 wrestler rujal summa today we are going to discuss about the basics on operating system now what is operating system the operating system is basically very important program that is get loaded into the computer so everybody knows that operating system is also known as the core of the computer system because whenever we are working in a computer system we need to use so many hardware there will be so many hardware with different way of working, but how these different hardware are basically going to function in a smooth manner. In that case, the operating system is going to help us. So, we can say that operating system is going to create an interface between the user and the computer hardware. Without the help of the operating system, it will be very much difficult for us to work with the computer system. In general, the operating systems work as an interface between the user and the computer hardware. The functions of operating system, when we talk about the functions of operating system, operating system basically performs different different activities. But in general, the functions of operating systems are categorized into two types. Or we can view the different functions of operating system in two viewpoints. They are the user viewpoint and the system viewpoint. When we talk about the user viewpoint, basically we are talking about the top-down approach. So, what is the meaning of this top-down approach? So, when we talk about a computer system, we are also a part of the computer because we are using the computer. So, after that the computer is there, then there are different hardware are there. And ultimately, the things are going to be done by the hardware. So, there is a layer we can see. So, when we talk about the top-down approach. So, as we user, we are just doing the activities and computer is going to give us the output. So, user viewpoint is also known as a top-down approach. And the system viewpoint, second one is the system viewpoint. And when we talk about the system viewpoint, it is basically a bottom-up approach. That means from the system point of view, like from the hardware, how the users are getting access to the computer. So, that is going to be ensured by the user viewpoint. So, in that way the functions are categorized into two types. When we talk about the user viewpoint, there are different functions which come under this category. The first one is the user interface. When we want to use the computer, we need an interface. Basically, it is the platform so that we can make use of the computer. So, the user interface is very important. Like suppose I want to work in a computer. Suppose I want to type something. So, I need a software. So, how I am going to get the software. This is nothing but the operating system which is going to provide us with the user interface. So, there are two types of user interface we have. The first one is the command line interface which is also known as the CLI. And the second one is graphical user interface which is known as the GUI. Second one is the program execution. So, when the program is getting executed, lot of activity need to takes place. The first thing is whenever we are going to start a program, some memory has to be allocated for the program. After that, the program will be loaded into it. Now, who is going to do that in a computer system? It is nothing but the operating system. The operating system is going to first allocate memory for the program. Then the program will be loaded into that memory. So, that activity is going to perform by the operating system. And that particular function comes under the program execution. And the third one is controlling of IO devices. We know that whenever we work in a computer, there are so many input and output devices connected to the computer. For example, we can talk about the mouse. We can talk about the printer. They are all the different input and output devices. Then after what happens like, how these different input and output devices are controlled by the computer. So, for that, the operating system has got some modules inside it, some functions inside it, so that those devices are basically smoothly controlled by the computer. Next is the accessing file system. We all know that whenever some data need to be stored inside the computer, so that data will be stored basically in the form of files. So, these files are actually going to have some space in the hard disk. Now, how the space will be allocated inside the hard disk? This is nothing but again going to be performed by the operating system. The operating system is going to create the file inside the hard disk, so that we can store the data permanently inside the hard disk. Next function is error detection and recovery. We all know that when the computer is functioning, there may be a lot of error. Sometimes it may happen that the computer starts responding as a whole. So, in that case, what happens like, how the computer is again going to start responding. So, if we talk about the earlier versions of the operating system, like we can talk about the Windows 98. So, on those operating system, that feature was not there. When the computer hangs, simply we have to restart the machine. But in the latest operating system, when we talk about the Windows 7, Windows 10, so in those operating system, what happens? Automatically, the program will start responding after sometime. So, this is again one of the very important functions performed by the operating system. So, in that way, the user viewpoint, we have got different functions. Next, let us talk about the functions, which we can see from the system viewpoint. The first one is the resource manager. Now, what is resource? We all know that whenever we are working in a computer, so there are different hardware we need to have. For example, I can talk about the CPU, then we have the different kinds of memories, like the cache memory, random access memory, then the hard disk. So, they all are basically considered as resources. Not only those, like for example, if we talk about the printer, scanner, they all come under the resource. Now, whenever we as a user want to make use of those resources, how those resources will be allocated to us or to our program. And that activity is going to again perform by the operating system. And that comes under the resource manager. So, here we should not get confused with the word like the resource manager. Whenever that manager word comes, it looks like as if it is a human being, but it is not. Because here we are talking about a function which is present inside the operating system. And that function is basically known as resource manager. And the second one is the control program address space. We all know that when the program is on and running, it is going to occupy some space in the memory. And those spaces may not be all the time continuously allocated to the program. It may be randomly in different places in the memory, it may be allocated. So, as a whole, the entire set of addresses which are actually used for a program or allocated to a program is known as an address space. So, that allocation of the address space or controlling the address space of the program is again going to be one of the very important responsibility of the operating system. And that is also going to be performed very smoothly by the operating system. So, this is all about today's class. Thank you.