Project Mercury's man-in-space real-time computer system: "you have a go, at least seven orbits"

Project Mercury was the first US venture to send a man into space. The project lasted 55 months, involved more than 2 million people, and cost more than $400 million. In retrospect, Project Mercury's real time computer programming, and data processing aspects seem a minor element of the total project. Historical accounts of Project Mercury do not say much, if anything, about its computer based activities. These computer based activities include the real time computing accomplishments of a team of about 100 scientists, programmers, and engineers that paved the way for future manned space projects and gave the computer profession its first glimpse of a real time computing system that was predicated on the safety requirements of a man-in-the-loop. The article describes the real time computational requirements, the procedures, and the equipment that were developed to support this pioneering project, as well as some personal observations.