question_answer 17)

You are given two circuits as shown in Fig., which consist of NAND gates. Identify the logic operation carried out by the two circuits. (a) (b)  

Answer:

In the fig. (a),          But which is an AND operation. Therefore the fig. (a) represents an AND gate. In fig. (b), But          and      (de Morgan theorem) = A + B which is an OR operation. Fig. (b) represents an OR gate.