[aus.mac] Fool Apple, 400k to 800k

s851736@yabbie.rmit.oz (Robert Krohn) (10/06/88)

Is it possible to fool the mac in thinking a 400k disk is an 800k one ?

Im trying to recover data from an 800k disk mistakanly initialised to 400k
(old 512 machine with the great line Do you want to initialise ? (or eject))
So Im hoping that data is still on the other side, but symantec tools wont
scan that side because it thinks it's a 400k.

Any other suggestions wellcomed !

Thanks in advance, Rob.


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=                                                                           =
=       Robert Krohn  RMIT Comm & Elec Eng, Melbourne, Australia.           =
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=       'My God, it's Full of Stars'                                        =
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jlc@goanna.oz (Jacob L. Cybulski) (10/06/88)

In article <880@yabbie.rmit.oz>, s851736@yabbie.rmit.oz (Robert Krohn) writes:
> Is it possible to fool the mac in thinking a 400k disk is an 800k one ?
> 
> Im trying to recover data from an 800k disk mistakanly initialised to 400k
> (old 512 machine with the great line Do you want to initialise ? (or eject))
> So Im hoping that data is still on the other side, but symantec tools wont
> scan that side because it thinks it's a 400k.

I think that the sequence of 800K disk tracks alternate between sides
to reduce the head movements during I/O. This means that when you
formatted your disk as 400K you've lost every second track of your
disk, you know the implications of that... the disk map points in all
directions and each of your files has been shattered to zillions of
pieces skattered all over the disk of which every second track has 
been wiped out. Hmmm... it is a sad story.

Jacob