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01

Software → Digital Logic

Adder

A digital circuit that performs binary addition.

Adder diagram

Motivation

Adders solve the problem of performing arithmetic with bits. Once a computer can add binary numbers, it can build more complex arithmetic operations on top.

Where it fits

Adders belong to digital logic and hardware building blocks. They are built from logic gates and are used inside ALUs.

Subconcepts

Half adder

Adds two bits and produces a sum and carry.

Full adder

Adds two bits plus an incoming carry, making multi-bit addition possible.

Mental model

A CPU does arithmetic by combining many small Boolean circuits that each handle tiny pieces of the calculation.