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I have a 4 GB miniSD card that is reporting it has 6 GB of space as opposed to the 4 GB it's supposed to have. Is there any way to flash the card so it will report the proper size?

I've tried Disk Utility on Mac, and diskpart on Windows, as well as GParted on Linux, none of which can seem to successfully format the card, or change/make a partition scheme.

I was hoping there was some low-level editor that might be able to "flash the firmware" or something of the sort on the card?

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I always use the HP USB Disk Storage Format Tool on Win XP and/or Win 7. It works much better than the native format tool. You might want to give this a try.

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Gives me an error saying the drive is write protected. (the lock switch is not on on the adapter). – WillFM Sep 16 '11 at 20:06
The lock switch does not write protect the device. (it is merely a software hint that the host should consider the device WP. So the switch probably is not an issue here). – Hennes Jan 18 '14 at 12:19

Try zeroing out the card by using the following command on Linux as root:

cat /dev/zero > /dev/<card>

Replace <card> with the actual name of the card device. This will erase any erroneous partition table that may exist on the card. After doing this, try repartitioning and reformatting the card again.

Edit: Since you indicate that doing this returns an I/O error, it appears that the card cannot be written to by any means and is probably unusable. A memory card of this kind generally costs less than $10 to replace; see

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I tried that, as well as the dd equivalent both return "Input/output error" – WillFM Sep 16 '11 at 17:09
Sounds like it time to buy another card then. – jftuga Sep 16 '11 at 18:23
I have another working one, was just trying to see If I could salvage this one. If its of any help, I do believe it started doing this when I flashed it to work with a proprietary device format of some sort, what I do not remember, as it was years ago. – WillFM Sep 16 '11 at 20:12
If it was a SD card (SECURE digital card) then it can be locked to a specific device, which would make it unusable on your PC our other devices. This feature is not often used and it does not explain why it reports its size as 6GB (unless the host now reads an encrypted value which mistakenly gets interpreted at 6GiB). – Hennes Jan 18 '14 at 12:18

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