PURPOSE: To reduce the insertion of a wait state into a machine cycle and to accelerate the execution time of a program by arranging a subroutine to be frequently called in a memory area in the same page as a main program.

CONSTITUTION: Processing 1 to processing 3 and a subroutine 1 to be called among respective processing 1 to 3 are arranged in a page (n) and processing 4, 5 and a subroutine 2 to be called between respective processing 4, 5 are arranged in a page (n+1). The subroutine 1 can be arranged in any position within the range of the page (n) and the subrutine 2 can be similarly arranged in any position within the range of the page (n+1). Even when the subroutine is frequently called in the arrangement, a page change is not generated in the program, and when the processing 3 is shifted to the processing 4 after ending the subroutine 1, a page change is generated only once.