links

https://medium.com/@dheeptuck/building-a-real-time-operating-system-rtos-ground-up-a70640c64e93 
                                                                                                
https://github.com/besp9510/rtos_ground_up                                                                                                

https://developer.arm.com/documentation/dui0056/d/using-the-procedure-call-standard/register-roles-and-names/register-names