Explanation of basic introduction of computer

1. COMPUTER SYSTEM SOFTWARE

2. ​​OPERATING SYSTEM
An operating system is a
program that acts as an
interface between the user
and the computer hardware
and controls the execution of
all kinds of programs.

3. Features of Operating System (OS)
 Here is a list important features of OS:
 Protected and supervisor mode
 Allows disk access and file systems Device drivers Networking
Security
 Program Execution
 Memory management Virtual Memory Multitasking
 Handling I/O operations
 Manipulation of the file system
 Error Detection and handling
 Resource allocation
 Information and Resource Protection

4. Following are some of important functions of an operating System.
 Memory Management
 Processor Management
 Device Management
 File Management
 Security
 Control over system performance
 Job accounting
 Error detecting aids
 Coordination between other software and users

5. Memory Management
Memory management refers to management of Primary Memory or Main Memory. Main
memory is a large array of words or bytes where each word or byte has its own address.
Main memory provides a fast storage that can be accessed directly by the CPU. For a
program to be executed, it must in the main memory. An Operating System does the
following activities for memory management −
 Keeps tracks of primary memory, i.e., what part of it are in use by whom, what part
are not in use.
 In multiprogramming, the OS decides which process will get memory when and how
much.
 Allocates the memory when a process requests it to do so.
 De-allocates the memory when a process no longer needs it or has been terminated.

6. Processor Management
In multiprogramming environment, the OS decides which process gets the processor when and for
how much time. This function is called process scheduling. An Operating System does the
following activities for processor management −
 Keeps tracks of processor and status of process. The program responsible for this task is
known as traffic controller.
 Allocates the processor (CPU) to a process.
 De-allocates processor when a process is no longer required.

7. Device Management
An Operating System manages device communication via their respective drivers. It does
the following activities for device management −
 Keeps tracks of all devices. Program responsible for this task is known as the I/O
controller.
 Decides which process gets the device when and for how much time.
 Allocates the device in the efficient way.
 De-allocates devices.

8. File Management
A file system is normally organized into directories for easy navigation and
usage. These directories may contain files and other directions.
An Operating System does the following activities for file management −;
 Keeps track of information, location, uses, status etc. The collective facilities
are often known as file system.
 Decides who gets the resources.
 Allocates the resources.
 De-allocates the resources.

9. Other Important Activities
Following are some of the important activities that an Operating System performs −
 Security − By means of password and similar other techniques, it prevents unauthorized access to programs
and data.
 Control over system performance − Recording delays between request for a service and response from the
system.
 Job accounting − Keeping track of time and resources used by various jobs and users.
 Error detecting aids − Production of dumps, traces, error messages, and other debugging and error
detecting aids.
 Coordination between other softwares and users − Coordination and assignment of compilers,
interpreters, assemblers and other software to the various users of the computer systems.

10. Advantage of using Operating System
a)Allows you to hide details of hardware by creating an abstraction
b)Easy to use with a GUI
c)Offers an environment in which a user may execute programs/applications
d)The operating system must make sure that the computer system convenient
to use
e)Operating System acts as an intermediary among applications and the
hardware components
f)It provides the computer system resources with easy to use format
g)Acts as an intermediator between all hardware's and software's of the
system

11. Disadvantages of using Operating
System
1)If any issue occurs in OS, you may lose all the contents which have been stored in your system
2)Operating system's software is quite expensive for small size organization which adds burden
on them. Example Windows
3)It is never entirely secure as a threat can occur at any time

12. TYPES OF OS
 There are two types of operating system:-
 Server OS
 Client OS

13. SERVER OS
 A server operating system (OS) is a type of operating
system that is designed to be installed and used on a
server computer.
 Examples: Linux, Windows 2016
 Some of the key features of a server operating system
include
 Ability to access the server both in GUI and command-
level interface
 Execute all or most processes from OS commands

14. Client OS :
 It is an operating system that operates within desktop. It is
used to obtain services from a server. It run on the client
devices like laptop, computer and is very simple operating
system.
 Examples:
 Windows 10
 MacOS

15. Difference between Server OS and Client
OS :
Server Operating System Client Operating System
It can be used to provide services to multiple
client.
It can obtain services from a server.
It can serve multiple client at a time. It serves a single user at a time.
It is complex operating system. It is simple operating system.
It runs on the server. It runs on the client devices like laptop,
computer etc.
It is an operating system that is designed to
be used on server.
It is an operating system that operates within
desktop.
It provides more security. It provides less security.
It has greater processing power. It has less processing power.
It is highly efficient. It is less efficient.
It is more stable. It is less stable.

16. UTILITY SOFTWARE
 These software analyse and maintain a computer.
 These software are focused on how OS works on that basis it
perform task to enable smooth functioning of computer.
 Some of popular utility software are described below:-
 Antivirus
 File Management Tool
 Compression Tool

17. Antivirus
 It is used to protect a computer from the virus. It detects a
virus and notify the user and take action to secure the
computer.
 The first antivirus program appeared in 1987 with the
introduction of an antivirus program from G Data Software
for the Atari ST. Later in the same year, VirusScan was
introduced by John McAfee, which later became the
McAfee antivirus program.
 Examples: Windows Defender, AVG, AVAST, MCAFEE etc.

18. File Management Tool:
 The software is used to manage files stored in a file
system. It can be used to create, group file. Like Windows
File Explorer is a file management tool.
 File system (like FAT32, NTFS) should not be confused
with File management tool former is a data structure used
to store file in a OS while later is used to perform task on
file stored in the file System.
 Some example of File management Tool are:
 File Manager in Windows.

19. Compression Tool:
 These tool are used to reduce the size of a file based on
the selected algorithm.
 Most operating systems include tools for compressing and
uncompressing files.Linux has tools for both .tar.gz and
.zip. Other compressed files, like .7z and .rar, require a
third-party compression utility to be installed.
 Some Examples are:
 WinAce
 WinZip

20. DISK CLEANUP TOOL
 It is computer utility maintenance which is included in Microsoft
Windows. It allows user to remove files that are no longer
needed or that can be safely deleted.
 Disk Cleanup tool can delete temporary internet files, old check
disk files, compress old filesand offline webpages. Disk cleanup
also allows you to empty the Recycle Bin, delete temporary
files, and delete Thumbnails.
 Some Disk Cleanup software are :-
 Iolo System mechanic
 IObit Advanced systemCare

21. DISK DEFRAGMENTER:
 It is a utility in Microsoft Windows designed to increase
access speed by rearranging file stored on a disk to
ocuppy contiguous storage locations, a technique is called
 Defragmentation.
 Some Disk Defragmenter are:-
 Auslogics Disk Defrag
 MyDefrag
 Perfect disk

22. Compiler, Interpreter, linker, loader
 Compliler:
Is the program that processes the statement written in a
particular programming language and turn them into machine
language or codes that the computer processor uses.
Regardless of the HL Language, all HL programs need to be
translated to machine code so that a computer can process
the program.
Some programs are translated using a compiler. When
programs are compiled, they are translated all at once.
Compiled programs typically execute more quickly than

23.  Assembler:
 is a program which converts assembly language into machine code.
 In assembler, a programmer can write a program into sequence of
assembler instructions, the sequence of assembler instruction is known as
source code and source program.

24.  Interpreter
 An interpreter is also a program like a compiler that converts
assembly language into binary but an interpreter goes through
one line of code at a time and executes it and then goes on to
the next line of the code and then the next and keeps going on
until there is an error in the line or the code has completed.
 Interpreter is differ from compiler such as.
 Interpreter is faster than compiler.
 It contains less memory.

25. Linker
 Linker is a program that
holds one or more object
files which is created by

26.  Loader
 Loader is a program that loads machine codes of a program
into the system memory. It is part of the OS of the computer
that is responsible for loading the program. It is the bare
beginning of the execution of a program. Loading a program
involves reading the contents of executable file into memory.
Only after the program is loaded the operating system starts the
program by passing control to the loaded program code. All the
OS that support loading have loader and many have loaders
permanently in their memory.

28. FOUNDATION OF OS
 What is an Operating System?
 A program which controls the execution of all other
programs(applications).
 Acts as an intermediary between the user(s) and the
computer.
 Objectives:
 –convenience,
 –efficiency,

30. Other Types of OS
 Batch Operating System
 Time-Sharing Operating System
 Embedded Operating System
 Multiprogramming Operating System
 Network Operating System
 Distributed Operating System

31. Batch Operating System
 In Batch Operating System, there is no direct interaction between
user and computer. Therefore, the user needs to prepare jobs and
save offline mode to punch card or paper tape or magnetic tape. After
creating the jobs, hand it over to the computer operator; then the
operator sort or creates the similar types of batches like B2, B3, and
B4. Now, the computer operator submits batches into the CPU to
execute the jobs one by one. After that, CPUs start executing jobs,
and when all jobs are finished, the computer operator provides the
output to the user.

32. Time-Sharing Operating System
 It is the type of operating system that allows us to
connect many people located at different locations to
share and use a specific system at a single time. The
time-sharing operating system is the logical extension
of the multiprogramming through which users can run
multiple tasks concurrently. Furthermore, it provides
each user his terminal for input or output that impacts
the program or processor currently running on the
system. It represents the CPU's time is shared
between many user processes. Or, the processor's

33. Embedded Operating System
 The Embedded operating system is the specific purpose operating system used in the computer
system's embedded hardware configuration. These operating systems are designed to work on
dedicated devices like automated teller machines (ATMs), airplane systems, digital home
assistants, and the internet of things (IoT) devices.

34. Multiprogramming Operating System
 Due to the CPU's underutilization and the
waiting for I/O resource till that CPU remains
idle. It shows the improper use of system
resources. Hence, the operating system
introduces a new concept that is known as
multiprogramming. A multiprogramming
operating system refers to the concepts wherein
two or more processes or programs activate
simultaneously to execute the processes one

36. Network Operating System
 A network operating system is an important category of the
operating system that operates on a server using network
devices like a switch, router, or firewall to handle data,
applications and other network resources. It provides
connectivity among the autonomous operating system,
called as a network operating system. The network
operating system is also useful to share data, files,
hardware devices and printer resources among multiple
computers to communicate with each other.

38. Types of network operating system
 Peer-to-peer network operating system: The type of network operating system allows users
to share files, resources between two or more computer machines using a LAN.

39.  Client-Server network operating system: It is the type of network operating system that allows the
users to access resources, functions, and applications through a common server or center hub of the
resources. The client workstation can access all resources that exist in the central hub of the network.
Multiple clients can access and share different types of the resource over the network from different
locations.

40.  Distributed Operating system
 A distributed operating system provides an environment in which multiple independent CPU or processor
communicates with each other through physically separate computational nodes. Each node contains specific
software that communicates with the global aggregate operating system. With the ease of a distributed
system, the programmer or developer can easily access any operating system and resource to execute the
computational tasks and achieve a common goal. It is the extension of a network operating system that
facilitates a high degree of connectivity to communicate with other users over the network.

41.  Multiprocessing Operating System
 It is the type of operating system that refers to using two or more central
processing units (CPU) in a single computer system. However, these
multiprocessor systems or parallel operating systems are used to increase
the computer system's efficiency. With the use of a multiprocessor system,
they share computer bus, clock, memory and input or output device for
concurrent execution of process or program and resource management in
the CPU.

42.  Real-Time Operating System
 A real-time operating system is an important type of operating system used
to provide services and data processing resources for applications in which
the time interval required to process & respond to input/output should be so
small without any delay real-time system. For example, real-life situations
governing an automatic car, traffic signal, nuclear reactor or an aircraft
require an immediate response to complete tasks within a specified time
delay. Hence, a real-time operating system must be fast and responsive for
an embedded system, weapon system, robots, scientific research &
experiments and various real-time objects.

43.  Types of the real-time operating
system:
 Hard Real-Time System
 These types of OS are used with
those required to complete critical

44. Generations of Operating System
 First Generation:The period of first generation: 1946-1959. Vacuum tube
based.
 Second Generation:The period of second generation: 1959-1965.
Transistor based.
 Third Generation:The period of third generation: 1965-1971. Integrated
Circuit based.
 Fourth Generation:The period of fourth generation: 1971-1980. VLSI
microprocessor based.
 Fifth Generation:The period of fifth generation: 1980-onwards. ULSI
microprocessor based.

45. DOS(DISK OPERATING SYSTEM)
 DOS was an variant of CP/M (Control Program/Monitor) which ran for the first time on IBM-PC in 1981. It is
called so because it resides on Floppy or Hard disk and provides command level interface between user and
the computer hardware. The different versions of MS-DOS have evolved over a period of time with Microsoft
introducing new features in each new releases. Starting with MS-DOS1.1, the latest version was MS-DOS6.22
released in 1994. There are various versions of DOS like MS-DOS(Microsoft), PC-DOS(IBM), Apple DOS, Dr-
DOS etc.
 Types of DOS command:
 1.) Internal DOS command
 2.) External DOS command

46. Internal DOS command
 These are in built commands of MS-DOS i.e. these are stored in Command
interpreter file (COMMAND.COM). These commands reside in the memory as long
as the machine is at he system prompt(C:>) level.

 Example
 DATE.
 TIME.
 DIR.
 VER etc

47. External DOS commands
 These are separate program (.com) files that reside in DOS directory
and when executed behave like commands.
 These are separate program (.com) files that reside in DOS directory
and when executed behave like commands.

48. BASIC DOS COMMANDS
 b) File Management Commands :
 COPY : Copies one or more files from source
disk/drive to the specified disk/drive.
 XCOPY : Copies files and directories, including
lower-level directories if they exists.
 DEL : Removes specified files from specified
disk/drive.
 REN : Changes the name of a file(Renaming).
 ATTRIB : Sets or shows file attributes (read,
write, hidden, Archive).
 BACKUP : Stores or back up one or more
files/directories from source disk/drive to other
destination disk/drive.
a)
Direct

49. VIRTUALIZATION OF OPERATING SYSTEM
 It is also called OS-level virtualization is a type of virtualization technology which work on OS layer.
 Here the kernel of an OS allows more than one isolated user-space instances to exist. Such instances
are called containers/software containers or virtualization engines. In other words, OS kernel will run a
single operating system & provide that operating system's functionality to replicate on each of the
isolated partitions.
 USES OF OS VIRTUALIZATION
 Used for virtual hosting environment.
 Used for securely allocation of finite hardware resources among a large number of distrusting users.
 System administrator uses it to integrate server hardware by moving services on separate hosts.
 To improvised security by separating several applications to several containers.
 These forms of virtualization don't require hardware to work efficiently.

50. HOW OS VIRTUALIZATION WORKS
 Connect to OS Virtualization Server
 Connect to virtual disk
 Then connect this virtual disk to the client
 OS is streamed to the client
 If further additional streaming is required, it is done

51. TYPES OF OS VIRTUALIZATION
 Linux virtualization
 Windows OS virtualization
 Linux OS virtualization: To virtualized Linux systems,
VMware workstation software is used. To install any
software virtually, users need VMware software to
install first.
 To create a virtual machine for Linux
OS the steps to be followed are:

52. WINDOWS OS VIRTUALIZATION
 Users need to install VMware first to install windows OS virtually.
 After installing such virtualization software the steps to install a new OS are:
 Click on "create new Virtual Machine"
 Browse the OS that is to be installed, and click Next
 Give the product key if required; and click Next
 In the 'New Virtual Machine Wizard' window; click Next
 Give it a name & location and click Next
 The next step will create disk and the user can see the 1st Window
screen.

53. Advantages of OS virtualization
 OS virtualization usually imposes little or no overhead.
 OS Virtualization is capable of live migration
 It can also use dynamic load balancing of containers between nodes and a cluster.
 The file level copy-on-write (CoW) mechanism is possible on OS virtualization which makes
easier to back up files, more space-efficient and simpler to cache than the block-level copy-on-
write schemes.