Test: Logic Gates - Computer Science Engineering (CSE) MCQ

• NOT Gate is also known as Inverter
• The 7404 is a high-speed CMOS Logic Quad NOT Gate.
• The 7404 is also known as Hex inverter.
• The contains Six independent NOT gates in one package. T
• The NOT gate consists of only one input and one output.
• A NOT gate is used to output the Boolean inverse of the applied input.
• Hence the name ‘Digital Inverter’ or ‘Inverting buffer’. The most commonly used NOT gate IC is 7404.
• The symbol  and truth table of NOT gate and a buffer given as 

NOR GATE:

Symbol:

Truth Table:

Output equation:  
Y=A+B
Output is high only when all inputs are low.
It is a universal gate

Q= AB
Output expression Q is equivalent to NAND gate.

The number of 2-input NAND gates required to implement a 2-input XOR gate is 4.

Similarly, the number of 2-input NOR gates required to implement a 2-input XNOR gate is 4.

Given, 

n = 3 as there are three gates with feedback

T_pd = 100 nsec
T = 2 × 3 × 10^-7
T= 6 × 10^-7
Fundamental Frequency is given by f

AND GATE:
The AND operation is performed the same as the ordinary multiplication of 1s and 0s.
The output of AND gate becomes 1 only when all the inputs are 1.
Hence AND gate is also called an all or nothing gate.

OR GATE:
The output of the OR gate becomes 1 even if one of its inputs is 1.
Hence OR gate is also called an any or all gate.

Let's assume two inputs be A and B.

and the output is Y.

 
 Using De-Morgan's Law:

 Symbols of various logic gates:

1.) OR Gate:

2.) AND Gate:

3.) NOT Gate:

4.) NOR Gate:

5.) NAND Gate:

6.) XOR Gate:

7.) XNOR Gate:

Given Boolean expression is,

F = AB + AC̅ + BC

F = BC + AC̅