1. Introduction to Process

Definition of Process

• Process: A process is a program in execution. It's more than just the code; it includes the program counter, stack, heap and data section. It is an active entity, unlike a program, which is a passive collection of instructions.
• Program vs. Process: A program becomes a process when it is loaded into memory and executed by the CPU. Multiple processes can originate from the same program, each operating independently.

Process States

• New: The process is being created. It hasn’t started executing yet.
• Running: The process's instructions are currently being executed by the CPU.
• Waiting: The process cannot proceed until some external event occurs, such as I/O completion.
• Ready: The process is in memory and ready to run when the CPU becomes available.
• Terminated: The process has finished execution and is being removed from memory.

2. Process Control Block (PCB)

Components of a PCB

• Process State: This indicates the current state of the process (New, Ready, Running, Waiting, Terminated).
• Process Number (PID): A unique identifier for each process.
• Program Counter: Points to the next instruction that the CPU will execute.
• CPU Registers: Store intermediate data and results during execution. They must be saved and restored during context switching.
• Memory Management Information: This includes base and limit registers, page tables, or segment tables depending on the memory management scheme used.