Sorry, this languished in my inbox for a while because it didn't have
a recognizable subject. I don't recognize the machines, either, but
maybe somebody on the PUPS list does.
If you are receiving this email, it is because I found
your name during a
websearch about 'classic computing'. At any rate, I have obtained two
computers and I'd like to find out what they are. if you could help me
identfy them i would greatly appreciate it. I was told by the source of
these computers (who seemed very convinvced) that they were PDP-4
computers. Every site I've seen that covers the pdp-4 says that there were
only about 50 of them ever sold. However, Digital's own site does mention
that some were sold for nuclear applications, and the computers I got were
indeed from a nuclear lab.
The thing is, there doesnt seem to be any mention of "Digital" or the PDP
I'll describe the computers:
One looks newer, it says "Tracor Northern TN-1610" on the faceplate. It
has 18 ligts across the face and 18 switches directly below, in a bank
labeled "Switch Register". There is another bank of 6 ligts labeled
CPU BUS, VIRT, PWR, BUS, USER"
There is a small bank of 3 switches labeled ADDR/DATA, PHYS/VIRT, and INTR.
There is a last bank of 6 switches labelled LOAD ADDR, EXAM, CONT,
ENAB/HALT, START, LOAD DATA. There is also a power switch.
On the bottom of the faceplate is a logo raised in plastic which I didn't
understand until I looked inside the case and found a circuit board which
said "California Data Procesors" (the logo said "CDP" in a funky
style), I've never heard of CDP- perhaps I heard "PDP4" when he actually
The second computer looks older. (1960's vs. 1970s).
It's faceplate says "ND812" and "Nuclear Data Inc". There is a
switch labelled "Select Register" with the following positions: Status, S,
R, K, J, Address, PC, External.
There is a keyswitch with three postions: Power off, Power on, Control off.
There is a bank of 12 lights, labelled "Selected Register", the lights are
labelled 0-11 and an extra (13th) light labeled "Overflow".
There is another bank of 12 lights, labeled "memory Register", again
labeled 0-11. Next to it is a pair of lights labeled "Memory Field" 0 or 1.
next to that is another pair of lights labeled "Run" and "Interrupt.
Under the lights is a bank of 12 switches labeled "Switch Register".
There are two switches simply labeled 0 and 1.
There are two switches labeled Start and Stop
Another two switches labeled Load AR and Load MR
Another two labeled Next Word and Cont
And another two labeled Step and Instr
The older computer seems put together in a complicated sort of way (stacked
PCB's wired together) whereas the newer one is more modular (I.E. large
cards that are simply slide in and out of sockets.)
Both seem to have core memory but it's arranged in such a way that I can't
actually see it with out breaking some paper seals which I dont want to do
unless necessary. The parts of the boards that I can see have intricate
patterns that seem to indicate core memory (plus the guy told me that they
both used core mem).
I have a (kind of lousy) digital camera and i can take pictures of the
faceplates if you think this might help in your identification.
As I said, both were in use in a lab. The older one has a set of two tape
drives (they look to be regular audio cassette size) and the newer one has
one tape drive. However I was supplied with piles of punched tape programs
(i guess there was a tape reader with these computers at some point?) i was
given a lot of documentation but most of it has "NDI" written on it and it
is about taking nuclear data measurements.
Both are in large rackmount cases (which I don't have) and were mounted
with other equipment.
I'm interested to know what these computers are, how much they cost when
new, and what their capabilities are. Supposedly they were replaced by a
single $4000 MCI interface card in a PC.
If you have no idea but you think you know someone who might, please do not
hesitate to suggest that person to me.
Thank you for taking the time to read this email.
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