For a beginner, the Professional knowledge of the microcomputer (MCU) is not easy understood because of its abstraction, such as the data or signals how to be operated inside of the MCU. Consequently, attend to help the beginner to learn these knowledge, based on fully understanding the working principles and processes of a MCU, in the virtual design environment of the Proteus (ISIS 7 professional), by mainly using a counter CD4518 and a decoder 74LS138, an experiment for simulating the basic performances of a MCU was designed. With this design, the beginner can simulate these operations as follows: programming a software code into memory unit, running the software code and clearing the code memory units of the MCU. With doing these simulations, an innovative method is proposed for the beginner how to easily understand and learn the technology of a MCU.