Abstract: The application of fuzzy set theory to the design of a class controllers which are lack of precise mathematical models is described in this paper. The fuzzy algorithm has been implemented in BASIC on DJS-130 computer. Some characteristics of fuzzy controller are simulated on digital computer and compared with PI controller. The results obtained from simulation, show that the fuzzy controller has a faster step response, higher accuracy and less sensitive to parameter changes. A real time on-line fuzzy control system and man-machine interaction can be implemented by using a small digital computer, specially a microcomputer as the controller.