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Re: debian-user-digest Digest V2004 #49



Martin McCormick <martin@dc.cis.okstate.edu wrote:

<SNIP>
	I did all that and found that the disk is

DS HD sect=18 /tmp/testfile: PDP-11 UNIX/RT ldp

	I can use dd to seemingly copy the entire disk image with no
trouble or at least not one error.

dd bs=2x80x18b of=/dev/fd0 if=/tmp/floppy.image

	If I try to write floppy.image back to /dev/fd0 with a blank
but formatted disk in it, the resulting disk appears to have the same
data on it but it won't boot and the Linux mount command complains
about bogus FAT's.

	Is there any sort of Linux analysis tool that works in the
command mode that might tell me what is wrong with the copies I am
making?

	These disks are not copy-protected at all and one can use the
comm server to make new copies but this is not as convenient as using
a computer to manage backups.

	It would be nice to be able to mount the disks, but being able
to make a binary copy to and from an image would be fine, also.

	Also, the problem may lie in the way I use superformat to
format a totally blank diskette.  I do:

	  superformat /dev/fd0 --verify_later sect=18 cyl=80

	I think what I need is to format all the tracks with no FAT.
The PDP-11 disk has a different FAT structure, at least that is what I
think is happening.

There may be nothing wrong with the copiewd image, or with the disk once you copy the image onto it. Formatting (with, or without the FAT) is irrelavant since copying back the image with dd will overwrite the formatting. The question is: Why do you think that you should be able to boot a PC with software written for a PDP-11? I don't even know if what you have is a bootable disk, but even if it is it would only boot on a PDP-11.

BTW the last time I worked with a PDP-11 wan an 11/15 and that was back when I was in college in the late 1970's. I can't even find a PDP-11 for sale on E-Bay.

Marc Shapiro



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