During the operation of a program, it is often useful to jump to a subroutine containing a program section that is used several times. At the end of the subroutine, the processor must return to the...

During the operation of a program, it is often useful to jump to a subroutine containing a program section that is used several times. At the end of the subroutine, the processor must return to the instruction following the jump to subroutine instruction. Explain how this may be achieved. Your solution should take into account the fact that subroutines can be nested, in that one can call another.