question_answer

                The truth table for a logic gate is:

Input		Output
A	B	Y
1	1	0
0	1	1
1	0	1
0	0	1

                The logic gate is:                                                                                                                                              

A)                 NAND gate      

B)                 XOR gate            

C)                 NOR gate          

D)                 OR gate

Correct Answer: A

Solution :

                The given truth table is for NAND gate. The output for NAND gate is 1 only when one of its inputs is zero.                 The Boolean expression for NAND gate is                 \[Y=\overline{A\,.\,B}\]                 That is                 \[\overline{1\,.1}=\bar{1}=0\]                   \[\overline{0\,.1}=\bar{0}=1\]                 \[\overline{1\,.0}=\bar{0}=1\]                 \[\overline{0\,.0}=\bar{0}=1\]                 Note:    The symbol for NAND gate can be shown as: