wmson2000

Brand new 1 day Axim owner - but a veteran Palm user.

Bought a 256mb SD card (it is a SanDisk) and it seems to work fine - recognized by the Ax, copied a few files/programs to test it out, haven't noticed any problems.

But I do have one question. When I go to 'Home' and 'Memory', it says there is only 241.13 'Total storage card memory'. Is this normal? Is there some "overhead" that I'm not aware of? Or do I have a card that isn't giving me all of the 256mb that it's supposed to?

Thanks

JakeRich

It's overhead. The 256 is unformatted size. Formatting, directory, etc, consume the difference. It's the same as with hard drives on the PC. And most people don't realize but a 1.44 floppy drive is actually 2 Meg before formatting.

Basically, you didn't get ripped, it's the way it is.

wmson2000

Okay,

I'm just a little surprised - on my canon digital camera, I get pretty muc what the card says (or canon's menu is being generous with it's feedback to me). The same is true with the 16mb card I had in my palm m505 - it showed me 15.x of available memory.

One additional thought - is the overhead a percentage of the card's available resources or is it a fixed amount. For example, with the difference I'm experiencing, If I had bought a 16mb card I'd only have a couple of mb of space left if it's a fixed amount

I don't feel cheated, just want to know so when I buy another card, I'll be able to choose wisely!

Thanks

boran_blok

while very plausible your statements are not correct, formatting doesnt take that much space away from a disk, the reason you're seeing your 256 MD card as 241,3 Mb is because the harddisk and flash-memory manufacturers choose to express the zise of their cards with 1 MB = 1,000,000 bytes, instead of the "normal" 1,048,576 bytes (I say "normal" cous technically harddisk and flash card manufacturers are right, and mega stands for 1,000,000) but for computers (using binary, and not decimal) the higher 1,048,576 value is used, hence your OS (PPC 2002 in your case) sais that there is a smaller amount of memory present than what is said on the card.

wmson2000

good answer, thanks

boran_blok

the reason your 16 Mb card gets shown almost 16 Mb is because 16,000,000 bytes and 16,777,216 bytes (16 MB as seen by the computer) are only 777,216 bytes different (around 800 KB so yer camera will have shown 15.2 MB or 15.3 depending on what mood it is ;))

the difference in your SD card is one between 256,000,000 and 268,435,456 bytes or 12,435,456 bytes difference and if we calculate 256,000,000 bytes is 250,000 KB is 244.140625 MB (according to my calculator) now I can imagine yer file allocation table for 244 Mb will take around 3 MB away from it, so there u have yer formatting overhead and end up with 241,13 MB

in formatting tehre is a certain overhead for the file allocation table, which takes an amount which is proportional to a certain percentage of the disc but as you can see around 3 MB on 244 MB is around 1.23 % (rounded up) so we're not talking very big numbers here.

PS: a calculator and some binary knowledge is handy ;)

rogue0185

Quote:

Originally posted by boran_blok@Feb 4 2003, 08:14 AM (I say "normal" cous technically harddisk and flash card manufacturers are right, and mega stands for 1,000,000)

Mega may mean one million (10^6) but megabyte (2^20) is a word unto itself created to specifically describe 1024 kilobytes which was created to describe 1024 bytes.

Any dictionary that dares define a megabyte as "one million bytes" would place it only as an secondary definition.

The manufacturers are not "right". They are simply taking advantage of the fact that the government hasn't put it's foot down with regards to advertised capacity on memory cards like it once did with television sets (but never did with CRT monitors).

Megabyte was never intended to mean one million (10^6) bytes. It only came into being as a result of misuse. Much like the definition of "hacker" has become malformed as a result of similar misuse.

Wayfinder

I agree with your umbrage at the disfigurement of the term "hacker". When I first got into computers, being labled a "hacker" was an honor; it meant you knew computers from the inside out. Businesses hired "hackers". I don't know when the term was misappropriated to refer to illegal activities, but such things happen (alas).

As for the concept of 241meg=256meg due to the "megabyte definition"... if I'm right, that doesn't quite calculate out. If one takes the true definition of a megabyte as 1,024,000... then that amount * 241 comes to 246,784,000, which is still about 10 megabytes short of the advertised amount. 10 megabytes is too much overhead for formatting 256 megs, I think (but maybe I'm wrong. I don't know such things).

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McCade

Quote:

Mega may mean one million (10^6) but megabyte (2^20) is a word unto itself created to specifically describe 1024 kilobytes which was created to describe 1024 bytes. Any dictionary that dares define a megabyte as "one million bytes" would place it only as an secondary definition. The manufacturers are not "right". They are simply taking advantage of the fact that the government hasn't put it's foot down with regards to advertised capacity on memory cards like it once did with television sets (but never did with CRT monitors). Megabyte was never intended to mean one million (10^6) bytes. It only came into being as a result of misuse. Much like the definition of "hacker" has become malformed as a result of similar misuse.

OK I was taught that exact same thing in school. But recently I found out something that was very suprising to me. In December 1998 the International Electrotechnical Commission (IEC), the leading international organization for worldwide standardization in electrotechnology, approved as an IEC International Standard names and symbols for prefixes for binary multiples for use in the fields of data processing and data transmission. The prefixes are as follows:

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Prefixes for binary multiples
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Factor Name Symbol Origin Derivation
210 kibi Ki kilobinary: (2^10)^1 kilo: (10^3)^1
220 mebi Mi megabinary: (2^10)^2 mega: (10^3)^2
230 gibi Gi gigabinary: (2^10)^3 giga: (10^3)^3
240 tebi Ti terabinary: (2^10)^4 tera: (10^3)^4
250 pebi Pi petabinary: (2^10)^5 peta: (10^3)^5
260 exbi Ei exabinary: (2^10)^6 exa: (10^3)^6

--------------------------------------------------------------------------------

Examples and comparisons with SI prefixes
one kibibit 1 Kibit = 2^10 bit = 1024 bit
one kilobit 1 kbit = 10^3 bit = 1000 bit
one mebibyte 1 MiB = 2^20 B = 1 048 576 B
one megabyte 1 MB = 10^6 B = 1 000 000 B
one gibibyte 1 GiB = 2^30 B = 1 073 741 824 B
one gigabyte 1 GB = 10^9 B = 1 000 000 000 B

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For more information go to physics.nist.gov/cuu/Units/binary.html

One bonuse of this new "standard" is that it is fun to say and mess up your friends with. :D

McCade