This thesis presents an interactive design and NC code generating system for a class of turned parts whose geometries can be specified with 2D lines and circulararcs. Using the interactive graphics commands, the part geometry can be conveniently defined in 2D and NC machine instruction codes are automatically generated from the analysis of 1D geomerty. It also enables a user to visually verify the tool motion by means of animated display of the cutting tool path that has been generated at an intermediate step. FANUC M6A is used as target NC machine. The system has been implemented using "C" language on the VAX 11/780 running under 4.2 BSD UNIX operating system with Tektronix 4105 color graphics terminal.