Making foreign DOS boot floppies (IBM).

From: J. David Bryan <jdbryan_at_acm.org>
Date: Tue Apr 13 11:51:02 2004

On 12 Apr 2004 at 12:03, John Allain wrote:

> Step one seems to be generic: format command.
> Step two is ?

Step 2 is "install a DOS boot sector at cylinder 0, head 0, sector 1 of the
floppy." This is normally done automatically by the "format" command, but
the format command for a given OS will install a boot sector for that OS,
e.g., if you're running NT, the NT format command will install an NT boot
sector, i.e., one that tries to load NTLDR.


> Is there a way I can patch or debug the floppy after generic
> format to make it look bootable?

Copy the boot sector (512 bytes) from a known bootable DOS diskette to a
file on your hard drive. Then, to make a new diskette DOS-bootable, copy
the boot sector file to logical sector 0 of the floppy as "step 2" of your
process.

You didn't mention what your "higher-version OS" is, but if you're running
one of the Win9x-series, or WinNT up through version 4.0, you can run a
small "debug" script to copy the boot sector. This one will copy from the
floppy to the file "c:\bootsect.dos":

  L 100 0 0 1
  N C:\BOOTSECT.DOS
  R BX
  0
  R CX
  200
  W
  Q

...and this one will copy it back to a floppy:

  N C:\BOOTSECT.DOS
  L
  W 100 0 0 1
  Q

(This will work under NT 4.0 as well if you're logged in as
"Administrator". I don't believe that it will work under Win2K/XP, as
direct floppy writes from "debug" seem to have been disallowed even under
the Administrator account, although I haven't investigated thoroughly.)

                                      -- Dave
Received on Tue Apr 13 2004 - 11:51:02 BST