Real Time operating System
A Real Time Operating System, commonly known as an RTOS, is a software component that rapidly switches between tasks, giving the impression that multiple programs are being executed at the same time on a single processing core.
In actual fact the processing core can only execute one program at any one time, and what the RTOS is actually doing is rapidly switching between individual programming threads (or Tasks) to give the impression that multiple programs are executing simultaneously.
OS or RTOS?
The difference between an OS (Operating System) such as Windows or Unix and an RTOS (Real Time Operating System) found in embedded systems, is the response time to external events. OS’s typically provide a non-deterministic, soft real time response, where there are no guarantees as to when each task will complete, but they will try to stay responsive to the user. An RTOS differs in that it typically provides a hard real time response, providing a fast, highly deterministic reaction to external events. The difference between the two can be highlighted through examples – compare, for example, the editing of a document on a PC to the operation of a precision motor control.
Scheduling Algorithms
When switching between Tasks the RTOS has to choose the most appropriate task to load next. There are several scheduling algorithms available, including Round Robin, Co-operative and Hybrid scheduling. However, to provide a responsive system most RTOS’s use a pre-emptive scheduling algorithm.
Tasks and Prioirities
In a pre-emptive system each Task is given an individual priority value. The faster the required response, the higher the priority level assigned. When working in pre-emptive mode, the task chosen to execute is the highest priority task that is able to execute. This results in a highly responsive system.
System is nothing but group of peripherals connected to each other to process the input data and give output. System which is time dependent that is to process the input data and give output in given time, such systems are called real time systems. Real time system is divided into two systems
In actual fact the processing core can only execute one program at any one time, and what the RTOS is actually doing is rapidly switching between individual programming threads (or Tasks) to give the impression that multiple programs are executing simultaneously.
OS or RTOS?
The difference between an OS (Operating System) such as Windows or Unix and an RTOS (Real Time Operating System) found in embedded systems, is the response time to external events. OS’s typically provide a non-deterministic, soft real time response, where there are no guarantees as to when each task will complete, but they will try to stay responsive to the user. An RTOS differs in that it typically provides a hard real time response, providing a fast, highly deterministic reaction to external events. The difference between the two can be highlighted through examples – compare, for example, the editing of a document on a PC to the operation of a precision motor control.
Scheduling Algorithms
When switching between Tasks the RTOS has to choose the most appropriate task to load next. There are several scheduling algorithms available, including Round Robin, Co-operative and Hybrid scheduling. However, to provide a responsive system most RTOS’s use a pre-emptive scheduling algorithm.
Tasks and Prioirities
In a pre-emptive system each Task is given an individual priority value. The faster the required response, the higher the priority level assigned. When working in pre-emptive mode, the task chosen to execute is the highest priority task that is able to execute. This results in a highly responsive system.
System is nothing but group of peripherals connected to each other to process the input data and give output. System which is time dependent that is to process the input data and give output in given time, such systems are called real time systems. Real time system is divided into two systems
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