Time-sharing

Time -sharing was the first conceptual approach in computer technology to allow multiple users to work simultaneously on a computer ( multi-user system ), by shared the computing time of the existing single processor. Each individual user, it appeared there as if he would have the full resources of the computer always alone available.

Nowadays, the term time-sharing is, if he is even still used, often erroneously equated with the multitasking. Although both concepts relate to work in parallel on a processor, so based

  • Multitasking on an idea by Christopher Strachey and places emphasis on the almost simultaneous processing of processes,
  • Was during the time-sharing the first time in 1957 by Bob Bemer described and implemented in late 1957 by John McCarthy, while the conceptual focus lays on the simultaneous operation of many users.

The actual New from the user's perspective, accessing the computer through terminals. The user for the first time was able to interactively influence the computational behavior of the computer and did not have to wait for the sequential processing of files.

The mandatory requirements for time-sharing, which are taken for granted today, in the late 50s, however, a new, revolutionary were:

  • Scheduling, ie the possibility for controlled processor allocation to users or processes
  • Swapping the first possibility of a simple memory management
  • File systems with simultaneous access to files
  • Memory protection

The first used operating systems with time-sharing were:

If the implementation of time sharing by the execution time is divided into small areas, which are called time slots. According to certain regulations ( Schedule) the programs ( processes) are assigned to these time slices. Thus, to perform its tasks, a program for the duration of the time slice.

John McCarthy (computer scientist) Compatible Time-Sharing System
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