Abstmct-The crucial role played by tbe man-computer dialogue in computer-aided circuit design, and particularly witbin an interactive graphic medium, is demonstrated by reference to a working circuit design facility implemented on a minicomputer. The detailed nature of this facility and the techniques illustrated are related to the circuit design process and the behavio@ characteristics of the human designer. Special attention is given to the command dialogue, and to the introduction of flexibility allowing a user to modify the facility to suit his own needs.