A step-by-step analysis of the process a CPU would go through to add three numbers is demonstrated below. Assume an imaginary CPU has registers called A, B. C, and D. It has an 8 bit of data bus and a 16 bit of address bus. Therefore, the CPU can access memory from addresses 0000 to FFFFH (for a total of 10000H locations). The action to be performed by the CPU is to put hexadecimal value 21 into register A, and then add to register A values 42H and 12H.
