Patent US 4,031,369

A numerical control system having both linear and circular interpolating capabilities is described. Data from a permanent storage medium such as tape are input to a preprocessor. The preprocesor processes the data into a form acceptable to the system logic and makes all parameters for both linear and circular interpolation available to the system logic. Because linear interpolation is used, straight lines as well as arbitrary curves which are simulated by a series of short straight line segments can be drawn or cut. Additionally, because circular interpolation is used, arbitrary curves can be simulated by a series of arcs, each of the arcs being a portion of a different circle and the various circles having varying radii in accordance with the dictates of the arbitrary curve being cut or drawn. The ability to use both circular and linear interpolation substantially reduces the data processing because the interpolation technique requiring the least definition can be conveniently employed. Also, because of the particular interpolation techniques employed, a minimum of multiplication and division is required so that the system logic is substantially reduced. Additionally, because of the particular linear and circular interpolation techniques and because of the data processing technique employed, the execution time of real time tasks is reduced. This results in a substantial reduction in demands on the computing capabilities of the system, thereby significantly increasing the overall capabilities of the system.