An arithmetic logic unit (ALU) is digital circuit that incorporates the functionality of both a logic unit and an arithmetic unit, i.e. a unit capable of performing both basic arithmetic and comparison operations as well as bitwise operations.

The ALU is fundamental unit in almost all modern computer systems and can be found in virtually all CPUs. Depending on the exact architecture, the ALU may be combined with other components, however it is often treated conceptually as a distinct unit.

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