Question

What is the main logic gate? How many types are they? Draw their symbol and truth table.

Answer 1

Hint: There are various types of logic families which includes diode logic (DL), resistor transistor logic (RTL), emitted couple logic (ECL), transistor-transistor logic (TTL). In logic families the logic 0 is used to represent ‘true’ and the logic 1 is used to represent ‘false’.

Complete answer:
There are three types of gates: universal gates, primary gates and secondary gates. The universal gates include NOR gate and NAND gate. The primary or we can say the main gates are NOT gates, AND gates, OR gates. The last is the secondary gate which includes the XOR gate and XNOR gate.
So the main gates are:
NOT gate:
The NOT gate is also known as an inverter. The NOT gate has one input and one output so, if you give input as 1 then the output will appear as 0 and if you give input as 0 then output will appear as 1.

 THIS FIGURE SHOWS THE SYMBOL OF THE NOT GATE.$Y = \overline A $
TRUTH TABLE OF NOT GATE

INPUT	OUTPUT
1	0
0	1

AND gate:
The AND gate is defined as a digital logical gate in which the low input will give you low output whereas the high input will give you high output. Therefore, the input can be two or more than one signal whereas the output will be two signals only.
THE FIGURE GIVEN BELOW IS THE SYMBOL OF AND GATE.$Y = A.B$

TRUTH TABLE AND GATE:

INPUT A B	OUTPUT Y
0 0	0
0 1	0
1 0	0
1 1	1

OR gate:
The OR gate is defined as a digital logic gate in which if both the inputs are low then then the output is also low whereas if both the inputs are high or in fact if one input is high the output will be high only. Therefore, the input can be two signals or more than two signals.
THE FIGURE GIVEN BELOW IS THE SYMBOL OF OR GATE $Y = A + B$

TRUTH TABLE OF OR GATE:

INPUT A B	OUTPUT Y
0 0	0
0 1	1
1 0	1
1 1	1

Note: These all logic gates belong to the family of Transistor-transistor logic (TTL). All logic gates are introduced by 7400 series. The IC number (integrated chip number) of NOT is 7404, AND IC number is 7408 and the IC number of OR gate is 7432.