PDP-11 disk image question
jsw at ieee.org
Sat Feb 16 11:58:26 CST 2019
On 2/16/19 7:55 AM, Bill Gunshannon via cctalk wrote:
> So, I used SIMH to do an install of a complete OS on
> an RA81 disk. I would like to move this to a real disk
> and try it on a real PDP-11. Is there a way to do this
> using dd on a BSD machine? I tried but it created a
> non bootable system. Well, actually, it starts to boot
> but then fails very early in the startup process. I used
> "dd if=filename of=raw-device bs=1024". Could it be that
> the block size needs to be something else?
> I know that VTServer and PDPGUI can move disk images but
> it would take a week at 9600 baud and I think very little
> likelihood of it ever completing successfully.
As long as the media is presented as "Error Free", you should be able to
to change the block size. Since a RA81 (MSCP) remaps error blocks
automatically and invisibly, it should work. Is the media type the same
on SIMH and Real PDP11? If all else fails try bs=512.
For drives that have OS visible media defects, you should make sure the
block size matches the same on the media and also use the option
"conv=noerror,sync". Otherwise dd will actually reorders the blocks(!),
good first then zero fill the ones it cannot read.
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