Software engineers tend to think in deterministic terms. My code tells the machine exactly what to do and that's it. In real world systems there is uncertainty which requires different thinking. A real-time process needs both, a deadline and the concept of errors. A process must be completed within a deadline or there is an error. As the author said, the absolute time (or latency) is irrelevant. Think of a tennis match. you either hit the ball or you lose. There is a deadline and an error. It's not that complicated yet so many people are confused by the concept.
atonse|3 years ago
The OS that runs the ECU (engine control, sometimes other such safety systems), sometimes things like brakes, is an rtos because delays can cause death.
But the OS running your driver systems, music player, WiFi, climate control, etc is a non real-time OS, more like android, and that’s reflected in the delays you can sometimes see.