Half-Adder

Half-adder is used to add two bits. Therefore, half-adder  has two
inputs and two outputs, with  SUM and CARRY. Figure shows the truth table of a half-adder. The Boolean expressions for SUM and CARRY are,

SUM = AB’+A’B
CARRY = AB
These expressions shows`that,  SUM output is EX-OR gate and the CARRY output is AND gate.  Figure shows the be implementation of half-adder with all the combinations including the implementation using NAND gates only.

HA

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