A method of controlling a machine tool and other controlled devices, as well as a programmable numerical control (PNC) system, are disclosed. In at least one embodiment, the method of controlling includes receiving a first part program at a programmable logic controller (PLC), and storing the first part program in a string array library of a memory portion of the PLC. The method further includes communicating information between the PLC and an operator interface regarding the first part program, and providing a first signal from the PLC to a first port so as to cause the first machine tool to be operated in accordance with the first part program. Also, in at least some embodiments, the PNC system allows for control of multiple machine tools and/or other controlled devices, by way of one or more part programs, and/or for editing of a part program while that program is being executed.