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Re: [OM] Digital dweeb needs help

Subject: Re: [OM] Digital dweeb needs help
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Thu, 09 Aug 2012 12:01:34 -0400
The card shouldn't be worked out.  I'd believe that if it was 10 years 
ago but all modern flash memory chips do wear leveling and they should 
be good for at least 100,000 write cycles... maybe even much more by 
now.  Likely a bit/byte error somewhere but I can't yet figure out where 
that could occur that would not be noticed by both PC and camera.  I 
thought I understood the file system pretty well but there's obviously 
something I don't know.

Chuck Norcutt


On 8/9/2012 11:25 AM, Rick Beckrich wrote:
> You may have marked it. Could be the card is plum worked out. I haven't
> used this camera & card for several months, but both had worked faultlessly
> with this laptop for years.
> Add to that, it's an off-brand card whose name I can't recall at the moment.
>
> .
> On Thu, Aug 9, 2012 at 7:50 AM, Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx
>> wrote:
>
>> Actually, I think I would do a "full format" on the PC first followed by
>> a format in-camera followed by shooting a bunch of test images followed
>> by a read test in the PC.  If it fails after that throw it out.
>>
>> I've been trying to think of what sort of malady might cause the problem
>> described and not coming up with anything to my own satisfaction.  The
>> PC thinks the directory is empty so there are bits somewhere the PC
>> isn't reading correctly and/or the camera doesn't care about.
>>
>> When a camera formats a flash card it only does a "quick format" which
>> just zeros out the directory without erasing any of the image data.
>> When a PC does a format it also normally does a quick format but can
>> optionally do a full format.  A full format does a write to and read
>> back from every sector on the media.  If a read fails the sector will be
>> marked as bad and not used again.  That's at least what happens with a
>> hard or floppy disk.  Exactly what happens with a flash card which
>> employs "wear leveling" I don't know.  Although not mechanical, flash
>> cards do have a maximum number of write cycles.  Sectors near the front
>> of the media would normally get more usage than those at the back since
>> the media is rarely completely filled.  To keep the front sectors from
>> wearing faster the actual physical locations of sectors 0, 1, 2, 3, etc
>> don't correspond to their addresses.  The physical locations are
>> continually remapped to assure even usage across the media.  I assume
>> that the remapping algorithm knows how to take care of marking bad
>> physical sectors but don't know that for sure.  Regardless, I would
>> still recommend following my advice in the first paragraph.
>>
>> Chuck Norcutt
>>
>>
>> On 8/8/2012 12:45 PM, piers@xxxxxxxx wrote:
>>> Never mind trying to diagnose the problem, Rich, find a way round it -
>>> connect the camera to the PC via USB (you may need to bring the car
>>> into the house for this, unless you can extract the G5 from the car!).
>>> Having done that, you should be able to copy the image files to the
>>> PC. Then reformat the CF in the camera. Good lick!
>>>
>>> Piers
>>>
>>> On 08/08/2012, Rick Beckrich <ribec@xxxxxxxxx> wrote:
>>>> I cranked off some shots at last night's National Night Out celebration
>> at
>>>> the nearby town of North Beach on the lovely Chesapeake Bay.
>>>>
>>>>    Played back on the Canaon G5, some of the images looked worth
>> exploring
>>>> further.
>>>>
>>>>    However, when I booted the CF card to my laptop, the Zoom Bowser told
>> me
>>>> "No Pictures!"
>>>>
>>>>    Actually, it said "no images to download."
>>>>
>>>>    This morning I took the card back out to the G5 (It's my
>>>> keep-in-the-car-camera) and hit play - Voila!
>>>>    30+ frames, some good.
>>>>
>>>>    Back to the computer - SAME ZIP AS EARLIER.
>>>>
>>>>    Tried downloading with an HP program... same answer.
>>>>
>>>>    Help... PLEASE!
>>>>
>>>>    Analog Rick
>>>> --
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>>>>
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>>
>>
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