[Simh] Unattended background SIMH process

[Johnny Billquist]

On 2019-12-05 01:34, Paul Koning wrote:
> 
> 
>> On Dec 4, 2019, at 6:15 PM, Kevin Handy <khandy21yo at gmail.com> wrote:
>>
>> 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 a PDP11, this could be handled via a power fail interrupt, assuming the OS you have supports power fail and recovery. RSTS-11, with core memory (so you'd want to persist the memory across restarts) does. I'm not sure if others do.  (RSTS/E does not.)

Right. And all members of RSX do handle power fail and recovery. 
Individual programs can also be notified if a power fail even happened 
while they were running, in case there is something they need to do 
under such circumstances.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol