Last time I saw this video was 3 years ago. Whenever I want to refresh my paged/segmented/virtual memory knowledge, I skip all other videos on it and come straight to this. 0% bullshit 100% to the point/visualized explanation
my teacher just said: paging is dividing the memory into equal spaces.. and then i had to figure out what happens from this amazing vid... it's really fun when you understand how it works not just telling me stuff to memorize like a memory card
That is the best video I have ever seen on the internet about segmentation, paging and swapping operations. Explaining all the concepts on the same video allows us to understand the whole concept of memory management. Thank you so much for your help.
you should be the only one teaching this, most eveyone else in billions of google searches could not clearly explain the difference between logical, physicla and virtual memory, i was very confused betweeen logical and virtual, now with one image I totally get it.
I needed a refresher on segmented vs paged memory, and this was fantastic and concise. Wish this video was around when I learned about it the first time lol
It's been a long time i wasn't clear with the concept and after watching this video and many more videos of yours in this playlist.. All became crystal clear.. Thanks a lot.. 👍🏻
Couldn't wrap my head around with fragmentation and paging by MMU from the book, watched this video and went through the chapter again. Excellent explanation mate 👍
1. You sound like Daniel from the game Amnesia : The dark descent. 2. Awesome. Hours of reading in 7 minutes... Why I just cant understand why cant people explain something easily with examples like this, we would have conquered all planets by now with educators like you. I start to think that we make things sound difficult on purpose... Thank you!
Logical memory is smoke and mirrors! It is simply the way one program sees the memory. Each program is made to believe that it is the only thing running on the computer, and that it has all of the memory to itself. (thanks to the operating system). :)KD
Not exactly. The segmented memory can be also virtualized. The video shows it in a way segments must follow each other, even though it is usually the same as with pages, the only difference is external fragmentation and internal fragmentation (=unused space in a segment) problem at once with segments (tries to balance both types out) or internal fragmentation only with pages.
Your video is great, thank you. But I do not understand what does logical memory store? I mean, the logical memory part is not so clear. Sorry for the criticism.
logical memory is not real!!! The operating system (E.G. Windows) fools each program into thinking it is the only thing running on the computer. It fools each program into thinking it has all of the memory to itself. Logical memory is one program's view of the memory - it is how an individual program sees the memory. Physical memory on the other hand is what is really going on - that is, lots of different programs sharing the memory (oblivious of each other). :)KD
It takes longer to swap large amounts of data in an out. You might also swap out some smaller programs and data unnecessarily, then need them again immediately. There's definitely a balancing act to be performed here. For windows based computers, someone decided 4KB was optimal :)KD
so correct me if im wrong! segments are like those mentioned in say,x86 architecture ie code,data,stack etc?and at one time one process's one/more segments can be in physical ram(i mean is the ram concerned about "segments",which one!!,or it just "has the data"?) and these segments are atomic? but at 2:11 you say process is atomic?? im stupid but please explain this to me,ive got everything jumbled in my head one bonus question::windows has page file,so it def uses paging.what about segmentation?
Awesome video, only thing I don’t understand is how can a single page store memory for two processes? Does the page table keep track of which addresses within each page belongs to which process?
During the execution time of a process, it is in main memory, for sure. It is part of a Process Control Block data structure, also called program descriptor, which contains all the info about a process.
I wouldn't say that. The operating system is usually more than just one program (much more in fact). There are programs that control the user interface, process scheduling, memory management, etc. etc. Some of the OS processes that load when a system boots up (E.G. the so called kernel) are always running and will not become fragmented. :)KD
@@ComputerScienceLessons So if I understand it correctly, kernel address space is contiguous both in virtual memory and physical memory. Does that mean the kernel address space is always located at the same location on physical memory? I would be great if you could make an in-depth video about kernel address space with concepts like kernel image, kernel stack, kernel metadata, kernel ASLR and so on. Really appreciate your videos. thanks.
Excellent video! How is the address degined in paged memory? Is it supplied with a page number and an offset within that page? How does that work if some of the program is in memory, and other parts in virtual memory?
A memory address includes a column address and a row address, and more! My playlist on Random Access Memory goes into more details about this: th-cam.com/play/PLTd6ceoshpreE_xQfQ-akUMU1sEtthFdB.html Page replacement techniques depend on the operating system. There's a good starter article on Wikipedia about this: en.wikipedia.org/wiki/Page_replacement_algorithm. I hope this helps :)KD
may I ask how is modern os deal with memory management? I mean are they using pure paging or segmented paging. and also they're all hardware implements right? I'm learning os but I got so much confused between architecture because some of their content are duplicated to each other. Thanks for your video I'm really appreciate it.
BUT in order to work CPU must have access must be provided to page list where each currently running process is loaded to translate adresses, 368 support this, 286 only segmented, 88/86 none only real mode, page size, segment size is defined in hardware
Hello, in the virtual memory slide, is each stripe in the virtual memory space a page, is this correct? Im a student and I’m particularly curious about how virtual memory works in x86, I only know how VAX works which is twice as old as me 😂
It's not true that segments must be swapped entirely. Multics had segments, and the segments were divided into pages, and the pages were swapped to disk
He speaks so passionately and eloquently. He was born to be an educator.
He speaks like Mr Bean.
no
ya bro i aslo agree tis guy good explaning
the meat riding is crazy bro but yeah clear and concise.
Love how he emphasizes on key words on a phrase. This video is amazing.
Thank you. (I was thinking about remaking this one because the sound quality isn't great) :)KD
Lifesaver. Was trying to understand this from my lecturer for far too long, this saved me hours. Great concise explanation.
Thank you. I'm glad to be of service :)KD
@@ComputerScienceLessons cap
@@ComputerScienceLessons liked the video tho :(
Last time I saw this video was 3 years ago. Whenever I want to refresh my paged/segmented/virtual memory knowledge, I skip all other videos on it and come straight to this.
0% bullshit
100% to the point/visualized explanation
Thank you. Welcome back :)KD
@@ComputerScienceLessons Thank you for the warm welcome ^_^
Saved me 2 hours of rewatching my lecture on this. Thank you for such great content.
Glad to help :)KD
my teacher just said:
paging is dividing the memory into equal spaces..
and then i had to figure out what happens from this amazing vid...
it's really fun when you understand how it works not just telling me stuff to memorize like a memory card
I agree - you need to known WHY in order to appreciate something. :)KD
your videos are a gem! thank you for this. i am going to be going through them over break - UCSD student here.
Thanks for the lovely comment.
That is the best video I have ever seen on the internet about segmentation, paging and swapping operations. Explaining all the concepts on the same video allows us to understand the whole concept of memory management. Thank you so much for your help.
Thank you for this! I've read and watched several articles and videos but none of them were as detailed and easy to understand as this
Thank you :)KD
I swear you're helping me to pass my exam this friday.. First the negative binary addition and now paging. Thanks alot
You are most welcome. Keep up the good work, and the best of luck to you :)KD
you should be the only one teaching this, most eveyone else in billions of google searches could not clearly explain the difference between logical, physicla and virtual memory, i was very confused betweeen logical and virtual, now with one image I totally get it.
It's actually a really simple idea isn't it? Thanks for the comment, it's much appreciated. :)KD
Very clear and concise! Thank you for the good explanation!
You have such an amazing ability to simplify complex topics. Thank you
exam in 2 days, crunching learning hard. what a great video to get into the basics fast.
Delighted to help. Good luck. :)KD
Thank you for this amazing video, I've spent the whole day today trying to understand my lectures, this helped clear things up so much!
You are most welcome :)KD
such a great voice, tone with a clear explanation, awesome...
I needed a refresher on segmented vs paged memory, and this was fantastic and concise. Wish this video was around when I learned about it the first time lol
Thank you. Glad to help. :)KD
Thank you!!! Cannot understand this without you
It's been a long time i wasn't clear with the concept and after watching this video and many more videos of yours in this playlist.. All became crystal clear.. Thanks a lot.. 👍🏻
You are welcome :)KD
Currently, I am learning how do operating systems work. This video is super helpful. Thank you so much.
You're very welcome. :)KD
Personally I'm trying to make an operating system as a hobby and I randomly came across this so I watched it. Great explanation, I subbed
Thank you. If you're the next Bill Gates or Steve Jobs, remember me :)KD
@@ComputerScienceLessons I sure will, my friend
Thank you for this lesson on memory allocation in computers. Easy to understand.
You're welcome :)KD
Couldn't wrap my head around with fragmentation and paging by MMU from the book, watched this video and went through the chapter again. Excellent explanation mate 👍
Delighted to help :)KD
1. You sound like Daniel from the game Amnesia : The dark descent.
2. Awesome. Hours of reading in 7 minutes... Why I just cant understand why cant people explain something easily with examples like this, we would have conquered all planets by now with educators like you. I start to think that we make things sound difficult on purpose... Thank you!
WOW. Incredible video , this helped me understood the material in such a small amount of time !!!! Highly recommended
This helped topple to understand ***
You are very welcome :)KD
:)KD
Best video on TH-cam.
Stellar video. Clear and concise. Thank you.
Thank you :)KD
The 10 dislikes must be from my uni lecturers :)
No doubt! :)KD
I wish my professor spoke about these topics as concise as you do, thank you
You're very welcome :)KD
Clear and concise! This is great, thank you.
This makes a lot more sense, brilliant.
Glad to help :)KD
Helped me a lot with my exam. Thank you so much👍
You are most welcome. Delighted to help :)KD
love your videos... :-D . your voice + tempo makes it more interesting
Thanks for the lovely comment :)KD
Have an exam tmr and still haven't learnt this. I'm not stressing though because I know you won't disappoint :)
Good luck :)KD
another subtle, concise and golden one.
Your explanation is the best! Thanks!
Thanks for saying so :)KD
Beautifully done! I wish you were my professor.
Thank you so much :)KD
what an excellent explanation!! thanks a lot!!
Thank you. You are most welcome :)KD
this was the best explanation! thank you so much!!!
thank you my friend, you helped my midterm :)
amazing concise information on memory management 💙💙💙
Thank you :)KD
Thank you so much for making such amazing and clear lesson
You are most welcome. Thanks for the lovely comment:)KD
thank you so much for this, you have no idea how much you have helped me through!
My pleasure :)KD
Thanks
Here , 6:04 youre talking about the logical adress (logical memory) ? The logical memory is not necessary contiguous ?
Logical memory is smoke and mirrors! It is simply the way one program sees the memory. Each program is made to believe that it is the only thing running on the computer, and that it has all of the memory to itself. (thanks to the operating system). :)KD
This was one of the best videos on this topic I found. THANK YOU SO MUCH. btw I like British English. :-)
Delighted to help. Thanks for the lovely comment :)KD
Thank you for all the great content you put out! Keep up the good work
You are most welcome. More on the way :)KD
What a perfect explanation really good job
I got nothing to say, you nailed it
Thank you :)KD
This is insanely helpful
Glas to help :)KD
Very good articulation, please keep up!
flawless explanation!
Not exactly. The segmented memory can be also virtualized. The video shows it in a way segments must follow each other, even though it is usually the same as with pages, the only difference is external fragmentation and internal fragmentation (=unused space in a segment) problem at once with segments (tries to balance both types out) or internal fragmentation only with pages.
Beautiful presentation
Thank you very much :)KD
Thanks for a very nice explanation with helpful diagrams!
This got me with a good revision ❤️
Delighted to help :)KD
I am about to finish my second-to-last semester in my CS BA degree and just today found out there is a channel called computer science
This is mouth watery content
I've never heard it called that. Thank you :)KD
This is exactly what I need.
wonderful presentation
Thank you :)KD
Fantastic resource.
Thank you :)KD
YES! I LOVE these vids!
:) :) :) KD TY
Your video is great, thank you. But I do not understand what does logical memory store? I mean, the logical memory part is not so clear. Sorry for the criticism.
logical memory is not real!!! The operating system (E.G. Windows) fools each program into thinking it is the only thing running on the computer. It fools each program into thinking it has all of the memory to itself. Logical memory is one program's view of the memory - it is how an individual program sees the memory. Physical memory on the other hand is what is really going on - that is, lots of different programs sharing the memory (oblivious of each other). :)KD
@@ComputerScienceLessons :))) Thank you it is now clear. Keep doing such kinds of videos.
very clear and helpful presentation! thanks
Thank you!! Super easy to understand, loved it
You are welcome. Thanks for the comment :) KD
Amazing presentation!
Would there be a disadvantage for having a higher page size, 1gb for instance.
It takes longer to swap large amounts of data in an out. You might also swap out some smaller programs and data unnecessarily, then need them again immediately. There's definitely a balancing act to be performed here. For windows based computers, someone decided 4KB was optimal :)KD
so correct me if im wrong!
segments are like those mentioned in say,x86 architecture
ie code,data,stack etc?and at one time one process's one/more segments can be in physical ram(i mean is the ram concerned about "segments",which one!!,or it just "has the data"?)
and these segments are atomic? but at 2:11 you say process is atomic??
im stupid but please explain this to me,ive got everything jumbled in my head
one bonus question::windows has page file,so it def uses paging.what about segmentation?
My God, give this guy 1k more likes 🙏
Awesome video, only thing I don’t understand is how can a single page store memory for two processes?
Does the page table keep track of which addresses within each page belongs to which process?
the voice in IT is so unique
Thank you! Your video is very informative.
Please make a video on "Virtual segmented systems" .
Thank you
thank you for the explanation!
You're most welcome :)KD
You are the best!
You're too kind. Thank you :)KD
Very clear, thank you!
Thank you :)KD
best video ever 👍👍👍
great video❤
Thank you :)KD
Brilliant work. Thank you.
Where is the "page table" itself actually located, in memory or hard disk?
During the execution time of a process, it is in main memory, for sure. It is part of a Process Control Block data structure, also called program descriptor, which contains all the info about a process.
Is the physical address of the operating system never fragmented?
I wouldn't say that. The operating system is usually more than just one program (much more in fact). There are programs that control the user interface, process scheduling, memory management, etc. etc. Some of the OS processes that load when a system boots up (E.G. the so called kernel) are always running and will not become fragmented. :)KD
@@ComputerScienceLessons So if I understand it correctly, kernel address space is contiguous both in virtual memory and physical memory. Does that mean the kernel address space is always located at the same location on physical memory? I would be great if you could make an in-depth video about kernel address space with concepts like kernel image, kernel stack, kernel metadata, kernel ASLR and so on. Really appreciate your videos. thanks.
wow just wow! soooo helpful! thank you
Glad it was helpful. :)KD
Thank you, it was an understandable lecture. .
Excellent video! How is the address degined in paged memory? Is it supplied with a page number and an offset within that page? How does that work if some of the program is in memory, and other parts in virtual memory?
A memory address includes a column address and a row address, and more! My playlist on Random Access Memory goes into more details about this: th-cam.com/play/PLTd6ceoshpreE_xQfQ-akUMU1sEtthFdB.html
Page replacement techniques depend on the operating system. There's a good starter article on Wikipedia about this: en.wikipedia.org/wiki/Page_replacement_algorithm. I hope this helps :)KD
Watching before my masters exam tomorrow :)
The very best of luck to you :)KD
why is your voice so perfect?
may I ask how is modern os deal with memory management? I mean are they using pure paging or segmented paging. and also they're all hardware implements right?
I'm learning os but I got so much confused between architecture because some of their content are duplicated to each other. Thanks for your video I'm really appreciate it.
Could you help me? In which system is segmentation with paging used (give an example of at least one system)?
is this not contiguous vs non-contiguous?
That is certainly one big difference, but having small pages and mapping logical to physical memory is also important. :)KD
@@ComputerScienceLessons don't they both have 'tables' that link secondary memory (virtual memory) to primary (RAM) memory?
This helped alotttt thankyou
Delighted to help :)KD
Thank you very much, clear explanation :)))
You are welcome :)KD
BUT in order to work CPU must have access must be provided to page list where each currently running process is loaded to translate adresses, 368 support this, 286 only segmented, 88/86 none only real mode, page size, segment size is defined in hardware
Is there a huge difference between them in gaming?
What if swap memory is disabled??
Hello, in the virtual memory slide, is each stripe in the virtual memory space a page, is this correct? Im a student and I’m particularly curious about how virtual memory works in x86, I only know how VAX works which is twice as old as me 😂
thank you! really well explained
FI MUNI statnice? :D
This is a good information, and what about all Linux based systems?
One day, I hope to cover Linux.
Excellent - subbed!
Welcome aboard! :)KD
It's not true that segments must be swapped entirely. Multics had segments, and the segments were divided into pages, and the pages were swapped to disk
Thank you!
You're welcome :)KD
5:48 Disk thrashing or disk thrashing?
I always though of threshing as a farming term, but thrashing sounds a little cruel. Who knows? How about 'spinning like crazy'?
Gold thanks !