Abstract: A computer control is utilized to exclusively control the cycles of operation of a machine. The computer control contains a memory for storing a part program defining a number of independent machine processes. Each machine process is defined by a series of machine functions. In accordance with the execution of a part program or the exercise of pushbuttons, the control requests the execution of a machine process. An instruction block defining the first function in the process is examined, and the actual states of selected input signals defining the current machine conditions are compared to predetermined states. If there is a difference between the actual and predetermined states of the selected input signals, an error signal is generated identifying the selected input signals which are in error. If the actual and predetermined states are the same, an output signal is transferred to the machine to actuate a device thereby executing the first function.