Using the Programmable Logic Device $($PLD$)$ design in MultiSim

a$.$ Build a Half Adder using discrete gates $($two half adders and an OR gate$)$ and verify the truth table.

b$.$ Save it as a PLD$.$

$2.$ Build a Full Adder using two Half Adders from part I. Verify the truth table. Save it as a PLD$.$

$3.$ Using four Full Adders, construct a $4-$bit adder. Verify the operation of the circuit.

$4.$ Modify the $4-$bit adder to perform the subtraction of any two $4-$bit numbers.