Time sharing allows a large number of users at various remote terminals to simultaneously use a centrally located computer for problem solving. Each user operates independently and receives such fast response that he has the impression as if he is the only user. The operating system which has the time sharing facility supervises the scheduling of jobs, transfers control of the central processor from one user to another and moves programs in and out of the main memory. In effect, the computer gives time on a round robin basis to the users. Ordinarily the time allocated to each user is very small (25 cms.) and is known as “time slice”. As the time slice is very small, users get very fast response from the system. The CPU switches from one user to another either at the end of the allocated “time slice” or earlier through input/output interrupts.