PURPOSE: To attain the direct execution of the common modules formed into a single piece based on a real address stored in ROM by describing a call instruction, a jump instruction, etc., which define the real addresses of the common modules as their call destinations.

CONSTITUTION: The MS-DOS stored in a system disk 8 is loaded into a RAM, and a source file stored in a file disk 9 is evolved to a RAM 3 under the back-up of the MS-DOS. The source file is successively converted into an object file, an EXE practicable file and then a HEX file. In this case, 'tool1' of lists 2 and 5 and 'tool2' of lists 3 and 6 are identical with the jobs common to two jobs. Thus these functions are deleted out of an EXE file B and remain only in an EXE file A in the form of a single piece respectively. As a result, the common modules are quickly carried out.