THE CONCEPTS OF PROCESS IN O.S.

PROCESS CONCEPTS- An operating system executes a variety of programs:
Batch system – jobs
Time-shared systems – user programs or tasks
Textbook uses the terms job and process almost interchangeably.
Process – a program in execution; process execution must progress in sequential fashion.
A process includes:
: program counter
: stack
:data section


PROCESS STATE- As a process executes, it changes STATES

new: The process is being created.
running: Instructions are being executed.
waiting: The process is waiting for some event to occur.
ready: The process is waiting to be assigned to a processor
terminated: The process has finished execution.

PROCESS CONTROL BLOCK-Process Control Block (PCB)
Information associated with each process.
: Process ID
:Process state
:Program counter
:CPU registers
:CPU scheduling information
:Memory-management information
: Accounting informationn
:I/O status information

TRENDS-