Abstract: An improved modular solid power controller includes low cost low speed microcomputers embedded within the load cards to control a number of semiconductor power switches associated with corresponding electrical load circuits. A master controller microcomputer on the controller card communicates bilaterally with each of such slave microcomputers via a serial data path that extends along the backplane card and interconnects the former computer with each of the load cards, issuing commands in serial form and in high level language that is received by the addressed slave microprocessor, interpreted and acted upon by controlling the semiconductor power switches associated with the respective slave card.