A control system for a numerically controlled (NC) machine tool which includes a direct access, time sharing, general purpose host computer located remotely from the location of the machine tool, is provided with a dedicated microprocessor located proximate the machine tool. The dedicated microprocessor has a storage memory in which at least one control tape or program may be stored. The microprocessor is operatively connected to the general purpose computer through a telecommunication (telephone) data set. The dedicated microprocessor in turn is connected to the machine control unit (MCU) of the NC machine tool by a behind the tape reader interface. In operation, the general purpose computer is used on a time share basis to generate a suitable machine control program. The machine control program is transferred to the dedicated microprocessor by means of the telecommunication data set. Thereafter, the machine control program may be edited or revised on a real time basis at the machine tool. Once the machine control program is found acceptable, it is independent of the host computer and it may be shifted from one machine to another independently of machine tool location.