System for evaluating target board by using evaluation microcomputer in which strorage of environment data are powered by evaluation tool

In an evaluation system for evaluating a target board produced for use with a microprocessor, an evaluation microcomputer is connected between the target board and an evaluation tool. In the evaluation microcomputer: an emulation circuit emulates functions of the microprocessor, and supplies an emulation result to the evaluation tool through an interface circuit; the interface circuit interfaces the emulation circuit with the evaluation tool; and a data storing circuit stores data relating to the microprocessor. The emulation circuit and the interface circuit are powered by the target board, and the data storing circuit is powered by the evaluation tool. Alternatively, when the interface circuit further has the function of the data storing circuit, the interface circuit is powered by the evaluation tool.