The design and construction of a low-cost but high-performance digitally driven scanning electron microscope (SEM) system is described. The low cost of the system is achieved by designing the digital drive mechanism around a programmable desk calculator with expanded cassette or disk memory. Precision of beam placement and deflection, uniformity of beam current, and reproducibility of beam location; are achieved by combining the best elements of previously developed analog and digital beam-drive systems. A hybrid analog/digital technique is used to generate lines. Endpoint data for lines are specified digitally and a continuous line is generated between the endpoints at a constant writing speed. This technique results in the generation of lines free of steps, glitches, and transients, can be used for generation of rotated or skewed vectors, and is not limited to rectangular geometry. In order to facilitate high-speed operation, not limited by the relatively low-output cycle time of most small programmable calculators, and to conserve the limited memory capabilities of these machines, a dedicated hardware logic system is used to generate all endpoint data needed to fill in rectangular areas. Upon command, a special subprogram can be called to generate circles or other desired geometries. The system can be scaled in time and hence made compatible with mostx–yplotters to allow checking of the exposure program. The interface to the HP9820 and the hardware logic system described can be applied easily to other calculators with similar capabilities. Since its capabilities can be achieved at relatively low cost, this system could be of great use in smaller research establishments in programs involving SEM diagnostics and scanning electron-beam exposure of resists for microfabrication, particularly in the semiconductor device field.