Process & Process States :

PROCESS :

The term process was first introduced by the designers of multi system in 1960. A process is a program in execution .It is the basic unit of resource allocation in an operating system. A process has a starting and ending point. It most execute and progress sequentially. A process is controlled and scheduled by operating system. An operating system executes different programs depending on the system.

Process Attributes :

A process has the following attributes.

• Program counter :  It is used to keep track of the address of the next instruction to be executed
• Stack : A stack is used to store temporary data for the process.
• Data section : A data section is used that may contain global variable.
• Heap : A process may include a heap. It is the memory that is dynamically allocated during process execution.

Process in memory

Process states :

As a process executes, it changes states. The state of a process is defined in part by the current activity of that process. Each process may be in either of the following states .

• New :  The process is being created.
• Running :  Instructions are being executed.
• Waiting :  The process is waiting for some event to occur (such as an I/O completion or reception of a signal).
• Ready :  The process is waiting to be assigned to a processor.
• Terminated :  The process has finished execution.

Process state diagram