@Erik,

the 8051 is a good choice to execute multiple tasks simultaneously with the main loop method and interrupts.

But it is unable to deal effective and fast with a huge amount of memory, how it was needed for preemptive multitasking.

If you always write all the tasks in this way that, if nothing to do as waiting for an event or wasting time, then they return to the main quickly, the 8051 is able to do a real impressive amount of different tasks fully in real time.

Its only a matter of programming style than using an RTOS or not.


Peter