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New, to me DEC PDP8E

Mike_Z

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Dec 1, 2013
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Near Milwaukee Wisconsin
Last winter I was at a friends machine shop, machining some new parts for my Model T Ford, I spotted an old machine in the corner. It turned out to be a what is called an NC machine, not CNC, but NC. It has not been used for 25 years and it has a DEC PDP8E computer in it. So I naturally had to ask about it. I expressed my interest in having this computer. At first it didn't get much response, but I kept asking off and on. Anyway, this last weekend I was notified that I could have the unit, so I loaded it up on my truck and brought it home.

It seems complete, as far as I know, not being too familiar with this computer. It is pretty well covered with a light coating of machine oil and you can see that water must have gotten on it from the rust on the top cover.

IMG_0184.jpg

IMG_0188.jpg

I made a cart for it, so I could move it around, it's heavy! I have not plugged it in and will not for a while. I'm worried about ruining something. I found the serial number, it is #8789. I got the cover off and it is full of cards. I suspect mostly I/O so it could control the machine tool.

IMG_0189.jpg

Today I wanted to see what damage the water did. I removed the front panel card and found that switches 0 & 1 of the switch register are corroded to the point of being froze. All the other switches move. The card itself has oxidation and some corrosion on it. The omnibus plug also is rather green. The other cards, so far do not look like they have been affected.

IMG_0190.jpg

IMG_0192.jpg

My plan is to try and get this machine to run. What I'm going to do now is just clean and determine what parts are needed, find documentation and replacement parts. I'm not in any hurry to go it going and will keep this thread updated as I go. I'm sure I'll have a bunch of questions and they will be here. Mike
 

DDS

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Just wow! Given your familiarity with vintage cars you know the term "barn find". Well, Sir, you just came across one heck of a barn find! Congratulations!
 

commodorejohn

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Rad. (Though I wouldn't assume all those cards are I/O - IIRC all but the very late-period LSI PDP-8s had a CPU comprised of multiple discrete logic cards, plus I imagine a number of those are ROM or RAM.) Did it come with any non-industrial peripherals (disk/tape storage, etc.)?
 

inotarobot

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Hello,

Did you happen to take photos of it while it was still in the NC machine ?

Maybe ask them if there was documentation they had ?

What happened to the NC machine. ?

Could be good to try and locate that and see what else there was that connected to this unit that can be used with some of the internal PCB's

I suspect it may have had Analog interface cards, or stepper motor controller cards in the 8e that talked to the NC machine.

lots more questions to find out about.

As others said there may have been extra peripherals that went with the machine, and maybe the person that gave it to you just trashed those or is about to trash those, NOT realizing you were hoping for the full machine.

Be worth a follow up ASAP if not sooner.

regards
David
 
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AK6DN

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Silicon Valley USA
No core. Strange. I wonder exactly what the data store is.

Looks like there are two core stacks in the middle of the front backplane (the sets of triplet cards connected with the four top blocks).

Could be either two 4K stacks or two 8K stacks.
 

jackrubin

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Chicago, IL and Buchanan, MI
Hurry back and, in addition to trying to get the answers to the questions that David suggested, try to find the other half of the rack slides that this computer came out of, if you can follow my mangled grammar! Then, when you get a chance, take some pictures clearly showing the part numbers on the tags on top of the cards. That way we can help you figure out their function.

Jack
 

billdeg

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Nov 18, 2003
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Landenberg, PA USA
Hurry back and, in addition to trying to get the answers to the questions that David suggested, try to find the other half of the rack slides that this computer came out of, if you can follow my mangled grammar! Then, when you get a chance, take some pictures clearly showing the part numbers on the tags on top of the cards. That way we can help you figure out their function.

Jack

I have one. Start with the power supply. Get that running first.
 

billdeg

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Landenberg, PA USA
BTW - "NC" is a DEC term I believe based on the fact that I have a PDP 11/05 NC and a PDP 11/05 S which are roughly from the same year as the 8e. Not sure what the NC stands for, but it could simply refer to the mounting box type.

I don't know if my 8e is an NC, but it is like yours with the power supply transformer on the side, not the back. The photo below is very similar to yours, this unit has Core memory..



My system contains:
M8330 - CPU 1
M8300 - CPU 2
M8310 - CPU 3

M837 - Time Share and for memory extention beyond 4K

M8650 - terminal I/O

M7104 - Controller 1 for RK05
M7105 - Controller 2 for RK05
M7106 - Controller 3 for RK05
(these have an "over the top" controller cover for all three of these drive cards)

M882 - Clock card

M847 - Bootstrap loader for RK05

M935 - Unibus Bridge

M849 - Shield for RF interference

G111 - 8K Core (there are 4 8K core cards in this system = 32K)

8320 - bus terminator

Bill
 
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inotarobot

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Hi again,

when I wrote the earlier post I was about to take my Lady, the 2hr car journey into a main hospital in the center of Melbourne.
Finally back now.

Another thing I note you dont mention is the special key for the power switch on LH side of front panel. Its not in your photos.

See if they have any original/copy DEC and or the NC makers software, on any format ie paper tape, mag tape or cartridge or even in printed format.

As part of the 'PROVENCE' of the 8e machine you have, would be good to get as much info on what it was doing during its working life.
I don't know of any that, ran machine tools in general business; Any 8e's i know of were in Universities or Scientific establishments running programs for things like Mass Spectrometers etc.



Also if they are trashing the NC machine and they have manuals on it, try and score them.

Just maybe they plan to scrap the NC unit and may be willing to remove any parts that this 8e directly connected to, like stepper driver pcb's, that may have been in a separate rack mounted chassis in same unit the 8i was mounted in.

If its possible to get that also, then it gives you something to use the 8e for, especially if you happen to acquire the stepper motors as well.

If you do get that extra stuff, and dont wish to keep it, I would put my hand up for having ( 4 having read even paying some $ for) the extra bits and boards to go in my 8e.

Also, if the rest of system and NC machine is still there, and you are able to have other bits, but dont know what to get; and there is time; just get heaps of photos and post here. I and the other here can give you some guidance what to ask for or what to salvage to go with the 8e.

Hope I am not rambling to much and being unclear. Been a long tiring day.

regards
David
 
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m_thompson

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Rhode Island, USA
Please take a picture of the top of the boards so we can see the "M" and "G" numbers. Then we can tell you what you have.

I have the PDP-8/e that was used by Datacut to compile their GRAFX CAD/CAM software for programming NC tools.
 

NeXT

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Looks like there are two core stacks in the middle of the front backplane (the sets of triplet cards connected with the four top blocks).

Could be either two 4K stacks or two 8K stacks.
I'm totally thinking of the wrong model core stack. My bad.
 

Doug G

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I'll chime in with "what a great find". You seem to have a nice basic PDP-8/E with lots of memory and a disk controller (RK05). Have fun with it!.
 

KC9UDX

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Wow, am I late to this party!

What is/was the machine??

What is/was the control?? The only one I am familiar with that would have used a PDP/8 is a Fidia, but the possibilities for this are limitless.

The machine itself interests me more than the PDP/8. :D

The water probably wasn't water; it was cutting coolant, which can be any number of things. Usually though, it dries in a conductive film. I wouldn't power anything up without running each card through the dishwasher.
 

Mike_Z

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INOTAROBOT, no I didn't take any pictures of the machine, but I did ask about documentation. All they had was stuff regarding the machine tool itself. Nothing on the DEC. The NC machine is still there.

Jack Rubin, I'll post photos as I take them.

Billdeg, I have the front panel board on the bench now and plan on cleaning it. It is oil covered and has some oxidation on it also. A couple of switches are froze. I figured that I can power this board up by itself after it is clean and check it out and repair as needed. I figure on looking at the power supply after that. I'm sure the capacitors need to be looked at and I will not power it up with any parts of the computer connected.

INOTAROBOT, I do not have the barrel key, but I'm sure I can find one or make one. No software. It was all on paper tape, and mostly destroyed. The machine tool will remain unused as it has for the last 25 years.

I'll have to ask more about the machine, wasn't much interested in it.

Here are a couple pictures of the card tabs. The front cards must be the computer parts and the back cards the green ones are mostly all the same.

IMG_0198[1].jpg
IMG_0199[1].jpg
IMG_0200[1].jpg
IMG_0201[1].jpg

Thanks Mike
 

AK6DN

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Is it safe to dishwash core?

Put a 35 year old core module in a dishwasher? Are you really serious? I wouldn't even use a vacuum or air blower on it, unless at very low air velocity.

A (large enough) adjustable ultrasonic cleaner with distilled water might be all that I would consider. Otherwise just leave it alone.
 

Marty

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Jul 26, 2009
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Boulder , Colorado USA
Hi All;

I agree with Don, the cores themselves would most likely make, BUT, You would have to acquire the Lost art of Threading the cores.. And getting the wire that would be used for the threading, I don't know if it is special wire or not.. I Years ago worked for a company that had, before I came, wired Cores.. By the time I got there, we were wiring and assembling modules using Ram Ic's..

THANK YOU Marty
 
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