Question

Explain the universal property of NAND gate and realize AND, OR, NOT and XOR gates with their respective truth tables.

Answer 1

NAND is called universal gate because other logic gates can be realised using NAND gates.
(1) AND gate from NAND gates:

Inputs		Output
A	B	Y = AB
0	0	0
0	1	0
1	0	0
1	1	1

 (2) OR gate from NAND gates:

Inputs		Output
A	B	Y = A + B
0	0	0
0	1	1
1	0	1
1	1	1

 (3) NOT gate from NAND gate:

Inputs	Output
A	\(\bar A\)
0	1
1	0

 (4) XOR gate from NAND gates:

Inputs		Output
A	B	Y
0	0	0
0	1	1
1	0	1
1	1	0