Abstract: Knowledge bases are generated by a computer directly from flowcharts and logic trees. Only a few icons are used in the flowcharts so as to make the flowcharts easier to trace. Different colors are used to indicate the states of statements in the knowledge base. A simulator is provided to simulate knowledge base execution. The simulator displays the corresponding flowcharts and logic trees on the computer screen. The simulator shows which statement is being evaluated and provides various information useful for debugging and personnel training.