[Simh] Booting the vax750 simulator.

[Kevin Handy]

It would be interesting to know what R0 is trying to point to.

Is it just a bad value, memory that should be mapped, a device, ...

Source would be helpful, if you could figure out what the source is (likely
compiled C, since it;s Unix).

Since the simh code for the devices are mostly the same (?I think?) between
the VAX processors, could this be a bug in memory management? Does the 730
have a unique MMU? Anyway, it seems to be something different in simh
between the 730 ans the other VAX processors it boots fine on.

On Mon, Jul 6, 2015 at 2:13 PM, Ethan Dicks <ethan.dicks at gmail.com> wrote:

> On Mon, Jul 6, 2015 at 3:41 PM, Mark Pizzolato - Info Comm
> <Mark at infocomm.com> wrote:
> > Hi Mattis,
> >
> > I’m working with the disk image you provided.  I see the failure on the
> > VAX750 simulator.
> > Have you tried earlier versions of Ultrix on the 750 simulator?
> >
> > I initially look at the crash message:
> >
> > sim> b rq0
>
> In a similar vein, some months ago, I was trying to find why that
> wouldn't boot 4.3BSD on a Simh 11/730 RB730 disk and I got as far as
> tracing into BSD's driver rb.c since it was very early in the process
> that things went sideways.  I wouldn't be surprised if these two UNIX
> boot failures were related - differences/assumptions in how drivers
> will treat controllers in VMS that don't apply to UNIX.
>
> > machine check 2: non-existant reference error
> >        sumpar  = 2
> >         va      = 80001a90
> >         pc      = 80087c61
> >
> > I note that the PC mentioned is: 80087c61.
> >
> > If I do the following:
> >
> >      sim> BRE 80087c61>
> >      sim> SET CPU HISTORY=300
> >      sim> B RQ0
> >
> > Execution flows up to the indicated address and if I single step from
> there,
> > the exception is taken.
>
> I at least had (still have) the source for 4.3BSD.  I did narrow
> things down quite a bit, but then I ran off to learn more about how
> the disk controller works and haven't put any time into it for a few
> months.
>
> -ethan
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