Be sure you understand $2\text{'}$s complement representation of signed numbers. See Appendix

A$.$ The $4-$bit adder can be used for adding or subtracting since $(-$B$)$ represented in $2\text{'}$s

complement form can be added to A to get A$-$B $=$ A$+(-$B$).$

The bit operations for addition are the same for both unsigned addition and signed

addition using $2$s complement representation. This is why $2$s complement representation

is so widely used. The bit pattern result is the same for both, but the interpretation of the

value of the bits will be different for signed and unsigned numbers. $($See Appendix A$).$

Fill in the table below for your adder Y inputs and carry$-$in input for each of the four

operations listed. The operations are specified by p$1$ and p$0$ when p$3=$ p$2=0.$ The first

entry has already been completed for you.