Mumbai University Solved Question Papers
Digital System and Architecture
Previous Year Question Paper with Solution
BSc CS · Sem 1
Oct 2025 Examination
munotes.in
Mumbai
BSc CS Sem 1 Digital System and Architecture Oct 2025 Question Paper with Solutions
Get access to whole semester resourcesSemester Pass
MU B.Sc. (Computer Science) student group
Free to join
First published on munotes.in on 16 October 2026.
Published by munotes.in, Mumbai.
Model answers written and edited by the munotes.in editorial desk.
Passages from this volume may be quoted, in print, online or by an AI system, with credit: name munotes.in and link to this volume's page. The volume may not be reproduced as a whole. Full terms at munotes.in/content-license.
munotes.in is an independent study resource for students of the University of Mumbai. It is not affiliated with the University of Mumbai, and is not endorsed by it.
The University does not publish an official answer key for this paper. The answers in this volume are model answers, written to show how a full-mark answer is built. They are a study aid, not an authority on what an examiner marked.
The question paper reproduced here is the paper as set by the University of Mumbai at the Oct 2025 examination.
Contents
The questions below are the paper as the University of Mumbai set it at the Oct 2025 examination, in the order it was set.
MarksPage
MarksPage
The Paper as Set
The questions in this volume are the questions asked at the Oct 2025 examination, reproduced as the University of Mumbai set them, in the order it set them. Nothing has been reworded, added or left out. Only the answers are ours. See the original question paper.
Duration 1 hours · Total marks 30 · 12 questions answered
How to use this volume
Solve the paper first, under exam conditions and against the clock. Then read the answers here and mark your own. Reading a solution before attempting the question feels productive and teaches very little, because recognising an answer is not the same as being able to write one.
SECTION I
Q I
Answer any two of the following · 10 Marks
A.Define logic gates. Explain the different types of logic gates with their symbols and truth tables.[5]
Answer
For full marks, cover: the definition, then every gate with its symbol, Boolean expression and truth table, and the grouping into basic, universal and exclusive gates.
Definition
A logic gate is a digital circuit that performs one logical operation. It takes one or more binary inputs and produces one binary output. The output depends only on the present inputs. Gates are drawn with standard symbols, and each is defined by a truth table, which lists the output for every input combination.
Basic gates
- AND gate, Y = A . B. Symbol: a D shape. The output is 1 only if all inputs are 1.
- OR gate, Y = A + B. Symbol: a curved shield, pointed at the output. The output is 1 if any input is 1.
- NOT gate (inverter), Y = A'. Symbol: a triangle with a small circle (bubble) at the output. It has one input and inverts it.
| A | NOT A |
|---|---|
| 0 | 1 |
| 1 | 0 |
Universal gates
- NAND gate, Y = (A . B)'. Symbol: an AND shape with a bubble. The output is 0 only when all inputs are 1.
- NOR gate, Y = (A + B)'. Symbol: an OR shape with a bubble. The output is 1 only when all inputs are 0.
They are called universal because NOT, AND and OR, and so every circuit, can be built from NAND gates alone or from NOR gates alone.
Exclusive gates
- XOR gate, Y = A'B + AB'. Symbol: an OR shape with an extra curved line at the inputs. The output is 1 when the inputs are different.
- XNOR gate, Y = AB + A'B'. Symbol: the XOR shape with a bubble. The output is 1 when the inputs are equal.
Truth table of the two-input gates
| A | B | AND | OR | NAND | NOR | XOR | XNOR |
|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 |
| 0 | 1 | 0 | 1 | 1 | 0 | 1 | 0 |
| A | B | AND | OR | NAND | NOR | XOR | XNOR |
|---|---|---|---|---|---|---|---|
| 1 | 0 | 0 | 1 | 1 | 0 | 1 | 0 |
| 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 |
Notice that each bubbled gate's column is the exact opposite of its partner: NAND opposes AND, NOR opposes OR and XNOR opposes XOR.
Conclusion. Logic gates are the basic building blocks of digital systems. AND, OR and NOT are the basic gates, NAND and NOR are universal, and XOR and XNOR detect difference and equality. The symbol, the expression and the truth table together define each gate completely.
The rest of the answers
The first answer is free. The rest come with the B.Sc. (Computer Science) Semester 1 solved papers.
You have read the question paper and its first answer in full. Buy the solved papers once and you can read every answer of every solved paper in this semester.
Notes + practical solutions + solved papers: ₹798 Already bought it? Sign in
Or solved papers only: ₹499
Or notes + practical solutions: ₹499
The question paper itself stays free, and so does the syllabus.
Found an error in this volume? Report it and we will check it against the paper.