VAX-11/730 %BOOT-F-Unexpected Machine Check

Peter Coghlan cctalk at
Tue Jun 9 11:57:07 CDT 2015

> The issue that I'm having at the moment is that when I try to boot from either
> that RL02 pack or the R80, VMB.EXE reports "%BOOT-F-Unable to locate BOOT
> file". I don't know yet whether there's something not-right about the
> contents of the hard drives, or I need to configure something (?) so VMB.EXE
> knows what to look for.

There can be more than one system root on a VMS system disk, typically one each
for different nodes in a cluster, maybe under [SYS0], [SYS10], [SYS11] etc and
standalone backup can sometimes be found under [SYSE], if installed.

"Unable to locate BOOT file" may indicate that you are not reading the correct
system root or it may indicate that the disk is not bootable or maybe something
entirely different.  I am not well up on the 11/730 and I hope someone more
familiar with their system specific details will chime in.

On some other VAX machines but probably not an 11/730, the [SYSE] root would be
booted by entering something like:

boot /R5:E0000000 <device>

or maybe:

boot /R5:E000000 <device>

or maybe even:

boot <device>/E0000000


boot <device>/E000000

> The boot scripts on the console boot tape appear to set up VMB.EXE by shoving
> numbers into some registers prior to loading it, and I have not yet located
> any documentation about what the numbers mean.

If it is like other VAX variants that I am familar with, the top eight bits
(or maybe four bits - I forget which?) of the 32 bit number that ends up in
register R5 is what selects the system root you end up attempting to boot.

> I wonder if I might be able to back up the hard drives to an absurd number
> of emulated TU58 images, so that I could then examine those on my modern
> machine?

That sounds plausable.  If you backup to a saveset on the emulated TU58, BACKUP
should prompt you to change emulated tapes each time they fill up.

> I could probably back up onto magtape, but I don't have another means to
> read the tapes yet. I have another tape drive (which needs repair) that
> I'll eventually include in my PDP-11/44 restoration, but that's a big
> project, far in the future.

Good luck with that one!

> I wonder if the VMS5.3 standalone backup might know how to back up to some
> network device? I have an ethernet card in the VAX, so that might be a way
> to get data off the machine for examination.

Standalone backup is not network aware.  You need to get VMS booted before you
get to use the network.

> Any suggestions or clues would be greatly appreciated! I'm still learning how
> to tell the chickens from the eggs.

Looks like you're doing well so far!

Peter Coghlan.

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