Backing up ST506 disks

From: Fred Cisin <>
Date: Mon Aug 4 20:09:00 2003

On Mon, 4 Aug 2003, Joe wrote:
> >Not much. Put an ST506 controller into a PC. ST506/412 was the defacto
> >standard on PCs until IDE. although most PC people erroneously refer to
> >the cabling and interface as "MFM". The controllers used by IBM in the XT
> >were made by Xebec.
> >Once you have a controller and drive in your PC, you can write the code to
> >read and write sectors to be able to copy a drive.
> I don't think youd even have to write any code. You could boot it from a
> DOS disk and use Debug to read the raw disk sectors and write them to the
> new drive.

Unfortunately, the R command in DEBUG in MS/PC-DOS will balk at reading
even raw sectors if it doesn't see an MS/PC-DOS style partition table in
the first sector of the drive, and an MS/PC-DOS style "boot record" in the
first sector of each partition.

There have also been variations in sector size and sector numbering that
will stop the R command of DEBUG. (MS/PC-DOS uses 512 bytes per sector,
and the sectors on hard drives are numbered 1 - 17) If the alien system
numbers 0 - 16, or uses a sector other than 512 bytes, then DEBUG won't be

But it IS possible to read a lot of stuff other than MS/PC-DOS
using INT 13h

Fred Cisin            
Received on Mon Aug 04 2003 - 20:09:00 BST

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