Easy2Siksha Sample Paper
GNDU Most Repeated (Important) Quesons
BCA 5th Semester
Operang System (2021-2024)
Must-Prepare Quesons (80-100% Probability)
SECTION-A
1. What is an Operang System? Types/Working (3 mes)
2. What is a Process? CPU Scheduling importance/algorithms (3 mes)
2025 Smart Predicon Table
Based on 4-Year Queson Paper Analysis (2021-2024)
SECTION-A (Operang System Fundamentals & Process Management)
Queson Topic
Repeats
Years Appeared
Priority
What is an Operang System &
Types
3 Times
2021 (Q1), 2022 (Q1), 2023
(Q1)
Very
High
Process & CPU Scheduling
3 Times
2021 (Q2), 2022 (Q2), 2023
(Q2)
Very
High
Easy2Siksha Sample Paper
2025 GUARANTEED QUESTIONS (100% Appearance)
TOP 5 QUESTIONS - MUST PREPARE:
1. Deadlock: Denion, Occurrence, Handling (4/4 years)
GNDU Most Repeated (Important) Quesons
BCA 5th Semester
Operang System (2021-2024)
Must-Prepare Quesons (80-100% Probability)
SECTION-A
1. What is an Operang System? Types/Working (3 mes)
Ans: What is an Operating System? Types and Working
The Story of Your Computer's Brain
Imagine you're the manager of a massive restaurant with hundreds of customers,
dozens of waiters, multiple chefs, and limited kitchen space. Everyone wants something
different at the same time. How do you manage this chaos? You need a master
coordinator – someone who decides who gets served first, which chef cooks what, who
gets which table, and ensures nobody fights over the stove.
This master coordinator is exactly what an Operating System does for your computer!
Part 1: What is an Operating System?
An Operating System (OS) is the most important software that runs on your computer.
It's like the principal of a school who manages students (programs), teachers
(hardware), classrooms (memory), and ensures everything runs smoothly without
conflicts.
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Simple Definition:
"An Operating System is system software that acts as a bridge between computer
hardware and the user. It manages all the resources and provides an environment where
application programs can run efficiently."
Think of it this way: Without an OS, your computer is like a car without a driver – it has
an engine, wheels, and seats, but nobody to control it. The OS is that intelligent driver
who knows:
• When to accelerate (run programs faster)
• How to avoid crashes (handle errors)
• Where to park (save your files)
• How to multitask (switch between tasks)
Why Do We Need an Operating System?
Let me tell you a story. In the 1950s, programmers had to directly interact with
computer hardware using complicated switches and binary codes. If you wanted to print
something, you had to manually tell the printer: "Move here, pick this ink, press this
paper." It was exhausting!
Then someone thought: "What if we create a helper program that does all this boring
work for us?" And boom! The Operating System was born.
Key Roles of an Operating System:
1. Resource Manager – Like a librarian managing books, computers, and study
rooms
2. Interface Provider – Gives you beautiful icons instead of scary code
3. Security Guard – Protects your files from viruses and hackers
4. Multitasking Master – Lets you listen to music while typing an assignment
5. Error Handler – Shows "Oops! Something went wrong" instead of crashing
everything
How Does an Operating System Work?
Let's break this down with a real-life scenario:
Scenario: You click on Microsoft Word
Step 1: User Interface Layer
• You double-click the Word icon (this is the OS's graphical interface at work)
• The OS receives your click signal
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Step 2: Kernel Takes Charge
• The Kernel (the core brain of the OS) springs into action
• It checks: "Do we have enough RAM to run Word?"
• It asks: "Is the hard disk working properly?"
Step 3: Process Management
• OS creates a process for Microsoft Word
• Assigns it a unique ID (like a student roll number)
• Allocates RAM memory (gives it a classroom to work in)
Step 4: CPU Scheduling
• The OS tells the CPU: "Hey processor, run Word now!"
• If you also open Chrome, the OS switches between both programs so fast
(milliseconds) that you think both are running simultaneously
Step 5: Memory Management
• OS divides RAM like hotel rooms – each program gets its space
• If RAM is full, OS uses virtual memory (hard disk space) as backup
Step 6: File System Management
• When you save a document, OS finds empty space on the hard disk
• It creates a "file" and remembers its location (like a librarian remembering which
shelf has which book)
Step 7: Device Management
• If you print, OS communicates with the printer
• If you type, OS reads keyboard signals
• All through device drivers (translators between hardware and OS)
Architecture Diagram of Operating System Working
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Types of Operating Systems
Now comes the interesting part – there are different "flavors" of Operating Systems, just
like ice cream!
1. Batch Operating System
The Old-School Teacher Approach
Imagine a teacher who collects all homework at once, checks them one by one in her
room, and returns them the next day. No interruptions, just batch processing.
• How it works: Jobs are collected in batches, processed without user interaction
• Example: Old bank systems that processed transactions overnight
• Advantage: Efficient for repetitive tasks
• Disadvantage: No real-time interaction
2. Time-Sharing Operating System (Multi-Tasking)
The Modern Multi-Tasker
Think of a chef cooking multiple dishes simultaneously – 2 minutes on pasta, 3 minutes
on pizza, back to pasta. Each dish gets "time slices."
• How it works: CPU time is divided among multiple users/programs
• Example: Windows, Linux, macOS
• Advantage: Multiple programs run "simultaneously"
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• Disadvantage: If too many programs run, system slows down
Real-life example: You're listening to Spotify, typing in Word, and Chrome is
downloading a file – all at once! The OS is rapidly switching between them.
3. Distributed Operating System
The Team of Managers
Imagine a company with offices in different cities, but they work as ONE team sharing
documents and resources through the internet.
• How it works: Multiple computers connected via network work as a single
system
• Example: Google's servers, Cloud computing systems
• Advantage: High reliability, resource sharing
• Disadvantage: Complex to manage, security concerns
4. Real-Time Operating System (RTOS)
The Emergency Doctor
When someone has a heart attack, doctors don't say "Wait, I'll respond in 5 minutes."
They act IMMEDIATELY. RTOS is like that.
• How it works: Responds to inputs instantly within strict deadlines
• Example: Aircraft control systems, Medical equipment, Robots
• Advantage: Predictable, fast response
• Disadvantage: Limited flexibility
5. Network Operating System
The Office Network Manager
Remember your school computer lab where all computers share one printer and one
internet connection? That's a Network OS managing them.
• How it works: Manages network resources, file sharing, security
• Example: Windows Server, Novell NetWare
• Advantage: Centralized management, resource sharing
• Disadvantage: Expensive, requires server
6. Mobile Operating System
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The Pocket Manager
Your smartphone's OS – optimized for touch screens, battery life, and apps.
• How it works: Lightweight, touch-friendly, app-based
• Example: Android, iOS
• Advantage: User-friendly, portable
• Disadvantage: Limited multitasking compared to desktop
Working Flow of an Operating System (Complete Story)
Let me tell you the journey of "opening a photo":
1. You double-click a photo file
2. GUI (Graphical Interface) catches your click
3. File System locates the photo on hard disk
4. Process Manager creates a new process for "Photo Viewer app"
5. Memory Manager allocates RAM to load the photo
6. CPU Scheduler assigns CPU time to display the photo
7. Device Manager sends signals to Monitor to show pixels
8. You see the photo on screen!
All this happens in less than a second! That's the magic of OS.
Final Thoughts: Why OS is the Unsung Hero
The Operating System is like electricity – you don't notice it until it's gone. Imagine if
your computer had no OS:
• Every app would need to know how to talk to your specific printer
• You couldn't run two programs at once
• Saving files would require coding
• No protection from viruses
The OS silently works 24/7, managing chaos, preventing conflicts, and making your
digital life smooth.
In one sentence: An Operating System is the invisible conductor of a digital orchestra,
ensuring every instrument (hardware and software) plays in perfect harmony.
2. What is a Process? CPU Scheduling importance/algorithms (3 mes)
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Ans: Understanding Processes and CPU Scheduling: A Story
Imagine your computer as a bustling office. In this office, the CPU (Central Processing
Unit) is like the manager of all the work that needs to be done. The manager is
extremely skilled but can only focus on one task at a time. Meanwhile, there are
numerous employees (programs) who come in with different tasks to complete. These
tasks are called processes in computer science.
But what exactly is a process? Let’s break it down.
1. What is a Process?
A process is like a task assigned to an employee in our office analogy. It’s not just the
program itself—it’s the program in action. A program is a set of instructions lying on
your disk (like a blueprint). When the program is loaded into memory and the CPU starts
executing it, it becomes a process.
Key Characteristics of a Process:
1. Process ID (PID): Every process gets a unique identity, like an employee ID in the
office.
2. Program Counter (PC): Tells the CPU which instruction to execute next. Think of
it as the to-do list pointer.
3. Registers: These are like the memory slots on your desk, temporarily holding data
while the task is ongoing.
4. Memory Management Information: Keeps track of the space (like desk area) the
process occupies in memory.
5. State of the Process: A process can be in different states, just like employees can
be working, waiting for approval, or resting.
2. Process States
Processes move through different states in their lifecycle:
1. New: The task has just arrived in the office. It’s waiting to be accepted.
2. Ready: The process is ready to be executed. It’s like an employee waiting at the
manager’s desk for instructions.
3. Running: The CPU (manager) is currently working on the process. The task is
being actively handled.
4. Waiting/Blocked: The process is waiting for some event, like waiting for data
from disk or user input. Think of it as an employee waiting for a document from
another department.
5. Terminated: The task is finished, and the process leaves the office.
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Here’s a simple diagram of process states:
3. Why CPU Scheduling is Important
Imagine the office again. There’s one manager (CPU) and many employees (processes). If
the manager randomly chooses tasks, some employees might have to wait forever while
others get all the attention. This chaos can make the office extremely inefficient.
Similarly, in a computer system, many processes compete for the CPU. CPU Scheduling
is like the manager’s plan for deciding which employee gets the CPU next. Good
scheduling ensures:
1. Maximized CPU Utilization: The CPU spends less time idle, just like the manager
always stays productive.
2. Improved Throughput: More tasks are completed in a given time.
3. Reduced Waiting Time: Employees (processes) don’t get frustrated waiting too
long.
4. Fairness: Every process gets a chance, and no one starves.
5. Responsiveness: Important processes (like user interactions) get quicker
attention.
Without scheduling, the computer would feel like a disorganized office—slow,
inefficient, and chaotic.
4. CPU Scheduling Algorithms
Now, how does the manager decide which employee to attend to? This is where CPU
scheduling algorithms come in. Think of these as different strategies a manager uses to
maintain order in the office.
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4.1 First-Come, First-Served (FCFS)
• Idea: The first process to arrive gets executed first.
• Office analogy: Employees are served in the order they walk into the manager’s
office.
• Pros: Simple and fair.
• Cons: A long task can delay all others (convoy effect).
Diagram:
Process Queue: P1 -> P2 -> P3
Execution Order: P1 -> P2 -> P3
4.2 Shortest Job Next (SJN) / Shortest Job First (SJF)
• Idea: The process with the smallest burst time (execution time) is executed first.
• Office analogy: The manager quickly finishes small tasks to clear the desk faster.
• Pros: Minimizes average waiting time.
• Cons: Long tasks may starve.
Diagram:
Process Burst Time: P1=6, P2=2, P3=8
Execution Order: P2 -> P1 -> P3
4.3 Priority Scheduling
• Idea: Processes are assigned priorities; the CPU executes the highest priority
process first.
• Office analogy: VIP tasks or urgent requests are attended first.
• Pros: Important tasks get done sooner.
• Cons: Low-priority tasks may starve.
• Solution: Aging – gradually increase priority of waiting tasks.
4.4 Round Robin (RR)
• Idea: Each process gets a fixed time slice (quantum) and is cycled through the
CPU.
• Office analogy: The manager spends 10 minutes with each employee, then
moves to the next, cycling back to finish remaining tasks.
• Pros: Fair and responsive for interactive systems.
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• Cons: Choosing the right time slice is tricky. Too short = more context switching;
too long = behaves like FCFS.
Diagram:
Quantum = 4ms
P1=5, P2=3, P3=7
Execution Order: P1(4) -> P2(3) -> P3(4) -> P1(1) -> P3(3)
4.5 Multilevel Queue Scheduling
• Idea: Processes are grouped into queues based on priority or type. Each queue
has its own scheduling policy.
• Office analogy: Employees are divided into departments, and the manager
handles high-priority departments first.
• Pros: Handles multiple types of tasks efficiently.
• Cons: Rigid structure, not flexible for dynamic workloads.
4.6 Multilevel Feedback Queue
• Idea: Like Multilevel Queue but processes can move between queues based on
behavior (e.g., CPU-intensive vs. I/O-intensive).
• Office analogy: Employees can move between VIP and normal lanes depending
on urgency and task length.
• Pros: Highly flexible and efficient.
• Cons: Complex to implement.
5. Summary: CPU Scheduling in Real Life
Think of your computer as a smart office. Each process is an employee, and the CPU is
the manager. Without rules, chaos would reign: tasks would pile up, the manager would
be overworked, and some employees would never get attention. CPU scheduling
ensures balance, efficiency, and fairness.
• FCFS: Simple, like a queue at a counter.
• SJF: Quick wins first, clears small tasks fast.
• Priority: VIP treatment for important tasks.
• RR: Fair rotation, great for interactive systems.
• Multilevel Queues: Departmental organization.
• Multilevel Feedback: Dynamic, smart, adaptive management.
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6. Diagram: CPU Scheduling Concept
This shows how processes wait in the queue, are selected by the CPU scheduler, and
finally executed by the CPU.
Conclusion
A process is a living, breathing entity—a program in action. CPU scheduling is the art of
managing these processes efficiently. Understanding scheduling algorithms is not just
about memorizing names, but visualizing your computer as a busy office where tasks
need smart handling. With the right algorithm, the office (CPU) works efficiently,
employees (processes) stay happy, and the system runs smoothly.
Mastering this concept ensures you understand the heart of operating systems: how a
CPU makes everyone’s life productive.
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