[Simh] VAX/VMS

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On Tue, 16 Feb 2016 11:52:17 -0500
Paul Koning <paulkoning at comcast.net> wrote:

> 
> > On Feb 16, 2016, at 9:56 AM, Timothe Litt <litt at ieee.org> wrote:
> > 
> > ...
> > Nonetheless, Brooks (@IBM) definitely gets credit for the first
> > commercial line of architecturally (forward) compatible machines.  Prior
> > to that inspiration, every new machine was unique and most software
> > started over (including compilers).
> 
> I'm not sure that "first" is accurate.  If in the sense of a series of
> machines for which that feature is specifically marketed, perhaps.  But
> the PDP4/7/9/15 is another example that started somewhat earlier.  (PDP1
> doesn't quite match, as I understand it.)  CDC 6000 series definitely
> fits your definition, and those came out at the same time as the 360.
> The Burroughs B5000 series is somewhat older (1961, says Wikipedia).

More correctly we should say the IBM S/360 was the first series of
computers to be designed around an architecture so that the smallest and
largest models in the lineup were all architecturally identical (mostly!)
and that could all run the same OS (mostly). The upward compatibility came
later, but was enabled by a lot of sound architecture decisions including
one design regardless of capacity.

> Of all those, the IBM 360 descendants are perhaps the most commercially
> successful, and also probably the longest lived.

Not perhaps or probably, but certainly.