What is a Register in Computer?

Computer registers are memory storing units that operate at high speed. It’s a component of a computer’s processor. It can hold any type of data, including a bit sequence or a single piece of data.

  • Eight registers, a memory unit, and a control unit make up a basic computer. These devices must be connected on a regular basis.

Following is the list of some of the most common registers in computer:

RegisterSymbolNumber of BitsFunction
AccumulatorAC16It’s a processor register.
Program counterPC12It stores the address of the instruction.
Address RegisterAR12It is used for storing memory addresses.
Data RegisterDR16It is a general-purpose register used for storing data during calculations.
Instruction RegisterIR16It stores the current instruction being executed.
Temporary RegisterTR16It holds the temporary data.
Input RegisterINPR8It carries the input character.
Output RegisterOUTR8It carries the output character

Types of Registers Used in Computer

Registers are a type of computer memory used to accept, store, and transfer data and instructions used by the CPU right away. Processor registers refer to the registers used by the CPU.During the execution of a program, registers are used to store data temporarily.In most cases, the number of bits that a register can hold is used to determine its size.The common registers in a computer and the memory are depicted in the diagram below:

Basic computer Registers and memory

The following are the various computer registers and their functions:

  • Accumulator Register (AC): Accumulator Register is a general-purpose Register. The initial data to be processed, the intermediate result, and the final result of the processing operation are all stored in this register. If no specific address for the result operation is specified, the result of arithmetic operations is transferred to AC. The number of bits in the accumulator register equals the number of bits per word
  • Address Register(AR): The Address Register is the address of the memory location or Register where data is stored or retrieved. The size of the Address Register is equal to the width of the memory address is directly related to the size of the memory because it contains an address. If the memory has a size of 2n * m, then the address is specified using n bits
  • Data Register(DR): The operand is stored in the Data Register from memory. When a direct or indirect addressing operand is found, it is placed in the Data Register. This value was then used as data by the processor during its operation. It’s about the same size as a word in memory
  • Instruction Register(IR): The instruction is stored in the Instruction Register. The instruction register contains the currently executed instruction. Because it includes instructions, the number of bits in the Instruction Register equals the number of bits in the instruction, which is n bits for an n-bit CPU
  • Input Register(INPR): Input Register is a register that stores the data from an input device. The computer’s alphanumeric code determines the size of the input register
  • Program Counter(PC): The Program Counter serves as a pointer to the memory location where the next instruction is stored. The size of the PC is equal to the width of the memory address, and the number of bits in the PC is equal to the number of bits in the PC
  • Temporary Register(TR): The Temporary Register is used to hold data while it is being processed. As Temporary Register stores data, the number of bits it contains is the same as the number of bits in the data word
  • Output Register(OUTR): The data that needs to be sent to an output device is stored in the Output Register. Its size is determined by the alphanumeric code used by the computer

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