Time-sharing operating systems

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Time-sharing is a technique which enables many people, located at various terminals, to use a particular computer system at the same time. Time-sharing or multitasking is a logical extension of multi programming. Processor’s time which is shared among multiple users simultaneously is termed as time-sharing.

The main difference between Multi programmed Batch Systems and Time-Sharing Systems is that in case of Multi programmed batch systems, the objective is to maximize processor use, whereas in Time-Sharing Systems, the objective is to minimize response time.

Multiple jobs are executed by the CPU by switching between them, but the switches occur so frequently. Thus, the user can receive an immediate response. For example, in a transaction processing, the processor executes each user program in a short burst or quantum of computation. That is, if n users are present, then each user can get a time quantum. When the user submits the command, the response time is in few seconds at most.

The operating system uses CPU scheduling and multi programming to provide each user with a small portion of a time. Computer systems that were designed primarily as batch systems have been modified to time-sharing systems.

Advantages of Time sharing operating systems are as follows −

  • Provides the advantage of quick response.
  • Avoids duplication of software.
  • Reduces CPU idle time.

Disadvantages of Time-sharing operating systems are as follows −

  • Problem of reliability.
  • Question of security and integrity of user programs and data.
  • Problem of data communication.