Invert Inputs on XOR Gates?

[Dave Benemerito]

Hello everyone, I'm really new in Digital Logics and found many videos about it. I saw this video that adds binary numbers by Ben Eater on youtube:

.I was confused because his inputs for the first XOR gates are attached to ground from the DIP swtiches. I tried to do the same and it really did work but not for the whole adder circuit. I really want to know why this happens and know more how to use XOR Gates. Thanks

 

[BobK]

An XOR gate has an output of 0 if its inputs are the same and 1 if its inputs are different.

Write out the results of adding two binary digiits and see if you can figure out how an XOR gate can be part of the solution (but not all) for a crcuit to add binary numbers.

Bob