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. Using the stylus, the operator may selectively exercise command functions, enter selected data from the preparation, and retrieve data previously stored in the computer's memory, while simultaneously looking into the oculars of the microscope. In response to operator commands, the stage of the microscope is servo controlled by the computer in any desired coordinate system. In addition, a sensor is connected between the microscope and the computer for maintaining the constant magnification ratio that facilitates a continuous superposition of the graphics display image upon the preparation image. As a result, the computer microscope of the present invention constitutes a valuable research tool having flexibility and maximum utility at a relatively modest investment.