[Simh] Unattended background SIMH process

[Kevin Handy]

What it sounds like you need, is  for simh to detect the shutdown interrupt
itself, and then save the current state of everything in the machine to a
file. Upon power-up, it then needs to restore back to that state.
You;d have to save the current configuration settings,  state of memory,
cpu registers, device structures, etc., and then be able to read it all
back in and restore everything back to a working state. Could get
complicated, for example the disk drive have a timer in them so that they
don't respond instantly to read requests, so this type of thing would need
to be saved.
Is it possible to manually do this right now? Store the state of a machine,
them restore it back using simh commands to individually reset all the
devices?


On Fri, Nov 29, 2019 at 7:52 PM Jeremy Begg <jeremy at vsm.com.au> wrote:

> Hello Jim,
>
> >       Hello Jeremy ,  You call a /home/eric/stop_eric.sh in your systemd
> >procedure ,  But forgot to insert the contents of the file in your
> missive .
>
> That's because I never wrote the 'stop_eric.sh' script.  Apologies for not
> saying so in my posting!  The other postings in this discussion have given
> me some ideas I might persue but for the time being it's not a critical
> item
> for me.
>
> Regards,
>
>         Jeremy Begg
>
> >On Fri, 29 Nov 2019, Jeremy Begg wrote:
> >> Hi Seth,
> >>
> >>> Has anyone got a clean solution for running a background SIMH process
> >>> that doesn't involve `screen` or `tmux`?
> >>
> >> My solution is pretty clean and doesn't require any kind of virtual TTY.
> >>
> >> I have SIMH running under Ubuntu Linux 18.04 on an Intel i3 NUC box.
> >> It took a little trial and error to get it all working (mostly due to
> >> Ubuntu's use of 'netplan' and 'systemd') but it works well enough for
> me.
> >>
> >> It's configured so that my SIMH VAX starts up when Linux starts up.
> >> I don't have it configured to shutdown VAX/VMS or SIMH when Linux is
> >> shutting down, but for my purposes it doesn't need to.  (Or I just
> haven't
> >> gotten around to it yet; the machine is only rebooted when I want it
> to.)
> >>
> >>
> ------------------------------------------------------------------------------
> >> # /etc/systemd/system/simh-eric.service
> >> # Starts SIMH at system boot to run ERIC the Half-a-VAX
> >> # Created 21-Jul-2019 by Jeremy Begg
> >>
> >> [Unit]
> >> Description=ERIC the half-a-VAX
> >> Requires=network-online.target
> >> After=network-online.target
> >>
> >> [Service]
> >> User=eric
> >> ExecStart=/home/eric/start_eric.sh
> >> ExecStop=/home/eric/stop_eric.sh
> >> RemainAfterExit=yes
> >>
> >> [Install]
> >> WantedBy=multi-user.target
>
> >--
> >+---------------------------------------------------------------------+
> >| James   W.   Laferriere    | System    Techniques | Give me VMS     |
> >| Network & System Engineer  | 3237     Holden Road |  Give me Linux  |
> >| jiml at system-techniques.com | Fairbanks, AK. 99709 |   only  on  AXP |
> >+---------------------------------------------------------------------+
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