# How To Understand Ex3 Sum Mechanism?

Discussion in 'Homework Help' started by transgalactic, May 7, 2008.

1. ### transgalactic Thread Starter Active Member

Apr 29, 2008
74
0
i need to implement a circuit that inputs two 4bit numbers (y3 y2 y1 y0 x3 x2 x1 x0)
and it has an output of (c3 c2 c1 c0 s3 s2 s1 s0) where "c" is the carry
and "s" is the sum

i was given an example in which X=0101 (5) Y=1000 (8) and it outputs
S=1010 (10) and C=0011 (3)
5+8=13

i dont know what is the role of C and S
how do they split the numbers???

http://s290.photobucket.com/albums/ll279/t...nt=IMG_8831.jpg

i cant understand this circuit
????????

2. ### Papabravo Expert

Feb 24, 2006
12,212
2,697
That makes two of us. Whadya gonna do?

3. ### thingmaker3 Retired Moderator

May 16, 2005
5,073
8
This four bit adder circuit... it accept binary input and provides BCD output?

4. ### Papabravo Expert

Feb 24, 2006
12,212
2,697
I think your example is wrong. It certainly makes no sense to me.

5. ### beenthere Retired Moderator

Apr 20, 2004
15,808
295
Could it be doing excess 3 encoding?

6. ### Papabravo Expert

Feb 24, 2006
12,212
2,697
If you line up X and Y there should be no carries.

7. ### transgalactic Thread Starter Active Member

Apr 29, 2008
74
0
how can you explain that
S binary column is bigger by 6 then DEC number
and when the DEC number goes bigger then 10
then it has "1" and a normal number
the dec number is supposed to equal to the binay
noy to be smaller by 6
???

and in the EX3 column we each number is bigger by 3 then DEC number
and when the DEC number is smaller then 10
we dont have another 4 bits
?????????