[detaro]

RTOS literally means "OS with real-time capabilities", you can't say in general that an RTOS is not really an OS. QNX is very clearly an OS. Linux with real-time modifications is clearly an OS. And even with really small variants, like ThreadX in this case, they have many markers of an OS: It provides threads, with scheduling, synchronization and memory isolation (if the hardware supports that). It has a networking stack and file system abstractions. What exactly is it missing that makes it clearly "not an OS"?