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

You might find it helpful to read the source of a typical RTOS. There are several open-source examples out there, and the following yielded links in a little bit of quick searching:

• FreeRTOS
• eCos

A commercial RTOS that is well documented, available in source code form, and easy to work with is µC/OS-II. It has a very permissive license for educational use, and (a mildly out of date version of) its source can be had bound into a book describing its theory of operation using the actual implementation as example code. The book is MicroC OS II: The Real Time Kernel by Jean Labrosse.

I have used µC/OS-II in several projects over the years, and can recommend it.