[rescue] huge DEC rescue in TX?

Jonathan C. Patschke jp at celestrion.net
Wed Feb 2 08:08:26 CST 2005

On Wed, 2 Feb 2005, Wai-Sun Chia wrote:

> PDPs doesn't even have socket arrays!

That's funny.  There are quite a lot of socketed chips on mine.

> That's why they last so long! The Unibus PDPs have all discrete TTL
> CPUs; i.e. the CPU is implemented in multiple boards.

That is, indeed the case.  The point I was making was that the craziest
they got with connecting things together was the occasional socket here
and there.  Most everything else is soldered or, in the case of the
backplane, wire-wrapped together.

> Whereas the more "modern" Qbus/LSI-11 PDPs have microprocessors, they
> are just 40-pin DIP packages. Even so, the "CPU" is in around 3 to 4
> 40-pin ICs...

I think the "CPU" is just a single 40-pin DIP.  The others are the MMU
and additional microcoded instructions.  Everything about that platform
is an amazing study in efficiency and conservative[0] engineering.

[0] Well, aside from the 11/70.  There's -nothing- conservative about
     that beast.
Jonathan Patschke   )   "Let me hear you make decisions
Elgin, TX          (     without your television."
USA                 )        --Depeche Mode, "Stripped"

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