CPU registers perform a variety of functions, a primary one of which is to offer temporary storage for the CPU to access information stored on the hard drive. Every CPU register has a distinct function and the registers are essential components of CPU commonly recognized for memory allocation purposes.
Examples of CPU registers include the Memory Address Register (MAR), the Memory Buffer Register (MBR), I/O Address Register (I/O AR) and the Program Counter (PC). These CPU registers perform specific functions in the CPU. For example, the MAR stores the address where the memory for the CPU reads and writes data. The MBR stores the contents of the data the CPU reads from in the memory.