Time sharing operating systems

What Is Time Sharing System / Multi-Tasking System?

A technique which allow many people siting at various terminals to access particular computer system at the same time. Processor's time which is shared among multiple users simultaneously is termed as time-sharing. The main difference between Multiprogrammed Batch Systems and Time-Sharing Systems is that in Multiprogrammed batch systems, the aim is to maximize processor use, whereas in Time-Sharing Systems, the aim is to minimize response time, i.e A time sharing operating system is a multi tasking operating system in which the CPU time is divided equally among all the jobs waiting for the time on the CPU. Normally this time slice is 10 to 100 miceoseconds.

The implementation of  first time-sharing project was by John McCarthy in the last months of 1957 using a modified IBM 704 and later a modified IBM 7090. The first successful time-sharing system which was commercially launched was the Dartmouth Time Sharing System.

  1. Time Sharing Systems or multi tasking systems are the major advancement in the batch processing systems. They are the one which support simultaneous execution of multiple tasks using a single processor. The time sharing operating system assures that all the tasks get to access the CPU one by one and for a fixed small interval of time. This interval is known as the time quantum.

Time sharing operating systems?

  1. In above figure the user 5 is active but user 1, user 2, user 3, and user 4 are in waiting state whereas user 6 is in ready status. As soon as the time slice of user 5 is completed, the control moves on to the next ready user i.e. user 6. In this state user 2, user 3, user 4, and user 5 are in waiting state and user 1 is in ready state. The process continues in the same way and so on.The time-shared systems are more complex than the multi-programming systems. In time-shared systems multiple processes are managed simultaneously which requires an adequate management of main memory so that the processes can be swapped in or swapped out within a short time.

  2. We can assume this scenario similar to a wall clock. Various tasks in run are like digits of the clock, hand of the clock is like CPU access and the time sharing operating system ensures that CPU’s access is granted to each and every task one by one and for an equal amount of time. This is very much similar to the motion of the minute hand of a clock.
  3. Tasks running may be all of a single user or of different users too. OS schedules one task to access the CPU for the specified time quantum, and after the timer expires, the next task is scheduled. This switching takes place so fastly and seamlessly that all the users believe that their tasks are being executed all the time. However, it is not so in actuality.
  4. The primary focus of time sharing system is reducing the response time of each task. Response time is the time elapsed between the submission of the input and the moment its first output is obtained. Since all the tasks are being executed continuously and progressively, response time reduces a lot, both overall response time as well as the response time for each process.

Example of Time Sharing / multi tasking operating system

Time sharing systems are all around us. For example, while we are using our smartphone we can listen songs, search something, view pictures and various notifications appear side by side. All this is enabled by time sharing operating system only. OS does the switching between these tasks time and again so that they all are executed continuously.


  1. No starvation is there and all the processes can access the CPU for a fair amount of time.
  2. CPU’s utilization is very high.
  3. Response time for each task is reduced a lot


  1. Reliability problems.
  2. Security and integrity questions of user programs and data.
  3. Data communication issues.


Why to use time sharing operating systems?

In the era of modern technology there are lot many tasks and activities that are required be run at the same time. Like in smartphones the games,notification bar, weather forecasting, songs are all running at the same time so time sharing systems are more efficient to use. Real time operating systems also uses time sharing as a key for better performance.

Frequently Asked Questions

Ans: The main function of a batch processing system is to automatically keep executing the jobs in a batch. This is the important task of a batch processing system i.e. performed by the 'Batch Monitor' resided in the low end of main memory. This technique was possible due to the invention of hard-disk drives and card readers. Now the jobs could be stored on the disk to create the pool of jobs for its execution as a batch. view more..
Ans: There are many types of operating systems that can be listed to study the types the operating systems. These types of operating systems are important as they explain us the evolution of the operating system with time. This evolution took place due to the customer’s demands and due to the enhancement in technology. There are 5 types of operating System- Batch Operating Systems, Time Sharing Systems, Distributed Operating Systems, Network Operating Systems, Real Time Operating Systems view more..
Ans: Operating system acts as an interface between the user and the hardware. It is something which relieves the user from bothering about hardware related issues. what is multitasking, Multiprogramming, Multiuser Operating System, Multithreading view more..
Ans: Time Sharing Systems or multi-tasking systems are the major advancement in the batch processing systems. They are the one which support simultaneous execution of multiple tasks using a single processor. The time-sharing operating system assures that all the tasks get to access the CPU one by one and for a fixed small interval of time. This interval is known as the time quantum. view more..
Ans: Distributed Operating System is a recent advancement in the world of computer technology and are being widely accepted all-over the world and, that too, with a great pace view more..
Ans: Network Operating System is a collection of various computers which are all connected to a single host computer. It can be compared to a client – server architecture where the host computer acts as a server and rest of the systems act as clients which take services from the common server and access its resources also. view more..
Ans: Real time operating System (RTOS) is an operating system that serves the real-time systems. Before understanding the term “Real Time Operating System” we need to understand the two terms it comprises of i.e., Real Time Systems and Operating System. view more..
Ans: We can broadly classify these services into following five categories: Process management Device management Inter-process Communication File management Error detection view more..
Ans: there are 4 types of architectures of operating system: 1. Monolithic architecture 2. Layered architecture 3. Microkernel architecture 4. Hybrid architecture view more..
Ans: It is the oldest architecture of the operating system. We know that all the core software components of the operating system are collectively known as the kernel. view more..
Ans: This is an important architecture of operating system which is meant to overcome the disadvantages of early monolithic systems. view more..
Ans: The basic ideology in this architecture is to keep the kernel as small as possible. We know that kernel is the core part of the operating system and hence it should be meant for handling the most important services only. view more..
Ans: the idea was to combine the best functionalities of all old approaches and hence this design is termed as the hybrid structured operating system. view more..
Ans: System Calls and Programs All the present-day operating systems support the following two modes of operation for the CPU: User mode Kernel mode view more..
Ans: A batch system executes jobs, whereas a time-shared system has user programs, or tasks. Even on a single-user system such as Microsoft Windows, a user may be able to run several programs at one time: a word processor, a web browser, and an e-mail package. Even if the user can execute only one program at a time, the operating system may need to suppoft its own internal programmed activities, such as memory management. view more..
Ans: Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. view more..
Ans: Process scheduling selects processes from the queue and loads them into memory for execution. Process loads into the memory for CPU scheduling. The primary objective of the job scheduler is to provide a balanced mix of jobs, such as I/O bound and processor bound. ... Time-sharing operating systems have no long term scheduler. view more..
Ans: Inter process communication (IPC) is a mechanism which allows processes to communicate each other and synchronize their actions. The communication between these processes can be seen as a method of co-operation between them. Processes can communicate with each other using these two ways: Shared Memory. Message passing. view more..

Rating - 3/5