Thinkpads Forum

Greetings,

I know that the T61 does not support SDXC cards but I was pleased to discover that a 64GB SDXC card was recognized by the T61 (under Vista); however only 32GB are visible/usable*** - I have used the cards 32 GB for some month now without problems.

I would, however, like to know if the SD-card reader in the T61 can be upgraded to fully support SDXC - say to a model of the T420 - which raises two questions:

-- is the T420 SD-card reader separately available?
-- does it fit inot the T61?
-- does it work in the T61?

Maybe somebody has tried this out ....

thanks,
fk

*** which could mean that the address space of the SDHC standard is limited to 32GB

A quick search engine perusing yields that a Windows update is needed to 'add support for the exFAT file system.' Here is a page from microsoft for the update. Not sure if you have this update already? If you consider trying it then I would make sure a restore point will be created in case you need to rollback. It does mention XP a bit but if you scroll down in the second source link website from microsoft you will see-

The exFAT file system driver brings file system support parity to the following operating systems:

Windows Vista
Windows XP
Windows CE

http://www.microsoft.com/en-us/download ... x?id=19364

Sources: https://www.sdcard.org/consumers/sdxc_c ... sing_sdxc/
http://support.microsoft.com/kb/955704

EDIT: You may want to wait for more replies or do more research. I did see one thread in a forum that mentioned a hardware limitation so YMMV.

emeraldgirl08 wrote:A quick search engine perusing yields that a Windows update is needed to 'add support for the exFAT file system.' [...]

A valid point - thanks! But the card is already formatted in exFat.

emeraldgirl08 wrote:You may want to wait for more replies or do more research. I did see one thread in a forum that mentioned a hardware limitation so YMMV. [...]

Something like that would also be my guess e.g. the address bus in an SDHC reader not being able to access more than 32GB.

fk

felixkrull wrote:

emeraldgirl08 wrote:A quick search engine perusing yields that a Windows update is needed to 'add support for the exFAT file system.' [...]

A valid point - thanks! But the card is already formatted in exFat.

You appear to have missed the main point: In order to be able handling exFAT media, the operating system requires support for it. So in order to be able to properly manage exFAT media to their full extent, your OS requires to be retrofitted with that ability. Therefore, unless there actually is a hardware limitation, you might possibly enable full access to those 64 GB by simply installing the drivers mentioned before.

Please report any success/failure for future reference by those who never bother asking, but prefer to search the forum for already given answers.

Other than that, i recommend this external SDXC capable card reader: www.ebay.de/itm/221311978226. A comprehensive review featuring this very reader and comparison of various SDXC card readers by highly estimated forum member dr_st can be found here: forum.thinkpads.com/viewtopic.php?f=18&t=111973.

rumbero wrote:You appear to have missed the main point: In order to be able handling exFAT media, the operating system requires support for it. So in order to be able to properly manage exFAT media to their full extent, your OS requires to be retrofitted with that ability. Therefore, unless there actually is a hardware limitation, you might possibly enable full access to those 64 GB by simply installing the drivers mentioned before.

thanks. I double checked - Vista (patched to latest version) definetly has the exFat support- it can format and read exFat-medias. Furhermore, I tested the card with NTSF - same result: only 32 GB.

I have checked the SDHC specification:

http://users.ece.utexas.edu/~valvano/EE ... r_Spec.pdf

Quote from page 41:

"In High Capacity Cards, the 32-bit argument of memory access commands uses the memory
address in block address format. Block length is fixed to 512 bytes"

Translation: you can address 2 TB of memory even with SDHC cards. Now it gets interesting. This basically leaves the driver as the source for the limitation. Will report any further findingd ...


fk

felixkrull wrote:Translation: you can address 2 TB of memory even with SDHC cards. Now it gets interesting. This basically leaves the driver as the source for the limitation.

Well, make that "that leaves the firmware as the source for the limitation"

Looking quickly at the open-source Linux driver for sd cards, it appears that the driver is asking the card for it's capacity .... The firmware OTOH is closed source. Dead end.

but it certainly appears that there is no real reason for the 32gb limitation -> the filesystem supports greater sizes, the SDHC standard's memory addressing schema supports greater sizes, SDXC is obviously downward compatible in principle (or else my card would not be recognized at all), so the real reason is most probably to create upgrade pressure for the customer.

But this gets too off-topic now for the Thinkpad forum.

What is, however, on-topic is my above question: can the original SD card reader be replaced or is it married to the Motherboard??


thanks,
fk

I doubt you can replace the original card reader with something that will be compatible with your board.

I assume the T61 and X61 card readers are the same (*). I couldn't get the X61 reader to recognize 64GB cards when it was running XP. Now it's running Vista, but alas, I don't have a 64GB card available at the moment for testing. I'll have to see if I can find one around next week.

Unless you have other use for the Cardbus slot, the external reader suggested by rumbero is a nice option. It supports SDXC under Vista and should give you better speeds (again, assuming the T61 reader is the same kind as the one in the X61, which is pretty slow).

(*) May be a wrong assumption, actually. Even though both laptops use the same Cardbus controller, the X61 reader is described as SD only, while the T61 is described as multi-card reader.

New development: I installed Windows 7 64 bit instead od Vista (for a different reason)..... and lo and behold --> the card is now recognized with full 64 GB !!!

(I had to remove the existing partition with 32 GB and create a new one with the full 64GB)

What gives ???


fk

Have you looked at this article?
http://support.microsoft.com/kb/975823
http://www.microsoft.com/en-us/download ... px?id=4271
http://www.microsoft.com/en-us/download ... px?id=5292
"Install this update to support Secure Digital (SD) cards that are larger than 32 GB. After you install this item, you may have to restart your computer."

Also applied to Windows 7 but the hotfix was probably included in SP1.

jdrou wrote:Have you looked at this article?
http://support.microsoft.com/kb/975823
http://www.microsoft.com/en-us/download ... px?id=4271
http://www.microsoft.com/en-us/download ... px?id=5292
"Install this update to support Secure Digital (SD) cards that are larger than 32 GB. After you install this item, you may have to restart your computer."

Also applied to Windows 7 but the hotfix was probably included in SP1.

Amazing: one looks at the SDHC-specification, one looks for the latest driver, one looks for the correct filesystem.

In the end it turns out that Microsoft has a bug. And that the SDHC-limiation to 32 GB is obviously misinformation ....

thanks for the info!


fk