I make a search for context information saving method in microcontrollers (especially PIC), and the only thing i found is a patent of the "tamper resistant microprocessor". According to the patent a microprocessor save a contex information for one program whose execution is to be interrupted and the execution of that program can be restarted by restoring the execution state from the saved context information.
Is this what i am searching for? And if this is correct and i have understand correct this method is used for example in interrupts when you save the registers values that you need and probably the interrupt routine can change and when you return to the normal execution of the program you take back the saved values? Or when you pop a value to the stack that indicates an address that start a piece of code and when you return from a call instruction you retrieve this address??