 In 1969, their effort resulted in the completion of the RC 4000 Multiprogramming System.Its nucleus provided inter-process communication based on message-passing for up to 23 unprivileged processes, out of which 8 at a time were protected from one another.It further implemented scheduling of time slices of programs executed in parallel, initiation and control of program execution at the request of other running programs, and initiation of data transfers to or from peripherals.