The Last of The Line

[Johnny Billquist]

Patrick Finnegan <pat at computer-refuge.org>  skrev:

 > On Saturday 19 May 2007 06:35, Johnny Billquist wrote:
 > > > "Glen Slick" <glen.slick at gmail.com> skrev:
 > > >  > On 5/17/07, Rod Smallwood <RodSmallwood at mail.ediconsulting.co.uk>
wrote:
 > > >  >> > OK we have a change
 > > >  >> >
 > > >  >>> > >PMI memory goes in slots 1 and 2, CPU goes in 3
 > > >  >>> > >joe lang
 > > >  >> >
 > > >  >> > Rod
 > > >  >
 > > >  > From my understanding of this after looking at various manuals 
this
 > > >  > is true for an 11/73 or 11/83 with an H9872 backplane in a BA23
 > > >  > box, but not for an 11/84.
 > > >
 > > > Correct. So if people could stop assuming that an 11/84 have a q-bus,
 > > > we would get a long way towards clearing this up.
 > > > If people don't know about the 11/84 or 11/94, don't write answers
 > > > based on your knowledge of the q-bus based KDJ11 setups.
 >
 > My "11/94" (which was an upgraded 11/84, and which I got CPU-less)
 > actually does have a QBUS... it's got an Able Qniverter to hook the
 > UNIBUS in the chassis to the QBUS from the CPU, and both QBUS and UNIBUS
 > peripherals.
 >
 > Does anyone know how common that was?  I don't see any evidence pointing
 > towards it not being designed that way by DEC.  The chassis is DEC
 > badged, with a label on the side indicating that it was upgraded from an
 > 11/84 to be an 11/94 at some point.

Pat, what you have is what I would describe as an 11/93 with an 
Qniverter. That will not be exactly the same thing as an 11/94.
The KTJ11-B, which is DECs Unibus adapter, have some special signals to 
the CPU telling it that the KTJ11 is there, and that changes the 
behaviour of the Qbus, according to the manuals.

I haven't said that the wiring of the memory slots in an 11/84 (or 
11/94) isn't the same as in a Q/CD backplane. It must (by default) be 
atleast very similar to a Q/CD backplane. However, there are some 
special signals, and also some signals that change behaviour in an 11/84 
and 11/94, according to the manuals. And that will only happen if you 
have a KTJ11-B in there.

	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