Operating system notes(3 lectures)
L-1.1: Introduction to Operating System and its Functions
The topic is Introduction to operating system and its functionalities. Operating system works as
a interface between user and hardware. If user wants to access a particular hardware, he have
to write a program for it And through that program he 'll always access that device. Through
that program, user will always have to always access the device. Operating system is being used
as an interface between user and Hardware. It provides convenience Means I can access my
hardware in easiest way. accessing the hardware directly means there 's no authority in
between who can take back the hardware from me. The first operating system that 's used in
majority is Window's Now primary functionality of operating system. Major functionality of
operating system is resource governor or resource manager It manages the resources How we
manage resources ? If I 'm an alone user and accessing my system by my own Then at that point
I do n't need resource governor that much. System is useful and works as resource manager
How much hardware to be provided to which user or for how much amount. After that time it
will take back that device from the user.
In memory management we have a constraint in RAM i. e. limitation of size Means RAM in our
system is limited And all the processes gets executed first in the RAM. When a process is done,
then it takes out of it and bring the other one. This is called the swapping. Security and privacy
are also provided by the operating system. Operating system works between application, user
and hardware. It 's providing security in between the processes so that no processes can do
interfere or data change with each other. Security and privacy is also provided by the operating
system. In Linux, we opens the terminal and can write the command directly in it that's through
the command prompt. Have to keep in mind that it can be asked in normal theory or GATE or
UGC NET.
L-1.2: Batch Operating System | Types of Operating System
I will explain types of operating system . Batch operating system is batch operating system.
Multi programmed and multi-tasking are very important because many questions comes on it in
operating system and I 've already made a video on it and it 's link is in the description box.
Operator took your job but you do n't know when will you get the result. CPU will stay idle until
that time then it will execute it properly and then will come to next job. CPU allows to do input
output process in it until this time CPU stays Idle. . . This was a major disadvantage or problem
1
,at that time. IBM created this system called FORTRan FORTRAN system. It was designed by IBM
Along with that IBSYS 709X. The batch operating system gradually it got a lot of refinement.
Major refinement was the monitors to end the system of operators.
L-1.3: Multiprogramming and Multitasking Operating System in Hindi with real life examples
multiprogrammed operating system is generally non-preemptive. multitasking or timesharing is
multitasking, multiprogram or time-sharing operating system. gate [UNK]. What is the
difference between multitasking and multitasking. we are bringing multiple processes in the
ram and how execution of these processes takes place. multiprogram is multiprogram, but
multitasking is preemptive or time-sharing. multi programmed operating system is different
from multi programmed operating systems.. CPu is executing p1 process for some time, then
will preempt to p2,, then p3,, then p3, then p4 and so on. CPu should not be idle. Means CPu
should be idle as less as possible. different from the multi-tasking
L-1.4: Types of OS(Real Time OS, Distributed, Clustered & Embedded OS)
this para explains Real time, distributed, clustered and embedded operating system. Talking
about these all four operating system for competitive exams or with college\university exam
point of view then there 're no chances to get questions based on these. Mainly questions come
from multi programming, multi tasking or little bit on Batch also. In soft you can say , it 's little
bit soft , means you can divide it based on the application. Then comes distributed and cluster
In distributed , as the name says like distributed that the systems are not distributed to
operating system this is actually the environment. Each one have its own environment and
resources and its geographically separated. Increased availability, Fault tolerance. . . If any
system got fail here, then rest of the systems will bear its load Means you can easily do load
balancing here fault tolerance is also an important factor. Scalability is also important factor in
cloud computing. Embedded system are those which works only on a fixed functionality like
microwave, machine, AC all these are embedded systems.
L-1.5: Process States in Operating System| Schedulers(Long term,Short term,Medium term)
There is a scheduling method called round robin in which we are talking about time quantum..
In this, we says that we gave one process to CPu, but CPu will run that process up to a fixed
amount of itme. the moment that time quantum got expired. CPu will ask it to return back,
saying that it 'll run next process. the next we have is short term scheduler whose responsibility
is to pick a process from ready state and send it in the running state. process said here... Before.
2
, In these cases, CPu said that it 'll run those with higher priority first or your process 's time
quantum is over and you must go back, but in this case, process is saying itself that it wants to
read some file or wants to access, monitor or any other hardware. Then CPu will ask it to go. to
go in wait State means get block for some time, that 's called an i\o request now When its io
request got completed, file and data is done reading... Means its io got completed. now it wo
n't go back in the running state, there would some other process already in the. running state.
Then we 'll ask it. to come back the way mid-Tern scheduler is working here is the same way it 's
working here also so the difference here is only that we sent it back from the ready state, but
here it was waiting and completing the io work. CPu sent it here to do its io work. then we 'll
resume it again, and will bring it back in the ready queue again..
This is just very simple concept like virtual memory, swap in swap out and swap out. we have
some processes based on firm scheduler like we have least frequently used or most frequently
used. then we do filtering of some processes, so we can send few of them back. so some more
processes or high priority processes can come in ready queue. from there. It 'll get priority and
from here. You 'll resume and moved in ready state. So all these points will help you so much in
competitive exams. you'll understand in detail what preemptive, nonpreemptive, multitasking,
etc.
L-1.6: Imp Linux Commands(Operating System) | Must Watch for College/University &
Competitive exams
Gate [UNK] in today 's video we 're going to discuss about all Unix commands that 's an
important portion of operating system. Even in competitive exams. You can get many questions
on Unix command. Chmod command is used to assign only read permission to all the three
category of file. Chmod A RW means we are giving other permission to group and other.. If you
want to give read write, then 4 + 2 + 1 = 6 is the way we generally denote. This command can
be written or can be represented in octal notation. the more you 'll do execute on the linux
terminal. Then you'll understand about it more better as verbally. There 're a lot of variations
possible' Chmod 444 means read... means read to user read to group and read to others.. lseek
means Lseek is system call main system calls which. Calls which are important for your exam. in
Lseek,. If you want to move read, write, hand back and forth, then for that we use Lseek
command..
3
L-1.1: Introduction to Operating System and its Functions
The topic is Introduction to operating system and its functionalities. Operating system works as
a interface between user and hardware. If user wants to access a particular hardware, he have
to write a program for it And through that program he 'll always access that device. Through
that program, user will always have to always access the device. Operating system is being used
as an interface between user and Hardware. It provides convenience Means I can access my
hardware in easiest way. accessing the hardware directly means there 's no authority in
between who can take back the hardware from me. The first operating system that 's used in
majority is Window's Now primary functionality of operating system. Major functionality of
operating system is resource governor or resource manager It manages the resources How we
manage resources ? If I 'm an alone user and accessing my system by my own Then at that point
I do n't need resource governor that much. System is useful and works as resource manager
How much hardware to be provided to which user or for how much amount. After that time it
will take back that device from the user.
In memory management we have a constraint in RAM i. e. limitation of size Means RAM in our
system is limited And all the processes gets executed first in the RAM. When a process is done,
then it takes out of it and bring the other one. This is called the swapping. Security and privacy
are also provided by the operating system. Operating system works between application, user
and hardware. It 's providing security in between the processes so that no processes can do
interfere or data change with each other. Security and privacy is also provided by the operating
system. In Linux, we opens the terminal and can write the command directly in it that's through
the command prompt. Have to keep in mind that it can be asked in normal theory or GATE or
UGC NET.
L-1.2: Batch Operating System | Types of Operating System
I will explain types of operating system . Batch operating system is batch operating system.
Multi programmed and multi-tasking are very important because many questions comes on it in
operating system and I 've already made a video on it and it 's link is in the description box.
Operator took your job but you do n't know when will you get the result. CPU will stay idle until
that time then it will execute it properly and then will come to next job. CPU allows to do input
output process in it until this time CPU stays Idle. . . This was a major disadvantage or problem
1
,at that time. IBM created this system called FORTRan FORTRAN system. It was designed by IBM
Along with that IBSYS 709X. The batch operating system gradually it got a lot of refinement.
Major refinement was the monitors to end the system of operators.
L-1.3: Multiprogramming and Multitasking Operating System in Hindi with real life examples
multiprogrammed operating system is generally non-preemptive. multitasking or timesharing is
multitasking, multiprogram or time-sharing operating system. gate [UNK]. What is the
difference between multitasking and multitasking. we are bringing multiple processes in the
ram and how execution of these processes takes place. multiprogram is multiprogram, but
multitasking is preemptive or time-sharing. multi programmed operating system is different
from multi programmed operating systems.. CPu is executing p1 process for some time, then
will preempt to p2,, then p3,, then p3, then p4 and so on. CPu should not be idle. Means CPu
should be idle as less as possible. different from the multi-tasking
L-1.4: Types of OS(Real Time OS, Distributed, Clustered & Embedded OS)
this para explains Real time, distributed, clustered and embedded operating system. Talking
about these all four operating system for competitive exams or with college\university exam
point of view then there 're no chances to get questions based on these. Mainly questions come
from multi programming, multi tasking or little bit on Batch also. In soft you can say , it 's little
bit soft , means you can divide it based on the application. Then comes distributed and cluster
In distributed , as the name says like distributed that the systems are not distributed to
operating system this is actually the environment. Each one have its own environment and
resources and its geographically separated. Increased availability, Fault tolerance. . . If any
system got fail here, then rest of the systems will bear its load Means you can easily do load
balancing here fault tolerance is also an important factor. Scalability is also important factor in
cloud computing. Embedded system are those which works only on a fixed functionality like
microwave, machine, AC all these are embedded systems.
L-1.5: Process States in Operating System| Schedulers(Long term,Short term,Medium term)
There is a scheduling method called round robin in which we are talking about time quantum..
In this, we says that we gave one process to CPu, but CPu will run that process up to a fixed
amount of itme. the moment that time quantum got expired. CPu will ask it to return back,
saying that it 'll run next process. the next we have is short term scheduler whose responsibility
is to pick a process from ready state and send it in the running state. process said here... Before.
2
, In these cases, CPu said that it 'll run those with higher priority first or your process 's time
quantum is over and you must go back, but in this case, process is saying itself that it wants to
read some file or wants to access, monitor or any other hardware. Then CPu will ask it to go. to
go in wait State means get block for some time, that 's called an i\o request now When its io
request got completed, file and data is done reading... Means its io got completed. now it wo
n't go back in the running state, there would some other process already in the. running state.
Then we 'll ask it. to come back the way mid-Tern scheduler is working here is the same way it 's
working here also so the difference here is only that we sent it back from the ready state, but
here it was waiting and completing the io work. CPu sent it here to do its io work. then we 'll
resume it again, and will bring it back in the ready queue again..
This is just very simple concept like virtual memory, swap in swap out and swap out. we have
some processes based on firm scheduler like we have least frequently used or most frequently
used. then we do filtering of some processes, so we can send few of them back. so some more
processes or high priority processes can come in ready queue. from there. It 'll get priority and
from here. You 'll resume and moved in ready state. So all these points will help you so much in
competitive exams. you'll understand in detail what preemptive, nonpreemptive, multitasking,
etc.
L-1.6: Imp Linux Commands(Operating System) | Must Watch for College/University &
Competitive exams
Gate [UNK] in today 's video we 're going to discuss about all Unix commands that 's an
important portion of operating system. Even in competitive exams. You can get many questions
on Unix command. Chmod command is used to assign only read permission to all the three
category of file. Chmod A RW means we are giving other permission to group and other.. If you
want to give read write, then 4 + 2 + 1 = 6 is the way we generally denote. This command can
be written or can be represented in octal notation. the more you 'll do execute on the linux
terminal. Then you'll understand about it more better as verbally. There 're a lot of variations
possible' Chmod 444 means read... means read to user read to group and read to others.. lseek
means Lseek is system call main system calls which. Calls which are important for your exam. in
Lseek,. If you want to move read, write, hand back and forth, then for that we use Lseek
command..
3
