[techtalk] request for ideas

[R Pickett]

On Mon, 11 Oct 1999, Karl-Heinz Zimmer wrote:

> When reading the directory DOS notices that the contents are
> defferent from what it has in the cache.  (Cache was filled
> with data when accessing the drive before.)  So smart DOS does
> some very nice thing: *without* asking the user it overwrites
> the contents of the disk.  The cached directory contents are
> written just over the *real* directory structure because DOS
> tries to 'repair' the supposedly damaged directory.

Dir might (or might not) incorrectly DISPLAY the contents of the disk from
the cache, but even brain-dead DOS does not automatically dwiddle the FAT
table or directory tree of a piece of media while _reading_ it.

> This is not a fantasy story of mine but did really happen and
> things like this were the reason why i erased *all* MS software
> on my home PC two years ago.

I can see a scenario where 'dir a:' coughed up the incorrect information
from the cache, and therefore lead to user error that caused the loss of
data.

But think it through -- how is it going to compare the cached data to what's
on the disk, unless it reads the disk first?  And why would it read the disk
if it's in that error condition of not having the media changed flag set?
It thinks it's the same disk, so why would it even read, much less write,
the floppy?  That's just counter to the point of caching information.

In either case, if a floppy drive doesn't set the media changed flag, that's
a broken piece of hardware, not an OS issue.

-- 
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R Pickett                Look around you. This is what the world
emerson at hayseed.net      looks like at the end of the millenium.
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