What did computers without screens do?

William Donzelli wdonzelli at gmail.com
Mon Dec 14 17:58:16 CST 2015

I am starting to think that the age of the PDP-8 is finally coming to
a close. The last bastion of PDP-8ness - controlling machine tools and
industrial processes - well, think about that. When was the last time
you *actually* *saw* a PDP-8 in production doing this? The US has very
little left in the way of machine shops. They have mostly all closed
up and moved to China, and the ones that survive do so because they
upgraded their machines so their productivity can trump the Chinese
currency imbalance.

I was at HGR recently, and asked about machine tools and PDP-8s, and
the salesman said it has been years since they have seen that stuff.
What is coming out now is basically 1980s technology, at the oldest.
Most of what they see is 1990s and 2000s.

Yes, there are probably a *very* few PDP-8s still out there, but I
think that population number is approaching single digits.

Here is a challenge - show me a real PDP-8 (or clone) still in active
service. I want real evidence, not hearsay. I think it would be great
if they were still out there, doing their thing, but I am very


On Mon, Dec 14, 2015 at 5:16 PM, Ian S. King <isking at uw.edu> wrote:
> And think of all the PDP-8s *still* buried in the control units of
> factories across the world.  The majority of these machines had no
> displays, not even teleprinters.  Some had custom controls wired in through
> stock or custom modules, and some had no more "UI" than the front panel
> ("set switches 2 and 3 to the 'on' position and press the 'run' key").
> Some didn't even have that - the stock 8/m was a turnkey system.  The
> reasoning was the same as that behind the microcontroller replacing the
> 555: complex behavior could be modeled in software rather than intricate
> analog elements, and it was easy to change things if you needed to (e.g.,
> if you changed out an instrument or effector.  -- Ian
> On Mon, Dec 14, 2015 at 12:16 PM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
>> On Mon, Dec 14, 2015 at 2:05 PM, Mike <tulsamike3434 at gmail.com> wrote:
>> >> On Dec 14, 2015, at 12:34 PM, Chuck Guzis <cclist at sydex.com> wrote:
>> >>
>> >> The subject brought up the thought of how many display-less computers
>> we encounter every day without giving it a thought.  I think that probably
>> 100 would be a safe bet.
>> >> Looking over past this screen, I see my network hub, mouse, keyboard
>> and heaven knows how many display-less computers inside the actual shell of
>> my PC.
>> >
>> > .... if you think about it almost everything we touch has some kind of a
>> computer cycle! ! ! GREAT POINT!!!
>> Even lighting... I've pulled (and reused!) 8-pin PIC microcontrollers
>> out of discarded emergency lighting.  "In the old days", a switching
>> supply might have a 555 timer for an oscillator.  These days, an 8-pin
>> uC is cheap ($0.75 or far less) and allows the behavior to be changed
>> without a soldering iron, or allows the hardware design to be
>> completed and sent out for manufacture before the software is
>> complete.  If you want to change the frequency of a 555 oscillator,
>> you have to design in a potentiometer or remove and install different
>> value components.  If you want to change the frequency of a uC
>> oscillator, you reprogram it (or if you have enough pins, design in
>> some removable jumpers).
>> Short version is, even the cheap and simple 555 has been replaced in
>> many products with a cheap-as-or-cheaper-than microcontroller, not
>> because it's simpler, but because it allows for greater flexibility
>> and reduces the overall product cost.
>> -ethan
> --
> Ian S. King, MSIS, MSCS, Ph.D. Candidate
> The Information School <http://ischool.uw.edu>
> Dissertation: "Why the Conversation Mattered: Constructing a Sociotechnical
> Narrative Through a Design Lens
> Archivist, Voices From the Rwanda Tribunal <http://tribunalvoices.org>
> Value Sensitive Design Research Lab <http://vsdesign.org>
> University of Washington
> There is an old Vulcan saying: "Only Nixon could go to China."

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