[Simh] VAX 780 emulation - How to install Netbsd

[Johnny Billquist]

On 2014-12-28 18:02, Anders Magnusson wrote:
> Mark Pizzolato - Info Comm skrev den 2014-12-28 03:02:
>> As it turns out, there were issues with booting and basic installing
>> of NetBSD on the older VAX systems.  Much of NetBSD evolved after the
>> relatively low cost MicroVAX systems were very common.  It seems that
>> although some folks with older VAX hardware (VAX750, VAX780, VAX730
>> and VAX8600) may have been running NetBSD, they didn't install it from
>> CD media, but merely upgraded existing older BSD operating system
>> installs.
> I may be able to give some explanations here that can be helpful (as I
> was the one that actually ported NetBSD to VAX).
> Modulo some memory errors, this was >20 years ago.
>
> It was originally ported to 750 /w RP06, since that was what I had
> available.  I wrote three ways to load /boot (required both for
> installation and booting the system)
> - Fetch from the TU58 (to also get the needed microcode update). Older
> boot ROMs only accepted microcode patching if booted from TU58 by some
> reason.
> - Fetch from TU77 (key in a program in hex on the console).
> - Fetch from RP0x (using boot ROMs).
>
> The boot program could _not_ be loaded from VMB, neither from RA disks
> (missing boot ROMs, was added by DEC to some machines).
>
> Then we got hold of a 780, so I ported over NetBSD there.  Could only be
> installed from TU77 via hex load code typing.
> But;  subsequent loading of the system required boot to be loaded from
> the RX01 floppy, so it had to be copied there (using arff).
> boot could not be loaded via VMB, it had to be put in memory from the
> loader script.
> Note that the NetBSD 1.2 VAX release were put together on a 11/780. It
> took 11 days to compile the system and 2 to gzip the distribution files :-)
>
> The 8600 port was done similar to the 780.
>
> The MicroVAX port was written by Rick Macklem, and since these machines
> have some sort of sub-VMB in ROM the first parts of VMB-support were added.
>
> Around 2000 the boot procedure was finally altered so that VMB could be
> used as the boot program.
> Also other stuff like memory sizes are read from the RPB setup by VMB
> these days.
> But; when this was done virtually no big VAXen were still running, so
> the support for them may have bit-rotten.  This is what Johnny always
> encounters when he tries to power up his 8600 ;-)

Heh... Yes, which is why I also keep a copy of boot on the RL02...
But booting of my 8650 usually works fine, using VMB. But since I don't 
often upgrade boot blocks, things occasionally are messed up in current 
without me noticing.
Things have become easier to spot since simh added support for the 86x0 
machine, as I occasionally try more odd things that way.

Note that NetBSD will not boot on an 86x0 machine with more than 64MB of 
memory at the moment. Something broken that I have not had time to look at.

> So; bottom line:  If installing NetBSD on a non-MicroVAX machine, it is
> a safe bet to put the boot program on console media :-)

Agreed. It helps. But it also required that you know a bit more of how 
you do what...

Also, if booting older machines using VMB, you need to know the magic 
bits of R5, since it requires the same treatment as Ultrix. R5=0 will 
not boot NetBSD (or Ultrix).

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol