Operating Systems and Types is part of Information and Communication Technology. Below are notes on 70 sub-topics, followed by practice MCQs from State PSC and UPSC papers.

Core Functions of an Operating System: Resource, Process, Memory, File, and I/O Management

  • An Operating System (OS) is a system software that manages computer hardware and software resources.

Resource Management

Allocates and deallocates system resources (CPU, RAM, I/O devices, files) among competing processes. Does not generate a separate object file. Slower execution compared to compiled code.

    • Assembler Translates *assembly language* (lowlevel, symbolic) into machine code. (Compilers, Interpreters, and Assemblers are all types of system software and language translators).

Process Management

Manages creation, scheduling, termination, and synchronization of processes.

Memory Management

Tracks memory usage, allocates/deallocates memory space, and manages virtual memory.

File Management

Organizes, creates, deletes, reads, writes, and protects files and directories on storage devices.

I/O (Device) Management

Manages input/output operations, allocates I/O devices, and handles device drivers.

Protection and Security

Ensures system and data integrity, preventing unauthorized access.

User Interface

Provides means for user interaction (e.g., Command Line Interface - CLI, Graphical User Interface - GUI).

  • OS manages resources such as CPU, RAM (memory), I/O devices, and files on disk.

Booting

The process of loading the Operating System into primary memory (RAM) when a computer starts. This is the primary purpose of the boot process.

  • The boot loader (startup program) that loads the OS into primary memory is typically stored in Read-Only Memory (ROM) or flash memory.

POST (Power-On Self-Test)

A diagnostic test performed by the system's firmware (BIOS/UEFI) during computer startup to check the functionality of hardware components and peripheral units.

  • A daemon is an OS process that runs silently in the background, performing system tasks without direct user interaction.
  • The term "daemon" in computing is derived from Maxwell's demon of physics and thermodynamics.

File Management

Operating system component responsible for organizing, storing, and retrieving files efficiently.

File Systems

Method by which files are named, stored, and retrieved on a storage device.

NTFS (New Technology File System)

Default file system for Windows 10 (and later versions like 7, 8, 11). Supports large file sizes, advanced security, journaling, and compression.

FAT32 (File Allocation Table 32)

Older Windows file system, limited file size (4GB) and partition size (2TB).

ExFAT (Extended File Allocation Table)

Optimized for flash drives and external media, supporting larger file sizes than FAT32.

Ext4 (Fourth Extended File System)

Common default file system for Linux operating systems.

Directories (Folders)

Used in an operating system to logically organize and group related files, making them easier to locate and manage.

Shift + Delete (Windows OS)

Keyboard shortcut to permanently delete a file or folder, bypassing the Recycle Bin.

Memory Management: Paging, Segmentation, Virtual Memory

  • Paging: Memory management technique that divides physical memory into fixed-size blocks called frames.
  • Paging: Divides logical memory (process's address space) into same-size blocks called pages.
  • Paging: Maps logical pages to physical frames, allowing a process's physical address space to be non-contiguous.
  • Paging: Chief technique to eliminate external fragmentation; however, it can lead to internal fragmentation.
  • Segmentation: Memory management technique that divides logical memory into variable-size blocks called segments, corresponding to logical program units (e.g., code, data, stack).
  • Segmentation: Allows a user's view of memory. Can suffer from external fragmentation.
  • Virtual Memory: A memory management capability that allows an operating system to compensate for physical memory shortages by temporarily transferring data from RAM to disk storage.
  • Virtual Memory: Enables execution of processes that are not entirely in physical memory, using secondary storage as an extension of main memory.
  • Virtual Memory: Primarily implemented using paging (and sometimes segmentation) to manage the logical-to-physical address translation.

Operating System Architecture

Refers to the design and implementation structure of an OS, primarily involving the Kernel, Shell, and System Calls.

Kernel

    • The central, core part of an Operating System (e.g., UNIX, Linux).
    • Manages fundamental system resources: CPU, memory, processes, and I/O devices.
    • Operates in a privileged mode (kernel mode), providing essential services to other parts of the OS and applications.

Shell

    • The user interface to the Operating System, typically a Command Line Interface (CLI).
    • Interprets user commands (typed or from scripts).
    • Translates user commands into System Calls for the Kernel to execute.
    • Examples include Bash, Zsh, and Csh.
  • System Calls
    • The primary mechanism for user-level programs to request services from the Operating System's Kernel.
    • Handle privileged instructions that require interaction with hardware or other system resources.
    • Act as an interface between user applications and the Kernel, ensuring controlled access to system functions.

`uname -a` Command

    • A command used in Unix-like operating systems (e.g., Ubuntu) to display detailed system information.
    • Provides comprehensive details including kernel name, network hostname, kernel release, kernel version, machine hardware name, and operating system.

Windows

  • An Operating System (OS) is software that manages computer hardware and software resources, providing common services for computer programs.
  • Windows
    • Proprietary graphical OS developed by Microsoft.
    • Versions include Windows XP, Windows NT, Windows 11.
    • Default startup mode is

Normal mode.

  • Linux/Unix

Unix

      • An operating system developed at

Bell Labs.

      • Widely used in supercomputers and minicomputers.
      • It is an OS, not a programming language.
    • Linux
      • An open-source, Unix-like operating system kernel.
      • Often considered a Unix-like system.

GNU (GNU's Not Unix) is an operating system and an extensive collection of free software, started by Richard Stallman. It is open-source and Unix-compatible.

software, started by Richard

Stallman. It is open-source

and Unix-compatible.

      • Linux Distributions (flavors) Ubuntu, Fedora, Gentoo, Solus, Lubuntu, Manjaro.

Not Linux flavors

Solaris (a Unix-based OS, distinct from Linux).

macOS

    • Proprietary graphical OS developed by Apple Inc. for its Macintosh line of computers.
    • Known for its user-friendly interface and robust Unix-based foundation.

Android

    • A mobile operating system developed by Google, based on a modified version of the Linux kernel.

Key Versions and Names

      • Android 4.3: Jelly Bean
      • Android 4.4: Kitkat
      • Android 5.0: Lollipop
      • Android 6.0: Marshmallow

iOS

    • A mobile operating system created and developed by Apple Inc. exclusively for its hardware.
    • Powers many of the company's mobile devices, including the iPhone and iPod Touch.

Other Mobile Operating Systems

Tizen, Palm OS, Web OS, Symbian OS.

Applications/Software Suites

MS-Office, MS-Excel, MS-Access, Google Chrome (web browser), Tally (accounting software), Microsoft Word.

Programming Languages

JAVA, C, Ada, Modula, Ruby, Delphi.

Databases

ORACLE.

Web Browsers

Mosaic.

Hardware/Components

Floppy (storage), ROM (hardware).

Other

MP6 (not a recognized OS).

Process

  • Process An instance of a computer program that is being executed. It requires system resources such as CPU time, memory, files, and I/O devices.

Thread

A light-weight process; the smallest unit of execution that can be managed independently by a scheduler. Threads within the same process share code, data, and resources, but have their own program counter, registers, and stack.

New

The process is being created.

Ready

The process is waiting to be assigned to a processor (CPU).

Running (Executing)

Instructions are being executed by the CPU.

Waiting (Blocked)

The process is waiting for some event to occur (e.g., I/O completion, signal).

Terminated

The process has finished execution.

Typical Process Transitions

New → Ready → Running → Terminated. A process in the Running state may move to the Waiting state (e.g., for I/O) and then return to the Ready state once the event completes.

Purpose

To decide which process in the ready queue gets the CPU next.

Scheduler

An operating system module responsible for selecting the next process to be executed by the CPU and deciding its priority.

Algorithms

Include First-Come, First-Served (FCFS), Shortest Job First (SJF), Priority Scheduling, Round Robin, Multilevel Queue Scheduling, etc.

Process Termination

A process can be terminated due to various reasons:

Normal Exit

The process completes its execution voluntarily (e.g., `exit()` system call).

Fatal Error

An unrecoverable error occurs during execution (e.g., division by zero, invalid memory access).

Killed by Another Process

A parent process terminates a child process, or an external signal forces termination (e.g., `kill` command).

    • System

Shutdown/User

Intervention External factors leading to process termination.

Types of Operating Systems: Batch, Time-sharing, Distributed, Network, Real-time (RTOS), Mobile, Embedded

  • Batch Operating System: Executes jobs in batches without direct user interaction; programs and data submitted offline; focuses on maximizing CPU utilization; no timesharing or multi-user capabilities.
  • Time-sharing Operating System (Multitasking OS): Allows multiple users/ processes to share CPU time; each process gets a small time slice (quantum); CPU switches rapidly, creating illusion of parallel execution; process moves to 'Ready state' when its time slice is completed; Examples: UNIX (multi-user, time-sharing), macOS, Windows.
  • Distributed Operating System: Manages a collection of independent networked computers as a single coherent system; resources are shared across machines; enhances reliability, fault tolerance, and computational speed.
  • Network Operating System (NOS): Runs on a server, enabling client computers to share network resources (files, printers, security); each client has its own OS; Examples: Windows Server, Linux servers.
  • Real-time Operating System (RTOS): Designed for applications with strict time deadlines (e.g., industrial control, medical systems); prioritizes processes, minimizes execution time and latency; guarantees completion of critical tasks within specific time constraints; works independently with minimal interdependencies.
  • Mobile Operating System: Designed for mobile devices (smartphones, tablets); optimized for touch interfaces, battery life, limited resources; Examples: Android, iOS.
  • Embedded Operating System: Specialized OS integrated into hardware of dedicated devices (e.g., washing machines, car systems); highly specific, resource-constrained, often a type of RTOS.
  • Key OS Characteristics & Examples:
    • MS-DOS: Single-user, single-tasking; does not implement true multitasking.
    • UNIX: Multi-user, multi-tasking, time-sharing operating system.
    • Windows (XP, 2000, 98, NT, 11): Generally multi-user and multi-tasking (preemptive for 32-bit applications).
    • macOS (MAC): Multi-user, multitasking.
  • OS Generations: Disk drives became prevalent during the Third Generation OS (1965-1980), characterized by ICs, multiprogramming, and time-sharing.

User Interfaces (UI) facilitate interaction between users and computers.

  • Graphical User Interface (GUI)
    • Interacts through visual elements: icons, windows, menus, buttons, and a mouse pointer.

Examples

Windows, macOS, Android, and many Linux distributions (e.g., Ubuntu with GNOME/KDE).

    • Generally considered intuitive and user-friendly for beginners.

Desktop

The primary background screen for icons and windows.

Taskbar

Usually at the bottom, displays open applications, the Start button, and a notification area.

      • Notification

Area

(on

Taskbar) Contains system icons, including the clock and calendar.

Command Line Interface (CLI)

    • Interacts by typing text commands into a command prompt or shell.
    • Requires users to memorize specific commands and their syntax.
    • Often preferred for automation, scripting, direct system control, and remote administration due to efficiency and power.

Examples

MS-DOS, Unix, core Linux (via terminal), Windows Command Prompt/ PowerShell.

5. Data Communication and Transmission Modes

MS-DOS

Exclusively uses a Command-based Interface.

Unix

Primarily uses a Command-based Interface.

    • Common

Linux/Unix

CLI

commands

      • `ls`: Lists directory contents (files and subdirectories) in the current working directory.
      • `cd`: Changes the current working directory.
      • `pwd`: Prints the current working directory.

Virtualization and Hypervisors

  • Virtualization: Technology that creates virtual (software-based) versions of computing resources, including servers, storage, networks, and operating systems.
  • It enables running multiple operating systems (Guest OSes) simultaneously on a single physical machine (Host).
  • Virtualization facilitates efficient sharing of underlying physical hardware resources (e.g., CPU, memory, storage) among the multiple virtualized instances.

Practice MCQs: Operating Systems and Types

Core Functions of an Operating System: Resource, Process, Memory, File, and I/O Management

  1. Which one of the following is not a function of operating system?

    Asked in: UPSC CBI DSP LDCE 2023

    1. Protection and security
    2. Store and handle data
    3. Device management
    4. File management
    Show answer

    Answer: B. Store and handle data

    Core functions of an operating system include process management, memory management, file management, device management, and protection and security. Storing and handling the content of data is primarily the role of application software, facilitated by the OS's file and storage management capabilities.

  2. Operating System is a/an __________. A) Software B) Hardware C) Firmware D) Industryware

    Asked in: Jail Warders Exam 2022

    1. Software
    2. Hardware
    3. Firmware
    4. Industryware
    Show answer

    Answer: A. Software

    An operating system (OS) is a system software that manages computer hardware, software resources, and provides common services for computer programs. It acts as an interface between the user and the computer hardware.

  3. Which of the following are resources of operating system ?

    Asked in: Revenue Sub Inspector Exam 2022

    1. RAM
    2. CPU
    3. Files in disk
    4. All of the above
    Show answer

    Answer: D. All of the above

    An operating system manages various hardware and software resources, including memory (RAM), processing power (CPU), and storage (files on disk).

  4. During boosting, the operating system checks every peripheral unit. This procedure is known as

    Asked in: GS CompOp 07 2024 1009 2024

    1. POST
    2. BIOS
    3. BUS
    4. CHKDSK
    Show answer

    Answer: A. POST

    POST (Power-On Self-Test) is a diagnostic sequence that a computer executes when it is first turned on.

  5. What is the primary purpose of the boot process ?

    Asked in: Sub Inspector 2024

    1. To shut down the computer
    2. To update the software
    3. To clean the disk
    4. To start the operating system
    Show answer

    Answer: D. To start the operating system

    The boot process is a fundamental concept in computing and is often tested in basic computer knowledge sections.

  6. Consider the following statements : (i) In computer parlance, daemon is a malicious virus of enormous damaging capabilities. (ii) In computer parlance, daemon is an invisible storage device. (iii) In computer parlance, daemon is a process in an operating system that runs in the background. (iv) The use of the word daemon in computer parlance was inspired by Maxwell's demon of physics and thermodynamics. Which of the statements given above is/are correct?

    Asked in: GS INSPFAC 01 2024 2108 2024

    1. (i)
    2. (ii)
    3. (iii) only
    4. (iii) and (iv)
    Show answer

    Answer: D. (iii) and (iv)

    - Daemon: In Unix-like operating systems, a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user. Examples include web server daemons, database daemons, and system logging daemons. - Maxwell's Demon: A thought experiment conceived by physicist James Clerk Maxwell to illustrate his ideas about thermodynamics and statistical mechanics.

  7. The process of loading the Operating System in memory is called

    Asked in: Assistant Registrar Exam 2023

    1. Booting
    2. Compiling
    3. Debugging
    4. Loading
    Show answer

    Answer: A. Booting

    Booting is the fundamental process that makes a computer operational by loading its operating system into memory.

  8. The Startup Program (boot loader) that loads the operating system into primary memory, is stored in-

    Asked in: Veterinary Extension Officer Exam 2024

    1. Random Access Memory (RAM)
    2. Read Only Memory (ROM)
    3. Cache Memory
    4. Main Memory
    Show answer

    Answer: B. Read Only Memory (ROM)

    The startup program (boot loader) that loads the operating system is stored in Read-Only Memory (ROM) or its equivalent firmware.

File Management: Concepts, Directory Structures, Access Methods

  1. What file system is used by default in Windows 10 ?

    Asked in: Deputy Superintendent of Police (Police Telecom) Exam 2024

    1. FAT 32
    2. NTFS
    3. ExFAT
    4. Ext4
    Show answer

    Answer: B. NTFS

    NTFS is the modern and advanced file system standard for Windows operating systems, providing robust features for data management and security.

  2. Directories in operating system are used for :

    Asked in: Draftsman Examination 2023

    1. keeping tracks of Program
    2. keeping tracks of Hardware
    3. keeping tracks of Process
    4. keeping tracks of Files
    Show answer

    Answer: D. keeping tracks of Files

    Directories in an operating system are primarily used for keeping track of and organizing files.

  3. In Windows OS, in order to permanently delete a file from the computer, which of the following keys should be pressed ?

    Asked in: Junior Assistant Exam 2022

    1. Ctrl + Delete
    2. Alt + Delete
    3. Delete + Delete
    4. Shift + Delete
    Show answer

    Answer: D. Shift + Delete

    This question tests basic knowledge of operating system functionalities and keyboard shortcuts related to file management.

Memory Management: Paging, Segmentation, Virtual Memory

  1. Which one of the following is a technique of dividing the physical memory space into multiple blocks ?

    Asked in: UPSC CISF AC EXE 2022

    1. Fragmentation
    2. Paging
    3. Segmentation
    4. Swapping
    Show answer

    Answer: B. Paging

    Paging divides physical memory into fixed-size frames and logical memory into same-size pages, enabling processes to be loaded into non-contiguous physical memory locations.

  2. The memory management scheme that permits the physical address space of a process to non-contiguous space is called :-

    Asked in: Assistant Engineer (AE) Exam 2013

    1. Paging
    2. Spooling
    3. Swapping
    4. None of the above
    Show answer

    Answer: A. Paging

    Paging is a memory management scheme that allows the physical address space of a process to be non-contiguous. It divides the logical address space into fixed-size blocks called pages, and the physical address space into fixed-size blocks called frames. A page can be mapped to any available frame, allowing for non-contiguous allocation of physical memory.

Operating System Architecture: Kernel, Shell, System Calls

  1. The central part of the UNIX Operating System is :

    Asked in: MPPSC CS Prelims 2024

    1. Command Shell
    2. Kernel
    3. Directories and Program
    4. Files
    Show answer

    Answer: B. Kernel

    The kernel is the central part of the UNIX operating system. It is responsible for managing system resources such as memory, processes, and hardware. It acts as a bridge between the hardware and the user applications.

  2. Which of the following command is used to display more detailed information of the system in Ubuntu ? - (5) Question not attempted

    Asked in: Asst. Fisheries Development Officer 2024

    1. uname-a
    2. uname-k
    3. uname-z
    4. kernel
    Show answer

    Answer: A. uname-a

    The `uname` command is a powerful utility for gathering information about the operating system kernel and the underlying hardware.

  3. All the privileged instructions, that is, the instructions, which need to interact with hardware and other resources, and, therefore, passed on to the operating system for execution, are known as

    Asked in: law officier 2025

    1. OS procedures
    2. Kernel functions
    3. System calls
    4. None of the above
    Show answer

    Answer: C. System calls

    System calls are the mechanism by which user programs request privileged operations or services from the operating system kernel that involve hardware interaction.

Overview of Major Operating Systems: Windows, Linux/Unix, macOS, Android, iOS

  1. What is not true about GNU operating system?

    Asked in: CGPSC Prelims Exam 2021

    1. Its full form is 'GNU's Not Unix'
    2. It was started by Richard Stallman
    3. It's an open source software
    4. It is not compatible with Unix
    Show answer

    Answer: D. It is not compatible with Unix

    GNU is a significant project in the history of free and open-source software, aiming to create a complete Unix-like operating system composed entirely of free software.

  2. The latest android mobile operating system-6.0 is named as

    Asked in: RPSC RAS Prelims 2016

    1. Kitkat
    2. Marshmallow
    3. Lollipop
    4. Jelly Bean
    Show answer

    Answer: B. Marshmallow

    Google traditionally names its major Android operating system releases after desserts or sweets in alphabetical order. Android 6.0 followed Lollipop (5.x) and preceded Nougat (7.x).

  3. Match the Android OS versions with their names : OS version Name (a) Android 6.0 1. Kitkat (b) Android 5.0 2. Lollipop (c) Android 4.4 3. Jelly Bean (d) Android 4.3 4. Marshmallow

    Asked in: TNPSC CS Prelims 2015

    1. (a)-4, (b)-2, (c)-3, (d)-1
    2. (a)-4, (b)-3, (c)-1, (d)-2
    3. (a)-4, (b)-2, (c)-1, (d)-2
    4. (a)-3, (b)-1, (c)-2, (d)-4
    Show answer

    Answer: A. (a)-4, (b)-2, (c)-3, (d)-1

    Android OS versions are historically named after desserts in alphabetical order. Android 4.3 is Jelly Marshmallow.

  4. Which of the following is an Operating System ?

    Asked in: UKPSC CS Prelims 2016 · tcs tps gr ii 2014 prelim general studies 2014

    1. UNIX
    2. JAVA
    3. ORACLE
    4. MS-Office
    Show answer

    Answer: A. UNIX

    An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs. UNIX is a family of multi-user, multitasking computer operating systems.

  5. Which one of the following is not an operating system?

    Asked in: UPSC CAPF 2022 · UPSC CBI DSP LDCE 2023

    1. MS-Windows
    2. Linux
    3. Ubuntu
    4. MS-Excel
    Show answer

    Answer: D. MS-Excel

    The question asks to identify which option is not an operating system. Operating systems are fundamental software that allows other programs to run and manage hardware, while application software performs specific user tasks.

  6. Which one of the following is not an operating system ?

    Asked in: UPSC CISF AC EXE 2018 · Forest Officer (RFO) 2018

    1. UNIX
    2. Microsoft Windows
    3. LINUX
    4. Microsoft Access
    Show answer

    Answer: D. Microsoft Access

    - An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs. Examples include UNIX, Windows, and Linux. - Microsoft Access is application software used for creating and managing databases.

  7. Which of the following is the default mode for windows to start ?

    Asked in: ae 2024

    1. Command prompt
    2. Safe mode
    3. Normal mode
    4. None of these
    Show answer

    Answer: C. Normal mode

    Operating systems are designed to boot into a standard, functional state. This standard state is what is referred to as the 'Normal mode'.

  8. Which operating system is used in mostly super, mini computers developed by India ?

    Asked in: Chief Fire Officer Exam 2021

    1. C
    2. Unix
    3. Ada
    4. Modula
    Show answer

    Answer: B. Unix

    Unix is a powerful and versatile operating system commonly used in servers and high-end computing.

  9. Which one of the following is an operating system of mobile devices?

    Asked in: ASSISTANT ENGINEER(ELECTRICAL) 2016

    1. Linux
    2. Ubuntu
    3. Tizen
    4. Windows NT
    Show answer

    Answer: C. Tizen

    Tizen is an operating system specifically designed for mobile and embedded devices, making it a direct answer to the question.

  10. Which of the following is NOT an Operating System ?

    Asked in: Group B Exam 2012

    1. Linux
    2. Unix
    3. DOS
    4. Tally
    Show answer

    Answer: D. Tally

    RO ARO pre -2023 This question assesses basic knowledge of computer software categories, specifically distinguishing between operating systems and application software.

  11. Which of the followings is not an Operating System ?

    Asked in: Lower Subordinate Service Examination 2021

    1. Unix
    2. Linux
    3. Java
    4. Windows-11
    Show answer

    Answer: C. Java

    This question tests fundamental knowledge of computer science terminology, distinguishing between an operating system and a programming language/platform.

  12. Which one of the following is an example of operating system?

    Asked in: Section Officer(LDCE) 2021 22 2021

    1. Microsoft Word
    2. Microsoft Excel
    3. Microsoft Access
    4. Microsoft Windows
    Show answer

    Answer: D. Microsoft Windows

    Microsoft Windows is an operating system, while Microsoft Word, Excel, and Access are application software.

Process Management: Concepts of Processes and Threads, Process States, CPU Scheduling Algorithms

  1. Which one of the following is the correct sequence of the different states of a process in process management function of an operating system ?

    Asked in: UPSC CISF AC EXE 2018

    1. New, Ready, Waiting, Executing, Terminating
    2. New, Waiting, Ready, Executing, Terminating
    3. New, Waiting, Ready, Terminating, Executing
    4. Ready, New, Waiting, Executing, Terminating
    Show answer

    Answer: A. New, Ready, Waiting, Executing, Terminating

    - Standard process states include: New (process being created), Ready (waiting to be assigned to a processor), Running/Executing (instructions are being executed), Waiting/Blocked (waiting for some event to occur, e.g., I/O completion), and Terminated (process has finished execution). - A typical transition sequence is: New -> Ready -> Running - > Terminated. - From Running, a process can go to Waiting (e.g., for I/O) or Terminated. - From Waiting, a process goes back to Ready when the event occurs. - While the transition Ready -> Waiting is not standard in basic models, Option A includes the key states in an order that, compared to the clearly incorrect sequences in B, C, and D, is the most plausible interpretation of a simplified or specific state model used by the question setter, where perhaps 'Waiting' represents a state a process enters after being Ready but before getting the CPU if certain resources are needed immediately. However, the standard transition from Waiting is back to Ready, not directly to Executing. Despite this, A lists the common states in an order that is less incorrect than the others.

  2. What is used for deciding priority to allocate CPU time to a process?

    Asked in: UPSC CISF AC EXE 2019

    1. Linker
    2. Scheduler
    3. Loader
    4. Debugger
    Show answer

    Answer: B. Scheduler

    In an operating system, the Scheduler (specifically, the CPU scheduler) is responsible for deciding which process among the ready processes should be allocated the CPU. Scheduling algorithms often use priority as a key factor in making this decision, giving higher priority processes preferential access to the CPU. Linkers, loaders, and debuggers are software tools involved in the development and execution lifecycle but are not primarily responsible for runtime CPU allocation priority.

  3. A process can be terminated due to

    Asked in: JUNIOR laboratory assistant 2025

    1. Normal exit
    2. Fatal error
    3. Killed by another process
    4. More than one of the above
    Show answer

    Answer: D. More than one of the above

    Processes are fundamental units of execution within an operating system. Their termination can occur for various reasons, reflecting both planned completion and unexpected events.

Types of Operating Systems: Batch, Time-sharing, Distributed, Network, Real-time (RTOS), Mobile, Embedded

  1. Which one of the following is not a multi- user operating system ?

    Asked in: UPSC CISF AC EXE 2023

    1. UNIX
    2. Windows XP
    3. MS-DOS
    4. Windows 2000
    Show answer

    Answer: C. MS-DOS

    - Multi-user operating systems allow multiple users to access and use the system concurrently. - UNIX, Windows 2000, and even later versions like Windows XP (though primarily desktop OS, they have features like Fast User Switching and support for services running under different users, and Windows 2000 was a significant multi-user capable OS designed for servers/workstations) are capable of multi-user operation to varying extents. - MS-DOS strictly lacks multi-user capabilities.

  2. ______ has the capability to prioritise the process, minimize the execution time and work independently with no interdependencies.

    Asked in: ae 2020

    1. DOS
    2. MTOS
    3. RTOS
    4. MPOS
    Show answer

    Answer: C. RTOS

    ae -2025 This question relates to operating systems, specifically those designed for real-time applications where performance and predictability are paramount.

  3. Which is a multi user, time-sharing operating system?

    Asked in: Assistant Engineer (AE) Exam 2013

    1. DOS
    2. UNIX
    3. Ms-Office
    4. Android
    Show answer

    Answer: B. UNIX

    UNIX is a classic example of an operating system designed for concurrent access by multiple users and efficient sharing of system resources through time-sharing.

  4. In a timeshare operating system, when the time slot assigned to a process is completed, the process switches from the current state to?

    Asked in: JUNIOR laboratory assistant 2025

    1. Suspended state
    2. Terminated state
    3. Ready state
    4. More than one of the above
    Show answer

    Answer: C. Ready state

    Timesharing is a CPU scheduling technique where the CPU is shared among multiple processes. Each process gets a small time slice (quantum). When this quantum expires, the scheduler selects another process to run, and the current process is put back into the queue of processes waiting for CPU time.

  5. Disks were invented in OS generation.

    Asked in: law officier 2025

    1. First
    2. Second
    3. Third
    4. None of the above
    Show answer

    Answer: B. Second

    Disks, as a form of computer storage, were invented and became prominent during the second generation of computer development.

  6. Which of the following is a single user operating system ?

    Asked in: Rakshak 2023

    1. Windows
    2. MS-DOS
    3. MAC
    4. None of these
    Show answer

    Answer: B. MS-DOS

    MS-DOS is a classic example of a single-user operating system, whereas Windows and macOS are designed for multi-user environments.

  7. Which of the following operating system does not implement true multitasking ?

    Asked in: ro aro 2024

    1. Windows 98
    2. Windows NT
    3. MS-DOS
    4. Windows 11
    Show answer

    Answer: C. MS-DOS

    The evolution of operating systems has significantly improved user productivity through multitasking capabilities.

User Interfaces: Command Line Interface (CLI) vs. Graphical User Interface (GUI)

  1. Where do you find the clock and calendar in/ on your computer?

    Asked in: APSC CCE Prelims Exam 2016

    1. On the Taskbar
    2. On the Start Menu
    3. On the Desktop
    4. In the Control Panel
    Show answer

    Answer: A. On the Taskbar

    - The Taskbar is the bar located typically at the bottom of the screen, which displays open applications and the notification area (also known as the system tray). - The clock and date are usually displayed in the notification area on the right side of the Taskbar. Clicking on them typically opens a larger calendar view.

  2. Which of the following is not shown in the Windows taskbar?

    Asked in: APSC CCE Prelims Exam 2016

    1. Taskbar
    2. Menu bar
    3. Desktop
    4. Startmenu
    Show answer

    Answer: B. Menu bar

    - The Windows taskbar contains the Start button (accessing the Start Menu), icons for running applications, pinned applications, and the notification area (system tray). - The Taskbar is the bar itself. The Desktop is the area behind the Taskbar. The Start Menu is accessed via a button on the Taskbar. - A "Menu bar" in the conventional sense (like in software applications) is not a component displayed on the Taskbar.

  3. MS-DOS is an operating system with which of the following type of user interface ?

    Asked in: MPPSC CS Prelims 2025

    1. Graphical User Interface
    2. Touch-based User Interface
    3. Command-based Interface
    4. Voice-based Interface
    Show answer

    Answer: C. Command-based Interface

    mppsc 2025-2025 Users interact with MS-DOS by typing commands at a prompt, making it a command-based interface.

  4. In Linux operating system, "ls" command is used to ________. - (5) Question not attempted

    Asked in: Asst. Fisheries Development Officer 2024

    1. Display the current working directory.
    2. Display information about files in the current working directory.
    3. Navigate between different folders.
    4. Get basic information about the OS.
    Show answer

    Answer: B. Display information about files in the current working directory.

    The `ls` command is one of the most fundamental and frequently used commands in the Linux command line.

  5. Which of the following operating systems is primarily based on a Graphical User Interface (GUI)?

    Asked in: GK CDPO 33 2023 2709 2024

    1. Android
    2. Windows
    3. Linux
    4. MacOS
    Show answer

    Answer: B. Windows

    The question differentiates operating systems based on their primary user interface. A GUI contrasts with a command-line interface (CLI).

  6. Unix is an operating system with the following type of user Interface-

    Asked in: Assistant Professor, Librarian and Sports Officer Examination 2024 · Forest Service Main Exam 2024

    1. Voice-based Interface
    2. Natural Language Interface
    3. Command-based Interface
    4. Touch-based Interface
    Show answer

    Answer: C. Command-based Interface

    The primary and historically significant user interface for the Unix operating system is command-based.