Operating System Tutorial

Operating System Tutorial provides the basic and advanced concepts of operating system . Our
Operating system tutorial is designed for beginners, professionals and GATE aspirants. We have
designed this tutorial after the completion of a deep research about every concept.

The content is described in detailed manner and has the ability to answer most of your queries.
The tutorial also contains the numerical examples based on previous year GATE questions which
will help you to address the problems in a practical manner.

Operating System can be defined as an interface between user and the hardware. It provides an
environment to the user so that, the user can perform its task in convenient and efficient way.

The Operating System Tutorial is divided into various parts based on its functions such as
Process Management, Process Synchronization, Deadlocks and File Management.

Operating System Definition and Function

In the Computer System (comprises of Hardware and software), Hardware can only understand
machine code (in the form of 0 and 1) which doesn't make any sense to a naive user.

We need a system which can act as an intermediary and manage all the processes and resources
present in the system.

An Operating System can be defined as an interface between user and hardware. It is

responsible for the execution of all the processes, Resource Allocation, CPU management, File
Management and many other tasks.

The purpose of an operating system is to provide an environment in which a user can execute
programs in convenient and efficient manner.

Structure of a Computer System

A Computer System consists of:

o Users (people who are using the computer)

o Application Programs (Compilers, Databases, Games, Video player, Browsers, etc.)
 o System Programs (Shells, Editors, Compilers, etc.)
o Operating System ( A special program which acts as an interface between user and hardware )
o Hardware ( CPU, Disks, Memory, etc)

What does an Operating system do?

1. Process Management
2. Process Synchronization
3. Memory Management
4. CPU Scheduling
5. File Management
6. Security

Windows Tutorial

Windows is a general name for Microsoft Windows. It is developed and marketed by an

American multinational company Microsoft. Microsoft Windows is a collection of several
proprietary graphical operating systems that provide a simple method to store files, run the
software, play games, watch videos, and connect to the Internet.

What is an Operating System?

An operating system or OS is system software. It provides an interface between computer user
and computer hardware. An operating system is used to perform all the basic tasks like file
management, process management, memory management, handling input and output devices,
and controlling peripheral devices such as disk drives and printers.

History of Windows
Windows was first introduced by Microsoft on 20 November 1985. After that, it was gaining
popularity day by day. Now, it is the most dominant desktop operating system around the world,
with a market share of around 82.74%. The macOS Operating system by Apple Inc. is the second
most popular with the share of 13.23%, and all varieties of Linux operating systems are
collectively in third place with the market share of 1.57%.

Early History
Bill Gates is known as the founder of Windows. Microsoft was founded by Bill Gates and Paul
Allen, the childhood friends on 4 April 1975 in Albuquerque, New Mexico, U.S.

The first project towards the making of Windows was Interface Manager. Microsoft was started
to work on this program in 1981, and in November 1983, it was announced under the name
"Windows," but Windows 1.0 was not released until November 1985. It was the time of Apple's
Macintosh, and that's the reason Windows 1.0 was not capable of competing with Apple's
operating system, but it achieved little popularity. Windows 1.0 was just an extension of MS-
DOS (an already released Microsoft's product), not a complete operating system. The first
Microsoft Windows was a graphical user interface for MS-DOS. But, in the later 1990s, this
product was evolved as a fully complete and modern operating system.

Windows Versions
The versions of Microsoft Windows are categorized as follows:

Early versions of Windows

The first version of Windows was Windows 1.0. It cannot be called a complete operating system
because it was just an extension of MS-DOS, which was already developed by Microsoft. The
shell of Windows 1.0 was a program named MS-DOS Executive. Windows 1.0 had introduced
some components like Clock, Calculator, Calendar, Clipboard viewer, Control Panel, Notepad,
Paint, Terminal, and Write, etc.

In December 1987, Microsoft released its second Windows version as Windows 2.0. It got more
popularity than its previous version Windows 2.0. Windows 2.0 has some improved features in
user interface and memory management.

The early versions of Windows acted as graphical shells because they ran on top of MS-DOS and
used it for file system services.
Windows 3.x
The third major version of Windows was Windows 3.0. It was released in 1990 and had an
improved design. Two other upgrades were released as Windows 3.1 and Windows 3.2 in 1992
and 1994, respectively. Microsoft tasted its first broad commercial success after the release of
Windows 3.x and sold 2 million copies in just the first six months of release.

Windows 9x (Windows 95, Windows 98)

Windows 9x was the next release of Windows. Windows 95 was released on 24 August 1995. It
was also the MS-DOS-based Windows but introduced support for native 32-bit applications. It
provided increased stability over its predecessors, added plug and play hardware, preemptive
multitasking, and also long file names of up to 255 characters.

It had two major versions Windows 95 and Windows 98

Windows NT (3.1/3.5/3.51/4.0/2000)
Windows NT was developed by a new development team of Microsoft to make it a secure,
multi-user operating system with POSIX compatibility. It was designed with a modular, portable
kernel with preemptive multitasking and support for multiple processor architectures.

Windows XP
Windows XP was the next major version of Windows NT. It was first released on 25 October
2001. It was introduced to add security and networking features.
It was the first Windows version that was marketed in two main editions: the "Home" edition and
the "Professional" edition.

The "Home" edition was targeted towards consumers for personal computer use, while the
"Professional" edition was targeted towards business environments and power users. It included
the "Media Center" edition later, which was designed for home theater PCs and provided support
for DVD playback, TV tuner cards, DVR functionality, and remote controls, etc.

Windows XP was one of the most successful versions of Windows.

Windows Vista
After Windows XP's immense success, Windows Vista was released on 30 November 2006 for
volume licensing and 30 January 2007 for consumers. It had included a lot of new features such
as a redesigned shell and user interface to significant technical changes. It extended some
security features also.

Windows 7
Windows 7 and its Server edition Windows Server 2008 R2 were released as RTM on 22 July
2009. Three months later, Windows 7 was released to the public. Windows 7 had introduced a
large number of new features, such as a redesigned Windows shell with an updated taskbar,
multi-touch support, a home networking system called HomeGroup, and many performance
improvements.

Windows 7 was supposed to be the most popular version of Windows to date.

Windows 8 and 8.1

Windows 8 was released as the successor to Windows 7. It was released on 26 October, 2012. It
had introduced a number of significant changes such as the introduction of a user interface based
around Microsoft's Metro design language with optimizations for touch-based devices such as
tablets and all-in-one PCs. It was more convenient for touch-screen devices and laptops.

Microsoft released its newer version Windows 8.1 on 17 October 2013 and includes features
such as new live tile sizes, deeper OneDrive integration, and many other revisions.

Windows 8 and Windows 8.1 were criticized for the removal of the Start menu.

Windows 10
Microsoft announced Windows 10 as the successor to Windows 8.1 on 30 September 2014.
Windows 10 was released on 29 July 2015. Windows 10 is the part of the Windows NT family
of operating systems.
Microsoft has not announced any newer version of Windows after Windows 10.

What is Linux Operating System?

Introduction to Linux
Linux is an open-source Unix-like operating system-based family on the Linux kernel, and the
OS kernel was first published on 17 September 1991 by Linus Torvalds. Typically, Linux is
packaged as the Linux distribution, which contains the supporting libraries and system software
and kernel, several of which are offered by the GNU Project. Several Linux distributions use the
term "Linux" in the title, but the Free Software Foundation uses the "GNU/Linux" title to
focus on the necessity of GNU software, causing a few controversies.

Famous Linux distributions are Ubuntu, Fedora Linux, and Debian, the latter of which is
composed of several different modifications and distributions, including Xubuntu and Lubuntu.
Commercial distributions are SUSE Linux Enterprise and Red Hat Enterprise Linux. Desktop
distributions of Linux are windowing systems like Wayland or X11 and desktop environments
like KDE Plasma and GNOME.

o Originally, Linux was designed for personal computers that were Intel x86 architecture-
based, but it has since been moved to more environments than other operating systems.
o Including Android, Linux has the biggest installed base of every general-purpose
operating system because of the control of the Linux-based Android over smartphones as
of May 2022.
o However, Linux is used by just around 2.6% of desktop computers as of November 2022.
o Also, Linux executes on many embedded systems, i.e., devices whose OS is typically
designed into the firmware and is extremely customized to the system.
o It includes spacecraft (Perseverance rover, Dragon crew capsule, and Falcon 9 rocket),
automobiles (Toyota, Hyundai, Mercedes-Benz, Audi, and Tesla), televisions (LG and
Samsung Smart TVs), video game consoles, smart home devices, automation controls,
and routers.

Linux is one of the most outstanding examples of open-source and free software collaboration.
The source code may be distributed, modified, and used non-commercially or commercially by
everyone under the conditions of its respective licenses, like the GNU GPL (General Public
License). For example, the Linux kernel is licensed upon the GPLv2.

History of Linux OS
o Precursors
The Unix-based operating system was implemented and conceived in 1969 at AT&T's
Bell labs by Joe Ossanna, Douglas Mcllroy, Dennis Ritchie, and Ken Thompson in the
United States. First published in 1971, Unix was entirely written in assembly language, as
was the basic practice at the time. It was updated in the C language by Dennis Ritchie in
a key pioneering way in 1973. The availability of a Unix high-level language
implementation made its porting to distinct computer platforms convenient.
o Creation
Torvalds registered in a Unix course while visiting the University of Helsinki in the
1990's fall. The course used a MicroVAX minicomputer executing Ultrix, and one of the
needed texts was Operating Systems: Design and Implementation by Andrews S.
Tanenbaum. The textbook contained a copy of the MINIX operating system of
Tanenbaum. It was together with this course that Torvalds initially became open to Unix.
He became interested in operating systems in 1991. Frustrated by the MINIX licensing,
which limited it to only educational use at the time, he started to work on his operating
system kernel, which became the Linux Kernel eventually.
Torvalds started the Linux kernel development on MINIX, and software written for
MINIX was used on Linux as well. Later, Linux was cultivated, and then the
 development of the Linux kernel appeared on Linux systems. Also, GNU applications
replaced every MINIX component due to it was beneficial to use the free code through
the GNU Project with the new OS; code licensed upon the GNU GPL can be re-applied
in other computer functions as long as they are also published under a compatible or the
same license.
Torvalds started a switch from his actual license, which banned commercial distribution,
to the GNU GPL. Developers operated to develop GNU elements with the Linux Kernel,
making a free and fully functional operating system.
o Current development
The lead maintainer of the Linux Kernel is Greg Kroah-Hartman who guides its
development. The e executive director for the Free Software Foundation is William John
Sullivan, which in turn supported the GNU components. Corporations and individuals
finally develop non-GNU third-party components.
The third-party components are composed of a wide body of work and may contain both
user libraries and applications, and kernel modules. Linux community and vendors
distribute and combine the kernel, non-GNU components, and GNU components with
extra package management software in the fashion of Linux distributions.
o Popular and commercial uptake
In production environments, Linux adoption began to take off initially in the mid-1990s
in the supercomputing community instead of being used by only hobbyists, where
organizations like NASA began to increasingly replace their expensive machines with
inexpensive commodity computer clusters running Linux. Commercial use started when
IBM and Dell, pursued by Hewlett-Packard, began providing Linux support for escaping
the monopoly of Microsoft in the desktop OS market.
Linux systems are completely used in computing today, from embedded systems to every
supercomputer virtually, and have secured a position in server installations like the
famous LAMP application stack. The usage of Linux distributions in enterprise and home
desktops has been developing.
Also, Linux distributions have become famous in the netbook market, with several
devices moving with installed customized Linux distributions and Google publishing
their ChromeOS developed for netbooks.

Design of Linux OS
Various open-source developers admit that the Linux kernel was not developed but instead
evolved from natural selection. A Linux-based system is a compatible Unix-like OS, derived
much of its common design from principles made in Unix during the 1970s and 1980s. Such a
system applies the Linux kernel, a monolithic kernel which manages file systems, peripheral
access, networking, and process control. Device drivers are either directly integrated with the
kernel or included as modules loaded while the device is active.

Installed Linux System components include the below:

o A bootloader, for instance, systemd-boot, SYSLINUX, LILO, and GNU GRUB. It is a

program that can load the Linux kernel into the main memory of the computer by being
run by the computer after the firmware login is performed and when it's turned on.
o An init program, like the traditional sysvinit and the newer Upstart, OpenRC, and
systemd. It is the first process announced by the Linux kernel and the process tree root. In
other words, every process is opened from init. It initiates processes like login prompts
and system services (whether in terminal or graphical mode).
o Software libraries, which include code that can be applied by running processes. The
dynamic linker that handles the usage of dynamic libraries is called Id-linux.so on Linux
systems with ELF-format executable files. Also, header files will be added to define the
 interface of the installed libraries if the system is configured for the user to gather
software themselves. Besides, the most widely used software library is the GNU C
Library (glibc) on Linux systems. There are several other liabilities like Mesa and SDL.
o C standard library is required to execute C programs on a system using the GNU
C library being a standard. Alternatives like uClibc (developed for uClinux),
EGLIBC (glibc fork used by Debian once), and musl have been developed.
However, the first two are not maintained now. Android uses its C library, which
is known as Bionic.
o User interface
Also, the user interface is called a shell. It is either a GUI (graphical user interface), a
CLI (command-line interface), or controls attached to the related hardware, which is
normal for embedded systems. The default user interface is graphical for desktop
systems. However, the CLI is available by terminal emulator windows or on an isolated
virtual console.
Command-line interface shells are text-based UIs, which utilize text for both output and
input. The dominant shell is the bash (Bourne-Again Shell) used in Linux, originally
designed for the GNU project. Almost every low-level component of Linux, including
several userland parts, exclusively use the CLI. Particularly, the CLI is compatible with
delayed or repetitive task automation and gives very easy inter-process communication.
o GUI shells are the most famous user interfaces on desktop systems, packaged
with broad desktop environments like Xfce, Pantheon, LXDE, Cinnamon, MATE,
GNOME, and KDE Plasma, though a range of several user interfaces is available.
o Most famous user interfaces are working with the concept of the X Window
System, known as "X".
o It offers network transparency and allows a graphical application active on a
system to be shown on another in which a user may collaborate with the
application.
o Although, certain X Window System extensions are not able to work on the
network.
o Many X display servers are available with the X.Org Server, reference
implementation being the most famous.
o Video input infrastructure
Currently, Linux has two kernel-userspace APIs to handle video input devices: DVB API
 for TV reception and V4L2 API for radio and video streams.
This infrastructure requires to evolve to better fit with other devices due to the diversity
and complexity of different devices and because of the large number of standards and
formats managed by those APIs. A better userspace device library is also the success key
to having userspace applications which can work with every format supported by devices.

Uses of Linux OS
Several quantitative studies of open-source/free software concentrate on topics, such as
reliability and market share, with many studies examining Linux specifically. The Linux market
is developing, and the Linux OS market size is supposed to see a development of 19.2% by 2027,
reaching 15.64 billion dollars, compared to 3.89 billion in 2019. Proponents and analysts
attribute the associative Linux success to its freedom, low cost, reliability, and security from
vendor lock-in.

o Web servers
W3Cook releases stats that utilize the top 1,000,000 Alexa domains, which estimate that
96.55% of web servers use Linux, 1.73% use Windows, and 1.72% use FreeBSD as of
May 2015.
o Laptops and desktops
As of May 2022, the estimated Linux market share is around 2.5% on desktop computers,
according to web server statistics. Microsoft Windows include a market share of
approximately 75.5%, while macOS has around 14.9%.
 o Mobile devices
Android has become the leading OS for smartphones which is Linux kernel-based. In
July 2022, 71.9% of smartphones worldwide using the internet used Android. Also,
Android is a famous OS for tablets, being liable for more than 60% of table sales as of
2013.
o Film production
Linux has been the preferred platform in the film industry for years. The first big film
released on a Linux server was 1997's Titanic. Since then, big studios, including
Industrial Light & Magic, Weta Digital, Pixar, and DreamWorks Animation, have
relocated to Linux.
o Government use
Linux distros have also got popularity in several national and local governments. Kerala
has gone to the mandating extent that every state high school use Linux on their systems.
China utilizes Linux exclusively as the OS for its Loongson processor family for
achieving technology independence.
A few regions have integrated their Linux distribution in Spain, which is extensively used
in official and educational institutions. Also, Germany and France have taken steps
toward Linux adoption. The Red Star OS of North Korea is based on a Fedora Linux
version developed since 2002.

Linux OS Working
The Linux operating system follows of standard design that's the key to its several distributions
and variations. Every Linux distribution is based on the Linux kernel but can differ based on
factors like:

o Kernel version: Distros can be set up with more recent releases to add new aspects or
with previous releases to be more balanced.
o Kernel modules: It is software that can be unloaded and loaded into the kernel develop
functionality without restarting. Often, kernel modules are used for supporting:
o Device drivers, which utilize code that manages how linked devices work.
o File system drivers, which utilize code that manages how the kernel operates with
distinct file systems.
 o System calls, which utilize code that manages how programs claim services
through the kernel.
o Configuration options: Kernels unified with configuration options configured to add
only file system or device drivers are used for a few specialized distributions; for
instance, compiling the kernel for any wireless device without wired network device
drivers.
The kernel is the one thing that every system has in common running Linux. Linux
operates by:
o Booting and loading the Linux kernel.
o The kernel handles every system output and input once booted. The system is booted, and
processes can be initialized.
o The system can be utilized for processes that contain commands interactively entered by
the command line, network server functions, desktop applications, or any program or
application as system processes are booted.

The user experience can widely vary, relying on how the Linux system is being utilized while the
kernel may almost be identical with some compilation differences and divergence for
configuration. For example, a few use cases of Linux with distinct user experiences are:

o Desktop productivity systems, like those utilized by software developers or several

other professionals. The workstations of software development may be enhanced for
performance, while desktops may be enhanced for the utilization of desktop productivity
tools for administrative professionals.
o Network servers might not even add a command line window for direct access.
Remotely, these headless servers are handled by Windows sessions or network terminals.
Servers may be utilized by several but should directly be accessed by authorized system
admins only.
o Thin clients let users utilize a rich desktop environment with a lightweight device. It
includes Google Chromebooks and Raspberry Pi single-card systems.

Linux operates much similar to any GUI-based operating system when using it as a GUI with a
desktop environment. Applications and many other resources can be launched by pressing icons,
and files can be deleted, copied, or moved using a trackpad or mouse.

Linux distributions
Linux has accepted the copyleft provisions of the Free Software Foundation, which produced the
GNU GPL since its starting development. The GPL describes that anything taken for
modification and free must be freely distributed.
Hundreds of Linux versions, also called distros or distributions, are available. Usually,
distributions differentiate themselves through the pack by defining a specific goal, target market,
function, or philosophy.

There are many distributions made for particular target functions, like security, gaming,
desktops, servers, or embedded devices, such as Raspberry Pi systems. Almost every modern
distribution is ready to use and precompiled, while others, such as Gentoo Linux, are composed
of source code that any user can locally compile during starting installation to use their system
configuration.

Pros and Cons of Linux OS

Some benefits of using Linux are listed and explained below:

o Open source: The Linux kernel is published under the open-source software license of
GNU GPL. Most distributions contain several applications with various options in almost
all categories. Also, several distributions contain proprietary software, like device drivers
offered by manufacturers, to support hardware.
o Reliability: Linux is treated as a reliable operating system, and it is well-supported with
several security patches. Also, Linux is treated as a stable OS, which means it can
execute in almost every circumstance. Linux can also handle errors when running
unexpected input and software.
o Licensing costs: Linux has no accurate licensing fees, unlike Apple macOS or Microsoft
Windows. While system support is present for a fee from several Linux vendors, the
 operating system itself is free to use and copy. A few IT organizations have enhanced
their savings by moving their server software to Linux from a commercial operating
system.
o Backward compatibility: Linux and many open-source software tend to be frequently
updated for functional and security patches while having core functionality. Shell scripts
and configurations are likely to operate unchanged even if software updates are used.
Generally, Linux and other open-source applications do not alter their operation modes
with new versions, unlike economic software vendors that mount new releases of their
operating systems with new forms of work.
o Several choices: Between almost all infinite options, several available distros, and many
application options to configure, compile, and run Linux on almost all hardware
platforms, it's possible to develop Linux for almost all applications.

A few drawbacks of Linux are:

o Lack of standard: No standard version is available for Linux, which may be nice to
optimize Linux for specific applications, but less so to deploy desktop images and
standardized servers. The huge variety of options can convolute support as an outcome.
o Support costs: Support isn't free, while an organization can freely acquire Linux without
licensing fees. Almost all enterprise Linux distributors, such as Red Hat and SUSE,
provide support contracts. These license fees can significantly decrease savings
depending on the situation.
o Proprietary software: PC productivity software, such as Microsoft Office, can't be
utilized on Linux desktops, and many proprietary software may not be available for
Linux platforms.
 o Steep learning curve: Several users battle to learn to use Linux-based applications and
Linux desktops.
o Unsupported hardware: Several hardware manufacturers enable the device drivers of
Linux accessible for their products, but several don't.

What is a File System?

A file system is a process of managing how and where data on a storage disk, which is also
referred to as file management or FS. It is a logical disk component that compresses files
separated into groups, which is known as directories. It is abstract to a human user and related to
a computer; hence, it manages a disk's internal operations. Files and additional directories can be
in the directories. Although there are various file systems with Windows, NTFS is the most
common in modern times. It would be impossible for a file with the same name to exist and also
impossible to remove installed programs and recover specific files without file management, as
well as files would have no organization without a file structure. The file system enables you to
view a file in the current directory as files are often managed in a hierarchy.

A disk (e.g., Hard disk drive) has a file system, despite type and usage. Also, it contains
information about file size, file name, file location fragment information, and where disk data is
stored and also describes how a user or application may access the data. The operations like
metadata, file naming, storage management, and directories/folders are all managed by the file
system.

On a storage device, files are stored in sectors in which data is stored in groups of sectors called
blocks. The size and location of the files are identified by the file system, and it also helps to
recognize which sectors are ready to be used. Other than Windows, there are some other
operating systems that contain FAT and NTFS file system. But Apple product (like iOS and
macOS) uses HFS+ as operating system is horizon by many different kinds of file systems.
Sometimes the term "file system" is used in the reference of partitions. For instance, saying, "on
the hard drive, two files systems are available," that does not have to mean the drive is divided
between two file systems, NTFS and FAT. But it means two separate partitions are there that use
the same physical disk.

In order to work, a file system is required by most of the applications you come into contact
with; therefore, each partition should have one. Furthermore, if a program is built for use in
macOS, you will be unable to use this program on windows because programs are file system-
dependent.

Examples of file systems

The examples of file systems are given below:

FAT: FAT is a type of file system, which is developed for hard drives. It stands for file
allocation table and was first introduced in 1977, which is used for 12 or 16 bits for each and
every cluster access into the file allocation table (FAT). On hard drives and other computer
systems, it helps to manage files on Microsoft operating systems. In devices like digital cameras,
flash memory, and other portable devices, it is also often found that is used to store file
information. It also helps to extend the life of a hard drive as it minimizes the wear and tears on
the hard disc. Today, FAT is not used by later versions of Microsoft Windows like Windows XP,
Vista, 7, and 10 as they use NTFS. The FAT8, FAT12, FAT32, FAT16 are all the different
types of FAT (for file allocation table).

GFS: A GFS is a file system, which stands for Global File System. It has the ability to make
enable multiple computers to act as an integrated machine, which is first developed at the
University of Minnesota. But now it is maintained by Red Hat. When the physical distance of
two or more computers is high, and they are unable to send files directly with each other, a GFS
file system makes them capable of sharing a group of files directly. A computer can organize its
I/O to preserve file systems with the help of a global file system.

HFS: HFS (Hierarchical file system) is the file system that is used on a Macintosh computer for
creating a directory at the time a hard disk is formatted. Generally, its basic function is to
organize or hold the files on a Macintosh hard disk. Apple is not capable of supporting to write
to or format HFS disks since when OS X came on the market. Also, HFS-formatted drives are
not recognized by Windows computers as HFS is a Macintosh format. With the help of WIN32
or NTFS file systems, Windows hard drives are formatted.

NTFS: NTFS is the file system, which stands for NT file system and stores and retrieves files on
Windows NT operating system and other versions of Windows like Windows 2000, Windows
XP, Windows 7, and Windows 10. Sometimes, it is known as the New Technology File System.
As compared to the FAT and HPFS file system, it provides better methods of file recovery and
data protection and offers a number of improvements in terms of extendibility, security, and
performance.
UDF: A UDF is a file system, stands for Universal Disk Format and used first developed by
OSTA (Optical Storage Technology Association) in 1995 for ensuring consistency among data
written to several optical media. It is used with CD-ROMs and DVD-ROMs and is supported on
all operating systems. Now, it is used in the process of CD-R's and CD-RW's, called packet
writing.

Architecture of the File System

Two or three layers are contained by the file system. Sometimes, these layers function combined
and sometimes are explicitly separated. For file operations, the API (Application Program
Interface) is provided by the logical file system, like OPEN, CLOSE, READ, and more because
it is accountable for interaction with the user application. Also, for processing, the requested
operation is forwarded to the layer that is located below it. Furthermore, for various concurrent
instances of physical file systems, the second optional layer allows support, which is a virtual file
system. And each concurrent instance is called a file system implementation.

The third layer is responsible for handling buffering and memory management, which is called
the physical file system. It is concerned with the physical operation of the storage device and
processes physical blocks being read or written. Furthermore, to drive the storage device, this
layer interacts with the channel and the device drivers.

Types of file systems

There are various kinds of file systems, which are as follows:

1. Disk file systems

On the disk storage medium, a disk file system has the ability to randomly address data within a
few amounts of time. Also, it includes the anticipation that led to the speed of accessing data.
Without regard to the sequential location of the data, multiple users can access several data on
the disk with the help of a disk file system.

2. Flash file systems

A flash file system is responsible for restrictions, performance, and special abilities of flash
memory. It is superior to utilize a file system that is designed for a flash device; however, a disk
file system is the basic storage media, which can use a flash memory device.

3. Tape file systems

A tape file system is used to hold files on the tape as it is a tape format and file system. As
compared to disks, magnetic tapes are more powerful to access data for a long time, which are
the challenges for a general-purpose file system in terms of creation and efficient management.

4. Database file systems

A database-based file system is another method for file management. Files are recognized by
their characteristics (like a type of file, author, topic, etc.) rather than hierarchical structured
management.

5. Transactional file systems

Some programs require one or more changes to fail for any reason or need several file systems
changes but do not make any changes. For instance, a program may write configuration files or
libraries mand executables at the time of installing or updating the software. The software may
be unusable or broken if the software is stopped while updating or installing. Also, the entire
system may leave in an unusable state if the process of installing or updating the software is
incomplete.

6. Network file systems

A network file system offers access to files on a server. In remote network-connected computers,
with the help of local interfaces, programs are able to transparently create, manage and access
hierarchical files and directories. The file-system-like clients for FTP and WebDAV, and AFS,
SMB protocols, NFS are all examples of the network file systems.

7. Shared disk file systems

A shared-disk file system allows the same external disk subsystem to be accessed by multiple
machines, but when the number of machines accesses the same external disk subsystem, there
may be occurred collisions in this condition; so, to prevent the collision, the file system decides
which subsystem to be accessed.

8. Minimal file system

In the 1970s, for some initial microcomputer users, disk and digital tape devices were much
expensive. A few cheaper basic data storage systems used common audio cassette tape was
designed. On the cassette recorder, the user was informed about pressing "RECORD" when there
was required to write data by system. And, to notify the system, press "RETURN" on the
keyboard. Also, on the cassette recorder, the user was needed to press the "PLAY" button when
the system required to read data.

9. Flat file systems

The subdirectories are not available in the flat system. It contains the only directory, and all files
are held in a single directory. Due to the relatively small amount of data space available, this
type of file system was adequate when floppy disk media was available for the first time.

What is E-mail?
E-mail is defined as the transmission of messages on the Internet. It is one of the most commonly
used features over communications networks that may contain text, files, images, or other
attachments. Generally, it is information that is stored on a computer sent through a network to a
specified individual or group of individuals.

Email messages are conveyed through email servers; it uses multiple protocols within
the TCP/IP suite. For example, SMTP is a protocol, stands for simple mail transfer protocol and
used to send messages whereas other protocols IMAP or POP are used to retrieve messages from
a mail server. If you want to login to your mail account, you just need to enter a valid email
address, password, and the mail servers used to send and receive messages.

Although most of the webmail servers automatically configure your mail account, therefore, you
only required to enter your email address and password. However, you may need to manually
configure each account if you use an email client like Microsoft Outlook or Apple Mail. In
addition, to enter the email address and password, you may also need to enter incoming and
outgoing mail servers and the correct port numbers for each one.

Email messages include three components, which are as follows:

o Message envelope: It depicts the email's electronic format.

o Message header: It contains email subject line and sender/recipient information.
o Message body: It comprises images, text, and other file attachments.

The email was developed to support rich text with custom formatting, and the original email
standard is only capable of supporting plain text messages. In modern times, email
supports HTML (Hypertext markup language), which makes it capable of emails to support the
same formatting as websites. The email that supports HTML can contain links, images, CSS
layouts, and also can send files or "email attachments" along with messages. Most of the mail
servers enable users to send several attachments with each message. The attachments were
typically limited to one megabyte in the early days of email. Still, nowadays, many mail servers
are able to support email attachments of 20 megabytes or more in size.
In 1971, as a test e-mail message, Ray Tomlinson sent the first e-mail to himself. This email was
contained the text "something like QWERTYUIOP." However, the e-mail message was still
transmitted through ARPANET, despite sending the e-mail to himself. Most of the electronic
mail was being sent as compared to postal mail till 1996.

Differences between email and webmail

The term email is commonly used to describe both browser-based electronic mail and non-
browser-based electronic mail today. The AOL and Gmail are browser-based electronic mails,
whereas Outlook for Office 365 is non-browser-based electronic mail. However, to define email,
a difference was earlier made as a non-browser program that needed a dedicated client and email
server. The non-browser emails offered some advantages, which are enhanced security,
integration with corporate software platforms, and lack of advertisements.

Uses of email
Email can be used in different ways: it can be used to communicate either within an organization
or personally, including between two people or a large group of people. Most people get benefit
from communicating by email with colleagues or friends or individuals or small groups. It allows
you to communicate with others around the world and send and receive images, documents,
links, and other attachments. Additionally, it offers benefit users to communicate with the
flexibility on their own schedule.

There is another benefit of using email; if you use it to communicate between two people or
small groups that will beneficial to remind participants of approaching due dates and time-
sensitive activities and send professional follow-up emails after appointments. Users can also use
the email to quickly remind all upcoming events or inform the group of a time change.
Furthermore, it can be used by companies or organizations to convey information to large
numbers of employees or customers. Mainly, email is used for newsletters, where mailing list
subscribers are sent email marketing campaigns directly and promoted content from a company.

Email can also be used to move a latent sale into a completed purchase or turn leads into paying
customers. For example, a company may create an email that is used to send emails
automatically to online customers who contain products in their shopping cart. This email can
help to remind consumers that they have items in their cart and stimulate them to purchase those
items before the items run out of stock. Also, emails are used to get reviews by customers after
making a purchase. They can survey by including a question to review the quality of service.

Different types of Email

There are many types of email; such are as follows:

Newsletters: It is studying by Clutch, the newsletter is the most common type of email that are
routinely sent to all mailing list subscribers, either daily, weekly, or monthly. These emails often
contain from the blog or website, links curated from other sources, and selected content that the
company has recently published. Typically, Newsletter emails are sent on a consistent schedule,
and they offer businesses the option to convey important information to their client through a
single source. Newsletters might also incorporate upcoming events or new, webinars from the
company, or other updates.

Lead Nurturing: Lead-nurturing emails are a series of related emails that marketers use to take
users on a journey that may impact their buying behavior. These emails are typically sent over a
period of several days or weeks. Lead-nurturing emails are also known as trigger campaigns,
which are used for solutions in an attempt to move any prospective sale into a completed
purchase and educate potential buyers on the services. These emails are not only helpful for
converting emails but also drive engagement. Furthermore, lead-nurturing emails are initiated by
a potential buyer taking initial action, such as clicking links on a promotional email or
downloading a free sample.

Promotional emails: It is the most common type of B2B (Business to Business) email, which is
used to inform the email list of your new or existing products or services. These types of emails
contain creating new or repeat customers, speeding up the buying process, or encouraging
contacts to take some type of action. It provides some critical benefits to buyers, such as a free
month of service, reduced or omitted fees for managed services, or percentage off the purchase
price.

Standalone Emails: These emails are popular like newsletters emails, but they contain a
limitation. If you want to send an email with multiple links or blurbs, your main call-to-action
can weaken. Your subscriber may skip your email and move on, as they may click on the first
link or two in your email but may not come back to the others.

Onboarding emails: An onboarding email is a message that is used to strengthen customer

loyalty, also known as post-sale emails. These emails receive users right after subscription. The
onboarding emails are sent to buyers to familiarize and educate them about how to use a product
effectively. Additionally, when clients faced with large-scale service deployments, these emails
help them facilitate user adoption.

Transactional: These emails are related to account activity or a commercial transaction and sent
from one sender to one recipient. Some examples of transactional email are purchase
confirmations, password reminder emails, and personalized product notifications. These emails
are used when you have any kind of e-commerce component to your business. As compared to
any other type of email, the transactional email messages have 8x the opens and clicks.

Plain-Text Emails: It is a simple email that does not include images or graphics and no
formatting; it only contains the text. These types of emails may worth it if you try to only ever
send fancy formatted emails, text-only messages. According to HubSpot, although people prefer
fully designed emails with various images, plain text emails with less HTML won out in every
A/B test. In fact, HTML emails contain lower open and click-through rates, and plain text emails
can be great for blog content, event invitations, and survey or feedback requests. Even if you do
not send plainer emails, but you can boost your open and click through rates by simplifying your
emails and including fewer images.
 Welcome emails: It is a type of B2B email and common parts of onboarding emails that help
users get acquainted with the brand. These emails can improve subscriber constancy as they
include additional information, which helps to the new subscriber in terms of a business
objective. Generally, welcome emails are sent buyers who got a subscription to a business's opt-
in activities, such as a blog, mailing list, or webinar. Also, these emails can help businesses to
build a better relationship between customers.

What is a Memo?
A memo is actually short for Memorandum. It is one of the most used means of official
communication in the business world. Its main purpose is to serve as a reminder or to give some
instructions. Again these like circulars are a means of mass communication, i.e. to communicate
with a large number of people within the organization.

Usually, we write a memo is for one of the following five reasons

i. as a reminder

ii. highlight an event or circumstance

iii. to recount an event

iv. keep an official record of anything

v. to pass information or instructions

Memos have been a popular way for commuting for over a century now. This is because they have
many advantages as seen below:

 They are a very cost effective way of mass communication. And their transmission is also
very cheap.

 Another advantage is its simplicity. They are very simple to write and understand.

 Memos tend to be brief and to the point. They also reach a lot of people. So they are very
time-saving as well.

 They also serve as evidence in case of a dispute

The Format of a Memo

Let us see the steps of writing a memo.

1. Heading: After the name and address of the company (which is on the letterhead) we type the
word “Memo‟ or „Memorandum‟ at the top of the page in the center.
 2. Recipient: Address the recipients in the correct format, Example -„ To: All Employees of the
Sale Division‟

3. Writer: Write the name of the person writing the memo, Example – „From: Mr. ABC, Head
of Sales‟

4. Additional Recipients: These are the people who will receive a courtesy copy of the memo.
We don‟t address the memos to them, but we keep them in the loop.

5. Date: The date of writing the memos is an important detail that one must include.

6. Subject Line: This will give the reader a brief idea about the information in the memos. The
line must be brief, precise and to the point. Example – Subject: Meeting of all employees of
the Sale Division.

7. The body of a memo: This is where all the information is contained. A formal salutation is
not required in a memo. Just relay the necessary information with clarity and precision. The
body must not be too long. The ending must restate the issue and end on a positive note.

8. Proofread: Finally, proofread the memo before sending it.

According to Lexico.com, a proposal is “[a] plan or suggestion, especially a formal or written
one, put forward for consideration by others.”

The Oxford-powered online dictionary also gives a second meaning, which is “to make an offer
of marriage.”

This article deals with the first definition, that is, a suggestion for gaining support for a plan or
scheme. The following are examples of such uses of the term:

A proposal must be both powerfully persuasive and easy to read.

In their proposal, the contractors set out their ideas for the design and construction of the
building, together with a price.

A great marketing proposal can make the difference between winning and losing a deal.

A clear, well-considered proposal forms the backbone of a research project.

In 2017, the Chinese authorities reviewed several proposals for the registration and management
of medical representatives.

Residents can now view a digital exhibition of the water company‟s proposal to refurbish the
local aqueduct.

Tips on proposal writing

To succeed in this era of rapid technological change, businesses have to prove that they have
their “customers‟ best interests in mind.” A winning proposal should sing this out loud and clear.

The Internet is awash with tips and suggestions on how to write proposals. And this section
offers yet another list. But there is really only one main tip: know your reader. Show them you
care about them and their concerns. The rest just follows from that. So here are our top tips and
guiding questions:

 Understand your readers and their needs and wants – not just the project
 Who is going to review the proposal? What are their roles? Who is the decision maker?
 Does the proposal address their main concerns?
 Don‟t switch off your reader by drowning them in jargon or boring them with clichés
 Be straightforward and to the point
 Emphasize benefits over features – features describe, while benefits sell
 Is it clear that you are the best person to do this work?
 Check the copy for grammar, spelling, typographical, and formatting errors
 Ask several people who are not familiar with your work to critique it for clarity, tone, interest,
ease of reading, and overall impression
 Could the document be shorter?
 If you use pictures, make them specific – don‟t use generic or stock photos
 Allow plenty of time for research and preparation

Example: A funding proposal

Often, in the worlds of business and government, the purpose of proposals is to gain support for
projects and schemes.

Non-Government Organizations (NGOs), for instance, write them to gain funding from donors.

The following list – adapted from a casual.pm template for NGOs – suggests some key elements
for a typical proposal:

 Date, name of organization seeking funding, Project title

 Background: Why this project, what problem does it solve?
 Objectives: A short list of specific and measurable goals
 Scope: Describe end result, work phases, and what is not included
 Timescale: Map showing each phase, start and end dates, outline of task
 Budget: List the costs, both one-off and recurring
 Key stakeholders: E.g. client, sponsor, project manager
 Monitoring and evaluation: How will progress be tracked during and at end?

There are many templates and other tools online to help you draft a good proposal. These can be
useful ways to get started and generate ideas.
Beware, however, that over-reliance on such tools can lead to generic proposals. Clients like to
feel special, and your proposals need to be uniquely tailored to them. No two should be the same.

What is Project Report?

In this tutorial we are going to learn about the Project report. We will also learn about the
different aspects which must be kept in mind while creating a report. We will also discuss the
content of a project report, what must be included in a project report in order to make it more
effective.

A project report is a document that contains the information about the proposed project and it
contains all the details of the project. The project report details the project proposal in order to
assess the feasibility of the planned plan/activity. In tother words we can say that a project report
is a written document that is related to a particular investment or a project.

It includes information that was used to evaluate the proposal and determine if it was feasible.
The project report consists the evaluated data on economical, technological, financial,
managerial, and manufacturing issues that may or may not happen while the project is being
build.

The project report includes comprehensive information on the necessary land and buildings,
annual manufacturing capacity, manufacturing process, machinery and equipment prices and
specifications, raw material requirements, power and water requirements, manpower
requirements, project marketing costs, efficiency, financial assessments, and economic viability.

A Project Report's Contents

A project report's contents are as follows:

1. General Information
The General information must provide information on the industry's history, current state,
challenges, and future prospects.

If the proposed company is a manufacturing unit, it must provide details about the product to be
produced as well as the reasons for choosing the product. The General information must describe
the product's demand in the local market, as well as in national market, and in the global
markets. It should clearly define business alternatives as well as the motivations for starting a
business.

2. Executive Summary
The business's goals and strategies for achieving results must be stated in a project report. This
report must consist the overall picture of the company which must be in terms of capital that
company holds, operations going on in the company, operating methods, and business execution.
It must include the assumptions and risks that are common in the industry.

3. Organization Summary
The planned organization structure and pattern for the unit should be included in the project
study. It must specify whether the company is a sole proprietorship, a partnership, or a joint
stock corporation. It must provide biographical information about the promoters, as well as
financial stability.

4. Project Description
A brief overview of the project must be given, including information on the following:

o The place of the project where it is being build.

o Raw material requirements,
o Target of production,
o Area required for the working
o Requirement of the Electricity
o Fuel requirements,
o Water requirements,
o Employment requirements of skilled and unskilled labour,
o Technology selected for the project,
o Production process,
o Projected production volumes, unit prices,
o Pollution treatment plants required.

If the company is service-oriented, it must specify the services it provides to customers. It should
provide a detailed description of how customers will be served.

5. Marketing Plan
The marketing plan must specify the selling price at which the commodity can be offere. It
should also include the tactics that will be used to win the market. If an after-sale service is
offered, it must be specified in the project.

It must define the product's mode of delivery from the manufacturing unit to the consumer. The
following must be included in the project report:
 o Type of customers,
o Target markets,
o Nature of market,
o Market segmentation,
o Future prospects of the market,
o The objective of the sales
o The cost of marketing,
o Market share of proposed venture,
o Demand of the product in the different market.
o It must identify potential product buyers as well as the distribution networks that will be
used to distribute the product.

6. Capital Structure and operating cost

The report must also specify the source of funding as well as the extent of the owner's and
borrowed funds. Working capital specifications must be specified, as well as the source of
supply, in the project.

Land, building and civil works maintenance, plant and equipment, miscellaneous fixed assets,
preliminary and preoperative costs, and working capital must all be factored into the overall
project cost estimate. This segment must also include a breakdown of the running costs.

7. Management Plan
The following should be included in the project report:

o Information about the business's promoters.

o Management team information.
o The roles playing team members.
o The organization's current staffing requirements.
o Management methods.
o Plans for recruiting and training personnel.
o Management programs and policies

8. Financial Aspects
This portion of the project report covers the accounting system and inventory management
system that will be used. The financial and economic viability of the company must be stated in
the project report.

9. Technical Aspects
A project report contains details about the project's technologies and strategic aspects. It includes
information on the project's chosen technology, the manufacturing process, machinery capability,
pollution control plants, and so on.

10. Project Implementation

The project implementation in the report must specify when the activities associated with
establishing the business will be completed. The timeline for project planning and execution is
seen in the implementation schemes.

11. Social responsibility

The Social responsibility units or projects are based on societal inputs. As a result, it makes a
significant contribution to society in terms of jobs, revenue, exports, and infrastructure. The
business's performance must be listed in the project report.

digital library
A digital library is a collection of documents in organized electronic form, available
on the Internet or on CD-ROM (compact-disk read-only memory) disks. Depending
on the specific library, a user may be able to access magazine articles, books, papers,
images, sound files, and videos.

On the Internet, the use of a digital library is enhanced by a Broadband connection

such as cable modem or DSL. Dial-up connections can be used to access plain-text
documents and some documents containing images, but for complex files and those
with animated video content, a downstream data speed of at least several hundred
kilobits per second ( kbps ) can make the user's experience less tedious, as well as
more informative. Internet-based digital libraries can be updated on a daily basis. This
is one of the greatest assets of this emerging technology.
On CD-ROM, the amount of data is limited to several hundred megabytes ( MB ) per
disk, but access is generally much faster than on an Internet connection. Several CD-
ROMs can be combined in a set, and because the disks are small, a large library can
be accommodated in a reasonable physical space. The main limitation of CD-ROM is
the fact that updating cannot be done as frequently as on the Internet. In addition,
producing and distributing CD-ROMs involves overhead costs that are largely
nonexistent in Internet-based libraries.

Some institutions have begun the task of converting classic books to electronic format
for distribution on the Internet. Some files can be viewed directly in HTML format;
others can be downloaded in PDF format and printed. Some publishers keep
electronic files of books and produce them one unit at a time in printed and bound
form on demand.

Electronic distribution of intellectual and artistic property has authors, agents, and
publishers concerned about the possibility of copyright infringement. It is much easier
to copy a CD-ROM, or to download an electronic book and make unauthorized copies
of it, than it is to reproduce bound volumes and distribute them illegitimately.
Fundamental changes in copyright law - and/or changes in the way in which the laws
are enforced - are likely to occur as digital libraries expand and their use becomes
more widespread.