Activity 18:
a
|
b
|
c
|
carry
|
sum
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
1
|
0
|
1
|
0
|
1
|
0
|
0
|
1
|
0
|
1
|
1
|
1
|
0
|
1
|
0
|
0
|
0
|
1
|
1
|
0
|
1
|
1
|
0
|
1
|
1
|
0
|
1
|
0
|
1
|
1
|
1
|
1
|
1
|
Function: sum
= LSB of a + b + c
carry = MSB of a
+ b + c
With just this
information I am going to try to figure out the chip construction.
B and C are an
Xor gate for sum and a and gate for carry. I think A would be
a sel bit
The hint from
the book says it can be made with two half adder’s and another simple gate.
A in the carry
in for this adder. This was a little bit harder then is should have been. I
think the variables used in the book need to be more clear on what they are for.
I looked up a full adder in another book I had and it said it is two inputs and
a carry in.
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