Not all Bit for Bit Copy Software

[admin]

is created equal.

There are several bit for bit programs out there, but not all work right.

I have an associate who works in a mill where they have a program on floppy disc which has some sectors scattered throughout which a computer will read as "bad sectors" - but they're not bad - they're some sort of copy protection.  

He said that they have several bit for bit copy utilities, but only one works to correctly beat this system.

Are we absolutely sure that a bit for bit copy (even with something like he's using) won't work?

Can the DD linux utility be used for something like this?

[A543]

Some of those systems from back in the eighties used physically damaged sectors. If the sector was readable the program aborted.  So if you attempted to copy the program to a good disk, it would no longer work, even with a bit to bit copy.
I once was fortunate enough to have a floppy with a bad sector on the same track and head as one of those copy protected disks. I used it as a target to copy one of those copy protected disks to. I used a low level sector editor to copy the disk and it worked. It was the only copy anyone could get to work.
I have considered that remapping of bad sectors could have something to do with the DMS key. If all Phatnoise drives have a certain sector remapped by design, and the Phatbox code knew how to access the original source sector, then that would be a neat trick to hide some data.

[AndyMan]

I remember back in the 80's working on Apple][ systems where the copy protection actually changed the way the WHOLE disc was written (apart from Track 0, Sector 0) which changed the drive parameters... that's going back some!