The full form of MAR is Memory Address Register, and the full form of MDR is Memory Data Register.
These registers are crucial components of a computer's central processing unit (CPU), specifically in memory management. Let's break down what each one does:
Memory Address Register (MAR)
- The MAR holds the memory address of the data or instruction that the CPU needs to access from memory.
- Think of it like a specific address on a street. The CPU needs to know where to find the information in the computer's memory.
- Before a read or write operation from/to memory, the CPU loads the desired memory address into the MAR.
Memory Data Register (MDR)
- The MDR, also sometimes called the Memory Buffer Register (MBR), contains the data being transferred to or from memory.
- After the MAR specifies the location, the MDR holds the actual data that's being read from that location or the data that's being written to that location.
- When reading from memory, the MDR receives the data from the memory location specified by the MAR. When writing to memory, the CPU places the data into the MDR, and the memory controller then writes that data to the memory location specified in the MAR.
In summary, the MAR specifies where to access memory, and the MDR holds what is being accessed (read or written). Both are vital for communication between the CPU and memory.
