(SEM IV) THEORY EXAMINATION 2024-25 OPERATING SYSTEM

This document contains the complete B.Tech (Semester IV) Theory Examination 2024–25 question paper for Operating System (BCS401). The paper spans four printed pages, carries 70 marks, and thoroughly evaluates a student's understanding of OS fundamentals, process management, scheduling algorithms, memory management, deadlock handling, disk scheduling, file systems, and concurrency control.

Section A – Short Conceptual Questions (14 Marks)

Section A includes seven 2-mark questions, each designed to test core OS concepts. Topics include:

Primary functions of an operating system (Page 1)

Processor assignment problem using permutations

Difference between process and program

Producer–Consumer buffer calculation

Total processes created using multiple fork() calls

Components stored in a PCB (Process Control Block)

Purpose of page replacement algorithms

These quick questions check basic conceptual clarity and logical reasoning.

Section B – Analytical & Medium-Difficulty Questions (21 Marks)

Students must attempt any three of the five questions. This section assesses scheduling, page replacement, system-level decisions, and performance analysis.

Topics include:

Detailed explanation of process states and state transition diagram (Page 1–2)

Drawing Gantt chart and computing average waiting time using Preemptive Priority Scheduling (Table shown on Page 2)

Comparison of FCFS, SJF, and Round Robin scheduling

Modified Optimal Page Replacement Algorithm with 3 frames and prediction of next 4 references (Page 2)

(Unshown Q2e—may involve threads, synchronization, or deadlock concepts)

This section requires numerical computations, diagram drawing, and algorithm comparison.

Section C – Long Descriptive & Scenario-Based Questions (35 Marks)

Students must answer one part from each question (Q3–Q7). These questions involve critical thinking, OS theory, memory design, and disk scheduling.

Q3 – Operating System Types / Deadlock Scenario

Differences between Batch, Interactive, and Time-Sharing OS, with real-world examples (Page 3)

OR deadlock explanation using two semaphores and wrong wait sequence

Q4 – Critical Section / Banker’s Logic

Critical Section Problem: definition + three required conditions (Mutual Exclusion, Progress, Bounded Waiting)

OR determining if system state is Safe/Unsafe & Deadlocked/Not Deadlocked, using tape drive allocation table (Page 3)

Q5 – Concurrency Limitations / File Directory Structures

Limitations of Dekker’s and Peterson’s solutions on multiprocessor systems

OR explanation of file directory types: single-level, two-level, tree, DAG, directory operations

Q6 – Memory Management / Disk Scheduling

Multiprogramming with variable partitions and improved memory utilization

OR total head movement in C-LOOK Disk Scheduling for a specific queue (Page 4)

Q7 – Demand Paging / RAID

Calculating maximum page table entries for a demand paging system (32-bit logical, 20-bit physical, 2048-byte pages)

OR detailed explanation of RAID 0, RAID 1, RAID 5 (Page 4)

This section evaluates advanced concepts and real-world application of OS principles.

Summary

The Operating System (BCS401) exam paper thoroughly covers:

OS architecture & functions

Scheduling algorithms (FCFS, SJF, RR, Priority)

Process creation, fork(), PCB

Deadlock avoidance & semaphore logic

Memory management, demand paging & page replacement

Disk scheduling (C-LOOK)

Directory structures

Concurrency control & synchronization

RAID levels & reliability

The question paper is a complete academic resource for engineering students learning the design and working of modern operating systems.