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hw27_SLN

# hw27_SLN - ECE 211 HW 27 SOLUTIONS p 1/13...

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ECE 211 HW 27 SOLUTIONS p 1/13 //home/vdimitrov/25851/b752c6bfc94a598440107b02e8f79807111e75d2.doc HW Set 27 SOLUTIONS 1. Construct a weighted decimal code using the weights (a) 5 4 2 1 (b) 8 4 2 -3 Solution: (a) N Codeword (5 4 2 1) Alternate Codeword 0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 1 0 0 0 0 1 0 1 6 1 0 0 1 0 1 1 0 7 1 0 1 0 0 1 1 1 8 1 0 1 1 9 1 1 0 0 (b) N Codeword (8 4 2 -3) 0 0 0 0 0 1 0 1 0 1 2 0 0 1 0 3 0 1 1 1 4 0 1 0 0 5 1 0 0 1 6 0 1 1 0 7 1 0 1 1 8 1 0 0 0 9 1 1 0 1 Each codeword is unique.

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ECE 211 HW 27 SOLUTIONS p 2/13 2. Construct a unit-distance decimal code in which the digit 3 has the codeword 0100. The codewords for digits 0 and 9 must differ in only one bit. Solution: One possible code: The codewords: N b3 b2 b1 b0 0 1 1 0 0 1 1 0 0 0 2 0 0 0 0 3 0 1 0 0 4 0 1 0 1 5 0 1 1 1 6 0 1 1 0 7 1 1 1 0 8 1 1 1 1 9 1 1 0 1
ECE 211 HW 27 SOLUTIONS p 3/13 3. Design a combinational circuit that detects a non-BCD codeword: Inputs: b3 b2 b1 b0, the bits of a BCD codeword Output: Z Operation: Z = 1 iff the input is not a valid BCD codeword. Assertion levels: All inputs and outputs are active-Low. Use logic gates in your circuit. Solution: Z = Σ m ( 10, 11, 12, 13, 14, 15 ) Map and Expression Circuit:

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ECE 211 HW 27 SOLUTIONS p 4/13 4. A 3-bit Gray code is a unit-distance with codewords 000, 001, 011, 010, 110, 111, 101, 100. Design a sequential circuit to count, either up or down, using this Gray code: Input: X Output: Q2 Q1 Q0 Operation: The Q2 Q1 Q0 state sequence is determined by the value of X: X = 1: The Gray code in the above sequence; from 100 go to 000. X = 0: The Gray code in the reverse sequence; from 000 goto 100. Assertion levels: X is active-High. Use D flip-flops in your circuit. Realize the combinational logic using a decoder and logic gates.
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• Fall '07
• nestor
• Error detection and correction, Parity bit, Konrad Zuse, Bidirectional Bidirectional Bidirectional Bidirectional Bidirectional Bidirectional Bidirectional

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