 Hello friends, myself Rohit Kumar R. Waghdharikar, working as an assistant professor in computer science and engineering department at Walsh Institute of Technology, Solapur. Today, we are going to discuss about the real-time operating system, learning outcomes. At the end of this lecture, our session, students will understand how systems respond within a specified time constraint with a given deadline. Let's start for the basics of RTOs. A real-time system means that the system response should be guaranteed within a specified timing constraint or system should meet the specified deadline in a given time. So now, what we can call it is here, these are the strictly deadline time-bound systems. This type of operating system has made up for the specific task. They will perform the specified task within a specific time. It's like a chronological order. Like after completion of one task, it will go for the second task, then it will go for the third task. In this way, this RTO system will work. Now let's take the example of RTOs, electric geyser. This electric geyser is nothing but the real-life example of RTOs. Now in this electric geyser, water is the medium. Electric heater is a source of heat and thermostat is a sensor that on or off the heater set point. Means in this electric geyser, to heat the water, we need to use a thermostat sensor. The role of this thermostat sensor is to check whether the water is heat or not. That is nothing but the electric geyser work. So now to perform this task, RTOs will use, means for the specific time, it will start the heater and after a specified time or set point, it will switch off the heaters. So now this one is nothing but the RTOs. The basic architecture of RTOs. Now in this architecture, let's see, we have one operator and the real-time computer system. Means here, the operator interacts with the real-time computer system and this is nothing but the man-machine interface. Means what? In previous example, electric heater, user will come into the bathroom and he will just switch on the geyser. So that is nothing but the operator and real-time computer systems man-machine interface. But now after that, what happened? This real-time computer system is going to interact with the controlled object. Now here controlled objects are nothing but the instrument interface. Means here, like the thermostat sensor. That is the object, controlled object of this real-time computer system. So now in this way, real-time operating systems are going to be work. So now let's see the different types of operating systems. Under this RTOs, we will have this soft RTOs and hard RTOs. Now hard has again classified into the two things, that is static and dynamic. And then dynamic is primitive dynamic and non-primitive and static again will have the primitive and non-primitive. Means what? Here in this type of RTOs, hard RTOs, the deadline is a fixed. It means anyhow that system has to achieve the given task within a specified amount of time. That is nothing but the hard system. So now here the static and dynamic. Because static means before going to start the execution of that program, it means before the compilation, at the time of compilation, we need to check. And now here dynamic, it means while executing, if some of the task get wrong or something is wrong is happened, then dynamically, automatically it will change the behavior and it will achieve the task anyhow. That is nothing but the dynamic. It means it will achieve at the run time and in static it will achieve at the before run time, that is compilation time. So now again here we will have the primitive and non-primitive means what? Primitive means what? It allows the disturbance or the interrupts and non-primitive means it is not going to entertain any other process while executing its own task. So that is nothing but the non-primitive. Now let's see the hard real time system. This type of system never miss its deadlines as already we have seen. Now let's take the example is a missile system and the flight control system. In the missile system that is a missile engineering, in this system there is no delay or no interrupt is allowed that is the missile system and even the flight control system because there will be n number of flights in the air. So at that time if something get wrong then maybe there will be the chances of flights to get a collide. So that is nothing but the hard real time system means there is no delay allowed in this system. Now soft, in the soft real time system it will allow for the minor delay. It means like take the example of banking system, in banking system getting the cash withdrawn in the hand, maybe it will delay, second or two second it doesn't matter. While transferring the amount from one account to the another account it will take some time. Actually it will always vary the time between these transactions. So that is the very minor delay is acceptable in the soft real time system. So that one is nothing but the banking. Now let's talk about the terms related to the RTOS. The first term is job. A job is a small piece of work that can be assigned to a processor and may or may not require the resources that is nothing but the job and task. A task is a set of related jobs that jointly provide some system functionality. Next one is a release time of a job. It's the time at which job becomes ready for the execution. That is nothing but the real time of a job. Real time of a job means it is a time taken by a job to finish its execution. Deadline of a job, it is the time by which a job should finish its execution. Deadline is of the two types again absolute deadline and relative deadline we will see in the next slides. So now here the relative deadline the maximum allowable response time of a job is called the relative and in absolute deadline of a job is equal to its relative deadline plus its release time. Response time of a job, it's the length of time from release time of a job to instant when it finishes. Now processors are also known as active resources in the RTOS. They are essential for the execution of a job. A job must have one or more processor in order to execute and proceed toward the completion. Now examples are the computer systems. Resources are also known as the passive resources. A job may or may not require a resource during its execution. For example the memory or mutates. Now here let's see one question. Now we have learned like what is the hard real time system and soft real time system and all. Now here just tell me whether forecast system comes in which type of RTOS, pause the video and write your answer. Now here it's an answer is by using soft real time system because in a weather forecast system there will be some delay will be acceptable. Means while I am getting the weather of my current location wherever I am I will get some different results many time because if I will check for the in the morning 10 am I am getting some results and after I will check the 10.5 am now again I am getting some different results. So that is nothing but some delay can be acceptable. That is nothing but the soft real time system. Now let's see one case study. The real time automation of agriculture environment. To perform this agriculture environment for the real time system we need to consider some parameters like to continuously monitor the soil moisture this can be done by some sensors. Then we need to continuously monitor the water level of the bale. Then again we need to check the temperature, humidity and dew points so as for forecast the weather condition. To monitor and control the whole system through the GSM model and also provide the detailed information about the field condition to the user through the SMS. If you look into this 5 tasks each has a different task these are the independent tasks. It means it has some specific sensors to check and after getting all the information where we need to send the details to the farmer also. So now for this purpose we need to use the real time operating systems. References are operating system concepts from the Galvin and system programming operating systems by the Dumdiri. Thank you.