Is there a tool to undelete MyDos files on a hard drive?

[+Larry]

This a bit more complicated than a floppy undelete, since these files were in a subdirectory.  I can probably restore them manually, but a tool would be nice (if one exists).

[Rybags]

Unknown.

Supposedly the disk structure is pretty close to 2.x

Subdirectories are just allocations of 8 sectors that hold further file/directory info probably in nearly the same structure as a normal Dos directory.

 

The key with file recovery anywhere is to stop using the disk and to boot from and recover to a different volume.

What is the overall disk or volume size?  Maybe you could upload it and someone could give it a look.

[+Larry]

Thanks Gary, but I've already started a new utility for this.  I think it will be easier than I had originally thought.  It is a small HD from a Black Box system -- 20000 DD sectors long.  I've been using Disk Wizard II to look things over.  Assuming I finish it (and it works!), I'll definitely post it here.  Nothing has been added to the drive, so nothing should be overwritten.

[Rybags]

So you have documentation of the disk layout?

 

I guess it's not too different from 2.x - probably extra flags or special values to say an entry is a subdir and not a file.

I wonder about the file # system though - I suppose the 64 values just get reused but that presents the risk of a corrupted disk not being detected if 2 files with the same # happen to occupy a common sector.

[Rybags]

Found some info re the disk layout.

 

https://atari.fox-1.nl/disk-formats-explained/

[Mathy]

Hello guys

 

I've recreated a lot of disks/partitions in the past.  Atari DOS system is way easier than SpartaDOS, thanks to the (non-existing) sector links.  MyDOS uses file numbers as long as it uses SD disks, not sure about ED/MD, but does not use them on DD disks.  VTOC on ED/MD on MyDOS is different than on AtariDOS, since Atari 2.5 copies part of the first VTOC into the second, where the second VTOC on a MyDOS disk continues where the first left off.

 

The site Rybags mentions is not very easy on the eyes.  Alpha Systems offered two books.  One was Advance Atari Protection Techniques, the other was the sequel to that book.  One of them had a very nice part on disk, VTOC and directory structures of the Atari DOS FMS.  MyDOS differs only slightly and only where it needs to be.

 

I'm looking forward to Larry's undelete utility.  Unfortunately, not everybody was careful when writing their software, which sometimes resulted in good (sub)directories being wiped or disks/partitions being formatted.  😞

 

Sincerely

 

Mathy

 

Edited September 4, 2022 by Mathy

[ivop]

15 hours ago, Larry said:

Nothing has been added to the drive, so nothing should be overwritten.

Is it possible to make a copy to a SIO2PC harddisk of the same size? I have no idea if there are sector copiers that can copy 20k of DD sectors.

[+Larry]

Yes, the first thing I did was to back it up.  I use a little Action! utility called Sectrbak to write a sector copy to a DD ATR image.  I use APE, but any device capable of using large images should work.  The beauty of it is no buffering -- read, write, read, write.  And Ive tested it -- it is virtually as fast as buffering since you are reading or writing with a HD or flash drive.  I'm on my phone now, but I'll post a copy later.

[+Larry]

Here is the latest version of SectorBack -- Beta version 0.63 for MyDos 4.5X.  It may or may not be useful for Sparta.  Includes the ACTION! source code.  I've used it successfully for quite a few years, BUT it does no error checking, and use at your own risk. 

 

The usual purpose is to create a large ATR backup image of your Double Density hard drive partition.  Or you can apply a backup to your HD if something has gone awry.  If you can write protect your hard drive when making a backup, it's good to do so.  Most importantly, make sure that your SOURCE and DESTINATION are correct.  If you do the opposite, SectorBack will happily write to your HD, trashing your data.  Also make sure that your image is DD and properly formatted.  It generally copies about 1000 sectors per minute, so for my use it takes about 12 minutes to do the in-use sectors from a 20K partition to an APE image.  Anyway, it is simple, but relatively fast, and has been useful for making backups.  It does no buffering of the data (hence simplifying the programming).  The first thought is that this would slow the program down a lot, but that is not true using a HD and an essentially zero-latency backup destination.

 

Larry

 

 

Sector Back 063.atr

[+bf2k+]

On 9/4/2022 at 1:59 PM, ivop said:

Is it possible to make a copy to a SIO2PC harddisk of the same size? I have no idea if there are sector copiers that can copy 20k of DD sectors.

Yes there are... HDSC comes to mind... part of the DLT SpartaDOS X project.  It's fast and robust.

 

I wrote one in compiled Basic that I have never released.  It isn't very fast but it will copy anything. SpartaDOS, AtariDOS, MyDOS etc.  Sectors are sectors.  But i think it has to be run from SpartaDOS for accessing the command line.  I don't know if it will run under MyDos.

[_The Doctor__]

Were you able to get the undeletion and recovery done?