Logic Gates.  

Logic gates

Digital systems are said to be constructed by using logic gates. These gates are the AND, OR, NOT, NAND, NOR, EXOR and EXNOR gate

Basic Gates:

          *AND GATE

          *OR GATE

          *NOT GATE   

 Universal Gates:

          *NOR GATE

          *NAND GATE

Exclusive Gates:

          *EXOR GATE

          *EXNOR GATE

AND GATE:

Logic diagram

Truth Table

The AND gate is a basic digital logic gate that implements logical conjunction - it behaves according to the truth table to the right. A HIGH output (1) results only if all the inputs to the AND gate are HIGH (1). If none or not all inputs to the AND gate are HIGH, LOW output results. The function can be extended to any number of inputs.

     

OR Gate:

Logic diagram

Truth Table

   

The OR gate is a digital logic gate that implements logical disjunction – it behaves according to the adjacent truth table. A HIGH output (1) results if one or both the inputs to the gate are HIGH (1). If neither input is high, a LOW output (0) results. 

NOT Gate: 

Logic diagram

Truth Table

In digital logic, an inverter or NOT gate is a logic gate which implements logical negation.

NAND Gate:

Logic diagram

Truth Table

In digital electronics, a NAND gate (NOT-AND) is a logic gate which produces an output which is false only if all its inputs are true; thus its output is complement to that of an AND gate. A LOW (0) output results only if all the inputs to the gate are HIGH (1); if any input is LOW (0), a HIGH (1) output result

NOR Gate:

Logic diagram

Truth Table

The NOR gate is a digital logic gate that implements logical NOR - it behaves according to the truth table to the right. A HIGH output (1) results if both the inputs to the gate are LOW (0); if one or both input is HIGH (1), a LOW output (0) results. NOR is the result of the negation of the OR operator. It can also in some senses be seen as the inverse of an AND gate.

EXOR Gate:

Logic diagram

Truth Table

XOR gate (sometimes EOR, or EXOR and pronounced as Exclusive OR) is a digital logic gate that gives a true (1 or HIGH) output when the number of true inputs is odd. An XOR gate implements an exclusive or; that is, a true output results if one, and only one, of the inputs to the gate is true. If both inputs are false (0/LOW) or both are true, a false output results. 

EXNOR Gate:

Logic diagram

Truth Table

The XNOR gate (sometimes ENOR, EXNOR or NXOR and pronounced as Exclusive NOR) is a digital logic gate whose function is the logical complement of the exclusive OR (XOR) gate.^[1] The two-input version implements logical equality, behaving according to the truth table to the right, and hence the gate is sometimes called an "equivalence gate". A high output (1) results if both of the inputs to the gate are the same. If one but not both inputs are high (1), a low output (0) results.

These are all the Logic gates.