[Simh] NetBSD 5.1 on MicoVAX 3900 boot error

[Mark Pizzolato]

On Saturday, April 22, 2017 at 12:55 PM, Anders Magnusson wrote:
> Den 2017-04-22 kl. 18:01, skrev Mark Pizzolato:
> > [...]
> >> qt0 at uba0 csr 174440 vec 764 ipl 17
> >> qt0: delqa-plus in Turbo mode, hardware address 08:00:2b:d3:52:d9
> > [...]
> >
> > Thanks for checking this Peter.
> >
> > Meanwhile, since NetBSD 6.1.5 works, and NetBSD 5.x.x doesn't, these
> > questions arise:
> >     1) What is different in that driver between those NetBSD versions?
> I looked at the CVS logs and no bugfixes to the qt code.

It might still be worth explicitly comparing the qt code between these 
NetBSD versions.

I compared (from the simulator's point of view) the sequence of interactions 
with the simh XQ device done by qt on both NetBSD 5.x and 6.x and they are 
identical up to the point where 5.x crashes.  

> >     2) Why were these differences introduced?
> >     3) Are you sure the qt driver NetBSD 5.x.x truly worked on real hardware?
> I have had a 3900 using qt since loong time ago, running NetBSD 5 at last.
> Not around for me anymore though.

It would seem to me that this could be debugged on the simulator along 
with code, link map and knowledge about what else is really going on if 
the driver code is actually unchanged between NetBSD 5.x and NetBSD 6.x.

- Mark