[Simh] Multiple telnet ports in SimH to RSTS/E 9.6

[Mark Pizzolato]

On Saturday, January 2, 2016 at 11:20 AM, Paul Koning wrote:
> > On Jan 2, 2016, at 6:20 AM, Johnny Billquist <bqt at softjar.se> wrote:
> >
> > On 2016-01-01 23:01, Paul Koning wrote:
> >>
> >>> On Jan 1, 2016, at 4:56 PM, Will Senn <will.senn at gmail.com> wrote:
> >>>
> >>>
> >>>
> >>> On 12/31/15 2:10 PM, Will Senn wrote:
> >>>>
> >>>> Paul Koning set me straight on figuring out that DZ, as configured, was
> actually working. Duh, press RETURN twice to get BAUD detected properly,
> then all is right in the world. The other devices might work too, but since DZ
> worked, I'm happy.
> >>>>
> >>>> Thanks for responding.
> >>>>
> >>>> Will
> >>>>
> >>> Oh. And one other thing. Not only do you have to press enter twice, for
> BAUD rate, but the main console session has be be started and
> timesharing/system startup has to be finished before you can attach another
> telnet session. I think this may have been the problem I was having originally
> rather than the BAUD rate. I had started the telnet session and booted the
> disk, but I hadn't started timesharing, when I fired up telnet on port 10001.
> >>
> >> That makes sense.  Until you've started timesharing, you're in a program
> called INIT, which is essentially the RSTS OS loader.  It's a standalone program
> that talks only to the console, as well as the disks on which RSTS lives (and, in
> limited ways, the  tape drives for accessing RSTS kit tapes).   None of the
> other terminal lines are enabled at that time.
> >>
> >> If you say "Start" for "start timesharing" (instead of just entering Return
> or "Yes") it does a somewhat more verbose startup which tells you about
> each controller that's disabled because it's not visible.
> >
> > If I read Will right, it does not make sense. Yes, you will not get any
> response until timesharing have started, but you should be able to telnet
> into the port as soon as simh has started. And once timesharing is running,
> you should be able to get a response. I don't think there is any reason why
> you would have to have even doing the telnet until timesharing have started.
> I know that you don't have to wait under RSX.
> 
> Yes, it would seem reasonable that the telnet connection would go through.
> And indeed it does.  I just ran that test.
> 
> Specifically, what happens when a RSTS system is in INIT: the telnet server in
> SimH accepts the connection, as usual.  But you do NOT get the "Connected
> to the PDP-11 simulator DZ device, line 0" message.

You don't get this due to the DZ device driver not having set the "Master Scan 
Enable" bit In the DZ CSR.  The DZ device only looks for incoming connections 
after this bit has been set.  Some operating systems (VMS) set this bit when 
the driver is loaded, clearly others (RSTS) must do it later OR maybe the driver 
isn't actually loaded until timeshareing is enabled...

Other MUX simulators generally will accept incoming connections whenever 
the device has been ATTACHed and simulator is executing instructions.

- Mark