Define Process States. Draw the diagram of PCB.

Process States

A process can be in one of several states at any given time. The state of a process is determined by its current activities and the resources it is using. The most common process states are:

• Running: The process is currently executing instructions.
• Ready: The process is waiting to be scheduled for execution.
• Waiting: The process is waiting for a resource, such as a file or a lock, to become available.
• Blocked: The process is unable to proceed because it is waiting for an event, such as the completion of an I/O operation.
• Terminated: The process has completed execution and all of its resources have been deallocated.

Process Control Block (PCB)

The process control block (PCB) is a data structure that contains information about a process. The PCB is created when a process is first created and it is destroyed when the process terminates. The PCB contains the following information:

• Process ID (PID): A unique identifier for the process.
• Program Counter (PC): The address of the next instruction to be executed.
• Stack Pointer (SP): The address of the top of the stack.
• General Purpose Registers: The values of the general purpose registers.
• Memory Management Information: The location and size of the process's memory segments.
• File Descriptors: The file descriptors for the files that the process has open.
• Process State: The current state of the process.

The PCB is used by the operating system to manage the process. The operating system uses the PCB to determine when the process should be scheduled for execution, when the process should be blocked, and when the process should be terminated.

Diagram of a PCB

The following diagram shows the layout of a typical PCB:

+------------------------------------------------+
| Process ID (4 bytes)                                |
+------------------------------------------------+
| Program Counter (4 bytes)                           |
+------------------------------------------------+
| Stack Pointer (4 bytes)                              |
+------------------------------------------------+
| General Purpose Registers (32 bytes)                 |
+------------------------------------------------+
| Memory Management Information (variable length)      |
+------------------------------------------------+
| File Descriptors (variable length)                  |
+------------------------------------------------+
| Process State (1 byte)                               |
+------------------------------------------------+

The PCB is a critical data structure in the operating system. It provides the operating system with the information it needs to manage the process.