CTEVT Regular/Back Exam-2081 Operating System Solutions

 

1(a) Define Operating System. Explain the functions of OS.

Definition of Operating System (OS):

An Operating System (OS) is a system software that serves as the backbone of a computer system. It enables users to communicate with hardware (like CPU, memory, and storage) and run application software. In simple words, the OS is the middleman that ensures everything on the computer works together smoothly.

Without an OS, users cannot perform tasks like opening a file, running applications, or using devices like a printer.

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Functions of the Operating System:

The OS performs various tasks to ensure the computer system runs effectively. Each function is explained below:

1. Process Management:

   • Handles processes, which are running programs.
   • Manages CPU scheduling, ensuring that each process gets a fair share of CPU time.
   • Allows multitasking (running several programs simultaneously).
   • Example: While typing in MS Word, the OS ensures background processes like antivirus scans run without affecting your work.

2. Memory Management:

   • Allocates memory (RAM) to different programs.
   • Tracks which part of memory is in use and by which program.
   • Frees up memory after a program is closed to avoid waste.
   • Example: When opening multiple tabs in a web browser, the OS efficiently allocates memory to each tab.

3. File Management:

   • Manages data storage in files and folders.
   • Provides operations like reading, writing, creating, deleting, and organizing files.
   • Example: Windows Explorer is a file management tool that lets you navigate, organize, and access files on your hard drive.

4. Device Management:

   • Controls hardware devices like printers, scanners, and monitors using device drivers.
   • Ensures smooth communication between hardware and software.
   • Example: When you connect a USB drive, the OS detects it and makes it ready for use.

5. Security and Protection:

   • Protects the system from unauthorized access by using features like passwords, encryption, and firewalls.
   • Prevents harmful programs (like viruses) from damaging system files.
   • Example: Antivirus software works alongside the OS to ensure security.

6. User Interface:

   • Provides a way for users to interact with the system.
   • Two types:
     • Graphical User Interface (GUI): Uses visuals (like icons and menus) for easy interaction.
       Example: Windows, macOS.
     • Command-Line Interface (CLI): Requires users to type commands.
       Example: Linux Terminal.

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1(b) What are the types of operating systems? Explain.

Types of Operating Systems:

1. Batch Operating System:

   • Processes jobs in batches without user interaction.
   • Jobs are collected, grouped, and executed sequentially.
   • Example: Early IBM systems.

2. Time-Sharing Operating System:

   • Allows multiple users to share computer resources at the same time.
   • Each user gets a small "time slice" to interact with the system.
   • Example: UNIX.

3. Distributed Operating System:

   • Manages a group of interconnected computers.
   • Makes multiple computers work as a single system.
   • Example: Windows Server, Amoeba OS.

4. Real-Time Operating System (RTOS):

   • Responds to inputs or events immediately, without delay.
   • Used in time-sensitive applications like medical equipment or robots.
   • Example: VxWorks, QNX.

5. Embedded Operating System:

   • Designed for specific hardware with limited resources.
   • Used in devices like washing machines, ATMs, or cars.
   • Example: OS in smartwatches or embedded Linux.

6. Network Operating System (NOS):

   • Manages network resources and provides services like file sharing, printing, and user authentication.
   • Example: Novell NetWare, Windows Server.

7. Mobile Operating System:

• Designed for mobile devices like smartphones and tablets.
• Offers features for calling, messaging, apps, and multimedia.
• Example: Android, iOS.

2(a) Define Process Control Block (PCB). Differentiate between Process and Program.

(Marks: 2 for Definition, 4 for Differentiation)

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Definition of Process Control Block (PCB):

A Process Control Block (PCB) is a data structure used by the operating system to store information about a process. A process is a program in execution, and the PCB acts as its "identity card" in the system, helping the OS keep track of all active processes.

The PCB contains essential details about a process, such as:

1. Process ID (PID): A unique identifier for each process.
2. Process State: Current state of the process (e.g., ready, running, waiting).
3. Program Counter: Points to the next instruction the process will execute.
4. CPU Registers: Values of CPU registers that the process was using.
5. Memory Management Information: Details about the memory allocated to the process.
6. I/O Status: Information about the I/O devices being used.
7. Priority: Indicates the priority level of the process.

Example:
If your computer is running multiple programs like a browser, a game, and a music player, the OS creates a PCB for each process to track its execution status and manage resources.

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Difference Between Process and Program:

Aspect	Process	Program
Definition	A process is a program in execution.	A program is a static set of instructions written to perform a task.
State	Dynamic (changes as it runs, e.g., from ready to running to terminated).	Static (remains the same until executed).
Example	Playing a video in VLC media player (process).	The VLC media player application installed on your computer (program).
Storage Location	Stored in main memory (RAM) while it executes.	Stored on disk (e.g., in .exe or .py format).
Control	Controlled by the operating system.	Controlled by the user (who decides when to run it).
Resource Utilization	Requires system resources like CPU, memory, and I/O devices.	Does not require resources until it is executed.