Drawing half adder circuits

Question

I am working with adder units, and specifically half adders.

At the moment I have the standard half-adder unit drawn up in Digital works, (just like the below image).

enter image description here

However, I have been asked to draw a half adder unit circuit using a selection of gates e.g AND OR XOR NOT.

So what other ways are there of drawing a half adder?

Your `S` is a XOR gate, and `C` is an AND gate. Apparently you already solved the problem. Maybe you want to eliminate the XOR gate and construct it using AND, OR, NOT gates ? There are several ways to construct XOR gates. — mmgp, Jan 07 '13 at 14:21
You might be better off asking on [http://electronics.stackexchange.com](http://electronics.stackexchange.com). — marko, Jan 08 '13 at 16:08

Paul R · Answer 1 · 2013-01-07T14:33:34.133

1

You can just re-factor the boolean logic for the S and C outputs, e.g.

S = A^B
  = A.B'+A'.B
  = (A.B)'.(A'.B')'
  = (A.B+A'B')'

C = A.B
  = (A'+B')'

and then draw the circuits using any of the above re-factored expressions.

edited Jan 07 '13 at 14:33

answered Jan 07 '13 at 14:22

Paul R

1 Answers1