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