Alu Worksheet question

[tdr]

Hello,
So i am now at point 4 in the Alu Worksheet where f(x) = x

The problem arrises at F. where it is false and so i have to do the first multiplication.
So i am multiplying 0100 x 1111 = 0111100.This is a signed number so 0 goes away but indicates that the number is positive so we have 111100 right?

Also this is a confusing answer because it has more bits than 4 and because i know we work in 4bit system i wonder if this answer is correct.
The previous exercises always got me no=f(x,y) but this doesn't.

What am i missing here?

[tdr]

Ok so i just finished the whole worksheet besides line 4,5,6,7 and the last one.

4,5,6,7 all have multiplication at f and the out =/= f(x,y)

And the last point i don't understand x|y = x or y wich means x+y , if so , here i also get a wrong answer.

[cadet1620]

There is no multiplication in the ALU.

When f=0 the ALU does binary AND which uses the symbol '&' in the worksheet.
When f=1 the ALU does arithmetic ADD which uses the symbol '+' in the worksheet.

The symbol '|' means binary OR. '+' in this worksheet always means ADD.

[tdr]

Thank you very much, i have successfully finished all of them now !!!

[cadet1620]

You should get 1111.

   1111
OR 1010
   ----
   1111

[tdr]

Yes i finally got that !I have mistaken | for &

[MarinaP]

Ha Ha!  

I think tdr has earned an    1111 & 1010   rather than an  1111 |  1010