What is the name of the operating system that reads and reacts in terms of actual time?

In my opinion, most of the modern day's OS (Windows + Linux) react to any interrupt call immediately.  For example, response to mouse click or key, the responds in real time.  If we go into detail, there are many characteristics of real time system like deterministic, responsive, reliable etc that we can discuss and elaborate but I think it's beyond the scope of this question.

 An operating system (OS) is software that manages computer hardware and software resources and provides common services for computer programs. The operating system is an essential component of the systemsoftware in a computer system. Application programs usually require an operating system to function