Issue 48: Oct 2004
Features
- | Foreword
- | Tip of the day
- | CCC To The Rescue!
- | Club Trek
- | Falcon030 AT Tower Case Fitting
Review
- | Xenomorph
M@ilbox
News
| 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. 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. 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
Useful link
Cheshunt Computer Club http://www.cix.co.uk/~derryck
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