What are types of registers

What are the types of registers with examples?



Register in CPU

Why registers are used in CPU

What are the types of registers?

General-purpose registers

Special purpose registers

Functions of types of registers

Advantages of Computer Registers

Disadvantages of Computer Registers



What are types of registers



Registers on the computer:

A register is a type of computer memory. It is used to quickly accept, store, and transfer data and different instructions that are being used immediately by the central processing unit (CPU). There are many registers that are used to perform different operations.

The registers that are used by the CPU are termed as “Processor Registers”. Processor registers hold an instruction, a storage address, or any data. The computer needs processor registers as well as registers. Processor registers are used for manipulating data and registers are used for holding memory addresses.

When the execution of an instruction is completed, the register holding the memory location is used to calculate the address of the next instruction.

Registers in CPU:

The CPU (central processing unit) has four general-purpose programming registers. Each of these registers is 32 bit wide. These are as follows:

  • EAX
  • EBX
  • ECX
  • EDX

Why registers are used in CPU:

In the architecture of the computer, a processor register is a very fast computer memory. It helps to speed up the execution of computer instructions. It provides quick access to commonly used values, the values which are being in the midst of a calculation at a given point in time.

What are the types of registers?

According to the functions and purpose, the registers are categorized into two types.

  1. General Purpose /registers
  2. Special Purpose Registers

General-purpose registers:

  • Accumulator
  • Data register
  • Counter register
  • Base register

Special purpose registers

  • Instruction registers
  • Memory address registers
  • Program counter
  • Memory buffer register


Also Read: Computer processing devices?


Functions of types of registers

Registers can perform a variety of functions. Basically it offers temporary storage for the CPU. Data/information that is stored on the hard drive. Each and every CPU register has a distinct function. All the registers are essential components of CPU. Commonly recognized for memory allocation purposes.

The most common registers which are used in a basic computer are shown in the following table.

A register can hold an instruction, a storage address, and any type of data like a bit sequence or individual character.

Some of the instructions specify registers as a part of instruction. Such as, an instruction may specify that contents of two defined registers be added and placed in a specified register. It can hold a 64-bit computer. If it is 64 bits register in length.

In some designs of computers, registers are small. For example, half-registers. These registers are for shorter instructions. Registers can have arbitrary names or can be numbered depending on the processor design and language rules.

A processor contains multiple index-registers. These registers are also known as address registers and registers of modification.

What are the types of registers?

The effective address of an entity in a computer includes:

  • Base
  • Index
  • Relative addresses

They all are stored in the index register. In shift registers, bits enter at one end emerge from the other end. In flip flops, the data is stored and processed. It is also called bitable gates.

Register and Memory configuration of a basic computer:

DR: Data Register

MAR: Memory Address Register

PC: Program counter

AC: Accumulator Register

IR: Instruction Register

TR: Temporary Register

IR: Input Register

OR: Output Register


types of registers



A memory unit has a capacity of 4096 words. Each word contains 16 bits. The data register contains 16 bits. It holds the operand read from the memory location. The memory address register contains 12 bits. It holds the address from the memory location.

The program counter contains 12 bits. The accumulator register is a general-purpose processing register. The instruction register holds the instructions read from the memory.

The temporary register holds temporary data during the processing. The input register is used to hold the input characters given by the user. The output register is used to hold the output after processing the input data.

What are the types of registers?

Advantages of Computer Registers

  • These registers are faster than cache memory.
  • No addressing mode or tags
  • Registers are deterministic
  • Possibility of multiple read ports
  • Typically 3 to 8 bits short identifier
  • They reduce memory traffic
  • The program size is shorter
  • Increase in the number of registers
  • Increase central processing unit efficiency


Disadvantages of Computer Registers

  • Need for saving and restoring on procedural calls and context switch.
  • For pointers, cannot take the address of a register
  • They cannot store strings or structure efficiently because of fixed size
  • Compiler must manage
  • Limited number
  • additional memory access is needed
  • The compiler needs to become more efficient in this aspect.


As you read types of registers. You can read more:

Internal parts of CPU