<P> The actual mathematical operation for each instruction is performed by a combinational logic circuit within the CPU 's processor known as the arithmetic logic unit or ALU . In general , a CPU executes an instruction by fetching it from memory , using its ALU to perform an operation , and then storing the result to memory . Beside the instructions for integer mathematics and logic operations , various other machine instructions exist , such as those for loading data from memory and storing it back , branching operations , and mathematical operations on floating - point numbers performed by the CPU 's floating - point unit ( FPU ) . </P>
<P> The actual mathematical operation for each instruction is performed by a combinational logic circuit within the CPU 's processor known as the arithmetic logic unit or ALU . In general , a CPU executes an instruction by fetching it from memory , using its ALU to perform an operation , and then storing the result to memory . Beside the instructions for integer mathematics and logic operations , various other machine instructions exist , such as those for loading data from memory and storing it back , branching operations , and mathematical operations on floating - point numbers performed by the CPU 's floating - point unit ( FPU ) . </P>
this holds the actual processing in the cpu
this holds the actual processing in the cpu
a combinational logic circuit within the CPU 's processor known as the arithmetic logic unit or ALU
a combinational logic circuit within the CPU 's processor known as the arithmetic logic unit or ALU