Need for Operating Systems from scratch

Vignesh Sekar
A free video tutorial from Vignesh Sekar
Software Engineer,Computer Science Instructor
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Operating Systems from scratch - Part 1

Learn the concepts of Operating Systems from scratch as Operating System forms the core of Computer Science

08:18:41 of on-demand video • Updated October 2020

  • You will become very familiar with the core concepts of Operating Systems
  • You will be able to challenge the interviewer on questions related to Operating Systems
  • You will view Computer Science in a different dimension
  • You will be able to answer all questions of exams like GATE,PGEE,ISRO (after completing all parts of OS course
  • You will be able to get a top grade in your Operating systems course in your Bachelor's degree
  • Understand how Operating Systems work
  • Understand how a process is created
  • Understand how CPU scheduling is done in Operating Systems
  • Understand the various scheduling algorithms we have in Operating Systems
  • Understand how CPU , Memory and Disk work together
  • Understand Memory managment in Operating Systems
  • Understand how a process is moved from hard disk to RAM
  • understand memory allocation strategies used by operating systems
English [Auto] Find so far we have seen whole mission core is placed in the hard disk of a computer. Right fine. Now let's see what do we really mean by operating system design that our hands can hold a maximum of 50 programs. Great. That is a that the capacity of the ram in such a way that it can hold the Maximov of programs in it. Also let's assume that our hard disk can hold 500 programs. And as you say so far this will be larger than say Sokratis fame. See we have already seen that. You cannot access the hard disk. That is key right. Any program LCP wants to access. You can only access the RAM directly. No. So definitely we need a we need to move the problem from hard disk to rather than an executive. Now my question is since Rangan Holborn leave the programs all of this 500 programs which programs are going to move to the right or left of the programs can be moved from high school right now out of these 500 programs in the hard days which would be programs. Are you going to move to the right that is a question see what might come up is one answer you may come up is we need to move up the programs which the C.P. you will live next in the future of the programs which you will be most likely to read for next right away. Because in case there's the program that CPA is asking for is present in the RAM it will dig release them for the CPA exec. Right. But I think if it is not present in the draft we need bitis the hardest. It is going to take lot of care. So you might say that we need to keep the programs which is most likely to be requested with a CPA next right. And there is there is a big problem here. The problem is we cannot tell the future exactly right. OCP you can ask for any program. We don't know which 50 programs will this EPU for the next. Right we cannot exactly tell the future so far that there is no other way other than going for prediction. We go for prediction which means we play really which would be programs with the CPI is most likely to refer in the near future when both of the programs we need to move from hartis to write those programs we need to move them hard to wrap. Now there are various algorithms we can break we can come up with various algorithm saying that this reprograms has to be more data of programs has to be it really depends on algorithm which we are implementing. That algorithm will be implemented by other operating systems. Right that algorithm will be implemented by our operating system. See this is all operating systems that look like it really is a big program which will have lots of functions and every function will implement them to implement the particular functionality. Here are our operating systems need to choose from the programs among these five hundred programs. This is one such functionality. No this functionality will be implemented by one of the functions of operating system. Ray one of the functions of operating system will be implementing this functionality not because it also has a responsibility as long gumshield you let a part of the program which is selecting with 50 programs among the 500 programs. He's also got a long time to do that. So the operating systems is a big coat of which London should do that. It's a small function right which is going to implement that. It is going to implement the selection of processors from hard to find. So this one is very clear right. Actually what we are doing we are not gambling nothing but resource allocation. We are doing something RSA allocation Resource Management way. See any ways we use our computer we can also say the most resource for example Sibiu is a resource and it's a resource hog. This is a resource. Even even our printer is a real resource Mozes resource any ways of using our computer is called resource. Right you can be a device where the device is nothing but a resource here in the ramp way because more than because the are trained to access the ram which is the resort. Now you build the operating system. But this is deciding which for the program should access the rate which would be programmed. Among those buying the program which would be program for access. So operating systems clearly is clearly implementing resource allocation. Great resource allocation resource management resources nothing but RAM. So this is the resource which is being exactly allocate by your using an operating system. Similar way that a lot of resource allocation schemes which are necessary in order to make our computer work. For example let me let me come up with an American I know US is your prothesis namely one name to be one and two in zero overlap right we have two brothers named you wouldn't be doing that right now. Sebille Nate needs to fix the program and then he needs to exit it right. Obviously needs to fix the program. I think it needs to get it. No it doesn't seem that this program one wants you. Which means both these programs are ready to get picked by you. What is the future right now among the school programs which program the you will select next rate among us to bring them back in. There is a confusion here right here. The result is nothing but C.P. you see the results of more than one process is competing to add to that resource right now which pre-processed with program seen by program or process both me one and the same right. That's a minor difference. You will see that a bit later as of now in that program and process both are say fine. Now all of these programs which problem should access that it's all about resource I mean the C.P. you and that is being decided by one of the functions of operating system. Right. One of the functions of operating system. Now this function will have the core which will clearly say which processor among this tool should access it be right there is see how this is done by using an algorithm. For example we might come up but we do need an algorithm here. For example this function might implement an algorithm saying there are two processes the process which is biggest incise should access those. Your first article you can implement a different algorithm saying that the process which is most in space should access be a first rate that is one that algorithm we can you implement a lot of algorithms. Another example is the process which came into the plant first from harbour's should access that you first see one more what and why. Obviously every program every program or process will definitely get the resource. There is no doubt about that. Even here I don't like all the spy programs but definitely more to that at some point in time it'll be definitely more. Oh the spider which should be more first that is important. They don't all pay him the programs will get the source which will get good results fast. That is important. Same is the case here. All of these due process don't know what the processes will get busy. You know the question is which process should get the sleep you first. That is important and that is being visited by your operating system. Re this functionality which in this case which process should access the CPP you first is best shot gumshield you let it is this. This function is also our shot don't share Guler will see that later. We are not actually discussing that once concept. I'm just giving you an idea. I'm on my list of people among those by every program so the program is be chosen by a function be called picaresque lump don't you. Not very long but I'm sure you left and out of these these many process which process should i should I get the sleep you first is being visited by your one dumb shit should you were right. So what is actually happening is again. Resource allocation is happening. Why. Because the result is nothing but sleep. You know have more than one prothesis great practice this EPU and the operating system is actually allocating the most luck of preprocess right. So the main part of the born and you need to model some of this video is the main function of operating systems resource allocation resource management. Both are the same right. Operating Systems is a core which will have lots of functions and the main functionality of operating system is nothing but resource allocation or resource management. Find.