[Simh] help needed booting SIMH 11/780 simulator (to run SysVR3)

[Rob]

Hi,
I'm trying to run a disk image from a VAX 8830 running SysVR3.2c
using SIMH.  My current approach is to run the 11/780 simulator but
I'm having trouble booting it.  I may have the wrong VMB.EXE file
or I may simply have hosed up the configuration file (part of the
boot directions involve a call to ROM but I don't know if that's
necessary, part involves poking values into memory (which I've multipled
by 4 assuming the original interface was using 32-bit words, I'm
guessing $200 as the load address for the vmb since the manual uses
a symbolic name "START").

I'm hoping somone can provide a working configuration file and perhaps
the VMB code for SIMH 11/780.

Any help is appreciated.  Please respond directly to me as I'm
not on this mailing list.

Thanks,
Rob Ginn
rob at olg.com

ps:

In case there are other suggestions as to how to approach the
problem, here is a summary of what I've done to date:

I started by trying to get SIMH to boot the 8830 disk image - despite
big architecture issues.  I had many problems but by digging through
memory and looking at the assembly code I determined that the VMB
code in the microvax image I had was not compatible with the boot
block format used by the microvax.

I eventually managed to get SIMH to boot the disk image by manually
replacing the 1st sector with a bootblock that was compatible with
the microvax.  Unfortunately, I was unable to get past the stand-alone
shell into the main UNIX OS because the architecture between the
88xx and microvax 3900 is too different.  However, SysVR3.2c is
supposed to support a microvax too so I tried to build a new kernel
for the microvax on the 8830 but the 8830 is too unstable for any
real work and the source code refused to build for that target (due
I thought to many patches applied over the years).

I located the original install media (9 track tapes and TK50 tapes)
and was (gasp!) able to read almost everything using an old Sun,
and old microvax w/NetBSD net-booted, and a small program I wrote
to pull off the tape files (with automatic record size detection).

I then tried to run through the install process but SIMH (with the
ka655 rom) would not boot the TK50 stand-alone restor tape image.
I suspected it was a difference between the ka655 and the ka630 so
I pulled the ROMs off a ka630 board and used a prom burner to read
them.  I wrote a program to combine them into a ROM image but being
unsure how to arrange them I tried all 4 logical permutatiions.
Sadly, neither SIMH or TS10 would boot into ROM with this image,
let alone boot the tape.  So, there must be other logical permutations
I didn't think of.  I deferred this approach ...

I decided to extract the root filesystem (from tape 1 of the
distribution) using other means.  The tape looked like a VMS backup
format (via cat -v) so I tried stand-alone backup programs under SIMH.

I tried the openvms stand-alone boot cd but that stand-alone backup
program said that the image was not correct.

I also tried a microvax-II stand-alone backup tape (one I pulled
off TK50 tape using my program) and it also complained about the
format (although slightly differently).  I therefore guessed that
the format of VMSBACKUP images has changed over the years.

I tried to manually extract the root filesystem by locating the
bootstrap code in the file and trimming the VMSBACKUP junk in front
of that but it wouldn't boot.  Replacing the bootblock on that also
failed -- it started to boot but then hung.  I suspected that the
disk image was incorrect (especially because it wasn't a multiple
of 512 bytes).

I guessed that the data I wanted had many wrappers involved so I
downloaded vmsbackup and hacked it to read from a series of files
(instead of tape).  I then did some experiments and added code to
it to dump a physvol type of record.  I then replaced the first
512 bytes with a microvax bootstrap.

I was finally able to boot into the stand-alone shell from the
original 3.1 install media - Yeah!  Unfortunately, although my
documentation indicates that this should support the microvax, that
version of the UNIX kernel was not present.  Only vaxbi and vax7xx
kernels were present (it's probably on the end of the single tape I
couldn't read the end of due to serious tape damage [section of
missing media, the tape is clear for about a foot] in the middle
of the tape to a different file -- I may try to chop off the front
of the tape and splice on a new leader since the damaged file is
certainly not necessary and I think it's the same as a file on
an upgrade tape I was able to read ...).  Thus I couldn't run
a distribution kernal on the microvax.

So, the approach is now to boot the image using SIMH 11/780 and
then try to build a microvax kernel from the source.

Which brings me back to the top of this email ...
(thanks for reading all this)