CCC
To The Rescue!
by Peter West
A friend of Mark
Branson's purchased a copy of an old will from
the Public Record Office on-line. The
PDF (Adobe's Portable Document Format) file
was downloaded and copied to floppy, but an
attempt to read the file later on a PC was unsuccessful;
worse, the original download couldn't be found
on the hard disk.
So Mark brought
the floppy along to the Cheshunt Computer Club
meeting to see if anyone could help. I put
the HD floppy in my Falcon and the directory
showed up without problems. After loading the
file into Porthos, this showed correctly that
it consisted of five pages, but only the first
page could be displayed - and that contained
only a logo and a copyright notice. The remaining
pages were just blanks.
![[Screen-shot: Read error]](images/cccttr01.gif)
I attempted to copy the file to his hard drive for
further examination and possible repair. However,
it would not copy from the desktop, bringing
up an alert that the data on the drive was damaged.
Trying to copy with Kobold also brought up a
damaged data alert, but I instructed
Kobold to ignore this and continue. Although the copied
file had the correct length, it would not display
in Porthos at all. Deciding to take a look at
the copied file with a hex editor (HexEdit),
this showed that although the start of the file
had copied OK, the portion after where the alert
had appeared was filled with nulls ($00).
Next an attempt
was made to view the original file on the floppy
in HexEdit to see if it was corrupted in some
obvious way. Attempting to load it brought up
a damaged data alert again and the file would
not load. This was because HexEdit loads the
complete file before it displays the data. Therefore
a switch was made to the Monitor function
of Harlekin III. This loads a file (or a portion
of the selected floppy or hard disk) a cluster
at a time and displays it in hexadecimal and ASCII.
This worked with a number of clusters at the
start of the file, but scrolling on further
brought up a damaged data alert again. This
confirmed the original suspicion that the floppy
disk itself was faulty.
Next we tried
KnifeST. Using the Analyse Floppy function
showed that three clusters of the file were
damaged. A look at the FAT indicated that file
was not fragmented since the cluster numbers
all ran consecutively. In theory it should have
been possible to rebuild most of the file (apart
from the damaged sectors or clusters) with Knife's
Build File function. However, since the PDF
file was over 540 KB long, this would have required
around 600 "Build" sequences, each needing four
or five mouse actions. Life's too short for this!
As a final attempt,
Diskus was brought into use. This is the most
powerful disk utility available for Ataris,
programmed by Dr Uwe Seimet of HD-Driver fame.
Unfortunately it is only available in German.
Beside comprehensive hexadecimal editing functions
it also has a very good copying facility for
files and disks that is able to omit faulty
sectors. It also has very comprehensive repair
facilities, but it was deemed too risky to apply
these to a floppy for which one didn't have
a backup! Anyway, the file was copied with
Diskus to a RAM-disk and then back to another
floppy.
![[Screen-shot: Diskus]](images/cccttr02.gif)
This copy still
only displayed the first page in Porthos. The
disk was brought to a member who had a PC. He
installed Acrobat Reader on the Windows 2000
machine (it had been on his hard drive but not
yet installed) and when the copied disk was
opened in Acrobat, it showed only a near-blank
page with just the copyright line on it. The
next page was blank completely. Derryck suggested
that we take a look at the thumbnails which
Acrobat (and Porthos, too!) produces and these
showed that while page 2 (where the faulty sectors
had been) was blank, pages 3, 4 and 5 were OK.
This was confirmed by looking at the pages themselves,
which showed the hand-written text with calligraphic
embellishments quite clearly.
So not a complete
success. Page 1 didn't matter, but page 2 would
have been useful. However, at least three quarters
of the information had been recovered. After
all this, it was suggested that the original
user contact the Public Records Office and ask for another download,
since they could provide them with the reference
number that was readable on the remaining PDF,
and there ought to be a record of the original
purchase. In the meantime they could make use
of the recovered information on their PC.
I hope this story
illustrates one of the advantages of belonging
to a computer club as helpful and friendly as
the Cheshunt one!
At the last meet I gave Peter a disk
with a corrupted file from which he managed to recover a big chunk of
data.
Well the lady came back off leave on Monday and was knocked out at
what we had managed to recover. She gives a big thank you to Peter and
the others that had assisted.
By now my head had well and truly swelled
with pride finally exploded when I found out that two of our (respected) IT
guys at work had failed to get anything at all. Total kudos for both CCC
and Atari!!!
Mark Shoreham-By-Sea
CCC meets monthly
in the Garden Room of Wolsey Hall, Windmill
Lane, Cheshunt, Hertfordshire 19:00 - 22:00, normally on the
fourth Wednesday of the month; the next meetings
will be 27 October, 24 November and 16 December (Xmas party!). If you are interested, contact
the Membership Secretary, Derryck Croker on
01923 673719 or e-mail derryck@cix.co.uk, and
take a look at the web site.
We have members
coming to meetings from all over the place -
even Shoreham on the South coast and Cambridge
- so if you can manage it, come and visit us.
For those without cars, the Cheshunt railway
station is in the same road, only some 15 minutes
by foot or a short bus ride away.
xlator@cix.co.uk
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