Half Adder
The addition of 2 bits is done using a combination circuit called a Half adder. The input variables are augend and addend bits and output variables are sum & carry bits. A and B are the two input bits. Truth Table:
Here we perform two operations Sum and Carry, thus we need two K-maps one for each to derive the expression.
Logical Expression:
1) for Sum:
Sum = A XOR B
2) for Carry:
Carry = A AND B
Implementation:
Note:
Half adder has only two inputs and there is no provision to add a carry coming from the lower order bits when multi addition is performed.
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