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PHYS3360/AEP3630 Electronic Circuits, Spring 2011, HW8
1
Combinational Logic
HW8
:
Saturday, Apr 2, 2011
DUE
:
Friday, Apr 8, 2011
READ
: Lab Manual, Chapter 10 (read ahead)
QUIZ8:
due Friday, Apr 8, 2011
Problems
1.
The Lab Manual discusses the full adder at some length. E.g. consider we are adding two nbit
binary numbers. Let the inputs A
i
and B
i
be the i
th
bits of the two numbers. The carry in bit Cin
i
represents any carry from the sum of the neighboring less significant bits at position i1. That is,
Cin
i
= 1 if A
i1
= B
i1
= 1, and 0 otherwise. The sum S
i
at position i is therefore the sum of A
i
, B
i
, and
Cin
i
. (Note that this is an arithmetic sum, not a Boolean OR.) A carry for this sum sets the carry
out bit, Cout
i
= 1, which then can be applied to the sum of the i + 1 bits. The truth table is given
below.
Cin
i
A
i
B
i
S
i
Cout
i
0
0
0
0
0
0
0
1
1
0
0
1
0
1
0
0
1
1
0
1
1
0
0
1
0
1
0
1
0
1
1
1
0
0
1
1
1
1
1
1
For one of the two outputs, S
i
, the Boolean function can be compactly written as:
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This note was uploaded on 06/10/2011 for the course AEP 3630 taught by Professor Bozarov during the Spring '08 term at Cornell University (Engineering School).
 Spring '08
 BOZAROV

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