Extracting .DWG files from a very old floppy backup

Part 1

An interesting job we received recently involved extracting .DWG files (created in AutoCAD release 10 from 1988) from a floppy disk. This would appear simple, just get a USB floppy drive, plug it into the Linux server, then mount and extract the files. However, of course, like with all computing things, it wasn't that simple!

The floppies had been created using a `backup` command in an old version of Windows. This created a .@@@ backup file and applied some form of compression to the .DWGs rendering them unopenable in compatible versions of AutoCAD.

Opening .DWG files in a text editor will reveal to you the version release of DWG that they are. The first thing in the file will be a code and then the language interpretation.

So, step one - work out what program created the backups! If the files were created in 1988, then the version of Windows would have been 2.1 and DOS 4.0, which we can use as a starting point. We can also surmise that there is a possibility that the final floppy in the archive may store a catalogue file which we need to see whether the data is salvageable.

The best bet then is to get a new old PC running Windows 2.1 / 3 to see if we can replicate the command and then restore the backup.

Part 2

It was a success! Check back soon for the details on the outcome

Strange Labs