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From: nagy%43198.hepnet@LBL.ARPA.UUCP
Newsgroups: mod.computers.vax
Subject: VMS and Ultrix on the same system
Message-ID: <8703231443.AA14137@ucbvax.Berkeley.EDU>
Date: Mon, 23-Mar-87 07:36:45 EST
Article-I.D.: ucbvax.8703231443.AA14137
Posted: Mon Mar 23 07:36:45 1987
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>I need to know if Ultrix & VMS can be run interchangeably on the same
>microvax.  A faculty member here is considering doing the evaluation of
>several types of software, where versions exist that run on 4.2BSD,
>and on VMS.  What difficulties are involved in switching between one
>operating system and the other?  Do they need to each be put on separate
>disks, or can they share the same disk?  Can software written for
>a VAX 750 (UNIX or VMS) run just as easily on a microvax II?
     
1. VMS and Ultrix use (radically) different file structures so you will
   need two disk drives.  To switch between them involves shutting down
   the current system and booting the new system.

2. To the best of my knowledge, you will have BIG problems reading files
   on the Ultrix disk from VMS and vice versa.  Maybe someone else out
   in net-land can help you with this one.

3. Under VMS, a VAX is a VAX, be it a MicroVAX for an 8800.  Software
   written on, compiled on and linked on one will run (the .EXE file)
   on the other.  At boot time, VMS loads the necessary code modules
   needed on the MicroVAX to emulate those instructions not part of the
   MicroVAX architecture but part of the full VAX architecture.  So your
   program will run, except for performance considerations (note: for
   PDP-11 compatibility mode, you need the VAX-11/RSX product which
   will provide a software emulator for PDP-11 instructions on MicroVAXes
   and the newer 8xxx machines).