[pups] Identifying old computers (was: [no subject])

Greg Lehey grog at lemis.com
Wed Aug 30 12:24:28 AEST 2000

On Friday, 18 August 2000 at 13:37:39 -0500, Spoof wrote:
> Hello!

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
> name anywhere.
> 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 "RUN,
> 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 '60s
> style),  I've never heard of CDP- perhaps I heard "PDP4" when he actually
> said "CDP-4"?
> The second computer looks older. (1960's vs. 1970s).
> It's faceplate says "ND812" and "Nuclear Data Inc".  There is a rotating
> 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.
> -Kev
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