AbstractThe computer today is a tool that can be used by everyone. On the other hand, it is important for the student of information sciences to correctly understand the operational principle of the computer as a basic knowledge required in understanding or solving the problems concerning the computer.To answer questions concerning the internal operation of the computer, it is necessary to understand the behavior of the actual circuit at the IC level. With the widespread use of the personal computer, it now seems possible to construct an efficient simulator for educational purposes. However, few reports have been presented concerning the approach at such a level.From such a viewpoint, the author developed a computer simulator aiming at the understanding of the operation of the registers and gates based on the machine language program. Two modes, i.e., the hardwired logic and microprogram, are executed by the control unit of the system. The operation can be switched to the set‐up constructed by a student. Several elaborations are made so that the operation actually is felt. For example, the operation is represented by a time‐chart so that the time‐relations among signals can be understood.A scheme is adopted whereby the generation program for the control signals is constructed directly from the time‐chart. It is expected that an efficient training for the operational principle over a wide range can be realized on a personal computer using the proposed system, relating the system behavior to the detailed circuit operations from the viewpoints of both software and h