Hi Stanley85,
If one of the two 4-bit words is "0" the result should also be "0".
If one of the 4-bit words is "1" the result should be equal to the
other 4-bit word. If one of the 4-bit words is "2" the result should
be equal to the other 4-bit word, but shifted one position to the
left. If one of the 4-bit words is "3", the result should be equal to
the other 4-bit word, but shifted one position to the left and added
to this 4-bit word. If one of the 4-bit words is "4", the result is equal
to the other 4-bit word, but shifted two positions to the left. If one
of the 4-bit words is "5" the result should be equal to the other 4-bit
word, but shifted two positions to the left and added to this 4-bit
word, and so on . . . .
The final circuit will have eight inputs and also eight outputs.
I really don't have a clue what this circuit should look like, I got my
degree by asking questions on forums like this.
on1aag.