Equality Detector

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Equality Detector

• Lecture L6.3
• Section 6.1

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Equality Detector
XNOR
X Y Z 0 0 1 0 1 0 1 0 0 1 1 1
X
Z
Y
Z !(X Y)
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4-Bit Equality Comparator
A A3..A0 B B3..B0 C C3..C0
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Sets
A A3..A0 B B3..B0 C C3..C0
A represents A3, A2, A1, A0 B represents
B3, B2, B1, B0 C represents C3, C2, C1, C0
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ABEL Program
MODULE eqcomp1 TITLE '4-BIT EQUALITY DETECTOR, R.
Haskell, 9/21/02 DECLARATIONS " INPUT PINS
" A3..A0 PIN 6, 7, 11, 5 A A3..A0 B3..B0
PIN 72, 71, 66, 70 B B3..B0 " OUTPUT PINS
" A_EQ_B PIN 36 C3..C0 NODE C C3..C0
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ABEL Program (cont.)
EQUATIONS C !(A B) A_EQ_B C0 C1 C2
C3 test_vectors (A, B -gt A_EQ_B) 0, 0 -gt
1 2, 5 -gt 0 10, 12 -gt 0 7, 8 -gt
0 4, 2 -gt 0 6, 6 -gt 1 15, 15 -gt
1 END
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EQUATIONS C !(A B) A_EQ_B C0 C1 C2
C3
C !(A B) C0 !(A0 B0) C1 !(A1 B1) C2
!(A2 B2) C3 !(A3 B3)
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Question
Expand the following ABEL equation for F A
A2..A0 B B2..B0 F F2..F0 F !A
B
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Question
Expand the following ABEL equation for F A
A2..A0 B B2..B0 F F2..F0 F !A
B F2 !A2 B2 F1 !A1 B1 F0 !A0
B0