DIN 44300 defines a real-time operating system (RTOS) as a system in which the operating systems for processing data are constantly ready for operation. And this in the form that the results are available within a given time within a guaranteed latency and processing time.
In addition to predictable timing, real-time operating systems must meet other requirements: For example, they must support multitasking and be able to execute and interrupt multiple threads simultaneously. This means that real-time operating systems must support multithreading and different priorities. Real-time operating systems provide mechanisms with defined behavior for synchronization and support priority inheritance. In addition, their delay behavior is predictable. Whether an operating system can be used for real-time applications can be tested with a benchmark.