Register vs Main Memory: Difference and Comparison

Key Takeaways

1. Register: Registers are small, high-speed storage locations within a computer’s CPU (Central Processing Unit). They store and manage data that the CPU is currently processing. Registers are the fastest memory storage in a computer, and they hold frequently used data and instructions to accelerate the execution of instructions.
2. Main Memory: Main memory, called RAM (Random Access Memory), is a larger and slower form of computer memory than registers. It is a temporary storage location for data and instructions the CPU needs to access during program execution. RAM is crucial for running applications and storing data that is actively being used by the computer.
3. Registers are an integral part of the CPU and provide the fastest data access, making them ideal for storing operands and intermediate results during calculations. On the other hand, main memory is larger in capacity but slower in access speed compared to registers. Together, registers and main memory work in tandem to enable the efficient execution of computer programs by allowing data to be moved between them as needed during processing.

What is Register?

A register is a small storage location of a computer. It is high-speed, and it is situated within the CPU. As a storage, it stores data that the CPU processes.

The access times of Registers are calculated in nanoseconds. It is also the fastest among the computer storages. Without registers, CPUs are incomplete. They are responsible for speeding up the data processing.

Registers control information when the instructions get executed. They are also used to hold operands and memory addresses. As they are extremely fast, they are perfect for storing data necessary for quick operations.

However, efficiency comes with a cost. It is expensive to implement them. The high cost is also caused by its small size. The number of registers in a computer range between 16 to 32. Its numbers are limited, while the main memory is much bigger—the instructions of the CPU control all of them.

What is Main Memory?

Another term for main memory is Random Access Memory or, in short, RAM. It offers a place for the computer to keep data used by the CPU while executing programs.

It is regarded as a volatile memory. The reason is that it is temporary. If you turn the computer off or restart, the data stored in RAM will be wiped off. It is quite the opposite of storage devices, such as hard or solid-state drives, that permanently hold the data.

The operating system manages the main memory. The OS decides how the data is stored and retrieved in the main memory.

Main memory not only stores data but also gives space to program instructions. It also keeps the data that different software needs to operate. It works to offer you the results quickly. So, if you open a file, it will load from the computer’s storage to the main memory.

Difference Between Register and Main Memory

1. The register is within the CPU, while the main memory is outside the CPU.
2. As the register is placed within the CPU, it is managed by the instructions of the CPU, while the operating system manages the main memory.
3. If we list down the memory hierarchy, the register will take the top place, whereas the main memory will come in the lower position.
4. The CPU accesses the register directly, but the memory bus accesses the main memory.
5. Data stored in the register is temporary, while the main memory stores the program and data.
6. Regarding data transfer, registers provide the highest rate while the rate of main memory is low.

Comparison Between Register and Main Memory

Parameter of Comparison	Register	Main Memory
Location	It is located within the CPU.	It is situated outside the CPU.
Capacity	Its capacity is very limited.	It has a large capacity.
Speed	It is known for its breakneck speed.	It is slower when compared to registers.
Goal	It is used to store data that helps in CPU operations.	It is used to store program instructions and data.
Required for	It is needed to speed up data processing.	It is needed to execute programs and tasks.
Data transfer rate	Its data transfer rate is the highest.	Compared to registers, the data transfer rate of the main memory is lower.
Expense	Registers are expensive.	Comparatively, the main memory is less expensive.

References

1. https://ieeexplore.ieee.org/abstract/document/4145108/
2. https://ieeexplore.ieee.org/abstract/document/1672774/

Last Updated : 29 September, 2023