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[OM] Re: OT: a few Mac questions

Subject: [OM] Re: OT: a few Mac questions
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Wed, 04 Apr 2007 09:39:50 -0400
Oh, balderdash!  IBM made the FAT12 and FAT16 specs public in the PC-DOS 
tech manuals as soon as the file systems were announced in the early 
80's.  IBM never had anything to do with FAT32 but, structurally, FAT32 
is little different from FAT16.  The only thing that's the least bit 
tricky about FAT32 is the long names support.  Gordon Letwin at 
Microsoft developed FAT32 and my own recollection is that Gordon was 
always fond of telling anyone and everyone he ran into about the 
ingenious way that long names support was implemented in FAT32.  That 
was Gordon's style.  I'm sure that anyone who has a copy of the Win95 
OSR2 SDK (August 1996) will find a complete technical description of 
FAT32 contained therein.

Microsoft does consider FAT32 proprietary in that they hold 4 patents on 
long names support.  But secret?  Hardly.  The patent applications on 
long names were filed in 1992 and 1995 and there would be no reason to 
try and protect the design as a trade secret beyond that point. 
Besides, as already noted, SDK users needed the information to write code.

As to proprietary methods for recovery from corrupted data, the 
fundamental file and FAT structure is really no different than FAT16 
before it.  Those methods have been around for almost 25 years.  If 
nothing else, FAT is structurally very simple.  Whatever recovery can be 
done can probably be figured out by a first year comp sci student.

And there's no reason for any file handler (FAT32 or otherwise) to 
jeopardize the integrity of the OS.

Chuck Norcutt


Jan Steinman wrote:
> 
>> From: Dan Mitchell <danmitchell@xxxxxxxx>

>>
>>  I'm still curious as to why the Mac's FAT32 handler is so fragile  
>> that it can require a total powerdown to get things working again
 >
> 
> Microsoft grudgingly made the FAT specs public only after everyone had  
> already reverse-engineered it. They certainly HAVE NOT made public  
> their techniques for recovering when it is corrupted!
> 
> Apple is attempting to deal with someone else's proprietary stuff here.
> 
> That said, I have never had to "total powerdown" to talk to a  
> corrupted USB device. It *does* go through an extensive re-try  
> sequence that you have to be patient with. I'd suggest a cup of coffee  
> rather than a power-down, then as soon as the system is responsive, re- 
> format that puppy!

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