What Is Time Sharing System?

When more than one users share same resources then it means that they are sharing computer's time. So time sharing systems allow multi-user to use computer resources by multitasking. All the users can perform different task by sharing same resources.
Actually, almost all mainframe and mini computers are time sharing systems.

You can also define time sharing as when more than one user uses a single computer.
They provide the facility of sharing a same computer among many users is the biggest advantage of these systems. I would like to talk about how time sharing systems came into existence. Before time sharing systems batch processing systems were used mostly. But when users of that system come to know that a batch processing system is unable to give direct response immediately, then idea of a new system came into existence. This new system was given name as "Time Sharing Systems".

In batch processing system only one program can be run during one cycle and these systems were unable to handle multi user programs but time sharing systems are capable to run multi user programs in one cycle. Users of these systems get the impression as they are using a single computer which resources are not shared among many users.

The idea of time sharing system was demonstrated as early as 1960, but since time-shared systems are difficult and expensive to build, they did not become common until the early 1970s.

Time sharing system is a multi-user, multi-process and interactive system. It allows multiple users to share computer simultaneously. It is used when several users are linked through communication networks to a single computer. The computer first works on one user's task for a fraction of time. It then goes to the next user's task. It is accomplished through time slicing. Each task gets a time slice in round robin fashion. The task continues until the time slice ends. The task stops when the given time slice is finished and waits for another time slice.

The computer operates very quickly and can distribute time slices to various tasks. The computer rapidly switches back and forth among different tasks. Time sharing systems use CPU scheduling and multiprogramming to provide each user with a small portion of time shared computer. The CPU can be allocated to a job only if that job is currently in memory.
A time sharing system is very complex. Jobs must be swapped in and out in a reasonable time. It may be achieved by using virtual memory. Virtual memory is a technique that allows the execution of a job that may not be completely in the memory. Unix, Linux, Windows NT Server and Windows 2000 Server are examples of time sharing systems.

Time sharing systems are the Operating systems that support multiprocessing and the processor is shared in time slices. A que of jobs are waiting and got processor for a limited time and then next process got processor. This kind of Operating systems are called time sharing systems.