On Sun, 20 Jan 2019 21:03:16 +0100, "R.Wieser" 
declaimed the following:

>Dennis,
>
>> You might also have lost the SD card reserved security space..
>
>And what might that be ?    Something similar to what the the old spinners
>had (to "fix" bad sectors) ?
>

 No... It was a small number of blocks intended to be used by security
software running on the host computer (the S in Secure Digital). Likely
meant to contain part of a decryption key which software could then use to
access files on the regular part of the card.

 Otherwise they are basically MultiMediaCard (MMC).

https://en.wikipedia.org/wiki/Secure_Digital#Card_security
https://en.wikipedia.org/wiki/Secure_Digital#File_system
"""
SD/SDHC/SDXC memory cards have a "Protected Area" on the card for the SD
standard's security function. Neither standard formatters nor the SD
Association formatter will erase it. The SD Association suggests that
devices or software which use the SD security function may format it.
"""
(Doesn't explain if using block erase operations on the device can hit that
area)


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 Wulfraed                 Dennis Lee Bieber         AF6VN
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