An application program for a central processing unit of a computer module is developed. Source code for the application is written and debugged. The source code for the application program is then compiled and assembled, to provide an executable application program. The executable application program is loaded into the computer module. Safety check executable code is inserted into the executable application program that is loaded into the computer module, to prevent the executable application program from reading, writing and jumping outside a designated memory area of the computer module. The executable application program with the safety check code inserted therein is stored in the computer module.