[Simh] Booting the vax750 simulator.

[Ethan Dicks]

On Wed, Jul 8, 2015 at 2:24 PM, Clem Cole <clemc at ccc.com> wrote:
>> > Definitely try a different disk.  UNIX device drivers do not use the
>> > hardware the same way that VMS drivers do.
>> >

My words, I think...

>> The VAX 750 UBA Buffered Data Path CSRs hadn't been implemented in the
>> original VAX 750 simulator and Matt's testing probably only was done on VMS.
>
> I'm amaze it was not found by now.   Amazing..

I'm not surprised at all.  It just took a case to expose the
difference and some persistent sleuthing.  Well done, all!

>>
>> They are now implemented and Ultrix boots just fine.
>
> Thank you!!

Yes, indeed.  Thanks to all who put some work into this.  Next: why
doesn't the RB80 boot 4.3BSD on a 11/730?   (if anyone wants to tackle
it, I'm happy to share my findings to date.  I hit a wall due to my
own limitations of understanding of the original hardware).

-ethan