Computer Architecture - Boolean functions

Question

I'm trying to revise for an exam and i'm rewatching a lecture :

http://vvcap.net/db/7r9irWuoU1v_L4_KT-A-.htp

I do not understand the slide, although I do know the logic gates/truth tables. This makes no sense to me. So, if someone could explain what's going on, that'd be really cool.

Answer 1

I don't know if it is the diagram or the logic that makes no sense to you.

In the diagram, there is a horizontal line for each input (from bottom to top: A, B, C, not A, not B, not C), and their paths are shown by the vertical lines that join it. The bottom line shows that A enters from input (bottom left vertical line) and has 3 exits leading to the gates numbered 5, 6, and 7 (and you can see that the top labels for these gates all include A, whereas gate 4 includes not A).

The logic is: (not A and B and C) or (A and not B and C) or (A and B and not C) or (A and B and C) Basically, any combination of the inputs where at least two are 1.