# Logic Gates - Did I connect them correctly?

I have 2 logic gates problems I need to solve applying de morgan's laws and I just wanted to make sure whether I did it correctly or not.

1. I am supposed to create the function F=abc+d using only the NOR gates.

1. Create function F=anegb+abc+negbc only using NANDs.

I'd be glad if any logic gate pro could take a quick look at it and let me know what you think.

Are they okay or am I not even close?

Thanks a lot!

• Feed in all the different input combinations, see if the outputs do what you expect. That will tell you if it is correct. – Tom Carpenter Mar 19 '16 at 17:20
• I will however say they are incomplete. Your inputs are A, B, C and D. Yet in both circuits you have !A and !B as inputs. – Tom Carpenter Mar 19 '16 at 17:43

There are several errors. I suggest using WolframAlpha.com to check your logic. In the second problem, for example, for the first gate type in "evaluate (not A) nand (not B)" and you will see that the result is "A or B" instead of the "A and B" that you show.

You will see that "A or B" is the correct answer by applying the first of De Morgan's laws:

not (A and B) == (not A) or (not B)


not ((not A) and (not B)) => (not (not A)) or (not (not B)) => A or B