This thesis aims to develop a NC-code interpreter software by using the personal computer. This development system is part of the open architecture CNC controller. It consists of a personal computer, and software for interpret the CNC code, which is used for calculation, and controlling the XYZ table via counter and D/A interface card. Teh G-Code commands used in this thesis are positioning at rapid feed rate (G00), linear interpolation (G01), clockwise circular interpolation (G02), counterclockwise circular interpolation (G03), Dwell (G04), circular interpolation in the XY, XZ and YZ plane (G17-G19) and work coordinate system selection (G54-G59). Other codes can be implemented easier. This program is compatible with absolute reference as well as increment reference (G90, G91) and can be conducted by using both the English systems and the metric (G20, G21).