COA | Cache | Introduction to Direct mapping | Ravindrababu Ravula | Free GATE CS Classes

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[@intrepid_grovyle]

"ill keep teaching until you say it is is easy" this man is an angel :') he's so nice and his explanation is so patient and clear. wish my prof was like this!!!

[@MrEyee2]

You Sir, just won my medal of tutorship respect, reserved for only those with godlike teaching abilities! Thanks.

[@harshgupta399]

Sir why teachers like you are not at our colleges?after studying from ur lectures I feel I'm wasting money in college

[@cricketfunda2228]

Good ..In my clg also teacher are not good..They waste students time

[@aniapascua6528]

This video is great! Before I even finished watching it, I understood the concept. Was really stuck on my hw assignment, but after watching this was able to complete it in no time. Thank you so much!

[@queenofmoderation7668]

God bless you! I cannot express how thankful I m for these awesome videos.

[@amitmistry8283]

O Boy! You make the world simple , I was literally hitting down my head in computer Architecture book. What a simple example and explanation you show here understood the concept very clear sir. Hats off ! Marvelous work. Thank you very very much...

[@jrobinraj666]

Sir, Respect ++ You make concepts very clear. I trust you more than my books;) I like the way you end your every lecture with a tick on the board.

[@tsvmanojturlapati4492]

GOD BLESS YOU WITH ALLKINDS OF WEALTH SIR.ALL DOUBTS CLARIFIED WITH ONE VIDEO.

[@MyCrazyguitarman]

Dude. You are an amazing teacher. Thank you so much for this.

[@Mbc43m276]

Cant thank this man enough. One of the best lectures

[@TheDevika001]

after going through so many books, ppts and PDFs . Finally I understood Direct Mapping🙏

[@canberkardc6704]

After 20 videos,I can understand Indıan accent xd Thank you sir you da one

[@dharijan84]

Sir I never doubted your lectures until today so, can you please tell me how did that line at 21:19 appear creepily? It feels like i took a little detour in the middle of your lecture and went straight to Paranormal Activity series!

[@swapnilpalande79]

if i clear my exam than all credit goes to u sir........ best teacher ever i found.........

[@NoajmIsMyName]

21:12 What causing that ink at the bottom ? lol

[@pg9280]

Was of great help.. thank you.. pls keep uploading more videos on comp. Architecture

[@radhesham4653]

Thanks allot Ravindrababu Ravula.... Your lectures are very much helpful, specially this one on Cache and its mapping techniques. I had made PPT slides for all the mapping techniques as you had explained. i want to share it also so that people can get benefit of it. Thanks

[@jayasankerm3353]

Sirr....i want a teacher like u Superb sir. I like ur classes so much 👌👌

[@naeemshaikh6790]

At 23.27 while mapping the block numbers with the line number 1, i think there is mistake while calculating the words to be loaded in line 1. The correct words in line 1 should be 20,21,22,23. ( Tag for Line 2 is : 01 Line number : 01 so the address formed will be 01 01 00, 01 01 01, 01 01 10, 01 01 11 that gives u 20, 21 , 22 and 23). Check it out, I might be wrong in doing this.

[@TastyLaserCakes]

Remember that Line #1 can hold the following blocks from main memory. Line #1 can hold blocks (1, 5, 9, 13). Block #13 can be represented by the following most significant 4-bits (1101). Breaking this into their Tag and Line# counterparts we have the most significant 2-bits as (11) representing Tag while the least significant 2-bits (01) represents the Line #1. This allows us to see that Line #1 in cache is actually holding contents of Block #13 of main memory, these contents being (52, 53, 54, 55) as seen in the video. Notice that Tag 11 is also found in Line# 3 (1111). Tag (11) Line# (11). I hope this helps.

[@rammohan3876]

In the video what he expalined is corret... let me clear you. in line 1, 1,5,9 and 13 blocks can occupy. 13 the block words are 52,53,54,55. so his explanation is correct. he explained in this section in terms of word accessing. Hope this is clear :)

[@ayahawari5242]

this is just a scenario... each line can get a tag either 00 or 01 or 10 or 11

[@franciscomelojunior2535]

I was wrong, 1101: 13 block line, which are the numbers 52,53,54,55

[@ibrar406]

he tells us the tag for line 1 is '11'. Why are you looking at tag for line 2, if were mapping for line 1?

[@arpitasinha4163]

Hello sir, I donot understand in the last part of video that why you have taken the cache tag no as- 00,11,10,11 i think it should be like- 00,01,10,11 because in your first eg you said that while mapping main memory block number with cache line no- you said that least significant bits (00) will occupy cache line 0. Similarly least significant bits (01) will occupy cache line 1 and so on. please help me understand this. Regards

[@aanishparuchuri4047]

some good stuff It would be great if you could arrange your playlist in order for computer organization and also add the video "direct mapping problems" to it.

[@crescenciomirandaferrol5027]

Sir, I think there is a mistake aronf 29:44 in the tags associated with the 4 block cache memory. What you say to be a hit, I think is a miss because second line is 01 not 11 as you wrote. Please, tell me if I am wrong. Thanks.

[@vellankisaipradeep4306]

i dont want u all not to miss any of these.... u won my heart sir ,,, thanks

[@maximus370]

Things get spooky at 21:19 at the bottom left of the screen XD Great video though

[@sensi59]

agree :D

[@sathyaramesh6978]

What was dat...ha ha

[@random23579]

man, you're a genius. no one could explain it better

[@kamilia4461]

indian tutorials are amazing and you're the top one .......thank you sooooo much

[@venkannachimata6946]

Thank you sir for ur great leacture, it helps me a lot..

[@kunalsinghgusain2070]

18:20 because value of last two bits is equivalent (block number) mod 4.

[@KENILDINESHPATELBCE]

Thank you sir.........the lecture has been very useful!

[@supriyalakkam9953]

No mistakes in the lecture everything is clear. I am ur great fan sir thank you so much... 💗

[@djigi2002]

there is a mistake 21.50 location in the video, u can find that he has written 1 as 11 under the tag column, which is i suppose wrong.

[@bucky3300]

Tanmoy Debnath bulls eye 👁️‍🗨️ apart from that small mistake the lecture is osm and very helpful

[@gauravgaur5014]

@@djigi2002The tag and line number need not be same,the tag if taken as 11 generates blocks 52,53,54,55 in the cache whereas the tag value of 01 for the same line 1 will generate blocks 20,21,22,23 in the cache.

[@SaranshPagey]

Thankyou So Much Sir, It helped me alot on last day of my exam. You have awesome teaching skill and i got that easily :)

[@mingmou9762]

Such a detailed explanation, it helped me a lot, thank you!!!

[@anitamazumder_songs]

Your way of explanation is really good.

[@mnitcse5523]

for block 4(in mm) = 0100 (block_no=> tag = 01 and line no. = 00 ) right so why block 4 is present in line no. 00 with tag 00 (in cache memory) ? observe that tags are different but line no. is same plz correct me at 20:55

[@siddharthbhonsle9514]

u just saved me from getting a back 😂 keep teaching this way and nobody will fail.. 😊

[@ashishsharma696]

What would be the mapping of blocks to lines if main memory size is 20 words?

[@sravanraja72]

You are awesome sir and I understand it very well. They way you reached is like cake walk.thanks a ton.

[@bhavikthanki8821]

Sir I have one question how can be tag no 2 blocks are same ??? In this example two lines have same tag 11..

[@seesharpcoder]

This is just an example. You need not to put tags in in any sequential manner necessarily.

[@Jeetu0301]

@27:00 What is the logic. 15 concatenated with two 0's?

[@aakarshitsrivastava6888]

All my doubts get cleared by your explanation thanks a lot Sir

[@tharunps8048]

You really have an awesome teaching skill

[@AhtishamAbbasiOffical]

its not an precise way .sir if this example is that m.m=4GB then how to manage it ???we cannot make such type of conversion which u draw in a map of just 16 block

[@neeta123ist]

Very good lecture! thank u sir!

[@cruisingtraveller7218]

How are we deciding the size of Block number and Block offset?

[@aayush5474]

honestly if there was no 75% attendance mandatory in indian colleges i would sit at home and watch ur lectures

[@sukhjindersingh6485]

It's very helpful Thank you sir.🌺

[@christinrajesh1325]

Sir can you explain this lecture with no of blocks are 32 and the no.of lines=8 . I have a doubt in this .how will you take the tag value? Please anyone explain.

[@lexlee6625]

Quick question: Does the TAG refers to which memory block is in the cache line? For example, for the cache line at position 0 (the first cache line), memory blocks 0, 4, 8 and 12 are loaded inside. Thus they each take up position number 0, 1, 2 and 3 respectively. Hence, if the TAG is 10 (2 in decimal) , does this mean that only the memory block that is supposedly in the second position (memory block #8 in this case) is loaded into that cache line and the rest aren’t? Help is greatly appreciated thanks!

[@fahadbinkhalidpk]

Yes, you are right!

[@sachingaur7752]

I was impressed when I saw your video first time since then you're my ideal person. salute for your effort.

[@mahendernaik653]

U have used two 11 , so when tag bit refers 11 then which is responded ? Does tag bit depends on line bits?

[@noormuhammad7301]

A.a Sir g why our teacher not teach us like you , after listen your lecture i am feeling very happy sir ALLAH Bless you and show the right path our teachers that makes the student life difficult .

[@ishikasingh9555]

even du pros arent this gr8!!! amazing sir...ur way of explaining is just awesome

[@soumyajyotidas6449]

What will be the block offset and block number if block size is 1 word?

[@kyrinky]

Can anyone please tell me what he says around minute 7:45; he is explaining why it's 6 bits but I does not matter what I do I cannot understand what he says right after, why is the address bits? I am truly sorry for sounding rude, I am not entitled to any of this.

[@kyrinky]

+Kyrinky Looked it up and found that 2^n =64 [words in main memory] is the formula used to find how many bits each address will have; in this case, our n must be 6 since 2^6=64.

[@obelix_gaul]

+Kyrinky Yes main memory can hold 64 words for this example, so it can be represented using a minimum 6 bits, that is 2^6= 64

[@rajatrana2020]

+Kyrinky Thanks ..I too didn't get it at first

[@rammohan3876]

Yes you are correct.... all addresses will be calculated with 2^n formula. here 6 bits 2^6=64 addresses/bytes/words what ever you treat them.

[@dheerajgupta1421]

Madhu Kashyap other way u can say like this suppose if u have k bits then total addressable memory location could be 2^k. there 64 memory words are taken so 64=2^6

[@worldcitizen7890]

(Block Address) modulo (Number of blocks in cache) This is how you get block address in direct mapped cache

[@l.v.sedits231]

sir ,where can i find some notes/material to this topic

[@rajbrothers5113]

i didn't get whether the cache lines contain block no. or the words.and How the tag is assigned in the cache lines, is it random or depends upon the previous operations or else ?

[@rajatrana2020]

Cache lines are just the replica of blocks in MM. They have the content of Block

[@cookingisfun6231]

sir pls upload the remaining section of dbms...

[@soumyajyotidas6449]

sir in the cache,how is the tag 00,01,10,11 getting in the lines of cache

[@SunnyKumar-wp6wp]

Really your teaching is gud.. keep it up....... I will share your channel in my college.... ..

[@keshavshinde8886]

after three time repite lec finaly i am understand .....tnx sir

[@chinmayachowdary]

Great explanations. I had gone through few of your lectures.

[@swathik3491]

sir in tag field why the 2-bit combination 00 11 10 11 at time 21:40 plz someone explains me

[@kunalalandkar2597]

In tag field we can put any 2 bit value, it may be probablity that all tag field contain 11 11 11 11 also.

[@nimeshranatunge734]

Superb explaining....thanks sir

[@karthik23839]

why the second tag is 11, its supposed to be 01 ri8?

[@kartikchauhan5498]

I don't know if anyone noticed it or not but at 21:14 something drops on the board at the bottom right corner. I guess that is Ink but it really looked weird how it spilled over the board...

[@ShashwatVikram]

Paranormal Activity :)

[@MrMasterRhythm]

I was looking in the comments to see if anyone else noticed this too! hahaha!

[@rupshree8994]

very nice ...explanation sir how can I get your full video lecture of computer organization

[@ThePotentialCrisis]

Great Video! Very easy to understand and very helpful. Thank you.

[@mianroshaan2830]

At 22:05 when you describes tag , you took 11 that represents two tag can we do this? tags should be unique isn't it?

[@KR-pj6ol]

@ 21:19 something strange is happening on the board, at the bottom side!!!!!1

[@anujn1184]

i have a query sir at 25:04 you multiplied 13 with 4 i got the logic of 13 but not of 4 can you help and also how did you write the tag numbers(11 is repeating) i did not get that as well pls.... help

[@BhupenderSingh98]

It's about shifting in binary, 2 more bits are added, left shift, multiply by 4

[@Banarasiya-1]

I think there is mistake at 21:32

[@shivanisrivarshini180]

Can anyone say is the tag value of cache is fixed or will change and how its getting worked im a bit confused with tag bits of cache

[@omkarwarade1455]

Same here

[@naveen9835]

thank u sir jee ............. pls add remaining lec of Computer networking..................again thank u

[@soumyadatta223]

Naveen Kumar can u tell why tag of second line is 11

[@PratikRatnaparkhi]

was there a mistake in 21.51, when you draw another cache diagram on the board, you divide four memory blocks as, 00,11,10,11, when i thought it would be 00,01,10,11. please correct me if I am wrong, that was confusing for me.

[@kyrinky]

+Pratik Ratnaparkhi I think it is an error, I agree with you. It might help future viewers from getting confused.

[@obelix_gaul]

+Pratik Ratnaparkhi Yes you are right the second tag should be 01 and not 11, but the logic is understandable...

[@TeoB832]

+Pratik Ratnaparkhi Those are the TAG bits for the cache lines. I think he just chose arbitrarily. For the second line as is, it would translate to "block number 1101 is here right now." If the TAG was 01 like you said, it would just translate to "block number 0101 is cached here right now." PS: Any of blocks 0001, 0101, 1001, and 1101 can be cached to that location.

[@IsmailHossain-dz5nt]

+Pratik Ratnaparkhi I agree with +TeoB8 on this. The tags are arbitrary and could have been 00,01,10,11. For Tag = 11, the words were 52,53,54,55 from line 13. But had he chosen the tags to be 01, the words would've been 20,21,22,23 from line 5.

[@kijidada]

He says it is just a configuration... there might be 01 in the place of 11 at the 2nd cache line. Actually the CPU doesn't search with the tag number..rather it searches with the Cache line number... so Tag number can be repeated but Cache line number cannot... Hope this helps.. :)

[@himanshutomar7187]

will bit offset be always last 2 significant digit of the address generated by cpu

[@nalinasuresh9567]

I did not understand how two taga on Cache has tag=11 ?

[@radhikagarodia2477]

Can u please tell me the link of ur os paging video!!

[@Uniquethinker1729-v5u]

Excellent explanation all my doubts are cleared

[@MegaArjun2]

hi sir i really like the way you teach and the way you talk about each topic. Can i know if take one on one training for any subjects. thanks for your efforts.

[@bhavanabhavs9314]

I need videos on address sequencing pls

[@Notoriouszyanga]

cache hit.rightBeforeExam.

[@jagadishbagul8634]

sir, I am not able to find your lecture on paging . can you please provide me the one.

[@mdelyaz4494]

i didn't get whether the cache lines contain block no. or the words.and How the tag is assigned in the cache lines, is it random or depends upon the previous operations or else ...................

[@rammohan3876]

cache line whole = block number = tag + line number. tags are assigned inline with line number + block number....

[@subalakshmiramadass681]

line contains block num not words . the confusion here is how 4 blocks in each line but actually one block only(whenever we need 0/4/8/12 it goes only to line 0- only one at a time) accommodate the line

[@abhirupray2494]

Why the second tag is always 11?can you please explain

[@kashifshinwari8597]

sir u clear my mind completly, tnks alot of...

[@nishantbaranwal7107]

sir i got confused, firstly you used round robin for putting words in cache memory, then while solving your example, they were not arranged in round robin order. plz clarify it

[@TAMOGHNAMAITRABCE]

Awesome explanation

[@Bulu-nj8ci]

I can't understand how processor generate 6 bit addresss

[@abhinavs03]

that is just a example for simplicity.

[@rimpinag6346]

Sir plz complete the Computer and Organization for CSE

[@rimpinag6346]

@@ravindrababu_ravula okk sir

[@pravip2716]

Sir,it made me to understand co well please upload more videos

[@jai9958]

i like the class..thankyou :) but , i have a doubt.. sir; At time 2:45 you said that block size is equal to line size..but at 14:20 you mapped 4 blocks into a line using many to one function. i didn't understand how 4 blocks can exist in a line .

[@kuelf123]

Many to one is just the mapping style. It only means that any block among those four blocks when referenced is moved to that line. Only one of those four blocks will reside in that cache line at a time

[@malhardeshmukh9095]

@6:50 blocks and lines aren't the same?

[@xenosgaming5837]

sir how will this method work if 1 word is equal to 2bytes .

[@gohjingxuan3821]

THANKS FOR THE EXPLAINATION BEST TEACHER EVER

[@mrgkpro]

Thank you very much, sir. I think I'm wasting time at my university

[@abhishekdk5040]

why do we need tag when we have block offset?

[@Anurag-hs6nu]

12:20 thumbnail 😌

[@rubengarcia9906]

Thank you so much Ravi your encouragement at min 23. is so thoughtful of you

[@BhupenderSingh98]

I can help with the subtitles, let me know if you want it