[lll-o-lll]

> You can divide realtime applications into safety-critical and non-safety-critical ones.

No. This is a common misconception. The distinction between a hard realtime system and a soft realtime system is simply whether missing a timing deadline leads to a) failure of the system or b) degradation of the system (but the system continues to operate). Safety is not part of it.

Interacting with the real physical world often imposes “hard realtime” constraints (think signal processing). Whether this has safety implications simply depends on the application.