Difference between Cache Memory and Register

The computer's memory units are cache memory and register. But they differ in terms of access time, speed, size, and so on. Cache memory is a type of memory that saves data that the processor has recently used. In contrast, the register is a high-speed storage device that stores the data that the CPU is now processing.

As the processor loads an instruction or associated data from the main memory into the processor chip (registers), a copy of it is stored in the cache memory. When the processor retrieves operands from memory for the ALU to perform an operation, it stores them in registers. The registers are smaller and faster than the cache memory.

In this article, you will learn the difference between Cache memory and Registers. But before discussing the differences, you must know about Cache memory and Registers with their advantages and disadvantages.

What is Cache Register?

The cache memory is a smaller but faster component of a computer system that is located between the main memory and the CPU. The cache must be faster than the main memory for this arrangement to be effective. The strategy for such an arrangement is particularly cost-effective for fast memory devices because they may easily install the main memory while increasing its performance speed.

Types of Cache Memory

There are various types of Cache memory. Some main types of cache memory are as follows:

1. L1 Cache

L1 cache is the first cache level. It stores data that the CPU has recently utilized. It stores recently utilized data from the CPU cores for rapid access by other portions of the system. The data in this area is regularly accessed because it is close to the processor. L1 caches are typically quite small in size, ranging from 8 KB to 128 KB.

2. L2 Cache

The L2 cache is slower than the L1 cache and has significantly more capacity, ranging from 64 KB to 16 MB. Modern CPUs include the advanced transfer cache, which is a sort of L2 cache that is built directly on the processor chip. Processors that use advanced transfer cache perform significantly faster than those that do not utilize it. PCs today often contain advanced transfer cache ranging from 512 KB to 12 MB.

3. L3 Cache

It is larger in size but slower than the L1 and L2 caches. It ranges in size from 1MB to 8 MB. Every core in a multi-core processor can have its own L1 and L2 caches, but all cores share a shared L3 cache. L3 cache has double the speed of the RAM.

Advantages and Disadvantages of Cache Memory

There are various advantages and disadvantages of Cache memory. Some advantages and disadvantages of cache memory are as follows:

Advantages

1. It is significantly faster than both primary and secondary memory.
2. It has a faster data access time than primary memory.
3. It stores all the data and instructions that the CPU frequently uses, increasing CPU performance.
4. It is a type of high-speed semiconductor memory that can help the CPU run faster.
5. It saved a program that could be executed in a short amount of time.

Disadvantages

1. It temporarily stores the data.
2. It is more costly than other memory.
3. Cache data is kept as long as the system is powered on.
4. Its storage capacity is quite useful.
5. When a computer is switched off, the data it contains is erased.

What is Register?

A register is the smallest data storage element. It is incorporated directly into a processor, so the registers function as specific memory regions that a CPU may directly access in a computer system. An individual register may store a small quantity of data (often 32 to 64 bits), an instruction, data storage addresses, or any other type of data, including such individual characters and bit sequences.

Types of Registers

There are various types of Registers. Some main types of the registers are as follows:

1. General Purpose Registers

It is also known as a processor register. They serve various roles, including holding operands loaded from memory for processing.

2. Memory Address Register

It defines the memory address from which the word will be read into Memory Buffer Register (MBR) or where the word from MBR will be written into memory.

3. Memory Buffer Register

It saves a word that is fetched from the main memory or an I/O unit. It even saves the word that the process needs to send back to the main memory or the I/O unit.

4. Instruction Buffer Register (IBR)

The IBR register temporarily stores the right-hand instruction from the memory word.

5. Instruction Register

It currently contains an 8-bit opcode (machine instruction) that is being executed.

6. Program Counter

PC has the memory address of the next instruction that has to be fetched for execution.

Advantages and Disadvantages of Register

There are various advantages and disadvantages of register. Some advantages and disadvantages of register are as follows:

Advantages

1. As it is the fastest memory block, it executes instructions faster than the main memory.
2. It offers the CPU faster access to instructions, data, and locations stored in it.
3. It is responsible for storing and retrieving variables that are accessed repeatedly.
4. It improves memory utilization while running the program.
5. It dramatically improves program performance.

Disadvantages

1. It is relatively more costly than other types of memory.
2. It cannot store a great amount of data because register memory is small in size.
3. If the instruction is larger than the Processor, the operation must use the cache or the main memory in addition to the register.

Key differences between Cache memory and Register

Here, you will learn the key differences between Cache memory and Register. Some of the key differences between Cache memory and Register are as follows:

1. The cache is the smallest in size and fastest memory component of the computer system. On the other hand, registers are fast storage elements that are present in a very small amount of the computer processor.
2. The processor utilizes cache memory to store recently utilized data. On the other hand, the processor utilizes registers to store operands that it is currently processing.
3. Access time to cache memory is reduced because it is directly connected to the CPU and implemented on the CPU chip itself. In contrast, the registers are also available on the CPU chip, and their access time is even faster than that of the cache memory.
4. When the CPU reads instructions or data from the main memory, it copies it into the cache memory. In contrast, the CPU recognizes operands from instructions or associated data, and it saves them in registers.
5. Any computer's cache memory can range from 2 MB to a few KBs. On the other hand, registers are the smallest memory units that may store up to one word of data or up to 64 bits.
6. Cache memory is a high-speed storage location for temporary data. On the other hand, registers are utilized to store data for processing and transfer temporarily.
7. Cache memory is a separate memory unit found on the CPU chip. In contrast, registers are the smallest high-speed component on the CPU chip.
8. Cache memory is classified into various levels, including L1, L2, and L3 cache. In contrast, the processor has various types of registers, including MAR, MBR, general-purpose registers, AC, PC, IR, IBR, etc.

Head-to-head comparison between Cache memory and Register

Here, you will learn head-to-head comparisons between Cache memory and Register. The main differences between Cache memory and Register are as follows:

Conclusion

The computer's memory units are cache memory and register. Only the primary cache (L1) and all types of registers are available on the processor. On the other hand, the registers are the smallest and fastest component of any computer system. Although both are smaller computer memory units, they serve different functions. The cache stores recently utilized instructions and data. In contrast, the processor stores instructions and data that it is presently processing in registers.