Faulty sdhc cards

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What it makes it difficult to verify the true memory size, and virtually impossible to hack the controller ROM, is the fact that handling of external memory (hard drives, flash, etc) has completely changed over time. In the old days, programs and applications would call DOS interrupts and/or BIOS routines to deal with floppies and HDs. At the time when hardware drivers moved to the kernel area which became heavily restricted (stability reasons, Windows NT4), the routines it selves step by step moved to external ROMs integrated in the drives. And flash memory is a very special case. As you may know, every "cell" of a flash chip can only make a limited amount of write cycles before it "dies". To extend life span, the controllers use sophisticated patterns to wear all parts about the same amount (in the beginning of the life span), a strategy which may change coming nearer to final failure. The real amount of memory is bigger (can be MUCH bigger) than the specifications, so dead cells will be replaced by new, before hidden ones for a long time. All this is not transparent for the operating system. The controller gets a detailed command or request by the OS, analyses it, and then acts with a replacement routine. On completing the task, it will send a confirmation to the OS, which is completely "faked" (because it has done something quite different from what the OS requested). These ROM routines are top secret and heavily protected against hacks of any kind, as their cleverness decides about speed and average life span much more than the hardware itself. Read more at pentax forums.                                                                    The first versions of the program h2testw (and some sister programs) were written to show the true memory size, because no other tool available would find anything wrong with these sticks. Only after a while the number of files you couldn't find any more would increase.

Obviously these faked sticks were mixed with the good ones when they were packaged for export. For a while, about 10% of most charges were "infected". They were sent to all European dealers, so buying at a shop with good reputation did not help.

This is a copy of a post which I found very interesting.
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