How do Real Time Operating Systems work?

Question

I mean how and why are realtime OSes able to meet deadlines without ever missing them? Or is this just a myth (that they do not miss deadlines)? How are they different from any

Answer 1

It is not that they are able to meet deadlines, it is rather that they have deadlines fixed whereas in a regular OS there is no such deadline.

In a regular OS the task scheduler is not really strict. That is the processor will execute so many instructions per second, but it may occasionally not do so. For example a task might be pre-empted to allow a higher priority one to execute (and may be for longer time). In RTOS the processor will always execute the same number of tasks.

Additionally there is usually a time limit for tasks to completed after which a failure is reported. This does not happen in regular OS.

Obviously there is lot more detail to explain, but the above are two of the important design aspects that are used in RTOS.