CY-404 Operating Systems - Jun 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDiscuss the evolution of Operating Systems and their impact on computing.
   How to answer

   • Define generations: serial, batch, multiprogramming, time-sharing, distributed, real-time/mobile
   • Key milestones: IBM OS/360, UNIX, personal OS, networked and distributed OS
   • Impact on computing: utilization, interactivity, portability, security, ubiquity
2. 7 Marks
   bExplain the services provided by an Operating System to users and applications.
   How to answer

   • List OS services: UI, program execution, I/O, file, communication, errors
   • Additional services: resource allocation, accounting, protection/security
   • Distinguish user vs application view with examples
3. 7 Marks
   aHow does the OS ensure security and protection? Explain with mechanisms used.
   How to answer

   • Define security vs protection goals
   • Mechanisms: authentication, access control, encryption, auditing
   • OS features: user modes, ACLs, firewalls, secure allocation
4. 7 Marks
   bDescribe in detail the SJF and Priority CPU scheduling algorithms with examples.
   How to answer

   • Define SJF: shortest burst next, preemptive vs non-preemptive with Gantt chart
   • Define Priority scheduling: priority numbers, preemptive vs non-preemptive
   • Compare with example calculation of waiting/turnaround time and starvation
5. 7 Marks
   aWhat is a Thread? Compare user-level and kernel-level threads with advantages and disadvantages.
   How to answer

   • Define thread vs process, benefits of multithreading
   • User-level threads: management, advantages and disadvantages
   • Kernel-level threads: management, advantages and disadvantages and comparison table
6. 7 Marks
   bDefine a Deadlock. Explain the necessary conditions and methods of deadlock prevention.
   How to answer

   • Define deadlock with resource-allocation example
   • List four Coffman necessary conditions
   • Prevention methods: negating each condition (spooling, ordering, preemption)
7. 7 Marks
   aDescribe page replacement algorithms: FIFO and LRU with examples.
   How to answer

   • Define page replacement and reference string concept
   • FIFO: algorithm, Belady's anomaly, worked example
   • LRU: stack/counter implementation, worked example and comparison
8. 7 Marks
   bDiscuss memory management in UNIX and Windows operating systems.
   How to answer

   • Outline UNIX memory management: paging, swap, virtual memory
   • Outline Windows memory management: virtual memory, paging, working sets
   • Compare features, similarities and differences
9. 7 Marks
   aWhat is the concept of Overlay? How it is useful in executing large programs?
   How to answer

   • Define overlay: dividing program into overlays kept in same memory region
   • Need: executing large program in limited physical memory
   • Working with driver/overlay tree example and advantages/limitations
10. 7 Marks
    bDescribe the file system structure. Explain the roles of different file system modules.
    How to answer

    • Describe layered file system structure diagram
    • Explain modules: application, logical FS, file-organization, basic FS, I/O control, devices
    • Roles in file operations: naming, access, allocation, device handling
11. 7 Marks
    aWrite detailed notes on disk scheduling algorithms: SSTF, SCAN and C-SCAN.
    How to answer

    • Define disk scheduling goal: minimize seek time
    • Explain SSTF, SCAN (elevator), C-SCAN working with head-movement example
    • Compare performance, starvation and use cases
12. 7 Marks
    bCompare the file systems in UNIX and Windows in terms of structure and performance.
    How to answer

    • Outline UNIX FS (UFS/ext, inodes) vs Windows FS (FAT, NTFS)
    • Compare structure: hierarchy, metadata, journaling, permissions
    • Compare performance: fragmentation, scalability, reliability
13. 7 Marks
    aDiscuss the structure and functions of the Kernel I/O subsystem.
    How to answer

    • Define kernel I/O subsystem purpose
    • Components: scheduling, buffering, caching, spooling, error handling, device reservation
    • Functions with block diagram
14. 7 Marks
    bWhat is Asynchronous I/O? How does it differ from synchronous I/O?
    How to answer

    • Define synchronous I/O: blocking, process waits
    • Define asynchronous I/O: non-blocking, callback/signal on completion
    • Differences table: CPU utilization, complexity, use cases
15. 14 Marks
    Write short notes on any two

    1. a)System calls for process management
    2. b)Segmentation
    3. c)System Calls for File Management
    4. d)I/O management in UNIX and Windows
    How to answer

    • Select any two topics from the four options
    • For each: definition, key concepts/types and OS role
    • Add examples/diagram and concluding uses