Process Control Block (PCB) of all running processes resides in RAM.

The Process Control Block (PCB) is a data structure that contains information about the currently running process in an operating system. It serves as the central repository for all the necessary information required by the operating system to manage a process. The PCB holds crucial details about the process, including its current state, program counter, register values, memory allocation, and other relevant information.

Explanation:

1. What is RAM?
RAM stands for Random Access Memory. It is a type of computer memory that allows data to be read from or written to in almost the same amount of time, regardless of the physical location of the data within the memory. RAM is a volatile memory, meaning that its contents are lost when the computer is powered off.

2. Why does the PCB reside in RAM?
The PCB needs to be stored in RAM because it is accessed frequently by the operating system during the execution of processes. Placing the PCB in RAM allows for faster and efficient access to the information it contains. Additionally, as RAM is a volatile memory, it ensures that the PCB is cleared when the process terminates or the system is shut down.

3. Role of PCB in process management:
The PCB is a critical component of process management in an operating system. It contains various fields that help in managing and controlling the execution of processes. Some of the key information stored in the PCB includes:

- Process ID (PID): A unique identifier for each process.
- Process State: Indicates whether the process is running, waiting, or terminated.
- Program Counter (PC): Keeps track of the address of the next instruction to be executed.
- CPU Registers: Stores the current values of the CPU registers.
- Memory Management Information: Contains details about the memory allocated to the process.
- I/O Status Information: Keeps track of the I/O devices associated with the process.
- Priority: Determines the scheduling priority of the process.
- Parent Process ID: The PID of the parent process.

Conclusion:
In conclusion, the Process Control Block (PCB) of all running processes resides in RAM. Placing the PCB in RAM allows for efficient access to the information it contains, facilitating the management and control of processes by the operating system.