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(Word Problem -Combinational Circuit) The list of operations for a combinational

ID: 1834750 • Letter: #

Question

(Word Problem -Combinational Circuit) The list of operations for a combinational circuit are given in the following table, where N1 and N2 are two-bit numbers, C1, C0 are control inputs, and N3 is a 4-bit number. Assume that we assign input variables AB to N1, CD to N2 and ABCD to N3. Thus if N1=2, then A=1 and B=0, etc. Also note that when the output should be negative, it is set to zero. The circuit contains one 4-bit output Z.(Z3 is the MSB.)

C1 C0 Function               Comment
0   0   Z= N1 plus N2
0   1   Z= N1 minus N2      Z= 0000 if N2 > N1
1   0   Z= N'3                   The One’s Complement of N3
1 1   Z= N'3 plus 1          The Two’s Complement of N3

a. Complete the following truth table.

b. Write expressions for Z3, Z2, Z1, and Z0 using little m sum of product notation.

Z3 =m

Z2 =m

Z1 =m

Z0 =m

m# C1 C0 A B C D Z3 Z2 Z1 Z0
0     0    0    0 0 0 0
1     0    0    0 0 0 1
2     0    0    0 0 1 0
3    0   0   0 0 1 1
4     0    0    0 1 0 0
0    0    0 1 0 1
6     0    0    0 1 1 0
7     0    0    0 1 1 1
8     0   0 1 0 0 0
9     0    0    1 0 0 1
0     0    1   0 1 0
11   0    0   1 0 1 1
12   0    0   1 1 0 0
13   0    0    1 1 0 1
14 0    0    1 1 1 0
0    0    1    1 1 1
16   0    1    0 0 0 0
17   0    1    0 0 0 1
18 0    1    0 0 1 0
19   0    1   0 0 1 1
0   1    0   1 0 0
21   0    1    0 1 0 1
22 0    1    0 1 1 0
23 0    1    0 1 1 1
24 0    1   1 0 0 0
0     1   1     0 0 1
26   0   1     1 0 1 0
27   0 1   1 0 1 1
28   0   1     1 1 0 0
29   0 1    1 1 0 1
0    1    1     1 1 0
31 0   1     1 1 1 1

m# C1 C0 A B C D Z3 Z2 Z1 Z0
32    1    0   0 0 0 0
33   1   0 0 0 0 1
34    1   0 0 0 1 0
35    1 0 0 0 1 1
36    1    0 0 1 0 0
37    1   0 0 1 0 1
38    1   0 0 1 1 0
39    1    0 0 1 1 1
40    1   0 1 0 0 0
41    1    0 1 0 0 1
42   1 0 1 0 1 0
43    1   0 1 0 1 1
44    1   0 1 1 0 0
45    1   0 1 1 0 1
46   1 0 1 1 1 0
47    1   0 1 1 1 1
48   1   1 0 0 0 0
49    1   1 0 0 0 1
50 1 1 0 0 1 0
51    1    1 0 0 1 1
52   1    1 0 1 0 0
53    1    1 0 1 0 1
54    1 1 0 1 1 0
55    1 1 0 1 1 1
56 1    1 1 0 0 0
57   1    1 1 0 0 1
58   1 1 1 0 1 0
59    1   1 1 0 1 1
60    1   1 1 1 0 0
61    1    1 1 1 0 1
62    1   1 1 1 1 0
63    1   1 1 1 1 1

Explanation / Answer

m# C1 C0 A B C D Z3 Z2 Z1 Z0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 2 0 0 0 0 1 0 0 0 1 0 3 0 0 0 0 1 1 0 0 1 1 4 0 0 0 1 0 0 0 0 0 1 5 0 0 0 1 0 1 0 0 1 0 6 0 0 0 1 1 0 0 0 1 1 7 0 0 0 1 1 1 0 1 0 0 8 0 0 1 0 0 0 0 0 1 0 9 0 0 1 0 0 1 0 0 1 1 10 0 0 1 0 1 0 0 1 0 0 11 0 0 1 0 1 1 0 1 0 1 12 0 0 1 1 0 0 0 0 1 1 13 0 0 1 1 0 1 0 1 0 0 14 0 0 1 1 1 0 0 1 0 1 15 0 0 1 1 1 1 0 1 1 0 16 0 1 0 0 0 0 0 0 0 0 17 0 1 0 0 0 1 0 0 0 0 18 0 1 0 0 1 0 0 0 0 0 19 0 1 0 0 1 1 0 0 0 0 20 0 1 0 1 0 0 0 0 0 1 21 0 1 0 1 0 1 0 0 0 0 22 0 1 0 1 1 0 0 0 0 0 23 0 1 0 1 1 1 0 0 0 0 24 0 1 1 0 0 0 0 0 1 0 25 0 1 1 0 0 1 0 0 0 1 26 0 1 1 0 1 0 0 0 0 0 27 0 1 1 0 1 1 0 0 0 0 28 0 1 1 1 0 0 0 0 1 1 29 0 1 1 1 0 1 0 0 1 0 30 0 1 1 1 1 0 0 0 0 1 31 0 1 1 1 1 1 0 0 0 0 m# C1 C0 A B C D Z3 Z2 Z1 Z0 Z4 32 1 0 0 0 0 0 1 1 1 1 33 1 0 0 0 0 1 1 1 1 0 34 1 0 0 0 1 0 1 1 0 1 35 1 0 0 0 1 1 1 1 0 0 36 1 0 0 1 0 0 1 0 1 1 37 1 0 0 1 0 1 1 0 1 0 38 1 0 0 1 1 0 1 0 0 1 39 1 0 0 1 1 1 1 0 0 0 40 1 0 1 0 0 0 0 1 1 1 41 1 0 1 0 0 1 0 1 1 0 42 1 0 1 0 1 0 0 1 0 1 43 1 0 1 0 1 1 0 1 0 0 44 1 0 1 1 0 0 0 0 1 1 45 1 0 1 1 0 1 0 0 1 0 46 1 0 1 1 1 0 0 0 0 1 47 1 0 1 1 1 1 0 0 0 0 48 1 1 0 0 0 0 0 0 0 0 1 49 1 1 0 0 0 1 1 1 1 1 50 1 1 0 0 1 0 1 1 1 0 51 1 1 0 0 1 1 1 1 0 1 52 1 1 0 1 0 0 1 1 0 0 53 1 1 0 1 0 1 1 0 1 1 54 1 1 0 1 1 0 1 0 1 0 55 1 1 0 1 1 1 1 0 0 1 56 1 1 1 0 0 0 1 0 0 0 57 1 1 1 0 0 1 0 1 1 1 58 1 1 1 0 1 0 0 1 1 0 59 1 1 1 0 1 1 0 1 0 1 60 1 1 1 1 0 0 0 1 0 0 61 1 1 1 1 0 1 0 0 1 1 62 1 1 1 1 1 0 0 0 1 0 63 1 1 1 1 1 1 0 0 0 1 Z3 =Sm(32,33,34,35,36,37,38,39,49,50,51,52,53,54,55,56) Z2 =Sm(7,10,11,13,14,15,32,33,3,35,40,41,42,43,49,50,51,52,57,58,59,60) Z1 =Sm(2,3,5,6,8,9,12,15,24,28,29,32,33,36,37,40,41,44,45,49,50,53,54,57,58,61,62) Z0 =Sm(1,3,4,6,9,11,12,14,20,25,28,30,32,34,36,38,40,42,44,46,49,51,53,55,57,59,61,63)