Originally posted by knoxploration So in other words, you agree that because of the speed increase on the newer spec for SDXC cards, they won't be able to be read by SDHC devices, then. So how do you propose a firmware update would allow old controllers to handle the near-tripling of the maximum speed spec?
Nope, not at all, I don't agree with that statement in the least. What I said was that SDHC devices would not be able to read SDXC cards at the full 300 mbytes/s, that's all.
As it is, currrent SDXC cards are just SDHC cards formatted with exFAT. There's no difference. SDHC Class 10 and SDXC cards both adhere to the SD 3.0 specification. You can stick an existing SDXC card in an SDHC reader and it works fine, at full speed. Only problem is, some operating systems can't read exFAT yet, so they'll try to format your SDXC card to FAT32, thereby turning it into a regular Class 10 SDHC card. Both Class10 SDHC and SDXC have the exact same read and write speeds, too. 300mbytes/s doesn't exist yet, it's part of the forthcoming SD 4.0 specification.
What the SD 4.0 specification will add is another pin to SDXC cards which will enable the higher read/write speeds. The rest of the pins will still be present and will still act exactly like they used to. So SDXC cards will always be compatible with SDHC readers, you just won't be able to read/write from them at 300mbit/s. And that's where a firmware update can't change things; no firmware update will allow the camera to use an SDXC card at its full, currently-non-existent future speed because that extra pin interface won't be present.
But a firmware update CAN add support for exFAT, so all the other benefits of SDXC can in fact be added to our cameras through a firmware update. These benefits include higher capacities, larger maximum file size, and faster file deleting (because that's an exFAT feature, not an SDXC feature).
It should be noted that the higher capacities have nothing to do with exFAT. FAT32 can have volumes up to 2 TB in size. The 32GB limit on SDHC cards was artificially imposed by the SD 2.0 specification, and has now bee lifted with SD 3.0. However, the larger maximum file size IS a benefit of exFAT, because files used to be limited to 4 GB on FAT32.