I have backup files that were made in DOS. They contain many hundreds of hours of work, and unfortunately they're locked away in a format that cannot be opened by anything in the format they are now.

I have a set of files with extensions .001 through .009. Obviously I can just unzip them, but they end up as a file with no extension. According to TrIDNET, a program for analyzing file types, it is a "Norton Backup File". Sounds like an open and shut case, right?

Well, no. I've been having trouble finding a backup or restore utility that can open them in any format. Putting these files on floppy disk images and trying to start restore procedures on them in virtualbox yields nothing, usually to the end of "didn't find any backup files". I'm running out of ideas.

I've tried

  • Putting each file on its own floppy image and mounting them on the virtual machine of MS-DOS and Windows 95.
  • I've tried putting the unzipped file onto an ISO and running restore from that disk in Windows 95.
  • I've tried finding restore programs that simply take files and unpack them.

Most utilities seem to want a drive letter specifically, and won't take individual file names. This has presented itself as a huge annoyance because it won't take the data file directly from a floppy image either.

At this point I'm curious what to try next. Is there some other way to put these on disk images to make them compatible with the restore utilies? Microsoft's restore didn't work, and neither did Norton's Backup utilities (versions 6 through 8). What am I missing?

  • Get HDD Hex Editor Neo (free) to examine the files and see the headers. If the first 2 letters in each file are "PK" then they're zip file, so get 7-Zip (free) to unpack the files. I suspect once they're unpacked (if they're zip files) they're individual files from the file system, only larger files were "split" so the parts would fit on a single diskette, so you will have to figure out how to put the pieces together. If they're not zip files you can still use the hex editor to examine them and see what you can find. (zip format: pkware.com/documents/casestudies/APPNOTE.TXT .) – Daniel R Hicks Aug 11 '14 at 0:32
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    The extensions indicate that the files are a set of backup or compressed data stored to several diskettes (since the data would not fit on 1 diskette). They were either created with a backup program or with a file compression utility. The best way to restore them is to determine the program that created them (as Daniel R Hicks stated by looking at the first 2 (40 would be better) characters in the first file). When you run the restore program, it will probably ask for the last disk (to get the index). – LDC3 Aug 11 '14 at 0:52
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    Well, this is a perfect example of how obsolescence can be harmful in unexpected ways long into the future. – That Brazilian Guy Aug 11 '14 at 0:57
  • Are each of those .00x files 1.44 MB in size? If so, it means each file represents a floppy disk. What is the filedate of the set? It can help in knowing the date it was created and possible software versions popular at that time. – That Brazilian Guy Aug 11 '14 at 1:23
  • willsworks.net/dosbkup.htm may be of interest. Looks like there were at least two versions of norton backup 1E and 2A so your version of norton backup is probably too new. Norton backup on dos seems to be versions - the software linked there seems plausible but there's no way to test it. – Journeyman Geek Aug 11 '14 at 2:03

I was having the same issue.

As long as you have the backup.001 control.001 and so on you can use DOSbox to restore. Works lovely.

mount on DOSbox c: and then mount a:, you will specify the paths.

then install through DOSbox http://mindprod.com/products4.html#RESTORE

use the command restore a: c:\*.* /S <---this last syntax is what can be keeping it from restoring.

Hope it works for you!

  • it is c: (back slash) for some reason it doesn't show it in my answer – carlos Mar 31 '15 at 21:08
  • You need to escape the backslash ie use \` instead of ` or surround the code with ` characters. I fixed your post for you ;) – DavidPostill Mar 31 '15 at 21:43

Can you try to run those utilities under DOSBox?

I'm not sure how well (or better than VirtualBox) it emulates the MS-DOS environment, but maybe that Norton utility handles it better.

I am assuming you can't upload any of those backups for having information you don't want to share. But if you have anything "shareable", maybe you should upload it to see if anyone can review it.

Also, if you need to map a directory to a drive, you can use SUBST. Run it with /? to see how, as I no longer remember how it works.

  • I did actually try DOSBox early in this escapade, it suffered the same problem as VirtualBox, where the restore program complains that the disk image has nothing readable on it... which is comical since I can open the pieces with 7-zip just fine. – user2085722 Aug 11 '14 at 2:31
  • You hit the nail on the head though, I cant share the files (since they are proprietary works of the friend asking me to open them). And since I don't know how he made them (and neither does he, it seems), I cant replicate what he did to make them to better understand it. – user2085722 Aug 11 '14 at 2:32
  • If I'm understanding correctly, you have a set of .00* files that extract a file that you can't read, right? Is this the file that is shown as "Norton Backup File"? If so, can you give us some blocks of the beginning of it? For example, the first 1024 bytes? They should contain enough information to identify the format, but not enough to do anything with it. – Valmiky Arquissandas Aug 11 '14 at 2:39
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    Wait, "is comical since I can open the pieces with 7-zip just fine"? Are you trying to open the .00* files with Norton? Or the extracted file? This is probably the one you should be looking at. – Valmiky Arquissandas Aug 11 '14 at 2:40
  • I cant point the restore applications to the unzipped file. They won't do anything with it. They demand a drive letter no matter how I open it. I cant use anything larger than a floppy image, so I cant fit the unpacked file on an image. So I've been trying to find specific formats to which I can put the archive onto floppies and THEN restore it. – user2085722 Aug 11 '14 at 3:25

Let me start by saying that this sounds tricky.

It would be helpful to know what software created the backups. Without knowing that, you are working in the dark, and so some blind experimentation may be needed.

If these files are of any real importance, your first step is to make sure you have suitable backups. Otherwise, whatever program you use to restore files might change the files. Also, it wasn't clear how you're using the floppies: if the data is on floppies, or if you were just using them as part of a restore technique. Floppy disks can deteriorate with age and usage, so get at least one copy of the data onto modern hardware. And, if you really care about the data, make another copy of the data (which should be easier after at least one copy is on non-floppies).

Software like DOSBox might use standards, like 1.44MB disk formats in disk images. However, actual backup software from that era would sometimes do things in ways that were not quite so standard, like fit 1.76MB on a floppy. So I would suspect that using software like DOSBox might cause restoration software to not work as expected. DOSBox gets lots of reviews for being great, but it can't handle data right if it doesn't see a copy of the data. To maximize the chances that you have every critical "bit" of data, it might be necessary to create disk images of any floppies.

I've heard that the Backup and Restore programs built into DOS are specific to the version of DOS being used. So you might need the restore program from the same version of DOS, if that is how they were backed up. Even worse, I have heard that such programs were buggy.

What you are missing might be the first file in a series. Some programs would start numbering, starting with the second archive file that was created. For instance, ARJ files would use file extensions of ARJ, A01, A02, A03, etc. RAR files would use file extensions of RAR, R01, R02, R03, etc. (Actually, RAR had another pattern of some sort as well, depending on the version of RAR being used.) As for a program that just used pure numbers, I don't readily recall one, but I do think that too many programs used the pattern of just naming files after numbers, so that is not a telltale sign that can let someone just easily point to one specific program. Any specific advice may be a long shot that is more likely to be wrong than right. I realize this wasn't intentional, but the question ends up being fairly broad just because there are multiple possible answers.

Providing further details in an answer is probably infeasible without more details. Knowing the characters of the archive files may be much more helpful for humans to figure out the file type. There may be a pretty decent probability that even just the first 3 to 5 characters might be sufficient to give some key clues, while being rather low in likelihood of sharing damaging data. To figure out those bytes, you would want to view the files in a hex editor. That actually stands a good chance of providing some substantial clues on how to open the files. You might want to get permission to share the files-- if not to the whole Internet, then perhaps with a rather trustworthy expert who is bound by an NDA.

You mention that utilities are asking for a drive letter. It could be helpful to know just what those utilities are. Most of the more useful programs I've used to interact with archive files would typically take a filename. So, knowing what software you suspect may be helpful for people to agree, or rule out some ideas.

Since it seems you're desiring drive letters, make sure you know about mounting directories to drive letters. In DOS, SUBST can do that. In Windows, SUBST might also work there. Also, SMB file sharing can do that (by mounting a shared folder... this can be done using NET USE from the command line). In theory, APPEND or JOIN might also do similar things, but in actuality what I've read over the years is that those programs are probably more trouble/danger than help, so you probably want to stay away from those. (Things like operating system bugs, or differences between versions, may make them more of a liability than a positive use.)

I wouldn't put much faith in the TrIDNET analysis. I'm not familiar with the program, and so it might do a fabulous job. However, the answer that it is an old Norton file just seems like an answer that might be based on guesswork.

I know I threw a lot of advice your way. If you were looking for an actual clear-cut answer, it was the part about using the Restore program from the right version of DOS. But, I do admit that although the answer might be technically correct, it may admittedly have a somewhat low chance of success if you don't know what software that was.

You sound like you might just be looking for advice/direction/any-hints at this point. Well, in my opinion, the most promising approach is probably to look at the hex bytes and get a better idea of what types of files you're working with. Then you'll at least be in a far more informed position to ask some more specific questions.

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