PDP 11/05 S vs 11/05 NC

william degnan billdegnan at gmail.com
Mon Dec 14 20:15:23 CST 2015

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


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