Logic Gates | Computer Architecture

Logic Gates

The manipulation of the binary information is done by logic circuit is called gates.
The input - output relationship of the binary variable for each gate can be represented in tabular form by a truth table.

Type of Logic Gates

1. AND

   
   

   Graphical View

   
   
   

   Algebric Function

   X = A . B OR X = AB

   
   

   Truth Table

   
   

   A	B	X
   0	0	0
   0	1	0
   1	0	0
   1	1	1




2. OR

   
   

   Graphical View

   
   
   

   Algebric Function

   X = A + B
   
   

   Truth Table

   
   

   A	B	X
   0	0	0
   0	1	1
   1	0	1
   1	1	1




3. Inverter

   
   

   Graphical View

   
   
   

   Algebric Function

   X = A̅ OR X = A'
   
   

   Truth Table

   
   

   A	X
   0	1
   1	0




4. Buffer

   
   

   Graphical View

   
   
   

   Algebric Function

   X = A
   
   

   Truth Table

   
   

   A	X
   0	0
   1	1




5. NAND

   
   

   Graphical View

   
   
   

   Algebric Function

   X = (A.B)'
   
   

   Truth Table

   
   

   A	B	X
   0	0	1
   0	1	1
   1	0	1
   1	1	0




6. NOR

   
   

   Graphical View

   
   
   

   Algebric Function

   X = (A + B)'
   
   

   Truth Table

   
   

   A	B	X
   0	0	1
   0	1	0
   1	0	0
   1	1	0




7. Exclusive-OR (XOR)

   
   

   Graphical View

   
   
   

   Algebric Function

   X = A ⊕ B OR X = A̅.B + AB̅
   
   

   Truth Table

   
   

   A	B	X
   0	0	0
   0	1	1
   1	0	1
   1	1	0




8. Exclusive-NOR

   
   

   Graphical View

   
   
   

   Algebric Function

   X = A ⊙ B OR X = A̅B̅ + AB
   
   

   Truth Table

   
   

   A	B	X
   0	0	1
   0	1	0
   1	0	0
   1	1	1