NUMERICAL CONTROL UNIT

A numerical control system for machining a workpiece including a reader for reading a machining control program for the workpiece, a control device for supplying a control signal to a machine tool for the workpiece, and a storage device disposed internal or external to the control device, for storing a conversion table for converting a first character string read from the program into a second character string representing a command. The control device operates in response to the reader reading the first character string to supply the control signal to the machine tool in accordance with the command of the second character string. The second character string may represent, e.g., a delete command or a repeat instruction command.