In the summer of 1967, Brinch Hansen left Regnecentralen's hardware group to become head of RC 4000 software development, where he led a team including Jørn Jensen, Peter Kraft and Søren Lauesen in defining a general-purpose RC 4000 multiprogramming system, with a goal to avoid developing a custom real-time control operating system for every RC 4000 installation, and to support batch processing and time-sharing as well. The resulting system was not a complete operating system, but a small kernel providing the mechanisms upon which operating systems for different purposes could be built. By the spring of 1969, a well-documented, reliable version of the RC 4000 multiprogramming system was running.