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SD and SDHC Card Size Overlap

The SD Association tried to keep the limit for regular "Standard
Capacity" SD cards at 2GB. But there was the technical possibility to
build 4GB SD cards and a huge demand for larger SD cards, well before
the SD 2.00 specification was finalized.

I bought my first 4GB SD card in October 2005, while SDHC was
announced as being in "Final Review" in January 2006. The first SDHC
cards were available in August 2006, and I bought my first SDHC card
in November 2006. This means that for covering the demand for 4GB
size, the SDHC standard was about one year too late.

Now we are dealing with the situation that there are regular SD cards
of more than 2GB and up to 4GB that are officially called
"non-compliant", and "compliant" SDHC cards of more than 2GB. In
real-life, the overlap applies to 4GB cards. 4GB "non-compliant" SD
cards will work in many SD host devices, either formatted to FAT16
with a non-standard cluster size of 64kB, or formatted to FAT32.
However, these cards might not work in SDHC compatible host devices,
where most of these are intentionally programmed to refuse the
"non-compliant" cards. On the other hand, 4GB SDHC cards will
definitely not work in host devices that are not prepared for SDHC
cards (either by default or through a firmware update).

en résumé et en français, il y a eu des cartes 4Go non HC avant
l'existence du standard SDHC. Elles se lisent en général sans problème
sur les *lecteurs* *non* SDHC et sans doute pas sur des lecteurs SDHC
(ca c'est génant si c'est vrai)

donc si on en a, ne pas jeter les lecteurs sd->usb... et on risque de
ne pas pouvoir s'en servir sur les nouveaux modèles

jdd