[Simh] Simulating power fail

[Paul Koning]

> On Sep 7, 2018, at 1:24 PM, Mark Pizzolato <Mark at infocomm.com> wrote:
> 
> On Friday, September 7, 2018 at 10:12 AM, Paul Koning wrote:
>>> On Sep 7, 2018, at 12:37 PM, Mark Pizzolato <Mark at infocomm.com> wrote:
>>> 
>>> On Friday, September 7, 2018 at 1:18 AM, Lars Brinkhoff wrote:
>>>> Timothe Litt wrote:
>>>>> Adding an API in the CPU of the form assert_powerfail( vector) - where
>>>>> the default is the usual 24/26, but a ROM can specify an alternate
>>>>> (usually its base address + 24/26). This is common to all initiators.
>>>> 
>>>> This touches on something else I have been thinking about.
>>>> 
>>>> Would it be appropriate to have a SIGTERM (and/or similar signals) trigger a
>>>> power fail in the PDP-11 and other simulators with corresponding
>>>> mechanisms?  SIGINT goes into the SCP console, and of course SIGKILL
>> instantly
>>>> switches off the simulated machine.
>>>> ...
>>> 
>>> Alternatively, I've got a simulator that's been running via a script in a
>>> background process for 10+ years.  The script it is running under receives
>>> one of these signals and that immediately drops out of sim_instr() and the
>>> script is configured to SAVE the simulator state to a file.
>> 
>> That's a fairly simple scripting exercise wrapped around SIMH.  You can catch
>> the signal, send control/E to get the sim> prompt, then suitable examine and
>> deposit commands to simulate a trap to 24.
> 
> SIGTERM and SIGINT already are caught in simh and when delivered they
> cause exit from simulator instruction execution and return to sim> prompt.
> No need for an extra wrapper or for sending control/E.

What I meant is that a wrapper can provide the controlled software shutdown, by talking to the software running in SIMH, and SIMH itself.  That way you can run the OS of your choice on the simulated machine of your choice, all nicely controlled from the host startup and shutdown machinery.

	paul