In development and operation of the mask-making laboratory, a precise positional measurement system is needed. This paper describes a system based on a Do-all coordinate measurement machine, controlled by a PDP-8 computer. The computer handles all sequential operations as well as computation necessary for coordinate transformation and feature location. The result is a system which can measure an array of 208 points to an accuracy of ±1 μm in less than two hours. Without computer control, measurement of such an array is not feasible.