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Old Oct 18, 2003, 1:00 AM   #21
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Nerds run amok...amazing we ever take any pictures!
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Old Oct 18, 2003, 8:25 AM   #22
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Nerds run amok...amazing we ever take any pictures!
:lol: :lol: :lol:

Another tidbit:... Everyone should realize there's a permanent flash in each and every camera as well (ie to hold the upgradable firmware). Theses are the 'NOR' flashes that were referred to previously, and just like any other electronics, cell phones, MP3 players are used to hold the controlling software. Theses devices are less dense with even slower write, more expensive, but error free (for code storage) and build by Intel (Strata Flash type) or AMD (Boot block type) and their licenses. 8)

Theses are different from the cheaper high-density NAND flash used for memory cards data storage which are manufactured exlusively in the Far East mainly by Toshiba and Samsung. The NOR flash, unlike the NAND type, do not have Error Correction or Wear leveling algorithm in them since a bit error means pretty much that the camera won't boot up. This is why everyone should be extra careful when they upgrade their firmware!

OFF we go to snap some pictures! ops:
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Old Oct 18, 2003, 11:51 AM   #23
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o Format the memory card in the camera before re-use.
-> Repeated deletions without a format is not a good practice!
But this raises a question for me: what is the difference of formatting the card vs. deleting the entire batch of pictures at once?
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Old Oct 18, 2003, 2:10 PM   #24
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NHL and eric s seem to be the experts but my take is that in camera format is not a low level format, it doesn't write zero's to the whole card and clean it free of data - it just resets file entries in the FAT tables.

Which is why it's so fast and you can recover your pics afterwards. So my bet is that deleting ALL the files by changing the first byte of the filename in the FAT, is pretty much as good as a format which is doing the same thing. Except the in-camera format will I think re-write the first logical sector - but if it's not corrupt this wouldn't matter. I think camera 'format' is something of a misnomer equivalent only to the fast format option for a floppy. This explains why sometimes people have trouble initialising a card which can be 'reset' by writing 00's to the memory via a reader, then doing an in cam format. VOX
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Old Oct 18, 2003, 5:26 PM   #25
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... So my bet is that deleting ALL the files by changing the first byte of the filename in the FAT, is pretty much as good as a format which is doing the same thing. Except the in-camera format will I think re-write the first logical sector - but if it's not corrupt this wouldn't matter. ... VOX
Sounds right to me, but I am no expert. There is still the issue of writing the FAT - 16 bit? 32 bit? 12 bit? ...? Since deleting a file involves writing, does the kind of FAT matter for a delete? I don't know, and I don't have to know so long as I let the camera do the formating.

In addition, (in my camera) there is a hiden system file on the memory and a directory structure after the in camera format. Not sure how the camera would work without those, and I have no desire to find out.

So you are likely to be able to make any number of different ways work, the safest way to clear all of your images from the camera's memory is to use the camera's format.
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Old Oct 18, 2003, 6:17 PM   #26
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In addition, (in my camera) there is a hiden system file on the memory and a directory structure after the in camera format. Not sure how the camera would work without those, and I have no desire to find out.
If the camera doesn't find the expected directory structure then it will create it again. Same as the first time you put the card in the camera. The only thing is that any information that the camera may be storing for its own use would be lost.
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Old Oct 18, 2003, 10:49 PM   #27
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People are correct, reformatting in camera is the equivalent to a fast format in dos. It builds the FAT table. I doubt it does anything else (it might on some odd cameras, don't know.) But the FAT table is the most common place for corruption to occure, so rebuilding it every now and then is a good thing.

So to answer luisr's question, there is very little difference between deleting everything and formatting in-camera. But that difference can be significant. Having a fresh, cleaning, healthy FAT table is a very good thing.

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Old Oct 19, 2003, 8:06 AM   #28
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OK let me put my Nerd hat back on again, since you guys are still thinking in term of 'hardisk' whick is fine (but only 1/2 of the picture). Haven't we just 'forgot' that there's a soft controller embedded in the firmware of each camera to implement this 'hardisk' function for raw flash like SM, sD, xD, MemoryStick etc... or a hardware controller for true IDE memory devices like CF cards or PCMCIA ATA-flash drives.

Unlike magnetic devices which have unlimited write cycles, and limited only by the wear and tear of the mechanisms, flashes have fixed cycles. Erase/write in flash are done by tunneling at high voltage causing oxidation to occur which will eventually fail if repeated without limit. For example if frame#1, frame#2,...etc, are always at the same physical locations in flash when the pictures are taken, theses locations will eventually fail first since they are used the most and the end frames will last the longest since they are used the least (BTW... ditto with FAT tables)!

What happen is see page 10 for Wear-Leveling Algorithm: A logical cluster from FAT is not located at a fixed location in flash, but moved around so as to avoid exercising the same physical location twice, ie in that example 005 cluster is moved from flash block #6 to flash block #8 (avoiding the bad block #7 mapped out by the same controller altogether). ie the flash card is a virtual device!

Page 6 below has an illustration of what's really taking place: http://www.samsung.com/Products/Semi...fo/filesys.pdf

BTW some companies have created great fortune by patenting theses flash controllers or embedding their IPs into the various CF cards... and we'd think that people are loosing their shirt in the stock market in the past 2 years! :lol: :lol: :lol:
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Old Oct 19, 2003, 10:04 AM   #29
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So very true. I hadn't fogotten that the FAT system is purely virtual on top of the physical flash chips, but I hadn't thought about that implication. So another benefit of reformatting is that it repositions the FAT table (a thing which is written to with every picture taken... making that physical area of the flash "wear out" faster. Very good point.

Chaulk up another good reason for reformatting! Glad I've gotten into the habit of doing it already.


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Old Oct 19, 2003, 12:42 PM   #30
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Then the manuals should state that cards should be formatted periodically. Mine doesn't. Just tells how to format the card.

Probably the number of cycles is very large. How many cycles does it take for a card, or at least, a particular memory location to wear out?
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