[rescue] FA: PDP11 Qbus cards CPU and Memory

[Greg A. Woods]

[ On Sunday, March 24, 2002 at 21:19:04 (-0500), Dave McGuire wrote: ]
> Subject: Re: [rescue] FA: PDP11 Qbus cards CPU and Memory
>
>   Umm, no.  SOME PDP11s have Unibus.  Some have Q-bus.

You miss the point entirely Dave.  Only "Micro"PDPs had a Q-bus.  Except
the orininal PDP-11/03 (which I forgot about in my first post) and then
the much later PDP-11/23-PLUS (and its baby brother the PDP-11/23-S).

There have to exceptions to all these marketing things....  Other than
those though there are no PDP-11's I know of with a Q-bus.  From a
marketing perspective that's the defining difference between a PDP-11
and the LSI-11's and later MicroPDP-11's.  Four years of DECdirect
catalogues and related system documentation on my shelves have
consistently used these terms to separately identify the Q-bus 11's from
the UNIBUS 11's all the way through the 1980's.

Indeed the original designation of the Q-bus was "LSI-11 bus"!

There's also another sure designation of Q-bus vs. UNIBUS for the
post-1980's machines, and that is of course that all 11/x3 machines are
the former and 11/x4 machines are the latter.

> > LSI-11's aka MicroPDP-11's have Qbus (or Unibus) (with the one exception
> > of the PDP-11/23-PLUS, which is a Qbus "micro" system, which is also at
> 
>   Umm, no.  An LSI-11 based system is a PDP11.  To my knowledge, there
> are no PDP11 systems, regardless of bus, that say "LSI-11" on the
> badge.

Oh, come on Dave.  If you don't have one then surely you would have
checked google before making such a reply!

I'm pretty sure I still have the majority of parts of an LSI-11/03
system somewhere.  The original front panel really did say "LSI-11".

There was an original LSI-11 (a chip set, a board, and a system), then
the LSI-11/2, the LSI-11/03, the LSI-11/23, and then finally the
MicroPDP-11/23 and on.  I've heard rumours there was an LSI-11/73, but I
don't know if that was an official name of a system, or just the name
for the an 11/70 "on a chip", aka the J-11.

> > the core of the so-called "Personal PDP-11", aka the "Professional 3xx"
> > series)
> 
>   Umm, no.  The Pro series are based on the F11 and J11 processors,
> a.k.a. LSI-11,

You'd do best not to argue with a guy who not only had one such machine
(since traded up to a "real" PDP-11), but also still has a "PDP-11
Systems And Options Catalog, January-March 1985" sitting here on his
desk open to the page titled "Professional 300 Series -- The Personal
PDP-11".  :-)

The F-11 is of course what's in an 11/23, and the J-11 is what's in an
11/73 (only in the 380 it's clocked way down at 10MHz because of a
design flaw -- it could have gone 18MHz, but not the 20MHz the original
design called for).

> but they have nothing akin to either Q-bus or Unibus.

Ah, yes, on that point you're absolutely right --  the Professional 300
series used the "CTI-bus"

-- 
								Greg A. Woods

+1 416 218-0098;  <gwoods at acm.org>;  <g.a.woods at ieee.org>;  <woods at robohack.ca>
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