PDP 11/05 S vs 11/05 NC

[Mattis Lind]

2015-12-15 3:15 GMT+01:00 william degnan <billdegnan at gmail.com>:

> On Mon, Dec 14, 2015 at 1:33 PM, Mattis Lind <mattislind at gmail.com> wrote:
>
> > 2015-12-14 17:12 GMT+01:00 william degnan <billdegnan at gmail.com>:
> >
> > > Just to change the subject..
> > >
> > > There were "S" and an "NC" version of 11/05 high profile system.  Why?
> > >
> > > I am curious if any DEC historians here know the reason for two
> versions
> > of
> > > the same DEC PDP 11/05 *high profile* computer (not talking about the
> low
> > > profile).    There are separate manuals for each type.
> > >
> >
> > Age? The NC (and ND if you are in 230VAC area) are in the BA11-D chassis
> > which uses the H750 PSU. The same chassis was used by for example 11/35.
> > The H750 PSU has partly the same assemblies  as the low PDP-11/05 chassis
> > and then also a H744. The memory system is somewhat different in that the
> > H214 is 8kW and the H217 is 16kW and the former is used in the NC/ND
> while
> > the S uses the latter.
> >
> > But of course there can be all sorts of other reasons as well.
> >
> > /Mattis
> >
> > >
> >
>
>
> Yes I did know that power supplies and RAM are different within the two
> versions, being that have both types of 11/05.  That's what prompted my
> question  - *why* did they make these two versions of the high-profile
> 11/05?  What was one used for vs. the other?  *Why did DEC do this*?
>
> It is simply that as long as the box had the M7260/M7261 CPU cards it was
> an "11/05"? (or 11/10)
>
> Those of you who knew DEC back then may have a perspective I don't on the
> subject.  Seems to me that they did not care, they just used what they had
> available.
>

Yes, and my guess that they are of different vintage. The BA11-D is the
older box used for the NC and the BA11-K is the more modern box used for
the S model. Over the years the memory requirements increased and thus they
had to increase the density.

I think the NC/ND models are the first 11/05s along with the low cabinet
model. The a few years later the S model was added.

/Mattis

>
> --
> Bill
>