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From: bzs@CSNET-RELAY.ARPA.UUCP
Newsgroups: mod.computers.vax
Subject: coexistence of ultrix and vms
Message-ID: <8605250151.AA25428@bu-cs.bu.edu>
Date: Sat, 24-May-86 21:51:14 EDT
Article-I.D.: bu-cs.8605250151.AA25428
Posted: Sat May 24 21:51:14 1986
Date-Received: Mon, 26-May-86 18:52:22 EDT
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>From: OPUS..BJORNDAHL@ENGVAX.UUCP (Portia)
>does anyone know if it is possible to put ultrix and uVMS on the same
>(and only) disk? and boot either one?

A long time ago, maybe 3 years, there was an article I believe
in Walter Zintz' column about this (was that the DEC Professional?)
Anyhow, he didn't give any particularly useful details other
than that it was someone in England he had run into who had done this
with SOME version of VMS and SOME version of UNIX and SOME Vax and
SOME disk.

At any rate, I think the strategy was you make a large contiguous file
under VMS. You then generate a UNIX which has been modified such that
the boot program and the disk partitions point to this area instead
of the normal 'zero'. You would build an image, roll it off from tape
to the contiguous partiton and boot (I suppose the console media would
have to be modified to allow the boot to start.)

Although finding the exact places to change might take a little while
I think it would only be a few integers and should turn out to be
fairly simple (unless I am missing something here.) And of course,
there would be numerous opportunities while running VMS to wreak
havoc (like deleting the contiguous file and having later to figure
out a way to put it into the exact same place, perhaps somehow the
boot could be convinced to prompt for the block offsets, like the
way SUN added another arg as in ':vmunix(major,minor,block-offset)'
on an interactive boot?)

Anyhow, sounds like a project, I'd buy another disk if I could...
Also, no guarantee that something hasn't changed in Ultrix to make
this less straightforward although I doubt it (disk partitioning?
hmm, maybe that makes it easier? Only need to change the boot program?)

You would of course need some sources tho not many. I propose it would
be an interesting/amusing/braggadaccio kind of thing for the Ultrix
group to do, if it's like I described, I mean, what the heck, it gets
lonely out there in the suburbs.

	-Barry Shein, Boston University