How to see which tracks contain data?

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TVR486
Posts: 6
Joined: Tue Jul 07, 2020 9:31 pm

How to see which tracks contain data?

Post by TVR486 »

Hello, so I have a hard to find 720k 3.5” disk (IBM) that reads pristine until the last 3 sectors. On a Win9x machine I was able to extract the only file on the disk which is a 450kb resource file. I think that I got lucky and the 450kb file was not on the bad part of the disk but I’d like to be sure.

Is there a way to find out which sectors/tracks contain the actual data/files and to see which contain no written data? I assume KF knows since it compiles a disk image but I’m not sure how to check. And again less verbosely, I want to make sure the 450kb file was not on one of three bad sectors at the end of the 720k disk.

Thank you!
SomeGuy
Posts: 295
Joined: Wed Feb 18, 2015 8:18 pm

Re: How to see which tracks contain data?

Post by SomeGuy »

If the data is not confidential, you could post the raw stream dump here for someone to check.

The kryoflux actually does NOT know anything about the file system, so extracting a file from a decoded image with bad sectors can easily result in a file with corrupted data.

You can also view the raw stream dump graphically with the HxC software tool. Often, but not always, you can view the content of the bad sectors and determine if they are just unused sector fill.
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mr.vince
Posts: 2144
Joined: Tue Oct 05, 2010 5:48 pm

Re: How to see which tracks contain data?

Post by mr.vince »

That isn't perfectly correct. If KF knows about the encoding of the data, it will of course display errors when creating the image. However, the file allocation table (FAT) is within this encoding, so yes, KF does not know about the whereabouts of a particular file. The FAT itself isn't that complicated and there are a lot of tools / bits of sourcecode out there.

See here: https://de.wikipedia.org/wiki/File_Allo ... ble#Aufbau

(Note: This is in German because the English version of this article is very different and lacking the data structure description).
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