ARITHMETIC LOGIC UNIT
Computers use logic gates to perform boolean operations and bits to store information.
We can use logic gates to build an arithmetic logic unit (ALU), which will allow us to compute bits.
An ALU is composed of 2 parts: an arithmetic unit and a logic unit.
The arithmetic unit handles all numerical operations in a computer, such as addition.
The logic unit performs logical operations, like AND and NOT, as well as simple numerical tests, like checking if a number is negative.
The arithmetic unit has several circuits, each built out of invididual logic gates, designed to perform several different math operations.
Simple ALUs don't have a specific circuit for multiplying and dividing and instead perform a series of additions or subtractions.
More complex ALU's have dedicated circuits for multiplication and division. These circuits are more complicated than the addition and subtraction circuits, which is why they are only used in more powerful ALU's.
The logic unit also has several circuits than can perform logical operations, numerical tests, and bit shift operations.
An ALU is represented by this symbol.
There are also several different types of circuits that can be used to perform each arithmetic and logical operation. These are selected when designing an ALU based on energy and thermal constraints, complexity, processing power, and price.