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Half Adder Truth Table
Input Output
0 0 0 0
0 1 1 0
1 0 1 0
1 1 0 1
Select An Input Value


The half adder is an example of a simple, functional digital circuit built from two logic gates.  The half adder adds two one-bit binary numbers (AB).  The output is the sum of the two bits (S) and the carry (C).

Note how the same two inputs are directed to two different gates.  The inputs to the XOR gate are also the inputs to the AND gate.  The input "wires" to the XOR gate are tied to the input wires of the AND gate; thus, when voltage is applied to the A input of the XOR gate, the A input to the AND gate receives the same voltage.

Select an input combination from the pull-down selector and view the resulting output.