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CSD · All 2025 papers

67 questions · 200 marks · 4 papers

Answer key

Indian Institute of Technology Madras

BS Degree Programme · Examination & Study Paper

Computer System Design

All 2025 papers

Official Paper

Examination Instructions & Guidelines

Solve on notebook/paper first before checking solutions.
MCQ: Exactly 1 option is correct. Negative marking applies.
MSQ: One or more options correct. Select all to score.
NAT: Numerical response. No negative marking.
Scientific calculator allowed for all calculations.
Official answer key is sealed at the end of this sheet.

Quiz 1 · 26 Oct 2025 (AN)Quiz 1

Q1MCQ3 Marks·Choose one option
Key ↓
1. AAND, NOT
2. BOR, XOR
3. CAND, OR
4. DNOT, AND
5. ENOT, XOR
6. FXOR, OR
7. GXOR, AND
Q2MCQ4 Marks·Choose one option
Key ↓
If (234)_a = (143)_b, where a and b are the bases of the respective numbers, what are the values of a and b?
1. Aa = 3, b = 4
2. Ba = 4,b = 5
3. Ca = 5, b = 6
4. Da = 6, b = 7
5. Ea = 7, b = 8
Q3MCQ4 Marks·Choose one option
Key ↓
What will be the output of the given circuit, as shown below?
1. A
2. B
3. C
4. D
Q4MCQ4 Marks·Choose one option
Key ↓
1. A2 or more inputs are at logic 0
2. B2 or more inputs are at logic 1
3. CAny odd number of inputs are at logic 0
4. DAny odd number of inputs are at logic 1
Q5MCQ4 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
5. E
Q6MCQ5 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
5. E
Q7MCQ5 Marks·Choose one option
Asked 3 times Key ↓
Consider the circuit shown below. Given that the inputs are supplied uniformly random,what is the probability of the output Y being at logic 0?
1. A0.75
2. B0.50
3. C0.33
4. D0.25
5. E1
Q8NAT3 Marks·Write the number
Key ↓
Given that NOT, 2-input AND/OR gates have delays of 1 ns, what will be the maximum delay of a 3x8 Decoder circuit? Note: if the answer is 1 ns, write 1.
Your answer:
Q9NAT3 Marks·Write the number
Key ↓
What is the minimum number of bits required to represent number (128)_(10) in binary ?
Your answer:
Q10NAT5 Marks·Write the number
Asked 4 times Key ↓
Your answer:
Q11NAT5 Marks·Write the number
Key ↓
Consider the circuit diagram shown below. Given that we only have 4:1 mux gates, what is the minimum number of mux gates needed to represent the circuit diagram above?
Your answer:
Q12NAT5 Marks·Write the number
Asked 5 times Key ↓
Answer the given question based on given timing diagram. Given that we only have 2-input NOR gates, what is the minimum number of NOR gates needed to represent a circuit with an output timing diagram same as Y?
Your answer:

End Term · 31 Aug 2025 (FN)End Term

Q13MCQ1 Mark·Choose one option
Asked 2 times Key ↓
In a 4-bit system, the one’s complement of the binary number 1100 is 0011.
1. ATrue
2. BFalse
Q14MCQ1 Mark·Choose one option
Asked 2 times Key ↓
A synchronous counter triggers all flipflops using a common clock signal, while an asynchronous counter triggers each flipflop using the output of the previous flipflop.
1. ATrue
2. BFalse
Q15MCQ1 Mark·Choose one option
Asked 2 times Key ↓
In a system with 64 unique states, 6 flipflops are sufficient to represent all the states.
1. ATrue
2. BFalse
Q16MCQ1 Mark·Choose one option
Asked 2 times Key ↓
In a decoder, at any point, exactly one of the outputs is 1 and all the rest are 0s.
1. ATrue
2. BFalse
Q17MCQ1 Mark·Choose one option
Asked 2 times Key ↓
According to Moore’s law, if a computer system has 2 million transistors today, then it will have approximately 32 million transistors in 8 years.
1. ATrue
2. BFalse
Q18MCQ3 Marks·Choose one option
Asked 2 times Key ↓
1. A
2. B
3. C
4. D
5. E
Q19NAT3 Marks·Write the number
Asked 5 times Key ↓
Your answer:
Q20NAT3 Marks·Write the number
Asked 3 times Key ↓
Your answer:
Q21NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q22NAT3 Marks·Write the number
Asked 4 times Key ↓
Your answer:
Q23NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q24NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q25NAT3 Marks·Write the number
Asked 2 times Key ↓
Consider a mod-12 up counter with an initial state of 0011. What will be the state of the counter after 25 clock pulses?
Your answer:
Q26NAT3 Marks·Write the number
Asked 3 times Key ↓
Your answer:
Q27NAT3 Marks·Write the number
Asked 2 times Key ↓
Consider a 9-bit Johnson counter. What is the total number of unique states it can cycle through?
Your answer:
Q28Short answer3 Marks·Write the answer
Asked 2 times Key ↓
Your answer:
Q29NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q30NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q31Short answer3 Marks·Write the answer
Asked 2 times Key ↓
Your answer:
Q32NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:

End Term · 31 Aug 2025 (AN)End Term

Q33MCQ1 Mark·Choose one option
Asked 2 times Key ↓
In a 4-bit system, the one’s complement of the binary number 1100 is 0111.
1. ATRUE
2. BFALSE
Q34MCQ1 Mark·Choose one option
Asked 2 times Key ↓
A synchronous counter triggers all flipflops using a common clock signal, while an asynchronous counter triggers each flipflop using the output of the previous flipflop.
1. ATRUE
2. BFALSE
Q35MCQ1 Mark·Choose one option
Asked 2 times Key ↓
In a system with 64 unique states, 4 flipflops are sufficient to represent all the states.
1. ATRUE
2. BFALSE
Q36MCQ1 Mark·Choose one option
Asked 2 times Key ↓
In a decoder, at any point, exactly one of the outputs is 1 and all the rest are 0s.
1. ATRUE
2. BFALSE
Q37MCQ1 Mark·Choose one option
Asked 2 times Key ↓
According to Moore’s law, if a computer system has 2 million transistors today, then it will have approximately 32 million transistors in 7 years.
1. ATRUE
2. BFALSE
Q38MCQ3 Marks·Choose one option
Asked 2 times Key ↓
1. A
2. B
3. C
4. D
5. E
Q39NAT3 Marks·Write the number
Asked 5 times Key ↓
Your answer:
Q40NAT3 Marks·Write the number
Asked 3 times Key ↓
Your answer:
Q41NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q42NAT3 Marks·Write the number
Asked 4 times Key ↓
Your answer:
Q43NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q44NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q45NAT3 Marks·Write the number
Asked 2 times Key ↓
Consider a mod-12 up counter with an initial state of 0111. What will be the state of the counter after 25 clock pulses?
Your answer:
Q46NAT3 Marks·Write the number
Asked 3 times Key ↓
Your answer:
Q47NAT3 Marks·Write the number
Asked 2 times Key ↓
Consider a 10-bit Johnson counter. What is the total number of unique states it can cycle through?
Your answer:
Q48Short answer3 Marks·Write the answer
Asked 2 times Key ↓
Your answer:
Q49NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q50NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:
Q51Short answer3 Marks·Write the answer
Asked 2 times Key ↓
Your answer:
Q52NAT3 Marks·Write the number
Asked 2 times Key ↓
Your answer:

Quiz 2 · 3 Aug 2025 (AN)Quiz 2

Q53MCQ1 Mark·Choose one option
Key ↓
In a J-K flipflop, when J = 1 and K = 1, it toggles the flipflop’s state.
1. ATRUE
2. BFALSE
Q54MCQ1 Mark·Choose one option
Key ↓
A multiplexer is a digital circuit that selects one of the several input signals and forwards it to a single output line.
1. ATRUE
2. BFALSE
Q55MCQ1 Mark·Choose one option
Key ↓
1. ATRUE
2. BFALSE
Q56MCQ1 Mark·Choose one option
Key ↓
In a positive-edge-triggered D flipflop, if the D input is 1 and the clock signal transitions from low to high, Q output is 0.
1. ATRUE
2. BFALSE
Q57MCQ1 Mark·Choose one option
Key ↓
Sequential circuits do not utilize feedback loops, while combinational circuits do.
1. ATRUE
2. BFALSE
Q58MCQ5 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
5. E
Q59MCQ5 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
Q60MCQ4 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
Q61MSQ5 Marks·Choose all correct options
Key ↓
Choose the correct option:
1. A
2. B
3. C
4. D
Q62NAT5 Marks·Write the number
Asked 5 times Key ↓
Your answer:
Q63NAT5 Marks·Write the number
Asked 3 times Key ↓
Your answer:
Q64NAT4 Marks·Write the number
Key ↓
Your answer:
Q65NAT6 Marks·Write the number
Key ↓
Your answer:
Read the passage below, then answer Q66–Q67
Answer the given two subquestions based on the given minterm :
Q66NAT3 Marks·Write the number
Asked 5 times Key ↓
If we want to implement the minimized expression using only 2-input NOR gates, what is the minimum number of NOR gates required, given inputs A, B, C, and D?
Your answer:
Q67NAT3 Marks·Write the number
Asked 4 times Key ↓
If we want to design the given minterm using 2:1 multiplexers, what is the minimum number of multiplexers required?
Your answer:

Official Key

Master Answer Key & Explanations

Official answer keys from IIT Madras BS past papers. Click any question to review.

Reveal Key

Q1G

Q2B

Q3A

Q4D

Q5D

Q6A

Q7B

Q83

Q98

Q102

Q111

Q122

Q13A

Q14A

Q15A

Q16A

Q17A

Q18E

Q193

Q205

Q215

Q222

Q236

Q243

Q25100

Q260

Q2718

Q280x06

Q2924

Q304

Q310x2D4D

Q3211101010

Q33B

Q34A

Q35B

Q36A

Q37B

Q38E

Q391

Q405

Q414

Q422

Q436

Q443

Q451000

Q460

Q4720

Q480x09

Q4918

Q508

Q510x2D4D

Q5211101100

Q53A

Q54A

Q55B

Q56B

Q57B

Q58B

Q59D

Q60B

Q61A, D

Q624

Q631001

Q641

Q65111

Q661

Q672

Questions and answer keys are reproduced from the official IIT Madras BS papers. BTechi is not affiliated with IIT Madras.