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gilsaluki

Way to Get Data from a Disk with One Bad Sector

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I have been using Silent Butler for about 6 months.  I used the Record disk (data disk) that came with the package.  Total the program would not access/read the disk (errors out on my Indus and 1050).  I tried to make a copy of the disk, no go.  I examined the disks's sectors using Disk Wiz.  There is one bad sector.  Is there a way, a program that I can use to extract the good sectors, maybe saving some of the data that is stored on them...or is all hope lost?

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55 minutes ago, gilsaluki said:

I have been using Silent Butler for about 6 months.  I used the Record disk (data disk) that came with the package.  Total the program would not access/read the disk (errors out on my Indus and 1050).  I tried to make a copy of the disk, no go.  I examined the disks's sectors using Disk Wiz.  There is one bad sector.  Is there a way, a program that I can use to extract the good sectors, maybe saving some of the data that is stored on them...or is all hope lost?

Most sector copiers will be able to make a copy and ignore/deal with the bad sector.

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When a bad sector is encountered with many sector copiers, it will result in a blank sector on the resulting copy.

 

Disk Wizard II is an example of one that will preserve the data received from that bad sector read when written to the resulting copy. Many times only a few bits or bytes of the sector are actually corrupt, and the remainder is intact. Errors in some types of data, especially text, are easy to spot and correct in a sector/hex editor.

 

https://archive.org/details/a8b_Disk_Wizard_II_v2.1_1984_C.A.P._Software

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Copying a disk with one bad sector is no problem, but how about disks that have bad tracks or many bad sectors per track?  Can a stock 1050 (for example) deal with that without many, many retries?  Is there a sector copier that can just make one attempt and continue?  (I don't think so, but...) Of course, modified drives like Happy, Archiver, etc. easily do this. This problem rears its head when using patching programs like Chipmunk, The Black Patch, etc.

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If it's a Dos type disk and the bad sector is part of a needed file then you might need to use a disk editor to recreate the file# and next sector link which is embedded at the end of sector.

Generally a bad sector won't return any data - the program you use to copy it might produce zeros or the contents of the previous sector depending on how it works.

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3 hours ago, Nezgar said:

When a bad sector is encountered with many sector copiers, it will result in a blank sector on the resulting copy.

 

Disk Wizard II is an example of one that will preserve the data received from that bad sector read when written to the resulting copy.

 

What other sector copiers will preserve the data received from a bad sector read when written to the resulting copy? Is there any list?

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18 minutes ago, OmaOhneBH said:

 

What other sector copiers will preserve the data received from a bad sector read when written to the resulting copy? Is there any list?

The Black Patch (CSS) sector copier does that.  

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30 minutes ago, OmaOhneBH said:

What other sector copiers will preserve the data received from a bad sector read when written to the resulting copy? Is there any list?

There are some but all write garbage data for missing sectors.

 

Disk Wizard is the only one I found so far which copies all data from existing but bad (CRC, weak, long) sectors but does not "invent" data for missing sectors (like Rybags describes in above posting).

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13 hours ago, Larry said:

Copying a disk with one bad sector is no problem, but how about disks that have bad tracks or many bad sectors per track?  Can a stock 1050 (for example) deal with that without many, many retries?  Is there a sector copier that can just make one attempt and continue?  (I don't think so, but...) Of course, modified drives like Happy, Archiver, etc. easily do this. This problem rears its head when using patching programs like Chipmunk, The Black Patch, etc.

 

Errrm, yes - Diskcopy from TurboDOS XL/XE can do that. Set "Continue on Error" to "On" and it will only try once to read a sector, if an error occurs it continues reading. BUT: Every error sector will be written as an empty sector.

 

MyCopier 1.x and 2.x can also do this (and both write empty sectors for error sectors). While you have to set the option "continue on error" manually in Diskcopy, MyCopier does that automatically.

 

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Okay.  Thanks for the input.  I was able to use a sector copier (from ANTIC Magazine, 130XE One-Pass Sector Copier) to make a backup of the corrupted disk.  I did select Continue with Error.   It seems to work fine now.  I will be more diligent to make a backup copy of the data from now on.  35 years, I should know this. 

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One note about sector copying I'd like to mention while on the subject. Most Sector Copiers will SKIP empty sectors when writing. This is nice and quicker if you are writing to a newly formatted disk. However, if your destination disk already has data on it, the copier will leave that data there if the source disk has blank sectors in that area. That could cause issues, especially VTOC residue left behind that could make a DOS think there are files on the disk that aren't really there anymore.

 

For example, here's a hex dump of the directory sectors of a copy of a game disk with only 4 games on it that was written to an old TurboBasic disk(yellow and green designate a sector each):

 

vtoc1.gif.9b25b9ae3bd09663983555688e74d93e.gif

 

The game disk only used the first directory sector as there were just 4 games on it, so the rest of the directory sectors were "empty" and thus the sector copier skipped over them and left the TurboBasic file entries still remaining in those sectors. In this example, most DOSes would stop reading the directory at that first zero status byte, but perhaps not all. And if there were 8 files instead of 4, that would fill up the first directory sector and the directory entries would run together so most DOSes would think those TurboBasic files were valid entries.

 

Moral of the story, always use a blank disk OR let the Sector Copier format the destination disk before the copy OR choose "Write Blank Sectors" if the copier has that option.

 

BTW: Same principle goes for copying floppies to ATRs. Make sure your PC software "zeroes" it's buffer between copies or writes directly to a Blank/"Zeroed" ATR file. You may have to force this by "loading" a blank ATR before each copy and saving it as a different name. I had to do this with the old SIO2PC software years ago.

 

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40 minutes ago, EddyFree said:


One note about sector copying I'd like to mention while on the subject. Most Sector Copiers will SKIP empty sectors when writing. This is nice and quicker if you are writing to a newly formatted disk. However, if your destination disk already has data on it, the copier will leave that data there if the source disk has blank sectors in that area. That could cause issues, especially VTOC residue left behind that could make a DOS think there are files on the disk that aren't really there anymore.

 

For example, here's a hex dump of the directory sectors of a copy of a game disk with only 4 games on it that was written to an old TurboBasic disk(yellow and green designate a sector each):

 

vtoc1.gif.9b25b9ae3bd09663983555688e74d93e.gif

 

The game disk only used the first directory sector as there were just 4 games on it, so the rest of the directory sectors were "empty" and thus the sector copier skipped over them and left the TurboBasic file entries still remaining in those sectors. In this example, most DOSes would stop reading the directory at that first zero status byte, but perhaps not all. And if there were 8 files instead of 4, that would fill up the first directory sector and the directory entries would run together so most DOSes would think those TurboBasic files were valid entries.

 

Moral of the story, always use a blank disk OR let the Sector Copier format the destination disk before the copy OR choose "Write Blank Sectors" if the copier has that option.

 

BTW: Same principle goes for copying floppies to ATRs. Make sure your PC software "zeroes" it's buffer between copies or writes directly to a Blank/"Zeroed" ATR file. You may have to force this by "loading" a blank ATR before each copy and saving it as a different name. I had to do this with the old SIO2PC software years ago.

 

 

This!!! I've been archiving a lot of old disks lately including a bunch of user group disks and so many of them read as full or close to full disks when there's only a few programs on it. Always use a fresh disk/ATR file!

 

 

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I know when AspeQt/RespeQt receive a format command from the Atari, it will zero out all sectors - just like a real atari drives and most (*cough* percom) 3rd party drives. So if your sector copier sends a format command to the emulated drive, it's guaranteed to have zeroed sectors for those not written...

 

Thought I read somewhere some DON'T zero the sectors when receiving a format command, and require explicitly choosing some option in the program to create a new disk... maybe like APE or older SIO2PC?

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