Experiment 9: Verification of Basic Logic Gates

Verification of basic logic gates

 

Verification and interpretation of truth tables for AND, OR, NOT, NAND, NOR Exclusive OR (EX-OR) Gates.  Implement  AND ,OR, NOT  functions  using  universal gates  NAND   &  NOR

 Apparatus: Component Development System(CDS), logic gates ICs, wires,2mm banana connectors

Theory:  Logic gates are electronic circuits which perform logical functions on one or more inputs to produce one output. When all the input combinations of a logic gate are written in a series and their corresponding outputs written along them, then this input/ output combination is called Truth Table.

Procedure:

1. Connect the V_CC +5v to the IC pin 14 w.r.t Ground pin 7.
2. Connect the inputs of logic gate to the logic switches and its output to the logic indicator (LED).
3. Apply various input combinations and observe output for each one.
4. Verify the truth table for each input/ output combination.
5. Repeat the process for all other logic gates.

AND Gate(7408)

 

AND gate produces an output as 1, when all its inputs are 1; otherwise the output is 0. This gate can have minimum 2 inputs but output is always one. Its output is 0 when any input is 0.

 

OR Gate(7432)

OR gate produces an output as 1, when any or all its inputs are 1; otherwise the output is 0. This gate can have minimum 2 inputs but output is always one. Its output is 0 when all input are 0.

NOT Gate(7404)

NOT gate produces the complement of its input. This gate is also called an INVERTER. It always has one input and one output. Its output is 0 when input is 1 and output is 1 when input is 0.

NAND Gate(7400)

NAND gate is actually a series of AND gate with NOT gate. If we connect the output of an AND gate to the input of a NOT gate, this combination will work as NOT-AND or NAND gate. Its output is 1 when any or all inputs are 0, otherwise output is 1.

NOR Gate(7402)

NOR gate is actually a series of OR gate with NOT gate. If we connect the output of an OR gate to the input of a NOT gate, this combination will work as NOT-OR or NOR gate. Its output is 0 when any or all inputs are 1, otherwise output is 1.

Exclusive OR (X-OR) Gate (7486)

X-OR gate produces an output as 1, when number of 1’s at its inputs is odd, otherwise output is 0. It has two inputs and one output.