VAX 11/750 Config and Diagnostics, anyone?

J Blaser oldcpu2 at
Thu Nov 15 01:48:58 CST 2007

Quoting Patrick Finnegan <pat at>:

> If you want some reference information, I assembled information 
> other pages, and information I discovered myself while setting up 
> 11/750, and have it here:

Yes, yes!  That's a very informative page you have there.  I'm 
surprised I overlooked it so far.  Thanks for pitching it to me.

> > I've now got the following installed in the backplane:
> >
> > <nothing> in CMI slot 1 (still looking for the optional L0001 FPU)
> > L0002 (DPM) in CMI slot 2
> > L0003 (MIC) in CMI slot 3
> > L0004 (UBI) in CMI slot 4
> > L0008 (PCS) in CMI slot 5
> > L0006 (RDM) in CMI slot 6 (optional, I guess, but came with 
> > boards) <nothing> in CMI slot 7 (I pulled the SI9700 from this 
> > <nothing> in CMI slot 8
> > <nothing> in CMI slot 9
> > L0016 (CMC2) in CMI slot 10
> >
> > M8750 (1MB RAM) in 'extended' slots 11-18 (8MB total)
> This sounds reasonable.  There are jumpers on the CMI 

Good to have your comments.  I've never had to build up a system 
'from scratch'...always had more or less functional systems come my 

> backplane, which
> you will need to set appropriately, both to tell the system that you 
> have an RDM card (though I'd probably just pull it out, but you'll 
> still want to check that it's set properly), and for the CMI option 
> slots (7-9).  If I recall, all the information necessary should be 
> printed on labels attached to the steel cover over the backplane, 
> behind the back door of the VAX.  In any case, if it's missing, I 
> a photograph of the label, which looks readable enough to me, on 
> site, above.

You know, my system included that printed label on it's door, too.  
Of course, that door was nearly the first item removed when I started 
cleaning the whole system up, and to tell the truth, I haven't 
touched it since.  I just spaced the fact that I had it at all.  It's just 
sitting in a corner waiting for a sort of 'final' reassembly in the future. 
 Again, thanks for pointing this out.  I can reference mine.  (And, yes, 
your photo is entirely readable.)

> > M9202 (Unibus 'joiner') in slots 19 and 20
> > M7485 (DZ11) in Unibus slot 21
> > <nothing> in Unibus slot 22
> > <nothing> in Unibus slot 23
> > <nothing> in Unibus slot 24
> > <nothing> in Unibus slot 25
> > <nothing> in Unibus slot 26
> > <nothing> in Unibus slot 27
> > M9313 (Unibus Term) in Unibus slot 28
> You will need to have G727 or G7273 grant continuity cards in all 
of the
> empty slots.  However, you should be able to do some basic tests 

Ah, I don't have any of those.  Being a unibus noob, let me ask if I 
can just move the M9313 terminator up, right 'behind' the DZ11, 
and skip the empty slots?  Or is there some 'special' wiring on the 
unibus backplane.  Admittedly, I've only worked with simple qbus 
stuff to date, and a backplane with wirewraps all over it has me a 
little nervous, to say the least.  :)

> without it, as the UNIBUS is a secondary CPU on the VAX, the 
> will still function even with a messed-up UNIBUS (at least to some 
> extent).  You probably won't get too far in booting anything, 
> with a broken UNIBUS grant chain.

Well, we'll see how far we get, *if* I can find some diagnostic 

> > I still don't have any mass storage interfaces (to support my RA81
> > and/or x2 Fujitsu SuperEagles...still looking for UDA50, Dilog
> DU256,
> > and/or Emulex UD33), but I was hoping that I have enough 
modules to
> > start testing the CPU, anyway.
> A UDA50 probably will be easier to find, though a 3rd party 
> (as long as it's not SCSI) will probably be cheaper if you can find 
> one. :)

Yeah, I'm on the hunt right now...I just don't want to spend a fortune, 
so I'm bargain shopping!  :)

> > contained CPU and system diagnostics.  I'm hoping someone 
has a set
> > of these tapes imaged somewhere that I could download and 
give a
> try.
> I might have some tape images...somewhere.  I found them online 
> somewhere, quite a few years ago, but can't find them anymore.  
I'm not
> sure what I have though, they may be more like VMS standalone 
> tapes, or something else.

Well, if you turn up anything, please let me know.  So far my search 
for online images has turned up nothing.  I'm sure someone, 
somewhere has them posted, but so far I'm drawing a blank.

I suppose I could just 'go for it' without doing any diagnostics, but 
until I get some kind of mass storage attached there's not much more 
that I can do with the system.

Also, I'm just wanting to assure myself that this hodge-podge 
collection of boards from various sources will actually work as a set.  
If I have a bum board I'd like to know it before I start trying to do real 
installation of VMS or whatever.

Many thanks for the pointers.  I'll get back to learning about CMI and 
Unibus backplane configuration...

- Jared

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