Half-adder is a combination of logic blocks, with two on bit binary inputs, A and B. The out puts are two one bit binary numbers C and D, where D is the "units" digit of the sum and C is the "carry" digit.

We saw in class that the following is an implementation of this system, showing the for A=1 and B=0, the sum, D=1 and the carry, C=1. The lighted light-emitting-diodes (LED) signify "1" and the off LED's signify " 0":

The next figure show the situation when the inputs are both "1":

The following figures show the pin connections for the logic blocks used in this project:
Pin Connection

The next figure show the actual lay out of this circuit, on the proto-board: