Editing Central processing unit (section)

===Arithmetic logic unit===
{{Main|Arithmetic logic unit}}
[[File:ALU block.gif|thumb|upright=1.3|Symbolic representation of an ALU and its input and output signals]]

The arithmetic logic unit (ALU) is a digital circuit within the processor that performs integer arithmetic and [[bitwise logic]] operations. The inputs to the ALU are the data words to be operated on (called [[operands]]), status information from previous operations, and a code from the control unit indicating which operation to perform. Depending on the instruction being executed, the operands may come from [[processor register|internal CPU registers]], external memory, or constants generated by the ALU itself.

When all input signals have settled and propagated through the ALU circuitry, the result of the performed operation appears at the ALU's outputs. The result consists of both a data word, which may be stored in a register or memory, and status information that is typically stored in a special, internal CPU register reserved for this purpose.

Modern CPUs typically contain more than one ALU to improve performance.