1. We require a circuit that can add 3 4-bit unsigned numbers. This could be done using 2 4-bit adders, however, we are going to do it this way:
(a) Write down the values of the carrys (Carrys[3:0]) and sums
(Sums[3:0]) output by the top row of full adders for the case
when X, Y, and Z are 5, 10, and 4, respectively. What is the final
sum (S[3:0]) and carry-out (CO)?
Carrys = _____ _____ _____ _____ Sums = _____ _____ _____ _____ S = _____ _____ _____ _____ CO = _____
(b) Describe how the circuit above works and how it adds three
numbers (in just a couple of sentences). Also explain how the
carry-out is derived.