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

The textbook/interview answer is "deterministic pre-emption". The system is guaranteed to transfer control within a bounded period of time if a higher priority process is ready to run (in the ready queue) or an interrupt is asserted (typically input external to the CPU/MCU).