Disk & Flash Memory Sizes

Electroenthusiast · Jan 22, 2012

Another question,
Why certain cellphones have a limit for expandable memory(those which use SD/microSD)?
I think Nokia 6300 has a limit of 4GB, but why?
Googled: Nokia 5130 has a limit of 8GB SD
ALL use

Ian Rogers · Jan 22, 2012

The SD limit is up to 2 gig and over 2 gig..... Again its down to the interface & software... How much the interface can handle (data wise)... The SD card has 512 bytes per sector and there is just over 4 million sectors... You have to make the interface able to be able to access all these sectors.

After 2 gig I think ( and I may be wrong ) the sectors doubled to 1k... So older versions of the SD interfaces couldn't access the data.. (unless you formatted to limit its size)

Electroenthusiast · Jan 22, 2012

Ian Rogers said:
The SD limit is up to 2 gig and over 2 gig..... Again its down to the interface & software... How much the interface can handle (data wise)... The SD card has 512 bytes per sector and there is just over 4 million sectors... You have to make the interface able to be able to access all these sectors.

After 2 gig I think ( and I may be wrong ) the sectors doubled to 1k... So older versions of the SD interfaces couldn't access the data.. (unless you formatted to limit its size)

Can you elaborate? Cos i think SD cards have no limitation like address bus.

Ian Rogers · Jan 22, 2012

The limitation is on the software drivers mainly.... The file pointer used will govern the size of the sectors you can get to.... We are stuck with FAT16 ... up to 2 gig... FAT32... up to 32 gig and FATX that can access even bigger drives..... There is also NTFS that can access all of the card.... BUT!!! and I have a big butt... The SD cards are mainly used in photography, so the FAT system is still used....

Electroenthusiast · Jan 22, 2012

Okay, lets come back to 'MEMORY'... All these while, we were discussing about why memory is POWER of 2. But now, i've found a source that contradicts this. Now, back to normal, i'm unclear. The source reads so:

The capacities listed are the absolute number of bytes available on a drive. For instance, a 4GB drive would have 4,000,000,000 bytes of space available on the disk. The problem is that PCs use factors of 2 for everything. As it turns out, the computer does not use groups of 1000 to store data, it uses groups of 1024 (2^10). Take 4,000,000,000 and divide it by 1024 bytes and you actually get a number of 3.906GB instead of 4.000GB.

If you have a 160GB hard disk, it'd actually be 156GB before it's formatted. Then once it's formatted, you've lost some more due to much more complex issues.

With a 500GB drive, formatted NTFS with 32K clusters and no waste reservation, I have a usable space of 465GB.

Isn't this completely contradicting what we thought/discussed? Memory = Power of 2 = 4000 or 4096

KeepItSimpleStupid · Jan 22, 2012

Ian: yes, the venerable PDP-11. I loved that machine. PDP 11/20, 11/50 and then the Q-bus machines 11/2, 11/23 and 11/23+

EE: Capacities are different for disk drives: 1K =1000 for disc drives. See: https://en.wikipedia.org/wiki/Hard_disk_drive

Electroenthusiast · Jan 23, 2012

KeepItSimpleStupid said:
EE: Capacities are different for disk drives: 1K =1000 for disc drives. See: https://en.wikipedia.org/wiki/Hard_disk_drive

I'm not saying about a disk drive. It was for Memory Stick/Flash Drives.

Edit:

4GigaBytes=4X10^9 Bytes.....
But in computer
1024 Bytes=1 KiloBytes, so on...

so calculating.....

4GB=4X10^9 Bytes
= ( 4X10^9 )/( 1024^3 ) GB
=3.72 GB)

Ian Rogers · Jan 23, 2012

Using an SD card.. there are two ways... FAT tables (used by MS filing systems) or raw......If you access the SD card without a FAT you can access the whole thing because YOU will have to make the software interface.... But, with large files and physical size of 8 gig and up, the hardware interface MUST use the 4bit interface as if you use SPI the access will be SLOOOOOW.

Most people favour the FAT system as it is used extensively.... I mean if you use a card in raw format... A PC wont see it.... So any data stored on the card will only be of use to your design.

And using the FAT system means you have to go by their rules... If they say 1k is 1000 and not 1024... Tough on us...

Electroenthusiast · Jan 23, 2012

Ian Rogers said:
Using an SD card.. there are two ways... FAT tables (used by MS filing systems) or raw......If you access the SD card without a FAT you can access the whole thing because YOU will have to make the software interface.... But, with large files and physical size of 8 gig and up, the hardware interface MUST use the 4bit interface as if you use SPI the access will be SLOOOOOW.

Most people favour the FAT system as it is used extensively.... I mean if you use a card in raw format... A PC wont see it.... So any data stored on the card will only be of use to your design.

And using the FAT system means you have to go by their rules... If they say 1k is 1000 and not 1024... Tough on us...

How does this hold good?

4GigaBytes=4X10^9 Bytes.....
But in computer
1024 Bytes=1 KiloBytes, so on...

so calculating.....

4GB=4X10^9 Bytes
= ( 4X10^9 )/( 1024^3 ) GB
=3.72 GB)

The calculation above holds good. I even checked this with my 4GB memory stick, it has 3.72GB of available size. . . . .. ... .
And, try to format a 4GB with its capacity, i.e., 4096MB/4GB. You'll find that you can't get more than 3.72 in any case. The calculation above seems to be correct, but it opposes '2^n' rule.

Ian Rogers · Jan 23, 2012

Isn't the 4gig memory stick formatted..... The FAT will be taking up the other 280Meg.

You're starting to confuse me...... As far as I know... 4 gig is equal to 4.29 gig in byte terms... I know it was mentioned that drives (including memory sticks) use 1k = 1000
But My first set of hard drives were 40 Meg ( I had two ) then I had 512 Meg.... then I had 2 gig all of which were in the 1k = 1024.

Now think on this one.... 40 Meg.... (should't that, by the 2^n theory, have been 32 Meg?).. I really don't think drive technology follow the same rules!!

KeepItSimpleStupid · Jan 23, 2012

Some stuff is here: https://en.wikipedia.org/wiki/Design_rule_for_Camera_File_system and the various other links.

Remember that a USB drive EMULATES a hard disk, so they may call it 4 GB of memory in 1024 bit chunks, but it may be a larger capacity hard disk. Just guessing here. In the articles they do mention "aligning" the data to fit a power of 2.

Yikes!

Electroenthusiast · Jan 24, 2012

KeepItSimpleStupid said:
Exactly, but the USB emulates a hard disk, therefore it has to look like one from the interface.

Start here and start following some of the links. https://en.wikipedia.org/wiki/Camera_File_System

So, it's memory on one level and a disk drive on the other. So, the memory inside the USB stick will have to conform to the hard drive specifications. My 4 GB USB drive shows a capacity of 3.73 GB and the number of bytes is considerably higher. Remember that there could be bad block tables, file allocation maps likely included and places for S.M.A.R.T data. Remember the days of hard and soft sectoring?

Will reply back after exploring this.

Electroenthusiast · Jan 24, 2012

Electroenthusiast said:
Will reply back after exploring this.

When a disk manufacturer says the unit holds "500 GB", they really mean 500,000,000,000 bytes. But Windows uses "GB" to mean 1024 x 1024 x 1024 bytes, or 1,073,741,824 bytes. Using that definition, it calls that same 500,000,000,000 bytes "465.66 GB".

Now, what about the space used up by files? Well, Windows still uses that definition of "GB". So if it says your big file is 1.000 GB, it is actually 1 073 741 824 bytes! In this system, by the way, 1.000 MB is actually 1024 x 1024 bytes, or 1,048,576 bytes. Looked at another way, to store a file that actually has 1,048,576 bytes of data in it, it will occupy on your drive a space that Windows will tell you is 1.000 MB, NOT 1.049 MB. The space is still all there. Windows just uses a slightly odd-sized "yardstick" when it goes measuring MB and GB. Source:Internet

In the case as we think, i Guess all the answerer here are wrong:??? https://uk.answers.yahoo.com/question/index?qid=20090522072623AAp4EfL

OK,
As said by KISS & Ian, the change i.e., decrease (compared to rated value) in hard disk capacity is because of file system in use.
There i can use NTFS, FAT32, exFAT...
I experimented by formatting the memory stick with various file systems and found the results as in the Image.

Ian Rogers · Jan 24, 2012

That really surprises me.... They said NTFS is far more neater that FAT32.... you just proved them wrong....

KeepItSimpleStupid · Jan 24, 2012

Ian. I did a DECUS presentaion of the RSTS-11 file system for the PDP-11. I knew that one intimately at the time. Cluster sizes, or multiples of 512 byte blocks became the way of indexing a full drive with only 16 bits. Clusters also figured in when doing files. There was never a set number, like a directory could hold x files. It also depended on the file size as well. We wrote optimizing programs that would rearrange the files so that they were contiguous for performance and even wrote programs that would back up and retreive a drive or file from MAGTAPE. Fun stuff when I was basically out of high school.

Electroenthusiast · Jan 25, 2012

Ian Rogers said:
That really surprises me.... They said NTFS is far more neater that FAT32.... you just proved them wrong....

Because, as we discussed time ago, the flash memories exist in 2...4..so on16 32.
so taking ex of 4gb, which is = to 4194304k , but available locations for storage= '3900702k', this is the number that we get after calculations as shown in the link above. What they've said seems to be right, but i still don't know.
The no 4194304 holds good power 2 law, whereas 3900702 doesn't hold good that law.
Now again, as shown in the image from my previous post, if it is because of file system used, then the fig should say 3.7/3.6 of 4GB. Because what i think file system limitation comes into role when a file is present/ not in an empty memory. Correct me if i'm wrong, i require still more elaboration from you folks.

Ian Rogers · Jan 25, 2012

The part that surprises me is there is less free space with NTFS... Microsoft said there should be more, as the filing system was more efficient... FATX, used on the PS3, is far more efficient. (microsoft calles it exFAT).

Electroenthusiast · Jan 25, 2012

NTFS is reliable in terms of size only when partition size is more than 8GB. Log files are created under NTFS which is used for automatic file system repairs.

But, did you get what i said in the previous post Ian?

Ian Rogers · Jan 25, 2012

Between you and me.... I really don't see what's deluding you now.... Are we still on about this (power of two).... Because oodles of posts back Nigel pointed out that 2^n just means n to the base 2 (binary)

2^2 is 2 to the power 2....... 2^4 ISN'T! This is 2 to the power 4!!! And as we have finally seen, hard drives / FAT systems do not necessarily follow this form...

MEMORY ... RAM ..... ROM ... are always 2^n so 4gig will be 2^32..

Electroenthusiast · Jan 25, 2012

Ian Rogers said:
MEMORY ... RAM ..... ROM ... are always 2^n so 4gig will be 2^32..

So does Flash Memory.
But what i asked was the reason 4GB gets down to 3.7*. So, what is your conclusion.
The link gives the reason that it's because manufac and OS have dissimilar method in accessing memory capacity.
Whereas IMHO, i have a feeling that 'Space Limitation/Reduction in Memory Stck size' happens only when a file is inside a flashmemory. If you place many files(total lesser than 3.7), the flashdrive will be full cos of File system.

And i think it's time now to end the thread with a conclusion, so please elaborate your views.
I've prolonged it to an extent. TY

Disk & Flash Memory Sizes

Active Member

User Extraordinaire

Active Member

User Extraordinaire

Active Member

Well-Known Member

Active Member

User Extraordinaire

Active Member

User Extraordinaire

Well-Known Member

Active Member

Active Member

User Extraordinaire

Well-Known Member

Active Member

User Extraordinaire

Active Member

User Extraordinaire

Active Member

Similar threads

Privacy & Transparency

Privacy & Transparency