Abstract: A modularized digital controller which serves as a means of achieving dync compensation and also acts as an interfacing device in a closed-loop digital servo-control configuration. The controller incorporates four functional modules, the first of which is designed for the particular type of system being controlled and the remaining three being identical for all systems. A nonlinear or course control mode is employed during the period of synchronization to large input commands from a master source and, after the system dynamic error has been reduced to a nominal size, a linear control algorithm is used.