PROGRAM EXECUTION CONTROL METHOD

PURPOSE: To transit control between plural processing modules easily at a high speed. CONSTITUTION: A head address 'i' of a subroutine A is stored in a stack memory area S by a PUSH instruction of a main program M and a return destination address 'm+2' is stored in the stack area S by a CALL instruction to transfer control to a subroutine B. When the process transits to the subroutine A after a prescribed processing W in the subroutine B, the program is branched to an address 'k+5' and an undesired return destination address 'm+2' of the main program M is eliminated from the stack memory area S by a POP instruction and the program transfers to the subroutine A by a return instruction. On the other hand, when the program restores to the main program M, the program is branched to an address 'k+1' and a return destination address 'm+2' of the stack memory area S is once saved by a POP instruction and an undesired head address 'i' of the subroutine A is eliminated and then a return destination address 'm+2' is stored in the stack memory area S. Then the program restores to the main program M by a return instruction.