Timesharing

Time-sharing is a computing approach that allows multiple users to interact with a computer as if they each had a dedicated machine. In a time-sharing system, a central processor rapidly switches among active tasks, giving each user or process a short time slice. The operating system manages scheduling, context switching, and protection, while I/O devices and user terminals or network connections provide the interface.

Historically, time-sharing emerged in the 1960s to maximize utilization of expensive mainframes. Notable systems included the MIT Compatible Time-Shsharing System (CTSS), the Dartmouth Time-Sharing System (DTSS), and the Multics project, as well as IBM's System/360 and related experiments. These systems introduced interactive computing, allowing commands to be executed in near real time rather than as batch jobs.

In operation, time-sharing relies on fast context switches to preserve and restore process state, virtual memory to isolate processes, and scheduling policies to balance responsiveness and throughput. The model influenced the development of multiprogramming and multitasking operating systems and formed the basis for modern interactive computing in servers, workstations, and personal computers.

Today, explicit time-sharing is less commonly named, but its principles persist in virtualization, cloud platforms, and multi-user server environments, where the CPU is shared among virtual machines or sessions with controlled isolation and scheduling.

Advantages include higher resource utilization, interactive response, and cost efficiency. Limitations involve scheduling overhead, variability in response time, and security concerns in shared environments.