Mini SD Card

[Guest VR6Pete]

bouht an orca mini SD card a while back (512mb) however when i view it in task manager it says it's only 488mb. is the correct? i've formatted it using the binaryes task man, but it's stills sayin the same size....

Pete

[Guest ChrisJM]

yea, its about right, you never get the full space, its usually the format that does it, so they come like it, its the same with pcs...

[Guest Confucious]

The sice of any storage is ussually the unformated size so some is lost iin formatting.

Also sometimes 1Mb is 1000Kb and others report it as 1024Kb hence giving a size discrepency and if they also call 1000b=1Kb instead of 1024B = 1Kb then 512/1.024/1.024 = 488

So it could be formatting or it could just be the definition of a K - is it 1024 (2 to the power of 10) 0r 1000?

[Guest Matty.PW]

The reason is, as Confusious stated:

In computer terms (the *correct* term, used by all computers, phones etc) 1kB = 1024Bytes, 1MB = 1024kB etc etc.

In manufacturer terms (the *wrong* term, and stupidly incorporated into every storage medium we buy today) 1kB = 1000 bytes, 1MB = 1000kB etc.

So you loose out on some space unfortunately :lol:

[Guest larsdennert]

Doesn't the OS take space in the form of fat tables and dir struct just like a regular drive?

[Guest Monolithix [MVP]]

A mixture of the two...

[Guest beersoft]

yes and no

yes the fat table takes up space, but it doesn't, if you know what i mean

when you format a drive (harddisc or sd card) its divided up into sectors or clusters (its late and im stupid), each sector/cluster/chunk is 4/8/16/32kb in size (depending on how you format it) and when you put a file on the drive it takes up so many sectors/chunks/whatevers.

bad analogy time: the drive is a car park with 32 spaces in a line, and each space is the equivilent of 32k, and each car is like a file, and can be anywhere between 1byte (pushbike) and 512k (motorhome with caravan), a car has to fill 1 space but if its big (like a van or something) it will fill more than 1 space, so if you have lots of files that are small they will still take up 32k of space(1 parking space) but if you had 5 motorhomes with caravans (6.2 spaces) they would take up 198k and leave 1 space left, but 32 pushbikes (at 1byte each) would fill the drive as well

ok got that? FAT sucks as a filesytem as 1 1k file takes up the same space as a 32k file.

but 10^2 is right and the drive makers have got it wrong

later

Owen

[Guest larsdennert]

I understand slack space but wouldn't an empty card have no slack? Isn't 10^2=100 and 2^10=1024 or 1Kb? In turn 2^20=1MB and 2^29=512MB which is 536,xxx,xxx bytes not 488,xxx,xxx? Maybe SD companys are cheating and putting 488MB on the card which is 512,xxx,xxx bytes

[Guest Confucious]

512,000,000B= 500,000Kb =488.28Mb taking 1024 B=1Kb and 1024Kb =1Mb

[Guest Monolithix [MVP]]

Also nb that the memory makers will gain very little benefit from cutting you 20mb less on your SD card....

[Guest larsdennert]

Many chip makers do pretty well selling chips that would otherwise go in the trash. For instance Intel will sell CPU chips that don't make their designed speed rating at a cheaper price and then derate the chip. Video card manufacturers disable defective DMA channels on cards and sell them as the "slower" model. I'm sure memory chip makers must have an easy way to disable defective on chip ram and sell the same chip with a different capacity and/or access speed too. So it's a possibility. I doubt they would sell a 512MB labeled card and have only 488MB good on it but who knows...

[Guest beersoft]

/.me retypes things again

the sd card makers think 1 meg as 1,000,000kb (1000 X1000)

the real world sees a meg as 1048576kb (1024 X 1024 )

not forgetting that there are 1024 bytes in a kilobyte, its simple base2 maths - 2,4,8,16,32,64,128,256,512,1024,2048 etc....

so to have 512 meg of usable space you need 536870912kb not the 512000000kb that you get on the card

so doing some simple maths

512000000 (space available on drive)

/

1048576 (what a meg is, in computer terms)

=

488.28125 (megabytes)

any questions?

later

Owen

[Guest chucky.egg]

any questions?

Yeah, who do we sue for misrepresentation of these products?

If I decide a Mb is only 100Kb then I can rebadge 64Mb cards and sell them as 512Mb cards

[Guest Disco Stu]

Since it's become the accepted custom to sell these products this way, your action will almost certainly fail, I'm afraid.

Then again, I'm only an accountant...