2 Oct
2009
2 Oct
'09
3:04 p.m.
I have never seen one alive, but I have the remains of one: logic unit
boards, miscellaneous generic flip-chips, some I/O boards, etc.
Unfortunately, no backplane. This was the original PDP-14
(Straight-14?). It was to have a core-rope ROM in the final installation
vs. core. I think there were later versions that had writable program
storage.
Shoppa, Tim wrote:
The PDP-14 was not a conventional computer... it was
what we call today a PLC
(programmable logic controller). Very adaptable to ladder logic and a bit more.
Very primitive, but the right thing for discrete logic control.
I have some notes about it here: http://www.chdickman.com/pdp14/
I think Motorola had a 16pin dip logic unit that did basically the same
thing.
DEC was pretty swift in how they allowed the PDP-14 to
be configured via a real computer (a -11 or -8). It wasn't the GUI of PLC
configuration today or even of the 80's, but it was a good start.
The parts I have came from a system that was to have run a stamping
press. In this case, the PDP-14 was basically a discrete I/O adapter for
a PDP-8/e.
The overall model of PLC configured or monitored by a
computer still holds true today, I think that DEC could have really taken this idea and
run with it but the overlap between industrial control and computers even today is less
than thorough. The computer geeks don't understand the industrial control and process
engineers for the most part (thus the common misuse of Windows PC's where a PLC could
do the job far better and without point-and-drool.)
PLCs to control the process and PCs to monitor the process. I don't know
that I want Vista in charge. It might be only a tool, but that tool
might be very expensive.
IMHO if you are interested in PDP-14 you must also be
interested in early Modicon PLC's, which were far more common, predate the PDP-14,
used core memory like the PDP-14, and which the PDP-14 was pretty much a clone of. I think
Modicon was also a Massachusets company like DEC.
The cool thing about MODICON is that a simple protocol that they devised
has been widely implemented. It has become a least common denominator
language for communication between devices and controllers.
-chuck