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Every process is represented in the operating system by a process control block also called a task control block. It contains more information regarding the process.

Process state- the status may be new, ready, running, and waiting, halted and so on.

Program counter- the counter picks out the address of the next instruction to be executed for this process.

CPU Registers: together with the program counter this state information should be saved when an interrupt take place, to permit the process to be continued correctly afterward.

Memory management information: comprise value of the segment tables or page tables, base and limit registers, depending on the memory system used by the OS.

Accounting information: comprise the amount of CPU and real time used, time limits, account numbers, job or process numbers, and etc.

I/O status information: Comprise the list of I/O devices allocated to this process, a list of open files and so on.