SUMMARYA new routing system is described, which can be applied to printed wiring boards of different wiring densities such that the number of wiring tracks permitted between two consecutive pins of an ordinary dual in line package ranges from one to four. This system is distinctive in that a single-row router is combined with a line-search router in such a way that the search for possible wire segments at the stage of the line search router is implemented channel by channel, with all interconnections within each channel completed later by the single-row router.The program operates on an ACOS 77/900 computer, and has been applied to numbers of boards. Some of the implementation results are also shown to reveal how much the described system may attain its potentialities in the practice of layout of high density printed wiring boards.