It will helps you to learn a Operating System concepts...

1. Unit 2: Introduction to
Operating System

2. Outlines
•Introduction
•Function of an operating system
•Types of operating system
•Booting procedure
•Basic system configuration
•Important terms

3. 2.1 What is called Operating System?
An operating system is the main control
program of a computer that manages all other
programs in a computer.
Operating System is the interface between the
user and the Computer.
Examples of operating system :-
Microsoft Windows (like Windows 10, Windows 8,
Windows 7, Windows Vista, and Windows XP),
Apple's macOS (formerly OS X) Chrome OS, and
flavors of the open source operating
system Linux.

4. 2.2 Functions of an Operating system
•Resource management
•Secondary storage management
•File management
•Security management
•Management of input/output devices
•Program execution
•Error detection

5. 2.3 Types of Operating system
There are basically three types of operating
systems available:
1. Single user operating systems
2. Multi user operating systems
3. Networked operating systems

6. 2.4 Single User Operating Systems
-In this type of operating system, a single user
can work on a computer
system at a time.
-The work done by him is not protected by any security
systems.
- Anybody can modify the work of any other user, as
there is no login password protection.
-Single user operating systems can also provide
multitasking capabilities, i.e. a user can work on
several programs at a time.
-Examples of this type of operating systems are DOS
(Disk Operating System), Windows.

7. 2.5 Multi User Operating Systems
- In this type of operating system, several users can
work on a single system
-Processing and each user is protected by a log-in
name and password.
-This operating system can also be called as multi user
multi-tasking operating system, where every user is
specifying his log-in name and a code word called
password and can carry out his work, which is
protected from any sort of mishandling. The access to
the work of any particular user always requires a
password without which a work can be termed as
illegal.
E.g. UNIX Operating System, LINUX

8. 2.6 Networked Operating Systems
-When two or more PCs are connected with each other
irrespective of any geographical area then we can call it
as a network.
-A computer network is a connection between two or more
computers.
-To operate the computer that forms a network, we need a
powerful operating system termed as networked operating
system in which information is centrally placed in a
computer called as server where remaining computers
are called as clients. Clients are always requesting
and servers are always fulfilling the requests.This type
of operating system can also be called as client-server
operating system.
Ex. Windows NT, Windows 2003 Server, Internet, LAN
(Local Area Network) .

9. 2.7 Booting procedure
- Every operating system has its starting procedure
called booting procedure.
-As soon as we start a computer the operating system
gets loaded from disk to the computer's memory.
 various steps
•Loading of the programs in the main memory
•Carrying out batch processing
•Time-sharing
•Information gathering
•Loading information in main memory

10. 2.7 Booting procedure
-The boot area contains the boot record and is the very
first part of an OS.
-The last step in the booting process is to load
COMMAND.COM, which is the basic command interpreter
to interact with the user. COMMAND.COM in turn
automatically searches for AUTOEXEC.BAT file, if
any, in the directory. After this file gets executed, the
computer comes under the full control of OS, so that it
can be successfully operated by the user.

11. 2.8 Basic System Configuration
-The details regarding the configuration are contained
in a file called Processing config.sys.
-It contains special commands, which configure your
computer’s hardware components so that the OS and
applications can use them.
-When OS starts, it carries out the commands in config.sys
file after loading two system files of OS: IO.SYS and MS-
DOS.sys.
-Typically the config.sys file is loaded in the root
directory of drive C.

12. 2.9 Important terms
1. Drive :- This is the space or location where we can
store the information.It is the representation for the
secondary storage devices such as floppy disks, hard
disks, CD-ROM etc.
It is represented with an alphabet followed by colon.
Ex.
A: (called as A drive) or
B: is specially for floppy disks
C: drive is for hard disks
D: drive or other drives can be used for compact disks
(CD) depending on the partition of the hard disk.

13. 2. File :- File is a collection of related information.
Every file has a name, its data and attributes. The
name of a file uniquely identifies it in the system and
is used by its
users to access it. A file’s data is its contents. The
contents of a file are a sequence of bits, bytes, lines
or records whose meaning is defined by the file’s
creator and
user.
File Access Methods:-
1. Sequential Access Files
2. Random Access Files
3. Directory/ Folder

14. •Sequential Access Files: Sequential access files are
normally used with sequential access storage media,
such as magnetic tape.
-Information stored in a sequential access file can be
accessed only sequentially, i.e. a process can read the
bytes or records in the file in the order in which they are
stored, starting at the beginning.
•Random Access Files: Random access files are
normally used with random access storage media, such as
-Unlike a sequential access file, information stored in a
random access file can be accessed randomly,
irrespective of the order in which the bytes or records are
stored.
-For example, a specific byte/record of the file can
be directly accessed without the need to read all the
bytes/records before it.

15. 3. Directory/ Folder: If several files have to be stored
containing different types of information, then if all of
them are stored at the same location, it will become
very difficult for the user to find a particular file from the
list of a number of files.
- In order to resolve the same, the folders/directories
are used which makes it convenient for the user to
search his file. A file can be stored in a special
location by providing a name to that location which is
called a directory or folder.

16. 4. Volume Label: Every storage device such as floppy,
hard disk or CD can be given a specific name, which can
be called as volume label.
For example, if a floppy drive is given a label My
Floppy then it is represented as My Floppy A:
5. Multitasking: This type of OS permits multiple
programs to be executed simultaneously by the same
computer. For example, a user of the computer can
simultaneously play games while a word document is
being printed.
-multiprogramming is the concurrent execution of
multiple jobs (of same or different users) in a multi-user
system, while multitasking is the concurrent execution of
multiple jobs (often referred to as tasks of same user) in
a single-user system.

17. 6 . Multithreading: Multithreading is a form of
multitasking that permits multiple parts of a
software program to be executed simultaneously.
For example, a user can perform a spell check in
a word document and Introduction to simultaneously
print another word document.
7. Multiprocessing: Multiprocessing involves the use
of multiple processors (more than one CPU) to
simultaneously execute multiple program. The
inclusion of multiple CPU’s in a single computer
system improves the performance to a large extent.

18. Glossary
1.Sequential Access Files- Files which are used
with sequential access
storage media like magnetic tape.
2.Random Access Files - File used with random
access storage media like magnetic or optical disks.
3.File - It is a collection of information having a name,
data and attributes.
4.Multiprocessing- It involves use of multiple
processors which execute multiple programs.