[Simh] Unattended background SIMH process

[Paul Koning]

> 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.)

	paul