JNTU
JNTU B.Tech II DIGITAL SYSTEM DESIGN Previous Question Paper (March - 2021 - R18)
Answer any five questions. All questions carry equal marks.
Main
Convert the following to Decimal and then to octal: i) (125F)16 ii) (10111111)2 iii) (4234)5.
Answer
i) (125F)16: Decimal = 1 × 163 + 2 × 162 + 5 × 161 + 15 × 160 = 4096 + 512 + 80 + 15 = 470310. Octal = (001 001 001 011 111)2 = (011 104 17)8 = 111378.
ii) (10111111)2: Decimal = 128 + 32 + 16 + 8 + 4 + 2 + 1 = 19110. Octal = (010 111 111)2 = 2778.
iii) (4234)5: Decimal = 4 × 53 + 2 × 52 + 3 × 51 + 4 × 50 = 500 + 50 + 15 + 4 = 56910. Octal = 569 / 8 = 71 remainder 1; 71 / 8 = 8 remainder 7; 8 / 8 = 1 remainder 0; 1 / 8 = 0 remainder 1. Result = 10718.
How do you convert a gray number to binary? Generate a 4-bit gray code directly using the mirror image property.
Answer
To convert a Gray code to binary, the Most Significant Bit (MSB) of the binary number is the same as the MSB of the Gray code. Each subsequent binary bit is obtained by performing an XOR operation between the current binary bit and the next Gray code bit.
Generating 4-bit Gray code using the mirror image property:
- Start with 1-bit Gray code: 0, 1.
- Mirror the 1-bit code to get 2-bit code: 00, 01, 11, 10.
- Mirror the 2-bit code to get 3-bit code: 000, 001, 011, 010, 110, 111, 101, 100.
- Mirror the 3-bit code to get 4-bit code: 0000, 0001, 0011, 0010, 0110, 0111, 0101, 0100, 1100, 1101, 1111, 1110, 1010, 1011, 1001, 1000.
Find all the prime implicants of the function using Quine McClusky method f(a,b,c,d) = Σ(7,9,12,13,14,15) + d(4,11).
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Design a circuit that converts 8421 BCD code to XS-3 code.
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With a neat circuit diagram and waveforms explain the operation of Master Slave JK flip flop.
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Explain the conversion of SR flip flop into JK and D flip flop with an excitation table.
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What are the capabilities and limitations of finite state machines? Explain.
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Draw the diagram of Mealy type FSM for serial adder.
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Describe the operation of TTL logic circuit working as NAND gate.
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Realize 2-input OR gates using CMOS logic and then explain its operation with the help of functional table.
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Convert the following expression into SOP and POS: i) (AB+C)(B+C') ii) x'+(x+y')(y+z').
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Implement the switching function using F = Σm(0,1,3,4,12,14,15) using an 8 input MUX.
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Design a 3-bit synchronous counter with T-flip flop and draw the diagram.
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Discuss the differences between combinational and sequential circuit.
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Mention the characteristics of different logic families. Also compare the performance of TTL, CMOS and ECL logic.
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Design a synchronous sequential circuit which goes through the following states: 1, 3, 5, 3, 6, 1, 3, 5.
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