Process States

The process state consist of everything necessary to resume the process execution if it is somehow put aside temporarily. The process state consists of at least following:

• Code for the program.
• Program's static data.
• Program's dynamic data.
• Program's procedure call stack.
• Contents of general purpose registers.
• Contents of program counter (PC)
• Contents of program status word (PSW).
• Operating Systems resource in use.

A process goes through a series of discrete process states.

• New State: The process being created.
• Running State: A process is said to be running if it has the CPU, that is, process actually using the CPU at that particular instant.
• Blocked (or waiting) State: A process is said to be blocked if it is waiting for some event to happen such that as an I/O completion before it can proceed. Note that a process is unable to run until some external event happens.
• Ready State: A process is said to be ready if it use a CPU if one were available. A ready state process is run able but temporarily stopped running to let another process run.
• Terminated state: The process has finished execution.