Priority control circuit

A priority control circuit for establishing connections between a data handling system element and a number of subsystems wherein request signals from subsystems are scanned and granted service in a sequence which is determined by their position in a priority ranking order. The scanner returns to the beginning of the order immediately after a request has been granted, the subsystem just serviced being bypassed in the next scan until all of the remaining request signals have been processed. Each time a request signal is encountered and service granted, the scanner returns to the beginning of the order, a new scan is begun and all prior requests serviced are bypassed. In the absence of any other requests or after all of the request signals have been serviced the bypassed subsystems are unlocked and a scan of all requests is begun.