Re: FAT16 help needed!!!

From: Lewin A.R.W. Edwards (larwe_at_larwe.com)
Date: 12/30/03 

Date: 30 Dec 2003 14:17:31 -0800

> I just checked. My digital camera (a cannon PowerShot S45) which I'd
> say should run under the term "embedded equipment" definately formats
> the media the "big floppy" way. It accepts both formats which is wise

How did you determine this, btw? It is not uncommon for Windows hosts
to show you only the int 24/25h "personality" of an inserted card,
i.e. no int 13h support - which means you can never see the MBR.
Example of drivers that work this way: Microtech DPCM-USB multi-card
reader/writer, but I'm aware of several others that have the same
behavior (just don't have their names to hand).

In testing literally hundreds of digital cameras for interoperability,
we never encountered one single camera that uses "big floppy" format.

> cause both formats IMHO seem to be widespread used. Then, considereing
> that Windows formats CF's the big floopy way I really think that it's

No! If I format a card on my Windows systems, if it already has an MBR
Windows will leave the MBR there. That is with either a PCMCIA adapter
or a USB adapter. If I destroy a card - zero it out - and then use
Windows to format it, the behavior depends on what I'm using to
connect the card to the Windows PC (and also the Windows version):

* PCMCIA card - Needs to be partitioned with FDISK and then formatted.
Haven't attempted this under NT-class Windows.

* USB reader with its own format utility - Right-clicking the volume
in My Computer and selecting Format invokes the OEM's format utility.
An MBR is automatically created.

* USB reader without a format utility, using generic storage class
driver - It winds up as a USB-floppy type volume.

Various other points come to mind, also, e.g. - will not work on
systems using True-IDE boot mode. Your point about be liberal with
what you accept and constrained with what you generate is well taken,
but in this case the conservative approach is _always_ to write
MBR-style cards.

Further, some formats (e.g. SSFDC) have hard-encoded in the format
specification a requirement to precede the filesystem with an MBR.
Truly, it is much safer to work with "hard disk" format.

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