[Simh] PDP11 on Simh for public access

[Paul Koning]

> On Jan 18, 2018, at 10:40 AM, Bryan Davies <bryan.e.davies at gmail.com> wrote:
> 
> Many thanks to all for the advice.   Unfortunately I'm still not quite there.

There is an easy solution if you have a recent RSTS.

The OS keeps date and time in location 1000-1004.  That is preserved across boot, and if on entry to INIT those locations contain what seems like a valid date, that's used as the system date/time.  This is why the more recent versions of RSTS don't prompt for date/time if you do a restart (SHUTUP with restart) or use the BOOT command in INIT.

Second, if you're running V10.1, the "Start timesharing" prompt has a 10 second timeout, and will default to "yes" (i.e., start RSTS) at that point.

So if you start SIMH with a startup script that deposits the date in 1000, and time in 1002, then issues the SIMH boot command, RSTS INIT will pick up that date/time and after 10 seconds will go on to start the OS.

RSTS date format: (year-1970)*1000 + day_in_year
RSTS time format: 1440 - (minutes_since_midnight)
RSTS seconds: 60 - (seconds_since_minute)

For example:

$ pdp11 pdp11-42.ini 

PDP-11 simulator V4.0-0 Beta        git commit id: d3b6018d
sim> d -d 1000 32004 
sim> d -d 1002 720
sim> d -d 1004 30
sim> bo rq
?
Thu Jan 18 11:02:00 2018

RSTS P10.1-L V101XM (DU0) INIT V10.1-0L

04-Jan-02 12:00 PM


Start timesharing? <Yes> NO

I entered the values in decimal (with -d) for convenience.  You can see the correct date and time are picked up by INIT.  Seconds are not displayed here but they are saved, so you can set them if you want to be that precise.

	paul