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maemo.org - Talk (https://talk.maemo.org/index.php)
-   Nokia N800 (https://talk.maemo.org/forumdisplay.php?f=25)
-   -   n800 sdhc compatibility (https://talk.maemo.org/showthread.php?t=24180)

hexagondun 2008-10-09 07:23
n800 sdhc compatibility
 
about to buy a used n800, just curious as to whether or not new firmware allows usage of higher capacity sdhc cards (12, 16 gig)

also, any serious differences in terms of web browsing performance between the 800 and the 810? just a last second question! thanks a lot...

pycage 2008-10-09 07:36
Re: n800 sdhc compatibility
 
SDHC is supported by the firmware, so there should be no problem with higher capacity cards. But I can't say for sure, since the highest I have is 8 GB.

There are no differences in webbrowsing performance between the 800 and 810. Both devices are powered by the same hardware and run the same firmware.

GeneralAntilles 2008-10-09 07:52
Re: n800 sdhc compatibility
 
SDHC has been officially supported since Summer 2007 (and for a while before that unofficially). The hardware limit is 2048GB. The SDHC spec currently says 32GB, but I'm not clearly on whether it's just an arbitrary limit or whether a firmware upgrade will be required later.

fanoush 2008-10-09 12:58
Re: n800 sdhc compatibility
 
Quote:
Originally Posted by GeneralAntilles (Post 231989)
The SDHC spec currently says 32GB, but I'm not clearly on whether it's just an arbitrary limit or whether a firmware upgrade will be required later.
This is arbitrary limit in the sense that it is practical limit of FAT32 filesystem. In theory FAT32 can extend to bigger sizes too but the FAT table grows in size and may be too large for some consumer devices (cameras, PDAs,..) with limited RAM. Also Windows refuse to format filesystem over 32GB with FAT32 and offer only NTFS. Otherwise there is no problem so no firmware upgrade needed. I'm quite curious how SD Association will approach it, 64GB is near. I guess they will just stick with FAT32 for a little longer or maybe remove filesystem requirement from specification.

GeneralAntilles 2008-10-09 13:02
Re: n800 sdhc compatibility
 
Quote:
Originally Posted by fanoush (Post 232031)
This is arbitrary limit in the sense that it is practical limit of FAT32 filesystem. In theory FAT32 can extend to bigger sizes too but the FAT table grows in size and may be too large for some consumer devices (cameras, PDAs,..) with limited RAM.
Ah, interesting. I had assumed it was a filesystem issue, but wasn't sure of the specifics.

TA-t3 2008-10-09 15:19
Re: n800 sdhc compatibility
 
I learned something new today when scanning the pandora forums - it seems wikipedia has been updated since last I looked. It has some details about what limits SDHC size:
http://en.wikipedia.org/wiki/SecureD...ibility_issues
Quote:
Devices that use SD cards identify the card by requesting a 128-bit identification string from the card. [...]
For the new SDHC high capacity card (2.0) implementation, 22 bits of the identification string are used to indicate the memory size in increments of 512 KBytes. Currently 16 of the 22 bits are allowed to be used, giving a maximum size of 32 GB.
(More at wikipedia link above)

fanoush 2008-10-09 18:56
Re: n800 sdhc compatibility
 
Quote:
Originally Posted by Wikipedia (Post 232096)
Currently 16 of the 22 bits are allowed to be used, giving a maximum size of 32 GB.
Well, yes, that's just another way of telling 'current standard is up to 32GB'. Once they extend specification to allow bigger cards they will allow those bits too.

BTW, linux reads all 22 capacity bits anyway
http://mxr.maemo.org/diablo/source/k.../mmc/mmc.c#701

EDIT:
From http://www.sdcard.org/developers/tec...Layer_Spec.pdf page 87
Quote:
C_SIZE
This field is expanded to 22 bits and can indicate up to 2 TBytes (It is the same as the maximum memory space specified by a 32-bit block address.)
This parameter is used to calculate the user data area capacity in the SD memory card (not include the protected area). The user data area capacity is calculated from C_SIZE as follows:
memory capacity = (C_SIZE+1) * 512K byte
As the maximum capacity of the Physical Layer Specification Version 2.00 is 32 GB, the upper 6 bits of this field shall be set to 0.

TA-t3 2008-10-10 10:17
Re: n800 sdhc compatibility
 
Quote:
BTW, linux reads all 22 capacity bits anyway
http://mxr.maemo.org/diablo/source/k.../mmc/mmc.c#701
Ah, interesting. The way I read the code is that whenever manufacturers start making SDHC cards which use more of the bits we won't even have to update the Linux kernel driver - it's all ready for the capacity increase. Good for me, because I've been telling people that the N8x0 will support whatever size you can buy, now or in the future! :)

dantrevino 2008-10-11 22:26
Re: n800 sdhc compatibility
 
i've got 2 16gb cards in mine.

tso 2008-10-11 22:33
Re: n800 sdhc compatibility
 
btw, it should not surprise anyone that microsoft have a new fat variant on its way:
http://en.wikipedia.org/wiki/ExFAT

anyone taking bets on its openness?

still, 16 exabyte on a single chip, sombody pass a towel...


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