Abstract: A programmable sequence controller and a sequence control system including a plurality of such controllers. Each sequence controller includes a program memory for storing a preprogrammed sequence of instructions for controlling a machine or part of a machine in response to the status of the machine or part being controlled. Each controller includes data transfer circuitry for receiving status data from another sequence controller on a common data bus and transmitting its own status data to all of the other sequence controllers on the common data bus. Each sequence controller includes an input-output (I/O) memory and an (I/O) flag memory for storing and keeping track of current status information from each of the plurality of controllers.