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1.
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New |
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A program is admitted to execute, but not yet ready to execute. The operating system will initialize the process by moving it to the ready state.
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2.
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Ready |
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The process is ready to execute and is waiting access to the processor.
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3.
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Running |
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The process is being executed by the processor. At any given time, only one process is in running state.
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4.
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Waiting |
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The process is suspended from execution, waiting for some system resource, such as I/O.
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5.
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Exit |
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The process has terminated and will be destroyed by the operating system.
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The processor alternates between executing operating system instructions and executing user processes. While the operating system is in control, it decides which process in the queue sholud be executed next.
A process being executed may be suspended for a variety of reasons. If it is suspended because the process requests I/O, then it is places in the appropriate I/O queue. If it is suspended because of a timeout or because the operating system must attend to processing some of it's task, then it is placed in ready state.
We know that the information of all the process that are in execution must be placed in main memory. Since there is fix amount of memory, so memory management is an important issue.
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