• Memory Address Registers (MAR): This register stores the address of the memory region to be accessed. The MAR and MDR (Memory Data Register) work together to help the CPU and main memory communicate.
• Memory Data Registers (MDR): These registers hold data that can be written to or read from the targeted place.
• R0, R1, R2,...Rn-1 are General Purpose Registers that are used to hold temporary data during any ongoing process. Assembly programming can access its contents. Modern CPU architectures prefer to employ more GPR so that register-to-register addressing, which is faster than other addressing modes, can be used more.
• The instruction that is about to be executed is stored in the Instruction Register (IR). The PC instruction is retrieved and saved in IR. The CPU begins executing the instruction as soon as it is placed in IR, and the PC points to the next instruction to be executed.

Read More: What do you understand by registers?