The register memory of a computer is the smallest and most quickly accessible memory in the machine. As opposed to main memory, it is included within the CPU in the form of registers, which are the smallest data-holding units available to the processor. A register is a temporary storage location for data, instructions, and memory addresses that are regularly utilised by the CPU and are to be used by it. They are used to store instructions that are presently being executed by the processor. Before any data can be processed, it needs to travel through a series of registers first. As a result, they are utilised by the CPU in order to process the data entered by the users.
Registers are used to store a tiny amount of data, often between 32 and 64 bits. Speed of a processor is determined by the number and size (in bits) of registers that are integrated into the processor’s design. Depending on their intended usage, registers can be classified into several categories. The Accumulator or AC, the Data Register or DR, the Address Register or AR, the Program Counter (PC), the I/O Address Register, and other registers are some of the most often used registers.
Computer registers are classified into the following types and functions:
- ● This 16-bit register is used to hold operands (variables) that will be worked on by the processor. It is referred to as the data register.
- ● It is used to temporarily store data that is being communicated to or received from a peripheral device while it is in transit.
- ● When the current instruction is completed, the programme counter (PC) stores the address of the memory location of the next instruction, which is to be retrieved once the current instruction has been finished.
- ● Consequently, it is utilised to preserve the path of execution for the several programmes and so runs the programmes one by one, as each instruction is finished before the next one is executed.
- ● Instructor Register is a 16-bit register that is used by the instructor. It is responsible for storing the instruction that has been retrieved from the main memory.
- ● As a result, it is utilised to store instruction codes that are later executed. The Control Unit reads the instructions from the Instructor Register, decodes them, and then puts them into action.
- ● Aaccumulator Register is a register with a capacity of 16 bits that is used to store the outcomes of the system’s operations. When the CPU generates results following a processing operation, the AC register is used to store those results.
- ● The Address Register is a 12-bit register that contains the address of a memory location in which instructions or data are placed in the memory of the computer.
- ● The I/O Address Register’s duty is to define the address of a certain I/O device, which is what it does.
- ● This register is responsible for exchanging data between an I/O module and the central processing unit (CPU).