Arithmetic and logical unit
- ALU redirects here. Alternative meaning: Alu sequence.
An arithmetic and logical unit (ALU)
is one of the core components of all central processing units. It is capable of calculating the results of a wide variety of common computations. The most common available operations are the integer arithmetic operations of addition, subtraction, and multiplication, the bitwise logic operations
, and XOR
, and various shift operations. Typically, a standard ALU does not handle integer division nor any floating point
operations. For these calculations a separate component, such as a divider or floating point unit
(FPU), is often used, although it is also possible that a microcode
program may use the ALU to emulate these operations.
The ALU takes as inputs the data to be operated on and a code from the control unit indicating which operation to perform, and for output provides the result of the computation. In some designs it may also take as input and output a set of condition codes, which can be used to indicate cases such as carry-in or carry-out, overflow, or other statuses.
See also: execution unit, multiplication ALU