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Claudio L. · 12-10-2018, 10:40 PM

(12-10-2018 08:20 PM)edryer Wrote: Wow, thank you Claudio!

Would you happen to know if we used a 4GB SD (the non HC rare ones that follow the SD spec) would it work? These are difficult to find I know. I did have one a long time ago in a camera that could only take 2GB max and it worked fine.

I can see them on eBay for around 20 Euros for a non name brand (may not even be real). I expect a decent named brand 4GB SD non HC to reach quite a bit more... probably more than a 128GB or even 256GB card. Crazy.

Unfortunately, while the SD specification allowed a lot of freedom to card manufacturers, software developers didn't care to implement all possible cases.
Large SD cards use larger sectors (this Wikipedia article might interest you), and developers simply reused their old code from DOS era with 512-byte hard-coded sector size.
The thing is, the SD card specification allows partial sector read/write, so you could have a card with 2048 byte sectors and still allow the host to read or write 512-byte chunks and so far so good. But the specification didn't make that part mandatory! The manufacturers went completely wild and they supported whatever bits and pieces were convenient to them.
Developers on the other hand, went completely conservative and never touched their 512-byte sector size in their code. After all, why bother supporting a feature if it will be available in only certain cards from certain manufacturers? You want your device to read all of them. As a result, the more "special" the card was, the more chances for trouble.
By the time SD 2.0 came out, the specification for SDHC made 512-byte sector support mandatory and discarded all the partial reads/writes support to keep it simple and universal.

Back to your 4GB cards: it will be hit and miss. 4 GB cards use larger sectors, if you get it from a responsible manufacturer that supported partial read/writes at 512-bytes, your poorly programmed device will be able to read it. Keep in mind that the SD card specification says 2GB is the maximum capacity for SD cards, so 4GB cards are non-standard (but unless there's a hard-coded limit, a proper driver should be able to read them). The bad part is that poorly programmed devices also had trouble doing math so close to the limit of the 32-bit integers, hence some 4GB cards are seen as 2GB cards by some devices.

I'd say stay away from the 4 GB cards, they are most likely trouble. 2 GB and lower are fine for the 50g. Unfortunately HP never updated the firmware of the 50g to support SDHC.