In a time sharing operating system, multiple users simultaneously access the system through terminals with the operating system interleaving the execution of each user program in a short bust or quantum of computation. Time sharing system give an impression to each user that the computer is dedicated to him because of the slow nature of human response compared to computer.
The type of events that lead to each state transition for a process and the possible transitions are:-
1. New: A new process is created to execute a program. This happens when user submit a job or an interactive user give a command through terminal.
2. Ready: The OS will move a process from the new state to the Ready state when it is prepared to take on an additional process.
3. Running: When it is time to select a new process to run the OS choose one of the processes in the ready state. This is the job of scheduler.
4. Exit: The currently running process is terminated by the operating system when it has completed or if it aborts. Termination can be due to many reasons other than completion of program execution, like arithmetic error, I/O failure, protection error, bounds violation etc.
5. Ready: When a running process reach its allotted time limit or when the allotted quantum of execution is over it is moved to ready list and remain there in a suspended state until again its allotted time arrive.
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