> A kernel (because that's where interrupt handlers are located).. Thought I would pull this one phrase out to demonstrate how we are clearly talking about dif

> A kernel (because that's where interrupt handlers are located).. Thought I would pull this one phrase out to demonstrate how we are clearly talking about different systems. For many embedded control systems, I would not say "the interrupt handlers are located in the kernel." On processors that have the distinction, interrupt handlers typically run in Supervisor mode (What the x86 calls "Ring 0"), but it's entirely possible that 100% of the code will run in Supervisor mode. When the kernel provides preemptive scheduling, it may handle a single interrupt (a timer); alternatively the kernel doesn't handle any interrupts, but instead provides an API call that application developer(s) must invoke for entering the scheduler. Many things that are called an "RTOS" in the embedded world would be called a "threading library" in the desktop world.