RTOS - Real Time O.S.

Real Time Operating System it is cool thing for critical device and infrastructure, from self-driving car to medical equipment to war machines. It is an O.S. for critical device when you are talking about nano seconds. It is differ from known operating system
that we use commercially at home, for our games (GPOS General Purpose Operating System). When it come to multi tasking RTOS is the real deal. I want to learn this stuff, we can say it is a little bit too late to me, but if will make me happier why not?