes These Algorithms Are Used. All These Are Donf By Operating System. Storage Management Harddisk Is The Secondary Storage Device, Which Stores Data Permanently. How To Store The Data In Harddisk? It Is Managed By Operating System, The Storage Of Data In Harddisk Is Managed By Operating System. Storage Management Is Done Through " File System " NIFS, CFS, NFS Are Used In Linux And Windows Operating System. The Data Will Be Stored In Harddisk And File System Manages The Data Storage In Harddisk. The Data Stored In Harddisk And File System Manages The Data Storage In Hard Disk And Data Stored In Harddisk Through Tracks & Various Sectors Based On The Architecture Of The Harddisk. Memory Management RAM Comes Under Memory Management. RAM Has Limited Size Where Harddisk Has Huge Storage Space. All The Processes Will Be Executed In RAM First. This Is Called As Multi Tasking Or Multi-Programming. All The Processes Will Be First Executed In RAM. From RAM The Processes Will Be Sent To CPU One-by-One. Operating System Allocates Certain Percentage Of Memory To The RAM Based On The Process And After Executing The Executed Value Will Be Taken And The Memory Size Gave To RAM Will Be Deallocated. For Every Process, This Happens. Allocation & Deallocation Of Memory, Managed By Operating System. This Allocating & Deallocating Memory To RAM And Sending Process & Receiving Executed Value From The RAM Called As Swapping. Security Security & Privacy Is Also Provided By Operating System. When User Switches On The System, The System Asks The 'Password' Only The User Who Has Password Can Only Use The System. Windows Uses Carbo Security Protocol And Saves That Password In Files And It Will Not Allot Unauthorized Users To Access System. Operating System Provides Security In Between The Processes In RAM. One Process In RAM Cannot Access Another Process Without Permission. Data Exchange Will Not Be Done And One Process Cannot Interfere With Another Process. Security And Privacy Is Also Provided By The Operating System.   Resource Management, Process Management(CPU Scheduling), Storage Management(Harddisk)- File System, Memory Management(RAM) Are Few Functionalities Of Operating System, There Are Many More Functionalities Are There.

HOW DO USER ACCESSES OPERATING SYSTEM? HAVE YOU OBSERVED? When You Switch On The System, Desktop Is The Interface With Which User Interact. User Opens My Computer, C D E F Drives And Opens Audio, Video, Document Files. User Can Access Files Only Through Application? Or User Can Directly Access The Operating System? Majority Of Users Accesses Operating System Through Applications. Example  If User Wants To Give Print File(Document) User Creates Document In MS Office(Application) From That Application, User Clicks "Ctrl+P" For Print. The Command From Application To Access The Hardware(Printer). Operating System In Between Application & Hardware Is Working Like Interface. User Cannot Feel That. This Is Very Good Creation. User Don't Know When He Is Accessing The OS And When He Is Not Accessing The Hardware.   Another way (SHELL) User Can Access Operating System Directly By Going Into Command Prompt(Cmd Pmpt) And Can Access Kernel. In Linux, User Opens Terminal To Access Operating System And User Enters Different Commands In It Like ( Print, Read, Write, Open Etc) Operating System Works With System Call. Any Command Given Through Application That Invokes System Call In OS.   Example When User Open A File In My Computer->D-Drive, User Double Clicks On The File And File Opens. Operating System Is Opening That File Through Open System Call There Are Alot Of System Calls Through Operating System Works Between User, Application & Hardware.

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Operating System Structure

Operating System Software Is Organised With Operating System Services And The Components Of The Operating System. The Picture Shows You The Operating System Services.

The Above Picture Shows The Overview Of The Operating System Services. Program Execution I/O Operation File Systems Communication Resource Allocation Accounting Error Detection Protection And Security All These Services Are Managed By The Operating System. These Services Work Together. An Operating System Is A Very Complex Software When You Are Developing This Complex Software, You Can Design In The Way In Which The Services Can Work Together. The Early Design Were:- 1. Monolithic/Simple Structure  Which Means There Is No Structure At All, But There Were Ideas To Organise The Interfaces Between The Services, The First Way To Do Those Was Layered Approach 2. Layered Approach  Then There Was Microkernel 3. Microkernel  4. Modular 5. Hybrid Many Modern System Today Use Hybrid, Which Is The Combination Of These Different Types Of Structures.  

Layered Design

Layered Designed Means That You Have Clearly Defined Interfaces Between The Services And The Services Are On A Particular Layer. See The Below Picture,

"Layer 0" Is The Hardware And "Layer N" Is The Applications And The Interface With The Operating System Then All Of The Services Of The Operating System Are Placed On Different Layer. So, A Layer Will Use All Of The Services What Is Below It And The It Will Provide Services What Is Above It. So The Problem Lies In " What If The Service Needs A Service That's In A Layer Above It?" And If It Wasn't Clearly Layered Out Then You Would Have Problems Because In A Strict Hierarchical Layer Software Development Structure You Can Only Use The Layers Below. But There Are Some Benefits Using The Layered Design, You Have Clear Design Clearly Defined Interfaces Between The Services And It Is Good For Development Purposes Because If You Know If A Layer Is Working And Then You Go To Get The Next Above It, You Start Working On The Next Layer Above It, You Start Run Into Problems Then You Know That That's The Problems Are Going To Be In The New Layer That You Are Making. So There Are Benefits If You Use Layered Structure.

  MICROKERNEL Design

In This Design, The Idea Was To Move Most The Services Out Into User'sSpace Run All Those Services As Your Applications And Have Very Very Small Kernal And So When System Goes To Load Up, All You Have To Load Up Is Very Small Kernal Which Is Basically A Communication A Little Bit Of Scheduling And Memory Management And Move All Of The Other Services Of Operating System Out Side Of Kernal Space. So The Benefits Of That Is Its Easier To Port Different Architectures, It's Easy To Extend, You Can Make New Services, That Are User Applications And You Just Have To Bind Them With And Have Them Work With The Micro Kernal, It's More Reliable, Its More Flexible, So There Are Lot Of Benefits To Using This microkernel The Detriment Comes In The Overhead, Now Because The Microkernal Needs To Have Control Of All Of The Applications On The System It Also Have Control Of All The Kernal Services That Are Run As User Applications On The System. So There Is A Ton Of System Calls Going On And A Ton Of System Calls For Communication, So That Is Not A Benefit Of This Because It Slows Down The Process, You Have To Constantly Have The Operating System Get Involved When Any Kind Of Services Need To Work Together.

  MODULAR

The Modular Is The Latest And Uses The Object-Oriented Approach, This Has Small Kernal. The Components Once They Are Loaded In They Can Work Together So Its Similar To A Layered And There Is Interfaces Between The Servies Its Similar To The Microkernel And That It Has A Small Kernal And More Flexible And This Is Clearly The Best Way For Implementation And However If You Notice When You Get To The Point Where You Are In Modular You Have All Of These Services Working Together And Interfacing With Each Other Without Kernal Involvement Then You Are Actually Almost Coming Right Back To Around To A Modal Effect Structure Where You Just Have Processes That Are Running On Your System And Not In Any Kind Of Strict Hierarchy.

HYBRID STRUCTURE

So Most Systems Do Use A Hybrid Structure Where They Would Have Some Type Of Layered Structure With Certain Functions And Services And Certains Layers And May Be A Microkernel And They Are Just Modulars There Is Always New Ideas Come Along But This Is Just A Basic Understanding Of The Different Ways You Can Structure The Services And The Software Of The Operating System.  

Modular Vs Layered

Modular vs Layered Comparision

Virtual Machine

Virtual Machine Allows One Hardware To Run Different Types Of Systems Now This Is Been Around A Very Long Time I Know Now You Can Run Windows On Apple Computer But The Idea Came About A long Time Ago Four Isolating Different Systems From Each Other On One Hardware For Testing, So It Was Developed A Long Time Ago This Virtual Machine It Usually Didn't Have A Host Operating System It Just Had A Host Software Which Was Called A Virtual Machine Monitor Or Virtual Machine Manager And You Could Run Different Completely Isolate Each System From Each Other And Run Different Processes All On One Hardware Or Run Different Operating Systems On The Same Hardware And One Could Crash And It Wouldn't Effect The Other One.

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Operating System

Operating - Controlling The Functioning, System - A Set Of Connected Things. Operating System Means Controlling The Functioning Of A Set Of Connected Things. This Is The Meaning Of Operating System.

Example - Head Of The Government Is A Operator Of The Systems. Every System In Government Has A Head, That System Is Operated By The That Head As Operator. How Is Operating The System Is This Subject? Confused? Hmm I'll Explain Operating Sy stem In A Computer. Windows 7, Windows 8, Windows 10, UNIX, Mach, MS-Dos, MS-Windows, Windows/NT, Chicago, OS/2, MacOs, VMS, VMS, And Vm Are The Operating Systems Of Computer.

Why Operating System?

What Is Operating Sy stem In Computer? Operating System(OS) Is A Program Or Software That Manages The Computer Hardware. Examples - Windows 7, Windows 8, Windows 10, UNIX, Mach, MS-Dos, MS-Windows, Windows/NT, Chicago, OS/2, MacOs, VMS, VMS. It Also Provides A Basis Of Application Programs And Acts As A Intermediary Between Computer User And Computer Hardware.

What Is a Computer System? A Computer Is A Mixture Of Monitor, Cpu, Mouse, Key Board Etc. Monitor, CPU, Mouse, keyboards Are The Computer Hardware. Monitor Mouse, Keyboard, Speaker, Microphone Are I/O Devices.               Read the full article