# Logic Circuits

## Understanding Logic Circuits

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**Logic Circuit**is a type of digital circuit which serves as the basic building block of digital systems like computers. - These circuits operate on logical inputs to produce logical outputs following certain logical relationships.

## Types of Logic Gates

**AND Gate**: It gives a high output (1) only if all its inputs are high.**OR Gate**: It gives a high output (1) if at least one of its inputs is high.**NOT Gate (Inverter)**: It gives a high output (1) when its input is low (0) and vice versa.**NAND Gate**: It acts as an AND Gate followed by a NOT Gate, and gives a low output (0) only when all inputs are high.**NOR Gate**: It behaves as an OR Gate followed by a NOT Gate, and produces a high output (0) if at least one of its inputs is high.**XOR Gate (Exclusive OR)**: It gives a high output (1) if an odd number of inputs are high.**XNOR Gate (Exclusive NOR)**: It gives a high output (1) if an even number of inputs are high.

## Applied Use of Logic Gates

**Half Adder**: A logic circuit with two inputs and two outputs (Sum and Carry) that can be used in mathematics for binary addition.**Full Adder**: A circuit further expanding on the Half Adder, which takes the carry from the previous addition into account. It is used to add three binary numbers.

## Key Concepts in Logic Circuits

**Truth Table**: A systematic representation of a logic gates’ operation, it lists all possible input combinations and their corresponding outputs.**Boolean Algebra**: Mathematical approach for describing and designing logical operations; very useful in simplifying complex logic circuits.**Logic Levels**: Systems usually have two logic levels, high level (representing 1) and low level (representing 0).

## Combinational vs Sequential Logic Circuits

**Combinational Logic Circuit**: Output is only dependent on the present input states. Examples include Adder, Subtractor, Decoder, Encoder.**Sequential Logic Circuit**: Output depends not only on the present inputs but also the past history of inputs. Examples are Flip Flop, Counter, Memory Unit.