What are registers?

Registers are electronic sequential logic circuits equipped with flip-flops and capable of storing data larger than one bit in digital form. They are widely used in modern digital electronics. The program counter, accumulator, and stack pointer present in a microprocessor are some common examples of registers. 

Types of registers

Registers can be categorised into two major types, namely:

• General purpose register: These types of registers are primarily used to store data. Data registers, counter registers and accumulators fall under the category of general-purpose registers.
• Special purpose register: These types of registers are designed to hold instructions or the state of a program before they are executed. Instruction registers and program counters are some of the most common examples of special-purpose registers. 

What are registers used for?

Registers have extensive uses in modern digital electronics. Most commonly they are used to:

• Store data, address and instructions. 
• Build digital memory chips including flash memory, and ROM chips, among others. 
• Make cache memory in the CPU.