Learn: MAR - Storing the Address

Welcome!You've already learned about the fetch-decode-execute cycle and the role of registers. Today, we'll focus on the Memory Address Register (MAR) and its key role in storing memory addresses during the fetch-execute process.

What is the MAR?The Memory Address Register (MAR) is a register inside the CPU. It holds the memory address of the data or instruction that the CPU needs to access.This address is sent to main memory to fetch data or instructions during the fetch-decode-execute cycle. Without the MAR, the CPU wouldn't know where to look in memory!

How Does the MAR Work?When the CPU needs an instruction or data, the memory address of that item is stored in the MAR. This address is then sent to the memory to retrieve the required information.For example, during the fetch stage, the MAR stores the address of the next instruction to be fetched. This is crucial for the CPU to operate efficiently and correctly.

Why Is the MAR Important?Without the MAR, the CPU would not be able to locate data or instructions in memory. The MAR ensures that the CPU can fetch the correct information efficiently.It works seamlessly with other registers, such as the MDR (Memory Data Register), which holds the actual data being transferred to or from memory.

How the MAR Fits into the Fetch-Execute CycleDuring the fetch stage, the Program Counter (PC) sends the address of the next instruction to the MAR. The MAR then communicates with the memory to retrieve the instruction or data from that address.This process ensures that the CPU gets the correct data or instructions in the right order.

Review Time!Great work! You've learned about the MAR, its role in storing memory addresses, and how it fits into the fetch-execute cycle. Let's test your understanding with a few questions.