I think it was explained in a very old message of the MSX mailing list, but it's very difficult to find it on the net.
I had found something in 2009, but can't find it back in 2012. Probably the author of RuMSX can give you the infos.
Load a protected floppy disk with Disk Manager to obtain a
supplemental file with DISK-ERRORS on the same folder of DSK.
"Ignore" bad sectors when found!!
Wouter wrote a program to convert .DER + dsk image into DMK image. But he needs someone to help and test it, someone who can run Disk Manager (Wouter and I run Linux, so running Disk Manager isn't possible (not even with Wine)).
I'm making DSK images from my friends floppy collection, and I stumbled upon a protected floppy.
The floppy works fine (it has a game on it), but when I try to make a DSK image from it, it says that there are a lot of bad sectors. When I try to read the floppy in MSX-Basic or MSX-Dos, it says "Disk I/O error".
I can remember that there was some sort of copy protection that gave the same bad sector effect, so I tried copying the floppy onto another floppy with special MSX copy software, and that seemed to work fine. The copied floppy worked also, but I still couldn't make a DSK image of it.
Is it possible to make a DSK image from these kind of protected floppies, and does anyone know how...?
Many thanks
Try to get hold on Near Dark's ReadIt. This tool also copies the bad sectors to the diskimage...
