ALU (Arithmetic and Logic Unit)
The part of a computer that performs all arithmetic computations, such as addition, multiplication and division.
The Control Unit
Directs operations to the proccessor to carry out from the main memory. To simplify th Control Unit is responsible for running programs that are loaded to main memory.
Registers are small temprorary memory locations located on the processor. They are used to store the data for the current instruction being processed.