Digital optical data storage and processing are rapidly increasing in technological importance. The magneto‐optic spatial light modulator (MOSLM) is a relatively low‐cost, small pixel optical parallel input device that is capable of binary amplitude or binary phase modulation of each pixel. Thus, it is well matched to digital optical coherent storage and processing technology. However, potential problems associated with its use include: lack of a design for a general minicomputer interface, lack of interactive data‐page file generation software, lack of ability to switch single pixels in some cases, lack of remote‐from‐computer operation capability, spurious pixel switching, and catastrophic failure due to thermal effects. The hardware and software components of a versatile minicomputer interface that has been successful in overcoming all of these problems are described. This interface allows easy data entry of entire data pages or single pixels and minimizes cross talk and noise developed over long cable lengths. In tests, the designed interface has produced highly stable operating characteristics.