PURPOSE: To easily perform the development of a program by computing input data for the simulation of the operation of input equipment by using the program developed for an electronic cash register (ECR).

CONSTITUTION: A simulation targeted program 61 corresponds to the application program of the ECR, and the application program is the one to perform every kind of transaction processing actually. Also, an input/output equipment control simulation program 62 corresponds to the input/output equipment control program of the ECR. An operating system 63 controls the program execution of the simulation targeted program 61 and the input/output equipment control simulation program 62, etc. In other words, the input/output equipment provided at a development supporting device for ECR itself is used as a simulator for the simulation of the operation of the input/output equipment. In such a way, a debug test for the program developed by a development supporting device itself can be performed.