Learn: Memory Address Register (MAR)

Welcome!You've already learned about the CPU, registers, and the fetch-decode-execute cycle. Now we'll focus on the Memory Address Register (MAR) and its role in storing memory addresses. Let's get started!

What is the Memory Address Register (MAR)?The Memory Address Register (MAR) is one of the key registers in the CPU. It stores the memory address of the data or instruction that needs to be accessed. This allows the CPU to locate and fetch the required information from the RAM or other memory locations.

Why is the MAR important?The MAR is essential in the fetch-decode-execute cycle because it helps the CPU know where to find the data or instructions it needs to process. Without the MAR, the CPU wouldn't be able to communicate effectively with the computer's memory.

How does the MAR work?When the CPU needs to fetch an instruction or data, the Program Counter sends the memory address of the required item to the MAR. The MAR then passes this address to the Memory Data Register (MDR), which fetches the actual data stored at this location. This process is crucial for the CPU to function correctly.

How does the MAR interact with other components?The MAR works closely with other parts of the CPU. For example, it gets the address from the Program Counter and passes it to the Memory Data Register (MDR). The MDR retrieves the data from memory and sends it to the Control Unit (CU) or Arithmetic Logic Unit (ALU) for processing.

How does the MAR support the fetch-decode-execute cycle?During the fetch stage, the CPU uses the Program Counter to determine the address of the next instruction. This address is stored in the MAR, which sends it to the memory to fetch the required data. This process repeats for every instruction as the CPU executes programmes.

Review Time!Great work! You've learned about the Memory Address Register (MAR), its function, and how it fits into the CPU and fetch-decode-execute cycle. Let's test your understanding!