Bclcnc—A Computer Numerical Control System

Summary

A Computer Numerical Control (CNC) system, which provides for cutter path programming for three axis contouring directly on the control minicomputer, is described. The system is built around a PDP-8/E computer and makes use of FOCAL an interpretive language both of which have been developed by Digital Equipment Corporation, Maynard, Massachusetts, USA. The computing capabilities of FOCAL were augmented with machine-tool control functions, switch sensing functions and a special routine for communicating with a large-scale computer over phone lines. All input/output and machine control is performed in the interrupt mode, thus, freeing the processor to perform computations most of the time. On line editing commands provide the operator with the flexibility needed to optimize the process.