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1. Logic Gates
Logic gates are those digital circuit which works according to some
logical relationship between input and output voltage.
Logic gates works only on 0(LOW) and 1(HIGH).
Remember:
–True= ON = 1
–False = OFF=0
Logic gates turn ON when a certain condition is true, and OFF when
the condition is false
2. What are logic gates?
Output depends on the logic gate and the input
Input is one of two states – high or low
Output is one of two states – high or low
There are seven types of logic gates
The number of output combination will be 2N .(where N is no. of
input)
Truth tablet is means for describing how logic circuit’s output depends
upon logic levels at input.
Boolean expression is representationof output of logic gate , through
which we can make truth table.
3. Classification of Gates
Logic gates one classified as:-
1. basic gates :- NOT, AND, OR.
2. universal gates :- NAND , NOR .
3. Special purpose gate :- X-OR , X-NOR.
4. NOT is the most simple logic gate.
NOT gate has one input terminal and one output terminal.
Output is complement or inversion of its applied input.
Another name for a NOT gate is inverter, because it inverts (makes
opposite) the input
NOT Gate
5. AND has two input terminal and one output terminal.
AND gate perform multiplication function.
When both inputs are high, output is high otherwise output is low.
AND Gate
6. OR gate has two input terminal and one output terminal.
OR gate performs addition function.
Output is high when any one or more input is high otherwise output is
low.
OR Gate
7. NAND gate has two and more input terminal and one output terminal.
NAND gate is combination of NOT and AND gate.
Output of NAND gate is complement of Product of it’s input.
If any one input is low, output is high. If all inputs is high, output is low
NAND Gate
8. NOR gate has two and more input terminal and one output terminal.
NOR gate combination of Not gate and OR gate.
Output of NOR gate is complement of sum of it’s input.
If both inputs are low, output is high. If one of the input is high, output
will be low.
NOR Gate