Introduction to os
operating system so operating
system is a course that is very important as far as compute science is concerned and also electronic students you may have this subject in your course so it is equally important
and this subject it consists mainly of theory as well as problems so we will first see the theory and also we will be
solving the problems related to this
subject and we will see what this
subject means and what we can learn from
this subject so first of all this is
just an introduction to operating system
and we will see what this operating
system actually means and what are the
functions of this operating system what
are the types of operating systems that
we have and we will just try to get a
brief idea of this subject all right so
let's get started so here it says that
an operating system also abbreviated as
OS is a program that manages the
computer hardware and it also says it
also provides a basis for application
programs and acts as an intermediary
between computer user and computer
hardware so before we understand these
two lines I will be explaining it to you
with a diagram so before we go into this
diagram here are some examples of some
operating systems that we widely use
these days first is your windows so you
may be using Windows in your desktop or
your laptops so it is one of the famous
operating systems used by many people
and also we have Linux and Ubuntu which
are also two open-source operating
systems that are widely used in your
desktops laptops and other devices and
then we have the Mac OS which is the
operating system from Apple so in their
laptops or in their mac books they used
Mac OS X and then in iPhones we find iOS
operating systems and then we have the
very famous Android which you must be
having in your phones so Android is one
of the famous operating systems that is
used for your mobile devices all right
so now before we try to understand these
two lines that we have written here let
us take a diagram to understand the
basic structure of computer system so that we can
understand what is an operating system
and what does an operating syste
actually do so here I have a diagram
which represents the basic structure or
the basic components of a computer
system so first of all in the lowermost
level we have the computer hardware and
what are computer hardware computer
hardware it consists of resources like
CPU which is a central processing unit
and then memory and then the i/o devices
which means input/output devices so your
resources like the processing units your
CPU and also your memory memory consists
of primary memory like your ramps and
your secondary memory like your roams
these things also I will be explaining
it in a detail way in another lecture
so let's first know that our memory as
well as the i/o devices IO devices means
the input/output devices these are the
devices that you use for either giving
input to your system or for getting
output out of your system so examples of
input devices will include your devices
like your keyboards mouse your
microphones these are devices that you
use for giving input into the system and
then output devices would be that
devices that you use for getting output
out of your systems that would be your
devices like monitors or speakers which
gives you output or which shows you or
makes you hear the output those are your
output devices so all these things they
fall under computer hardware so we
generally refer them to as resources
alright and then on top of this we have
the operating system but for now let us
just forget this operating system for a
while just let's just assume that it is
not there and then on top of this
operating system we have the system or
the application programs now there are
two kinds of software's we have which is
system software and application software
and system software's are the software's
that are used to directly modify or
directly give some command to that
computer hardware and operating system
is also a kind of system software but
let's not think about that and just not
get confused hearing
that butters mainly try to understand
water application programs application
programs are the programs or software's
that are used to perform a specific task
and that can be directly used by the
user and these are some examples that we
have here versus a word processor word
processors are like your Microsoft
Office Word which are software's used
for making document files I have
believed that we have all used Microsoft
Word and then we have spreadsheets
spreadsheets are like your Microsoft
Excel ok that is used for making tabular
data or for making some calculations in
your table or data and then we have
compilers so if you are a computer
science student you may be knowing what
compilers are so compilers are the
software's that we use for writing our
computer code like your codes like C++ C
or Java these are written into your
compilers and then we have the text
editors text editors are editors useful
modifying or writing text like your
notepad WordPad etc and then we have web
browsers web browsers are the software's
that enable you to browse the web even
as you are watching this video in
YouTube you may be using some web
browser to view this and examples of
this are Google Chrome Mozilla Firefox
Internet Explorer and so on so this is
not the only application program that we
have we have many many application
programs and these are just few examples
I took to make you understand so these
are the application programs we have and
on top of that we have the users that is
like users like you and me
who are trying to use this softwares for
performing specific tasks so let us take
a simple example that this user one he
wants to use the word processor let's
say it is Microsoft Office Word so we
want to use Word for typing some
documents and he wants to save it to his
system so let's see how he does it so we
imagine that there is no operating
system over here we just have this user
and the application programs and then
the computer hardware so if you wants to
write a document or if you want to type
something into Microsoft Word then he
have to tell the computer how
where that he wants to do it now how can
he do it since there is no operating
system he have to explicitly tell the
computer hardware what he wants to do in
the form of code so he have to first
open the Microsoft Word and he have to
tell the computer hardware that I want
to load Microsoft Word so please load it
into the main memory and then after it
is loaded he has to type something and
when he typed something whatever he
types it has to be displayed on the
monitor he have to tell the computer
hardware to do even that you have to
tell please display the things that I am
typing on the computer screen or on the
monitor and then after doing all that he
have to save it and even for saving it
you have to tell the computer hardware
that yeah I am done with all my typing
and now please save this file with a
particular file name to my hard disk so
for each and every small on my new task
you have to perform you have to
explicitly tell the computer hardware
what to do and how do you communicate to
it in the form of codes you have to
write source code you have to write
codes for each and everything that you
have to perform so we see that it is a
very tedious task or it is a very
difficult task to do this if there is no
operating system you have to manually
tell the computer hardware each and
everything that you have to do so if it
was like this then nobody would actually
use a computer system or at least common
people would not use the computer system
because it is such a tedious thing and
it is very difficult to perform even the
simplest of tasks so in order to avoid
this or to overcome this problem what we
have is an operating system so the
operating system resides between the
computer hardware and the users so it is
a intermediary that acts between the
computer hardware and user so let us
take our first example that we have
taken suppose the user one wants to type
something and save it into his Microsoft
Word so what he does he just double
click on the Microsoft Word and then the
rest of the things the operating system
takes care of it it just opens it for
him and then it makes the screen read
for him for typing and whatever he types
it the operating system tells the hardware
what to do so that it will be typed and
displayed on the screen and everything
that otherwise would have to be done
manually by the user is now taken care
of by the operating system and after
typing it he has to save it when he
saves it the operating system tells the
computer Hardware where to save it and
how to save it and how much memory to
allocate or saving it and everything is
done by the operating system so all
those my new things which we otherwise
had to do in the absence of operating
system is now done by the operating
system and it becomes very easy for the
user to use the computer system so the
user just opens the computer he just
takes or opens what he wants to use it
and he just uses it and all the
underlying things that has to happen all
the communication that has to happen
between the computer hardware and the user is taken care of by the operating
system it does all for the user and does
the computing or the usage of computer
becomes very easy for the users because
of the presence of the operating system
so that is the main task of an operating
system now if we look back at these two
lines that we have written now it will
make sense and now you would understand
what it actually means so let's read it
once again an operating system is a
program that manages the computer
hardware yes we saw that the computer
hardware how with resources like CPU
memory i/o devices everything is managed
by the operating system now and then it
also provides a basis for application
programs and acts as intermediary
between the computer user and the
computer hardware so it provides a basis
for the application programs so here we
have our application programs and it is
installed on the operating system it
provides a base for the application
programs and also it acts as an
intermediary between the computer user
and the computer hardware so here we
have the users and here we have the
hardware and in the operating system it
acts like an intermediary between the
user and the hardware thus making the
process of computation and the usage of
computers seamless and very easy for the
users so that is the main fun
of an operating system and I hope that
made you understand what an operating
system actually does now we will be
seeing some of the types of operating
systems that we have and also the
functions of operating system and what
are the goals that an operating system
needs to achieve so here I have some
types of operating system personas badge
operating system then time-sharing
operating system distributed operating
system network operating system a
real-time operating system multi
programming multi processing and
multitasking operating systems so it is
not limited to just this but these are
some main types of operating systems
that we have and don't worry even if you
don't understand them I will be doing
another lecture where I will explain all
the types of this operating system in a
clear manner I am just introducing this
to you so that you just get used to the
terms that we have here so all this
types of operating system they perform
in a different way based on the need
that we have so just remember that much
and you can keep this few points in mind
and then let's see what are the
functions of OS so the main functions of
OS are number one is it is an interface
between the user and the hardware yes we
just saw that right now we have users
here and we have the hardware here and
it acts like an interface between the
user and hardware and then the second
point is allocation of resources so I
already told you what I mean by
resources here what we mean by resources
are the hardware that we have like the
central processing unit the memory and
the input/output devices so when I user
or when different users wants to use the
different resources so they have to be
allocated our resources are not
unlimited we have a limited resources
that means we have limited hardware so
how this resources should be allocated
to users in such a way that everybody
gets their share and it performs in an
efficient manner all this is done by the
operating system so it allocates
resources to different users or
different processes in a good manner
that is the function of the operating
system and then it does the management
of memory secure
etc so I told you even when we were
typing this word processor we have to
first load it into the main memory then
after typing it it has to be saved into
the secondary memory or the hard disk so
don't worry if you don't understand what
is main memory secondary memory and all
this I will be explaining all this to
you in a clearer way in the coming
lectures so just want you to understand
that how the memory is managed
so how things are stored or where they
are stored everything is managed by the
operating system and how securely it is
done that is also managed light
operating systems so these are some of
the main functions of operating system
and now let us see what are the goals of
an operating system so we have studied
this much now we must be knowing just by
studying all these functions of
operating system and what it does we can
just assume what its goals will be
number one is convenience so I told you
in that example if we were not having an
operating system how tedious or how
tough it would be to execute even the
smallest of tasks by the user but having
an operating system on top of our
computer hardware makes it very easy for
the user to communicate to the compter
hardware so it becomes a very convenient
thing for the user to have this
operating system so the first goal of
operating system is to provide
convenience and then the second point is
efficiency now what do we mean by
efficiency if you were not having the
operating system and let's say we have
different users trying to access these
resources and how would you efficiently
manage the resources that you should get
this much resources or the other users
should get this much resources so if you
do it manually it is going to be very
tough and that is very less chance that
you can efficiently manage it so
operating system by taking care of all
these allocations of resources and
management of memory and everything it
provides you an efficient usage of your
system so the first point is a
convenience and then the second point is
efficiency so many operating systems are
designed mainly for convenience some are
design designed for efficiency but
mostly most or we can say many of the
operating system are designed for both
for both convenience as well as
efficiency so these are the goals of
operating system which we achieve by the
functions of this operating system so in
this lecture we have seen that types of
OS we have seen the functions of OS and
we have seen what is the basic structure
and the basic components we have in our
computer system and we see what the
operating system actually does
in order to make computation very easy
for us and we have also seen some
examples of the operating systems that
we widely use so I hope this was clear
to you this was just an introduction to
just get you started so that you can
know what an operating system actually
is and now you must be understanding.....
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