Time Slice

In the late 1950s and early 1960s, computer systems were envisioned that could be used simultaneously by several people, each at a typewriter-like terminal, each appearing to have exclusive use of the computer. The computer was to take advantage of the typing time of one user by turning its attention to another. If the computational tasks requested were short enough, then all users could be serviced, and the illusion of a single-user private computer would be maintained. Early systems served less than a dozen people, whereas modern systems service 10 to 1,000 or more. But what if there were one or more very long computational tasks?