AC : general purpose register ,holds data that the CPU needs to process
– MAR : The memory address register, which holds the memory address of the data being referenced.
– MBR : The memory buffer register, which holds either the data just read from memory or the data ready to be written to memory.
– PC : The program counter, which holds the address of the next instruction to be executed in the program.
– IR : The instruction register, which holds the next instruction to be executed.
– InREG : The input register, which holds data from the input device.
– OutREG : The output register, which holds data for the output device.