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PDP-12 #435 at the University of Minnesota Duluth

Wes Clark observed that he thinks he was involved in an initial batch of about 50 LINCs, and then when DEC took over they sold another 50 or 60 or so. Lab/8s I don't know about, but it's kind of interesting to think that by the time your 12 came out it had lapped all previous LINC models combined, possibly twice or three times!
 
Yeah, that is an interesting observation! Seems like far and away the most numerous incarnation of the LINC, at least at the time. (Not sure what remains of any of them.)
 
pahp said:
Yeah, that is an interesting observation! Seems like far and away the most numerous incarnation of the LINC, at least at the time. (Not sure what remains of any of them.)
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I always wondered how many Artronix PC and their derivatives were made/sold?

Vince
 
They seem to be super rare outside the medical community in St Luis. Possibly important to the development of MUMPS, etc. though.

Vince
 
Well, I finished testing the untested flip chips in the top half of the backplane. I found 3 FCs with what seem to be clear failures -- two M216's (Six Flip Flops) and an M103 (Device Selector). I still need to learn how to interpret the output from the FCT in order to figure out what needs to be done to fix these modules.

1673297950857.png
 
gnupublic said:
When I first came to the barn, I saw it standing there:
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🎶 Well, it was just fifty-one
You know it will be fun
And the way it looked --
rusty barn and dusty air
So how could I fix up another
Ooh, when I saw it standing there? 🎶

(with apologies to Lennon/McCartney)

gnupublic said:
So this is number 580! Will be fun to work on it!
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Yes, very exciting! Is there a year on it anywhere? Wikipedia says that 725 were built and it was discontinued in 1972, but their reference for that is another website. I'm looking for more confirmation about the end date and number of units sold.
gnupublic said:
It is quite good equiped, EAE, as far as I see. I will post more, when I have some progress.
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Nice! Let us know how we can be helpful.

I also see that your has the 8K expansion, which lets your machine address up to 32K.

Congrats!
 
pahp said:
Well, I finished testing the untested flip chips in the top half of the backplane. I found 3 FCs with what seem to be clear failures -- two M216's (Six Flip Flops) and an M103 (Device Selector). I still need to learn how to interpret the output from the FCT in order to figure out what needs to be done to fix these modules.
Click to expand...
Update: sent logs of the failures to @vrs42 and @m_thompson to learn how to interpret them, and they determined that the test case for M103 was incorrect. With the change, our M103 now passes all tests. So, that just leaves the two M216s failing in the top half. I'm going to now start testing everything I can in the bottom half while I prep my classes, and hopefully later this week will fix the two M216s. (I think we have equivalent chips in our stash that Warren and Dawson procured for us way back when.)

@vrs42 -- I think I'm going to submit a patch that tests a flip chip n times and then flashes all the lights / rings the terminal bell when it's done. I keep forgetting to set my kitchen timer...
 
The backplane of #435 has two planes six FC wide.
The #580 has the lower backplane 8 FC wide.
From the Maintenance Manual Volume III I have two versions, from 69 and 72. The later has the 8 FC wide lower backplane.
Is there a production number with the change from 6 wide to 8 wide lower backplanes?


There are three different production numbers for the PDP-12 I find: 725, 755 or 1000.

1. (755)
The PDP-12

Date of introduction: 1969 (February or earlier).
Date of withdrawal: 1973.
Total production run: 755.
Price: $27,900

2. (725)
in en.wikipedia.org article PDP-12

Release date 1969; 54 years ago
Discontinued 1972; 51 years ago
Units sold 725

3. (755)
in de.wikipedia.org article PDP-8

PDP-12 1969–1973 (?) 755 $ 27.900,00 TTL

4. (1000)
in Computer Engineering - C. Gordon Bell, J. Craig Mudge, John E. McNamara,
chapter 7:
(https://gordonbell.azurewebsites.net/Computer_Engineering/00000198.htm)
PDP-12
Projekt start 6/67
First shipment 6/69
Withdrawn 6/75
Number produced 1000
Price(minimum) $28100


Here at dustyoldcomputers (http://dustyoldcomputers.com/pdp12/location.html) you find a list (last entered date from 2008) of some PDP-12.
There is one PDP-12 with #729.
That makes me believe, that 725 is a typo from 755.

This list is not complete, meanwhile I know (inluding my #580) three more in Germany. One functional at Computermuseum-Stuttgart and a partly functional at Computer Cabinett Göttingen. Maybe It's worth to start a collection of existing PDP-12s.

Have fun,
Volker
 
Thanks for this, @gnupublic ! Yes, a running list of all known PDP-12s is something I was hoping to start (and still will, unless you want to). It does not feel like the end date and total number of units produced is very definitive.

I did not notice that your backplane was 8 FCs wide on the bottom! Good point! I wonder about that production change, too.
 
Update on our FC testing project. We are about 2/3 of the way through testing all the flip chips that are currently testable with Warren's tester. We have approximately five columns left to test in the bottom half of the backlane.

Previously I reported that we had a failing 103, and two failing 216s. After I asked @vrs42 and @m_thompson to help me understand how to interpret the errors from the tester, and they consulted DEC documentation, they realized that the test for the 103 had a bug. @vrs42 updated the test vectors and tested one of his 103s, and it worked. I got the fix to the m103 test, and that solved that problem.

Today, one of my students and I tested a bunch of chips in the first column of the lower half. Shortly after I left, he discovered an m617 that fails. So, there's another one to fix.

Honestly, I love getting news like this, because these are all fixable things, and once they're fixed the machine should be much more functional and reliable.

As always much thanks to @vrs42 and @m_thompson for their invaluable help and mentorship.
 
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