Logic Systems DesignLogo Design Contest

#3 Interesting design, would probably fit well on circuit boards we design but I would rank #4 higher.

#8 Simple and elegant, I prefer this over #9 since I'm not sure what the green background represents in this one. #12 is clever, the AND gate and the printed circuit tracks, every time I look at it I like it better!
I have to make a tough decision soon

#12 I was wondering how this would look if the top of the D was connected, or nearly so, to the the top of the S and the vertical bar of the D does not quite reach the top horizontal stroke of the D. Instead of the AND gate, what about the EXCLUSIVE OR gate.?