VAX 11/750 Config and Diagnostics, anyone?

Patrick Finnegan pat at
Wed Nov 14 23:54:21 CST 2007

On Wednesday 14 November 2007 20:15, J Blaser wrote:
> After a little effort, I think I now have the minimum boardset
> required to fire this baby up.  But just to make sure that yours
> truly, a complete Unibus and  big-iron VAX noob, has it figured
> correctly, I wanted to run my configuration by you guys before I
> shoot off my right foot (which would, of course, leave me with only a
> wrong foot).

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

> 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 other
> boards) <nothing> in CMI slot 7 (I pulled the SI9700 from this slot)
> <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 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 have 
a photograph of the label, which looks readable enough to me, on my 
site, above.

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

> 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 interface 
(as long as it's not SCSI) will probably be cheaper if you can find 
one. :)

> After reading through the various docs found on and
> it appears that a standard set of TU58 DECtape II
> carts were included with each system.  Several of these carts
> 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 backup 
tapes, or something else.

Purdue University ITAP/RCAC       ---
The Computer Refuge               ---

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