An Experimental Input System of Hand-Drawn Logic Circuit Diagram for LSI CAD

This paper outlines a computer input system that reads hand-drawn LSI logic circuit diagrams. The system discriminates between connection lines and gate symbols and identifies the gate type. The input device can read diagrams drawn on sheets of paper up to size A2 (40 x 55 cm). Simple algorithms for discriminating between connection lines and gate symbols are also presented. These algorithms enable rapid processing of input data because there is no preliminary processing such as thinning or smoothing of lines. A performance test was made using a circuit diagram drawn on a size A4 (18 x 25 cm) sheet of paper. The results show that the input device can be put into practical use and, when combined with an interactive graphic system, can contribute to more efficient LSI circuit design.