Define a Process in an Operating System. Explain the structure and…
Define a Process in an Operating System. Explain the structure and significance of a Process Control Block (PCB) in managing process execution.
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Concept of a Process
A process is simply a program in execution. While a program is a passive entity stored on a disk (like an .exe file), a process is an active entity that loaded into the main memory and holds allocated resources like CPU time, memory, and I/O devices.
Process Control Block (PCB)
What is a PCB?
A Process Control Block (PCB) is a data structure maintained by the Operating System for every active process. It serves as the repository of information, storing all the attributes needed to manage, track, and control that specific process.
Core Components of a PCB
Process ID (PID): A unique identification number assigned to each process by the OS.
Process State: Tracks the current status of the process (such as New, Ready, Running, Waiting, or Terminated).
Program Counter (PC): Stores the address of the next instruction to be executed for this process.
CPU Registers: Saves the contents of registers during context switching so the process can resume exactly where it left off.
Memory Management Info: Contains page tables, segment tables, or base/limit register values allocated to the process.
I/O Status Info: Keeps track of the list of open files and I/O devices allocated to the process.