In this work a new NC design, based on the existing APT system (processor and postprocessors) and consisting of an additional front-end interactive Basic preprocessor, is presented. Software was developed that enables a part programmer to generate a part program on a 16 K minicomputer (PDP11/34). In order to fully exploit the off-line capabilities of an intelligent terminal, routines were written that display the geometrical input. While verifying the latter the user is offered the opportunity to instantaneously modify the displayed geometry if required.

Subroutines of the APT part programming language (macros) were developed to cover basic geometrical configurations of turned parts (bar stock and forgings) and 2½ axes milled pockets. This approach reduces part programming to inserting dimensions of the workpiece and the technology involved.

As far as technology is concerned, a milling optimiza-routine was developed that can direct the user in the selection of a cutterradius, feed and rotational speed when machining pockets.