( i) NAND Gate When output of AND gate is applied as input to a NOT gate, then it is called a NAND gate.
Boolean expression Y = A * B( Y equals negated of A AND B)
( ii) NOR Gate When output of OR gate is applied as input to a NOT gate, then it is called a NOR gate.
Boolean expression Y = A + B( Y equals negated of A OR B)
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The Boolean expression obey commutative law associative law as well as distributive law.
1. A + B = B + A 2. A · B = B · A 3. A +( B + C) =( A + B) + C
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Demorgan’ s theorems 1. A + B = A * B
2. A * B = A + B