The basic objective of the development of man-machine interactive systems is to design a system that will most effectively take into account the limitations and talents of both man and machine, recognizing that the human factors are, in certain aspects, diametrically opposed to those of the computer. This document briefly investigates those elements of a man-machine system which directly affect the interaction between user and system. Hardware elements discussed include data input facilities, data output characteristics, audio input and output, graphic input and output, and user terminal configuration. The importance and intent of interactive generative languages for users are examined in the section on software elements, and the final section describes effective design features for environmental and architectural elements. A matrix comprised of prospective user categories and the elements affecting user-system interaction is included. (Author/SH)