Meaning – The term register, refers to a part of internal storage having a specified storage capacity and usually intended for a specific purpose.
Some registers are used internally and cannot be accessed outside the processor, while others are user-accessible. Most modern CPU architectures include both types of registers.
Internal registers include the instruction register (IR), memorybuffer register (MBR), memory data register (MDR), and memory address register (MAR).
User-accessible registers are larger than internal registers and typically hold data for a longer time. An address register contains memory addresses, which reference different blocks of memory within the system RAM.
Example of usage – “Registers vary in both number and size, depending on the CPU architecture. Some processors have 8 registers while others have 16, 32, or more. For many years, registers were 32-bit, but now many are 64-bit in size. A 64-bit register is necessary for a 64-bit processor since it enables the CPU to access 64-bit memory addresses.”