Abstract: A computer is coupled to a suitable light microscope in a closed-loop feedback system which facilitates total intervention by the operator. A graphics display electronically produces an image having two components: one, an image of the data stored in the computer's memory; and two, a set of programmed procedures and instructions available to the operator for manipulating the microscope via the computer. The graphics display is juxtaposed to, and optically aligned with, a beam splitter incorporated in the microscope. As a result, the electronically-produced image of the graphics display is superimposed pictorially upon the optical image of a preparation carried on the slide mounted in the microscope's stage. Suitable means are provided to facilitate operator control and intervention. In one embodiment, this means comprises a graphics tablet, interfaced with the computer, and provided with a hand-held stylus.