An operating system also abbreviated as OS is a program that manages the computer hardware and it also provides a basis for application programs and acts as an intermediary between computer user and computer hardware. Some examples of operating systems that we are using widely now days.
First is your windows so you may be using Windows in your desktop or your laptops so it is one of the famous operating systems used by many people and also we have Linux and Ubuntu which are also two open-source operating systems that are widely used in your desktops laptops and other devices and then we have the Mac OS which is the operating system from Apple so in their laptops or in their mac books they used Mac OS X and then in iPhones we find iOS operating systems and then we have the very famous Android which you must be having in your phones. So Android is one of the famous operating systems that is used for your mobile devices.
The basic structure of computer system so that we can understand what is an operating system and what does an operating system actually do so here I have a diagram which represents the basic structure or the basic components of a computer system.
Now we will discuss the component of this block diagram one by one.
So first of all in the lower most level we have the computer hardware and what is computer hardware? Computer hardware it consists of resources like CPU which is a central processing unit and then memory and then the I/O devices which means input/output devices. So your resources like the processing units your CPU and also your memory. Memory consists of primary memory like your RAM and your secondary memory like your ROMs. So let’s first know that our memory as well as the I/O devices. An I/O device means the input/output devices. These are the devices that you use for either giving input to your system or for getting output out of your system. So examples of input devices will include your devices like your keyboards, mouse, microphones. These are devices that you use for giving input into the system and then output devices would be that devices that you use for getting output out of your systems that would be your devices like monitors or speakers which gives you output or which shows you or makes you hear the output. Those are your output devices so all these things fall under computer hardware.
On top of the computer hardware in the block diagram we have the operating system but for now let us just forget this operating system for a while just let’s just assume that it is not there and then on top of this operating system we have the system or the application programs. Now there are two kinds of software’s we have which is system software and application software.
System software’s are the software’s that are used to directly modify or directly give some command to the computer hardware and operating system is also a kind of system software but let’s not think about that and just not get confused hearing that but mainly try to understand what are application programs? Application programs are the programs or software’s that are used to perform a specific task and that can be directly used by the user and these are some examples that we have in the above diagram which are word processor. word processors are like your Microsoft Office Word which are software’s used for making document files I have believed that we have all used Microsoft Word and then we have spread sheets. Spread sheets are like your Microsoft Excel that is used for making tabular data or for making some calculations in your table or data and then we have compilers. So compilers are the software’s that we use for writing our computer code like your codes like C++, C or Java these are written into your compilers and then we have the text editors. Text editors are editors useful modifying or writing text like your notepad WordPad etc and then we have web browsers web browsers are the software’s that enable you to browse the web even as you are watching video in YouTube. You may be using some web browser to view this and examples of these browsers are Google Chrome, Mozilla Firefox, Internet Explorer and so on. So these are the application programs we have and on top of that we have the users that are like users like you and me who are trying to use these softwares for performing specific tasks. So let us take a simple example that this user one he wants to use the word processor. Let’s say it is Microsoft Office Word so we want to use Word for typing some documents and he wants to save it to his system. So let’s see how he does it so we imagine that there is no operating system over here we just have this user and the application programs and then the computer hardware so if you wants to write a document or if you want to type something into Microsoft Word then he have to tell the computer how where that he wants to do it now how can he do it since there is no operating system. He has to explicitly tell the computer hardware what he wants to do in the form of code. So he has to first open the Microsoft Word and he have to tell the computer hardware that I want to load Microsoft Word. So please load it into the main memory and then after it is loaded he has to type something and when he typed something whatever he types it has to be displayed on the monitor. He has to tell the computer hardware to do even that you have to tell please display the things that I am typing on the computer screen or on the monitor and then after doing all that he have to save it and even for saving it you have to tell the computer hardware.
Now please save this file with a particular file name to my hard disk. so for each and every small on my new task you have to perform, you have to explicitly tell the computer hardware what to do and how do you communicate to it in the form of codes. You have to write source code you have to write codes for each and everything that you have to perform. So we see that it is a very tedious task or it is a very difficult task to do this if there is no operating system you have to manually tell the computer hardware. Each and everything that you have to do so if it was like this then nobody would actually use a computer system or at least common people would not use the computer system because it is such a tedious thing and it is very difficult to perform even the simplest of tasks. So in order to avoid this or to overcome this problem what we have is an operating system. So the operating system resides between the computer hardware and the users. So it is an intermediary that acts between the computer hardware and user so let us take our first example that we have taken suppose the user one wants to type something and save it into his Microsoft Word so what he does he just double click on the Microsoft Word and then the rest of the things the operating system takes care of it it just opens it for him and then it makes the screen ready for him for typing and whatever he types it.
The operating system tells the hardware what to do so that it will be typed and displayed on the screen and everything that otherwise would have to be done manually by the user is now taken care of by the operating system and after typing it he has to save it. When he saves it the operating system tells the computer Hardware where to save it and how to save it and how much memory to allocate or saving it and everything is done by the operating system. So all these new things which we otherwise had to do in the absence of operating system are now done by the operating system and it becomes very easy for the user to use the computer system. So the user just opens the computer he just takes or opens what he wants to use it and he just uses it and all the communication that has to happen between the computer hardware and the user is taken care of by the operating system. It does all for the user and does the computing or the usage of computer becomes very easy for the users because of the presence of the operating system so that is the main task of an operating system.
An operating system is a program that manages the computer hardware. We saw that the computer hardware how with resources like CPU memory i/o devices everything is managed by the operating system. Now and then it also provides a basis for application programs and acts as intermediary between the computer user and the computer hardware. So it provides a basis for the application programs. So here we have our application programs and it is installed on the operating system. It provides a base for the application programs and also it acts as an intermediary between the computer user and the computer hardware. Thus making the process of computation and the usage of computers seamless and very easy for the users so that is the main function of an operating system.\
Function of Operating System:
The main functions of OS are number one is it is an interface between the user and the hardware. It acts like an interface between the user and hardware and then the second point is allocation of resources. So I already told you what I mean by resources here what we mean by resources are the hardware that we have like the central processing unit, the memory and the input/output devices. So when I user or when different users wants to use the different resources. So they have to be allocated our resources are not unlimited. We have a limited resources that means we have limited hardware. So how this resources should be allocated to users in such a way that everybody gets their share and it performs in an efficient manner all this is done by the operating system. So it allocates resources to different users or different processes in a good manner that is the function of the operating system and then it does the management of memory secure etc. So I told you even when we were typing this word processor we have to first load it into the main memory then after typing it has to be saved into the secondary memory or the hard disk. How the memory is managed. So how things are stored or where they are stored everything is managed by the operating system and how securely it is done that is also managed light operating systems. So these are some of the main functions of operating system.
Goals of Operating System:
An operating system on top of our computer hardware makes it very easy for the user to communicate to the computer hardware. So it becomes a very convenient thing for the user to have this operating system. So the first goal of operating system is to provide convenience.
The second point is efficiency now what do we mean by efficiency if you were not having the operating system and let’s say we have different users trying to access. These resources and how would you efficiently manage the resources that you should get this much resources or the other users should get this much resources. So if you do it manually it is going to be very tough and that is very less chance that you can efficiently manage it. So operating system by taking care of all these allocations of resources and management of memory and everything it provides you an efficient usage of your system.
So the first point is a convenience and then the second point is efficiency. So many operating systems are designed mainly for convenience some are design designed for efficiency but mostly or we can say many of the operating system are designed for both convenience as well as efficiency. So these are the goals of operating system which we achieve by the functions of this operating system.