Is it possible to run Keil RTX Real-Time Operating System (RTX-RTOS) on the NRF51? Is this even possible on an M0?
We don't have any official example code for this, but we do believe that it would be possible. You may have use in taking a look at this and this question.
FYI: cdn.rawgit.com/.../getting_started_with_ucxpresso.nrf.pdf