The first computer graphic display of molecular structures was devised at M.I.T. in the mid-1960s. Taking advantage of Project MAC (Multi-Access Computer), one of the first timesharing mainframe computers (Fano and Corbato 1966), Cyrus Levinthal and his colleagues designed a "model-building" program to work with protein structures (Levinthal 1966). This program allowed the study of short-range interaction between atoms and the "online manipulation" of molecular structures. The display terminal (named Kludge) was a monochrome oscilloscope, showing the structures in wireframe fashion. Three-dimensional effect was achieved by having the structure rotate constantly on the screen. To compensate for any ambiguity as to the actual sense of the rotation, the rate of rotation could be controlled by globe-shaped device on which the user rested his/her hand (an ancestor of today's trackball). Technical details of this system were published in 1968 (Levinthal et al.).
What could be the full potential of such a set-up was not completely settled at the time, but there was no doubt that it was paving the way for the future. Thus, this is the conclusion of Cyrus Levinthal's description of the system in Scientific American (p. 52):
It is too early to evaluate the usefulness of the man-computer combination in solving real problems of molecular biology. It does seems likely, however, that only with this combination can the investigator use his "chemical insight" in an effective way. We already know that we can use the computer to build and display models of large molecules and that this procedure can be very useful in helping us to understand how such molecules function. But it may still be a few years before we have learned just how useful it is for the investigator to be able to interact with the computer while the molecular models is being constructed.Finally, it is worth noting that the development of this system coincided with the development of the Corey-Pauling-Koltun (CPK) space-filling atomic models, which were to remain for many years one of the most accessible (if not so practical) way of modeling macromolecular structures.
Fano, R. M. and F. J. Corbato (1966). "Time-Sharing on Computers." Scientific American 215(3): 128-140.
Levinthal, Cyrus (1966). "Molecular Model-Building by Computer." Scientific American 214(6): 42-52.
Levinthal, C., C. D. Barry, et al. (1968). Computer Graphics in
Macromolecular Chemistry. Emerging Concepts in Computer Graphics. D.
Secrest and J. Nievergelt, Eds. New York, W. A. Benjamin, Inc.: 231-253.