What are CPU Registers? Difference between Cache and Register Explained.

What are CPU Registers?

CPU Registers are temporary storage devices built inside a CPU (Processor). When you give any instructions to the CPU, it stores the instructions or data in the registers till the process is completed. A Register can hold Data, addresses, and Instructions.

Also, Read: What is a CPU (Processor)? Types of Processor in a Computer.

Difference Between Cache Memory and Registers:

Cache Memory is also a storage device that holds data temporarily. Hence, most people confuse between these two, we will explain them in simple words with understandable examples.

To explain in simple words, Registers store the data before processing, and Cache Memory stores the data after processing. Check out this example to understand the difference between Cache Memory and Registers easily.

Real-Life Example: Let’s take the office example again, which we have discussed in the Cache Memory article. As I said, Cache Memory is like the cabinet desks where you store the frequently used data. Now, suppose your boss has given you a new project (instruction). You will keep the files on your working desk, analyze them, then store them in your cabinets or storage.

Similarly, when you give the CPU any instructions, it puts the information in the registers, processes it, then stores it on Cache, RAM, or Hard Disk.

Processor

Here are some of the differences between Cache and Registers in table form.

Cache MemoryRegisters
Cache Stores Processed data.Registers store Unprocessed data.
Cache Memory could be located inside the CPU or on the motherboard.Registers are a part of the CPU.
CPU uses Cache to detect previously stored data.CPU uses registers to process new data.
Cache Memory Stores recently used data.Registers store the data that the CPU is currently processing.

Now that you recognize the difference between Register and Cache Memory, let’s learn a few more things about Registers.

Types of Registers in Computer:

CPU Registers are classified into 6 types based on their functions.

  • Memory Address Register (MAR)
  • Memory Buffer Register (MBR)
  • Memory Data Register (MDR)
  • Instruction Register (IR)
  • Program Counter (PC)
  • Accumulator
Computer Registers, CPU Registers, Difference between Cache and Register

Register Size:

Register size determines how much information the CPU can store it in. A Register can be of sizes 1 Byte, 2 Bytes, 4 Bytes, 8 Bytes, or 16 Bytes. Having a bigger size Register can increase the performance of the CPU. 

Which is faster? Cache or Registers:

CPU Registers are faster than CPU Cache. In fact, Registers are the fastest type of storage device in a computer. Registers are also the most expensive type of computer memory.

How to see the size of the Register?

Usually, the Register size is shown in Bit. A 32-bit Processor has 32 bits, which means 4 bytes. Similarly, a 64-bit Processor has 64 bits, which is 8 bytes.

Also, check out other Components of Computer.

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