COMPUTER AIDED DESIGN SYSTEM

PURPOSE:To make the best use of a wiring pattern set before the change of a design and to improve the design changing efficiency by restoring the saved wiring pattern to the pin of the changed parts and to the parts pin of a net list. CONSTITUTION:The wiring pattern to be deleted based on the results of comparison obtained between the old and new parts information and between the old and new connection information is saved into a memory 33 for patterns to be deleted. Then the wiring pattern saved in the memory 33 is restored to the pin of a changed parts or to the parts pin of a changed net list. In this case, a check means 49 applies the design rule check DRC to the wiring pattern and at the same time a restoring means 50 restores successively the wiring patterns. These restoring operations are carried on until the DRC is cleared. Thus the design can be effectively changed for the substrate pattern diagram corresponding to a circuit.