In this blog introduction to the operating system and then we'll discuss what are the functionalities of operating system So what operating system basically is an Operating system is a system software Means it's a software that is in your system And its basic functionality or definition is It works as an interface between user and hardware It's in very simple language that operating system is providing interaction between user and hardware Now if we'll see in this diagram first Which of these is hardware If we'll take the scenario of our laptop In our laptop or desktop What hardware basically is CPU Which we call brain of the system CPU Then input, output devices which includes keyboard, mouse, printer, scanner Then RAM that we call the main memory Then secondary memory i.e. Hard Disk So when we access a lot of this hardware When i'm accessing my system, then I'm just accessing these devices But Am I directly accessing those devices?
Is the user directly accessing the hardware and devices?
He's accessing through what?
Through the operating system, the operating system is working as an interface here Then second point is why?.
Why there's a need of operating system If there'll be no operating system then what will be the scenario So the scenario will be that if user wants to access a particular hardware, he have to write a program for it And through that program he'll always access that device Means he always have to write a program to access those devices He have to write different programs for different devices again and again So when he'll write this much program in repetition I have to give a print command simply I have a word file that needs to be printed then I can't print it directly First I have to write a program for it So that printer will know it that it has To print1 Similarly if we'll talk about CPU If I want to execute a process or a job then that job execution is later work, first we have to give CPU an instruction, And how we'll give that instruction? For that we have to write individual program And because of that the interaction between user and hardware will be very complex There could be another way also It could be possible that user is accessing one hardware And if other user wants to access that hardware then I'm not releasing it Why? Because I'm the user accessing the hardware directly, means there's no authority in between who can take back the hardware from me So there're a lot of reasons because of which we need to use operating system That's being used as an interface between user and Hardware We'll see that in functions,
All the functions of operating system, we can call them as these are the reasons why we are using operating system in our system So if I'll give basic example of operating system So the first operating system that's used in majority is Window's Now primary functionality of operating system If we'll say why we are using operating system The major\primary goal of operating system is To provide convenience To the user Yess
It provides convenience Means I can access my hardware in easiest way That is the functionality of operating system And this is the reason that's why Window's acquired the whole market up to many years There was a time when Window’s acquired 95% of the market means the whole market was acquired my Microsoft They had this much popularity! Because the major goal is convenience, and window's is providing convenience the most If you'll see in your or your friend's laptops, the operating system you'll get is window There could be different versions in Window's like 2007, 2008 etc that depends But why are we providing Window's basically? Because of convenience, but gradually with time, the problems that we were solving in our systems started to get complex And the value of time is increasing so much for the user Means user wants, that his problem should get execute very fast and for that we need through put What through put means in a simple definition is Number of tasks executed put unit time That is a simple definition of through put So the more no. of tasks are getting executed in a particular amount of time, the more will be my through put It means we need such operating systems now whose through put is high as well as convenience is high So the maximum use in through put is Linux Although Linux operating system doesn’t mean that it's not providing convenience I'm just comparing it because why window's acquired 95% of the market because of the only reason i.e. convenience But now if we'll see at present in 2018, it is approximate 82% Means, now their acquisition in market has become low as compared to last years
Now Linux, that was in 1-2% before has now increased because of through put And other than this we are having Apple's it's own operating system that is Mac or Macintosh, that also runs well in the market But that is a different thing these are real life example like window's, Linux and Macintosh But the major goal is convenience and through put Next part that comes here is What are the functionalities of operating system Means if I've put operating system in my system, then what are its functionalities
Then major functionality of operating system is First one is, resource governor or resource manager It manages the resources How we manage resources? If I'm an alone user and accessing my system by my own Then at that point I don't need resource governor that much Means, where ever there is parallel axis Means when multiple user are accessing a system that works happen in majority on server level If we would talk about a server where a lot of users are sending requests to access some data at that point operating system is useful and works as resource manager How much hardware to be provided to which user or for how much amount That is done by the operating system after that time it will take back that device from the user This is how we manage resources so that there'll be no load on the system the moment we open normal task manager in our system
Then you'll easily get a lot of values like that that how much percent we are using CPU, How much the RAM All that values are managed by operating system So there'll be no that much load on the system and not much less also means it tries to manage resources properly But specially where it uses is parallel processing, where multiple users are trying to access one device Second point is storage management Or we can say it as process management process management means we are managing processes in majority in our system Means we are executing processes, I opened the laptop and I'm working on Microsoft word on it Along with that I've opened my Window Media player also Along with that I've opened gaming app also Means I'm sitting with multiple process opened How to execute all these processes that is also done by the operating system How it works?? CPU scheduling Here we use CPU scheduling algorithms CPU scheduling means
If I wrote a simple program and saved it with .C, now I want to execute that program then that program became process Now if we want to execute the process then where will we do it? at the CPU Now how to execute that process at CPU That is done by the CPU scheduling And there comes a variety of algorithms that are useful to access and execute in a efficient way And who is handling all that management? Operating system Other than this we have storage management Storage management means Basically storage includes secondary devices i.e. Hard disk Means the data that we want to store in our system permanently Operating system is managing how to store that data And how we do storage management? Through file system NIFS, CFS etc CIFS and NFS Common interface file system, common internet file system and networked file system all these get used in Linux and Window's their major goal is
It manages how to store all my data in the hard disk permanently That how to store it in tracks or sector in disk's architecture, that is also managed by the operating system Then fourth one is memory management In memory management, what I have here is RAM Because If we would say why we have separated storage management and memory management, because storage management consist hard disk, It's operating system's functionality to manage hark disk but there's no constraint of hard disk, we have a constraint in RAM i.e. limitation of size Means RAM in our system is limited And all the processes gets executed first in the RAM This topics is called the concept of multi-tasking or multi programming Means all the processes that we have to execute
We bring all that first of all in the RAM And when it comes in the RAM, then we transfer it to CPU one by one So how much memory of the RAM we have to give and take that memory back when the process is done Allocation & Deallocation
Because the RAM is limited It shouldn't be like, the process has become executed but it's still in the RAM And the other process that wants to get executed is not able to come in RAM, because it's full already so what operating system does is When a process is done, then it takes out of it and bring the other one This is called the swapping, so these are whole individual topics and units, I'm discussing here that what the functionalities are I've already discussed about them,
Where we've talked about memory management, Storage management and disk or file system, we have already discussed CPU scheduling and resource management Other than this we have 5th I'm writing the functionality here i.e. security Security and privacy It's also provided by the operating system
Whenever we turn on our system, what we first get is the password So why we put that password? . So that authenticate person who have its proper password can access it And window's uses Kerberos security protocol to keep that password properly in secured files so that no one can access it Other than this, in the RAM as I told before, when we executes a process then it gets a portion in the RAM, like it got a memory allocation 0-100 One process is P2 ,
it got memory allocation of 101-200 If any process calls or executes any instruction outside the given segment, then that process gets block instantly Means if any instruction of P2 is accessing the data or interfering in the data, then that process gets blocked Means it's providing security in between the processes so that no processes can do interfere or data change with each other
So security and privacy is also provided by the operating system I've many other functionalities here but these are major functionalities of operating system Here I would like to tell a last point here, that as I wrote in diagram, user application What's the application here is . How do we access operating system as a normal user If you'll notice when you turn on your laptop then desktop appears, that's an interface, we can go to my computer, can access data,
We can access any movie or song in C, D, OR E drive Now in actual, user can either access through application or can access direct also We uses application in majority, like if I want to print a particular file then what I do is, First I'll create that file in Microsoft office That a kind of application when we enter ctrl+ P, then it asks "Do you want to print' Yes? then you gave the print command What is that print command actually? We are accessing the hardware with it But you are accessing the hardware through the application directly, and operating system is working as an interface here Do you feel anything like that? No
We as a user don't feel this So it's providing so nice interface that users don't even feel when they're accessing the hardware and when not Or the other way is shell Like if we would talk about window then we can access the operating system or kernel through command prompt And in Linux, we opens the terminal and can write the command directly in it That's through the command prompt we have to write particular command in it that's called System call Operating system basically works in a system call, here I'm just giving you an introduction that whenever operating system will work It'll work through a system call
So whenever we are giving a command through an application like print, then print will invoke a system call and that system call is right Sam way if you are opening a file in C or D drive with double click We just opened normally with double click and file got open But how operating system opened that file?? through open system call Means there're a lot of system calls like read, open, right through which operating system works between application, user and hardware So these are basic functionalities or goal of operating system that you have to keep in mind It can be asked in normal theory, or GATE or UGC NET In majority it will come in your college or university level exams Thank You!
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