Abstract: By storing, along with each signal or bit controlling a step to be taken in a process sequence, an additional signal or bit to be applied to the gating terminal or pin of respective ones of a plurality of "and" gates, to the other input terminal of each of which is supplied its respective input signal from aprocess control element, such as a sensor, switch or valve (each such input signal indicating a changed condition in the process which requires a changed process control sequence) any sequence may be interrupted following any step in that sequence and a new sequence may be called up to make the needed correction or change in the process.