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A new CAD tool has been developed that provides the ability to interact graphically with the simulation of an LSI circuit. The tool is called EDISIM, for EDItor plus SIMulator. Compared with the textual interface provided by most simulators, the graphic interface of edisim is simpler to learn and faster to use for both the novice and the experienced designer. EDISIM displays the layout of a chip on a color screen, and allows the user to set the logical value of a net merely by pointing to any feature on it, such as a diffusion region or a metal connection. Results are also displayed graphically-nets at logic 1 are solid color, those at logic 0 are hollow, and those in the unknown state have an "X" through them. The technique works well for small to medium size cells, but seems less useful on large designs when only a small fraction of the circuit can appear on the screen at once. This paper discusses the local CAD environment, the motivation for edisim, its user interface and implementation.