<I read about a multitasking kernel for the Microchip PIC microcontroller. <I think it used the counter/timer as a heartbeat, and could also do task <switched on the port change-of-state interrupt. No idea how big it is, <but I guess it's pretty small. It can be done on most CPUs no matter how small. Dynamic multitasking like Unix or VMS does is far more complex. The basic principles are the same. Allison