[Simh] Problem booting RSX11M on pdp11 (halt at loc 0)

[Mark Pizzolato]

On Sunday, March 25, 2018 at 11:53 AM, Phil Fisher wrote:
> Further to recent communications on this topic (for which many thanks to
> those persons) and some thinking I have a potential/possible reason that I
> would like comments on.
> 
> My thinking goes that if in the virtualisation setup I have the "disk" is not
> responding quickly enough for the RL driver in SimH then maybe it will return
> a buffer of zeros.

That theory is not correct.  "Time" for the RL simh device is measured in 
instructions simulated AND disk transfers occur immediately after that
number of instructions (BEFORE executing another instruction).  This makes
the simulation insensitive to the host system's CPU speed and I/O rates.

> Now even if I am on the right track for this, it leaves some questions (in no
> particular order):
> 
> a) others have reported being able to use SimH 4.0  under virtualisation with
> no issues although not with RSX11M.  So why would I be different?
> b) I would have thought that the driver for RL especially as it is emulating
> hardware would not "timeout" so quickly.
> c) If it did timeout, why have I not seen an error message?  Maybe I need to
> look somewhere else ... hmm.

There is absolutely no problem running simh in a virtual environment.
The simh PDP11 can even run within a simh VAX simulator running inside
a Virtual PC.

Odds are very good that your pdp11 boot disk image is corrupted
OR there is something else odd about your configuration file

> And the obvious statement that I am completely wrong and it is something I
> have configured incorrectly either in the virtualisation environment (except it
> gives same error under both Virtual Box and VMware Workstation) or in
> SimH.

The version you're running was released approximately 9 years ago.  The 
latest code can be working on your Linux system in a couple of minutes:

       $ wget https://github.com/simh/simh/archive/master.zip
       $ unzip master.zip
       $ cd simh-master
       $ make pdp11
       $ cp BIN/pdp11 {someplace}

Odds are that you will experience the same results with the latest code, but 
it may be easier to understand what is happening.

For your Windows system you can get the latest prebuilt windows binaries 
from https://github.com/simh/Win32-Development-Binaries

If you still have problems you can create an issue at 
https://github.com/simh/simh/issues and work through exactly what is wrong.

- Mark