PURPOSE: To set data without interrupting the execution of a program by setting the data by allocating addresses to be accessed in a target program to an external I/F.

CONSTITUTION: In a system which supports the development of a microcomputer by using an in-circuit emulator(ICE) 2, data setting to output data to be processed in the target program executed when emulation is performed by the ICE 2 is performed, and the external interface I/F) 21 is provided in the ICE 2. The data to be processed in the target program is set on the external I/F 21, and the address to be accessed in the program is allocated to the I/F 21. The ICE 2 makes access to the external I/F 21 while executing the program, and executes the program by using the data set on the external I/F 21. In this way, the data can be set without interrupting the execution of the program while the ICE 2 executes the target program.