ALU

ALU, often referred to as an arithmetic/logic unit, is a functional unit of a computer’s central processing unit (CPU) that carries out arithmetic and logical operations. It is an integrated circuit composed of a collection of logic gates that are interconnected with one another for the purpose of performing arithmetic and logic operations.

The ALU is responsible for performing the basic calculations necessary to execute machine code instructions and is usually the only component of the CPU that actually manipulates data. It typically takes the form of an integrated circuit such as a microprocessor, where a single die may carry multiple ALUs as well as other core components. An ALU can also exist on its own as a separate chip or even on a single transistor.

The functions of an ALU can range from very simple operations, such as the addition of two 8-bit numbers, to the more complex, such as performing complex arithmetic operations. It can also support complex operations such as Boolean logic operations (AND, OR, NOT, XOR), multiplication, and division. In addition, the ALU can carry out various other operations, such as indirection, shifting, and rotation.

The discerning feature of an ALU is the way in which it carries out operations. In terms of speed an ALU is slower than a microprocessor, and while ALUs lack much in terms of intelligence, they can still be programmed to perform certain tasks in order to execute program logic. It is for this reason that ALUs continue to be used in modern computers, as even the most powerful supercomputers often find that the ALU provides the most efficient way to carry out a given set of mathematical operations.