[Simh] tty magic(?) for talking to bootloaders?

[Mark Pizzolato]

On Saturday, September 21, 2019 at 4:03 PM, Tom Perrine wrote:
> So far I've got Multics, V7 and BSD4 running on SIMH in Google Cloud 
> Platform (GCP). I'm packaging some of these up into more turnkey images 
> and scripts so that more people can easily play with these Grand Olde 
> Operating Systemes.
>
> My end goal is a script that can be run on your local computer that 
> creates the cloud instance, installs and upgrades the OS, compiles 
> SIMH for the target HW, and boots the guest OS, all without any 
> needed input. I've got everything EXCEPT how to kick the OS boot in 
> the OS bootloader(s).
>
> My problem is that I probably haven't spent enough time with the docs 
> to figure out how to feed scripts "past" SIMH and into the bootloaders.
>
> I'd also love to be able to inject commands into the SIMH process 
> through the API, but that's a different story.
>
> For example, the PDP-11 V6 boot looks like this:
>
> test-pdp11:~$ !80simh-master/BIN/pdp11 dboot.ini
> PDP-11 simulator V4.0-0 Current        git commit id: d40268d1
> Disabling XQ@
>
> Now how do I get scripted input into the simulator so that I can give the 
> bootloader the "unix" filename at the @ prompt?  I have the same problem 
> with the Multics bootloader, too.

Put the following command in your dboot.ini file just before you start 
instruction execution with a BOOT, RUN, GO or other similar command:

	EXPECT "@" SEND "unix\r"; CONTINUE

If the prompt is really "@ ", then adjust accordingly.

See HELP EXPECT and/or HELP SEND for more details.

- Mark