Functions of an Operating System

An operating system (OS) is the system software that acts as an interface between the user and the computer hardware. Its major functions are described below:

1. Process Management The OS decides which process gets the processor, when, and for how long. It creates and deletes processes, suspends and resumes them, and provides mechanisms for process synchronization and communication. It also handles scheduling so that the CPU is used efficiently.

2. Memory Management The OS keeps track of every byte of main memory — which part is used and by whom. It allocates memory to programs when they request it, deallocates it when they finish, and decides which processes to load into memory when space is available. It also supports virtual memory.

3. File Management The OS manages files on storage devices. It creates, deletes, opens, closes, reads and writes files, maintains directories and folder structures, and controls access permissions so that unauthorized users cannot read or modify data.

4. Device / I/O Management The OS controls all input and output devices through device drivers. It allocates devices to processes, buffers data during transfer, and manages the flow of data between the CPU, memory, and peripherals such as keyboards, printers, and disks.

5. Memory and Resource Protection and Security The OS protects the system and user data from unauthorized access. It uses passwords, access rights, and privilege levels to prevent one user or process from interfering with another.

6. User Interface The OS provides an environment for the user to interact with the computer, either through a Command Line Interface (CLI) or a Graphical User Interface (GUI).

7. Error Detection and Handling The OS continuously monitors the system for errors in hardware and software, and takes appropriate action to correct them or to prevent the system from crashing.

8. Job Accounting and Performance Monitoring The OS keeps records of the resources used by each job or user, which helps in system performance monitoring and resource accounting.

In short, the operating system manages all hardware and software resources of a computer and provides a convenient, efficient, and secure environment for running programs.

(d) All of above

Android, Windows 7 and iOS are all operating systems: Android and iOS for mobile devices, Windows 7 for desktop computers.

An operating system is system software that controls the hardware, manages resources such as the CPU, memory and files, and provides an interface through which users run application programs.

Why GUI is more popular than CUI

A GUI (Graphical User Interface) operating system, such as Windows, uses windows, icons, menus and a pointer, whereas a CUI (Character User Interface) system, such as DOS, needs typed commands. GUI is more popular because:

• Easy to use: users select icons and menus with a mouse and need not remember commands.
• Easy to learn: even beginners can work after a short time, while CUI needs knowledge of exact command syntax.
• Attractive and user-friendly: graphics, colours and pictures make the work clear and pleasant.
• Multitasking: several programs can be opened in different windows and used together.
• Fewer errors: there is no need to type long commands, so typing mistakes are reduced.
• Consistent look: applications follow similar menus and buttons, so skills transfer from one program to another.

An open source operating system is an operating system whose source code is freely available. Anyone can view, modify, improve and redistribute it under its licence. Linux is an example.

Features of the Android mobile operating system

• Open source: it is based on the Linux kernel and developed under the Android Open Source Project, so manufacturers can customize it.
• Touch-based GUI: it is operated by touch, gestures and on-screen keyboards.
• Multitasking: several apps can run at the same time and the user can switch between them.
• Large app store: millions of apps are available through Google Play.
• Customizable: home screens, widgets, launchers and themes can be changed.
• Connectivity: it supports Wi-Fi, Bluetooth, mobile data, GPS and NFC.
• Google services integration: Gmail, Maps, Drive and Assistant work closely with it.
• Wide hardware support: it runs on phones, tablets, TVs and watches from many manufacturers.

Open source software is software whose source code is made public so that anyone can study, modify and share it freely, usually at no cost. Examples are Linux, Mozilla Firefox and LibreOffice.

Features of the iOS mobile operating system

iOS is the proprietary (closed source) operating system of Apple, used on iPhone and iPad.

• Touch-based GUI: it is operated by touch, swipe and multi-touch gestures with a clean, simple interface.
• Multitasking: apps can run in the background and the user can switch between them.
• Security and privacy: it has strong features such as app sandboxing, Face ID/Touch ID and regular updates.
• App Store: apps are checked by Apple before they are made available.
• Smooth performance: hardware and software are made by the same company, so they work well together.
• Siri and iCloud: a voice assistant and cloud storage are built in.
• Regular updates: supported devices receive updates directly from Apple.

(d) Google

Android is a Linux-based mobile operating system developed by Google (originally by Android Inc., bought by Google in 2005).

(d) Pascal

Pascal is a programming language, not an operating system. UNIX, MS-DOS and Linux are all operating systems.

(a) C

UNIX was rewritten in the C language by Dennis Ritchie and Ken Thompson at Bell Labs in the early 1970s, which made it portable to different hardware.

An operating system (OS) is system software that manages the hardware and software resources of a computer and provides a platform on which application programs run. It acts as an interface between the user and the hardware.

Roles of the operating system

1. Process management: it creates, schedules and terminates processes, and decides which program gets the CPU and for how long, so that multitasking is possible.
2. Memory management: it allocates main memory to programs when they need it and takes it back when they finish. It keeps track of used and free memory and protects one program's memory from another.
3. File management: it organizes data into files and folders, and controls creating, opening, copying, deleting, naming and access permissions.
4. Device management: it controls input/output devices such as the keyboard, printer and disk through device drivers, and handles requests from programs for these devices.
5. User interface: it provides a CUI (command line) or a GUI so that the user can communicate with the computer.
6. Security and protection: it prevents unauthorized access using passwords, user accounts and permissions, and protects data from other users or programs.
7. Resource allocation: it shares the CPU, memory and devices fairly among programs and users.
8. Error detection and handling: it detects hardware and software errors and takes suitable action, so that the system keeps working correctly.
9. Job accounting and networking: it records resource use and manages communication between computers in a network.
10. Booting: it is loaded into memory at start-up and makes the computer ready for use.

(a) first-come, first-served scheduling

In FCFS, the process that requests the CPU first is allocated the CPU first — the ready queue is maintained as a simple FIFO queue.

(d) Fedora

Fedora is a Linux distribution (distro), a package of the Linux kernel with software. Other examples are Ubuntu, Debian and Red Hat.

(a) Operating System

The operating system acts as the interface between the user and the computer hardware, managing hardware resources and running programs.

(d) All of above

Linux, Android (its AOSP code) and Moodle all have publicly available source code that users can study, modify and share, so all are open source.

(d) Windows 10

Windows 10 is proprietary software owned by Microsoft; its source code is not freely available. Linux, Android and Moodle release their source code under open source licences.

(a) Kernel

The kernel is the core of the operating system. It directly manages the CPU, memory and devices and provides services to all other parts of the system.

(d) All of the above

Windows is a GUI-based operating system, and it also supports multitasking (running several programs at once) and multiprogramming, so all the options describe it.

(a) DOS

DOS can run only one program at a time (single-tasking). Linux, Windows and Ubuntu are multitasking operating systems.

(d) Android

Android is the most widely used and fastest-growing mobile operating system. It is open source and used by many phone manufacturers.

(a) Productivity maximization

An operating system manages hardware resources and provides an environment so that users and programs can work efficiently, which maximizes the productivity of the computer system.

(d) all of the mentioned

The operating system handles booting from disk, disk initialization (formatting) and bad-block recovery, so all the listed tasks are its responsibility.

(c) Adobe Photoshop

Adobe Photoshop is application software used for a specific job, image editing. Android, Windows 7 and iOS are system software (operating systems).

(a) Application

MS Excel (spreadsheet) and MS Word (word processor) are application software designed to perform specific user tasks.

An operating system (OS) is system software that manages the hardware and software resources of a computer and acts as an interface between the user and the hardware. Examples: Windows, Linux, Android.

On the basis of the processing method, operating systems can be of the following types. Two of them are explained below.

1. Batch Processing Operating System

• Similar jobs are collected together into a batch and executed one after another without user interaction while they run.
• The user submits the job (with its data and control instructions) and gets the output later.
• It reduces the idle time of the CPU, but there is no direct interaction, and the turnaround time is long.
• Example uses: payroll processing, bank statements, billing.

2. Time-Sharing (Multitasking) Operating System

• The CPU time is divided into small slices, and each user or program gets a slice in turn. The switching is so fast that every user feels the computer is working only for them.
• It allows many users or programs to share the computer at the same time and gives a quick response.
• It needs a good memory management and scheduling system.
• Examples: UNIX, Linux, Windows.

Other types based on processing are real-time and multiprocessing operating systems.

An operating system is system software that manages the computer hardware and software resources and acts as a bridge between the user and the hardware.

Features of a GUI-based operating system

• Graphical interface: it uses windows, icons, menus and buttons instead of typed commands.
• Pointing device: the user operates it mainly with a mouse (or touch), by pointing, clicking and dragging.
• Easy to learn and use: no need to memorize commands, so beginners can work quickly.
• Multitasking: many programs can run together in separate windows, and the user can switch between them.
• WYSIWYG: what the user sees on screen is what is printed or produced.
• Multimedia support: pictures, audio and video can be handled easily.
• Consistent look and feel: menus, dialogue boxes and shortcuts work similarly across applications.
• Plug and play: hardware devices are detected and set up automatically.

Examples: Microsoft Windows, macOS, Ubuntu desktop.

Software is a set of programs and instructions that tells the computer hardware what to do. Without software, the hardware cannot do any useful work.

Categories of software

1. System software: it manages and controls the computer hardware and provides a platform for other software. Examples: operating systems (Windows, Linux), device drivers, utility programs and language translators.
2. Application software: it helps users perform specific tasks. Examples: MS Word, MS Excel, Photoshop, web browsers. It can be general purpose or customized (tailor-made).

Roles of an operating system

• Process management: schedules programs and allocates the CPU to them.
• Memory management: allocates and frees main memory and protects it.
• File management: creates, stores, retrieves and protects files and folders.
• Device management: controls input/output devices through drivers.
• User interface: gives a CUI or GUI for communication with the computer.
• Security: protects the system and data from unauthorized access.
• Error handling: detects errors and takes suitable action.

An operating system is system software that manages the computer hardware and software resources and works as an interface between the user and the hardware.

Layers of an operating system

An operating system is designed in layers, where each layer uses the services of the layer below it and provides services to the layer above it. From bottom to top:

1. Hardware layer: the physical parts of the computer such as the CPU, memory and I/O devices. It is the lowest level and is controlled by the layers above.
2. Kernel layer: the core of the OS. It directly controls the hardware and handles process management, memory management, device management and interrupts.
3. Shell layer: it accepts the user's commands or actions and passes them to the kernel for execution. It may be command-based (CUI) or graphical (GUI).
4. Application layer: the application programs and utilities, such as word processors and browsers, that run on top of the OS and are used directly by the user.

Thus the user works through the application and shell layers, which in turn use the kernel to operate the hardware. This layering makes the system easier to design, test and modify.

(d) None of the above

DOS is a command-line (CUI), single-user, single-tasking operating system. It is not GUI based, and it does not support multitasking or multiprogramming.