View Full Version : random rescude from a demolition site m768

April 13th, 2011, 07:50 PM

looked like a qbus card so i grabed it off the wall in a building i was sneaking around it thats set for demolition soon
it apears someone was raiding resistors off it sadly

anyone know what exactly it was for googling comes up with a pdp8 but nothing much els
did hunt around to see if i could find a unit sadly nothing

April 13th, 2011, 09:05 PM
It's a PDP-8 DEC Flip-Chip (http://www.pdp8online.com/pdp8cgi/query_docs/view.pl?id=801) [that's a good site btw]

M768 Delay Transmitter Rev F PCB E February 1971

It's part of a TU10 Tape Drive (http://www.textfiles.com/bitsavers/pdf/dec/magtape/tu10/EK-TU10-MM-007_maint_Aug77.pdf). I love these pneumatic tape drives like the TU10 and the TE16. Used to sit and watch em operate. Totally cool.Still worth rescuing from oblivion. Don't feel too sad for the rest, it probably went to scrap steel in China. Maybe they'll choke on it.

April 13th, 2011, 09:34 PM
looked like a qbus card so i grabbed it off the wall in a building i was sneaking around it that's set for demolition soon
it appears someone was raiding resistors off it sadly

anyone know what exactly it was for googling comes up with a pdp8 but nothing much else
did hunt around to see if i could find a unit sadly nothing

The M768 is a delay gizmo, used with the TU10 tape drive. It appears to decode the operation based on the inputs, and to delay the decoded signals by the correct amounts. Also seems to buffer the signals from the drive to/from negative logic
levels. (Check out the PDF link at the top of the post by RSX11M+.

I think those empty spots used to be diodes, like the little glass diodes next to them.


April 13th, 2011, 10:13 PM
sweet txs for the info as for tape drive theres one of these sitting there

April 13th, 2011, 10:21 PM
YA BABY! Go get her!

vrs42's post must have overlapped mine. The links take you to web folders with manuals, schematics, everything.

April 13th, 2011, 10:46 PM
i would not have a place to put that thing
though i should get in contact with the owner and see if they got any pdp's in the other building that still locked up tight or a vt100 or something

April 13th, 2011, 10:48 PM
Oh no....

Another subject for my nightmares.

Major bummer. :(

How far is Winnipeg from Ohio?

April 13th, 2011, 10:51 PM
i29 runs right into winnipeg and its in canada

7hrs drive from mineapolis st paul

April 17th, 2011, 07:59 PM
Got a nice pdp 8a sitting in a half demolished building a temping to rescue it got a nice bunch of software there's also a teletype x2 one with what appears to be a modem or something as it's got a rotary dial on it

April 17th, 2011, 09:14 PM
An 8A? Nice find.

April 17th, 2011, 11:07 PM
sorta shame they were guna bulldoze it right into the ground

o well found it in time


6649 witch has a H219A atached to it

and 4 other partial cardw with no model on the side of them

April 18th, 2011, 01:48 AM
That is a nice find!

Here is what you got:

M8315 – KK8A PDP-8/A CPU board (hex wide)
M8317 – KM8AA PDP-8/A bootstrap, powerfail (hex wide)
M8316 – DKC8AA PDP-8/A I/O serial/parallel/clock (hex wide)
G649 – MM8AA 8K Core stack.
H219A – MM8AA 8K Core memory control.

So it is G649 not 6649. You have a complete PDP-8/a. The other boards could be third party.

Lou - N2MIY
April 18th, 2011, 02:54 AM
Most excellent find! This is a nice little haul indeed!

The photo shows two bags with some 8-1/2"x11" papers in them with a dec papertape in front of them. Those are diagnostic programs on those tapes, and the papers included are the instructions and listings. Can you tell us the names of those diagnostics? Not all the listings have turned up and it would be interesting if you have any of the missing listings.

What's in the rest of the pile of papers?


April 18th, 2011, 08:16 AM
thers 3 bags of pdp tapes atactualy

the pile of tapes laying loose apear to be prgrams for the spectromitor that was allready striped of some parts

the pile of papers cover the unit and the machean it came in and some sales catilogs and some drawings for the unit and the macheane

could not find the tape drive for it would my h10 work with a pdp 8?

April 18th, 2011, 08:47 AM




the 4 cards are specific to the machean pulled them out ones not even a card just some sorta spacer



April 18th, 2011, 12:07 PM
WOW... stuff looks freshly minted.

Nice to see unburied treasure for a change.

April 18th, 2011, 12:13 PM
is there anything in there that could fill the gaps?

April 19th, 2011, 04:48 PM
am i wasting my time transcribing 1-4k ms8-a mos memory test?
or any of the other books that came with the dec pdp tapes in the ziplock bags?

April 19th, 2011, 05:28 PM
am i wasting my time transcribing 1-4k ms8-a mos memory test?
or any of the other books that came with the dec pdp tapes in the ziplock bags?
Heck NO!

...not that I need them. Anything PDP-8 is precious. Think like an historian... or an archaeologist.

April 19th, 2011, 05:32 PM
700 plus lines in the smallest one guna be up a while i guess haha using google docs if anyone wants to see what i have just pass me an email and i'll invite yea to view

Lou - N2MIY
April 19th, 2011, 05:51 PM
These listings are not on pdp8online.net. I have parts to build an 8/a (no front panel though, like my 11/04) and so am intersted in all of these diags. I'll send a pm.

Did you grab the teletype in the picture?


April 19th, 2011, 07:37 PM
yes i got both the teletypes as of now curently in my shed i will get one of them in the house as soon as i get the dust off it with the compressor and theres manuals and i scored on rolls of paper for them also

o and lou empty ur pm box u filled it up

April 20th, 2011, 12:35 AM
yes i got both the teletypes as of now curently in my shed i will get one of them in the house as soon as i get the dust off it with the compressor and theres manuals and i scored on rolls of paper for them also...

Printer paper and Paper Tape... boy there was a shocker... can't believe the paper prices.

I bought an LA120 a couple years ago... [right after I got my ASR33] almost fell over when I heard the price of a box for 11x17 tractor-feed fanfold. $65... Geeze!!

Anyway... thanks for the PM... I'll sleep much better knowing you're saving the past for posterity rather than letting the Chinese get the stuff for scrap steel.

April 20th, 2011, 12:49 AM
this apears to be in good shape do i dare try it after its sat for at least 9yrs? though prolly won't atempt to turn on till i get one of ths asr33's going

the other cards that were in the unit

90-503-h rev 0

90-545-y rev 1

90-503-g rev 1

Lou - N2MIY
April 20th, 2011, 02:30 AM
Ok, I did some housecleaning and made some room in the inbox.

It looks like you had to make some room in the shed! I am very glad you got TWO teletypes!

The G8018 is the power supply for the 8/a chassis (chassis model H9300). The other three cards are intersting also. I see that on one of them the etch says Fisher Scientific. These boards must have connected to some scientific instrument, maybe the spectrophotometer that is mentioned on the cover of one of the other manuals. At any rate, the board with the big black box in the middle is pretty nice. It has dual 12 bit analog to digital converters on it. Hang on to that one, some day I may want to swap you someting for it. (Hang on to all of them, of course!)

I am almost afraid to ask, but what other treasures lurk inside this building? Did you look inside boxes for other spare boards that might have been kept for this system?

As I think about what I have seen pictured, I guess this 8/a ran a scientific instrument, and the program that ran the instrument was loaded off papertape from the teletype. This would explain the plastic tapes in the little plastic boxes that had "operating system" or something like that on their lables.


April 20th, 2011, 12:33 PM
from the papers i found theres a whole corispondance giving history of how this machean came to be definatly going to put it into a binder and keep it as a token to this macheans past with photos and such cause sometimes the story that goes with the unit is facinating



gotta go back and look through the books see what other drawings that are laying around

grabed a shelf full of these binders

April 20th, 2011, 01:08 PM
Thats an awesome find.


Lou - N2MIY
April 20th, 2011, 03:21 PM
Awesome that you got the schematics that go with those three boards. The machine looks like a Jarrell Ash spectrometer. Here is a brochure on a slightly newer version: http://www.scribd.com/doc/38521223/Jarrell-Ash-Spectrometer-Brochure

There will be some beautiful optics in the box on the top of the machine. The door on the top right is where the sample goes. The stuff to the left has the optics. I would have loved to have this machine when I was in grad school!

This machine was for doing metallurgical analysis. Maybe they were studying ore since you have a lot of mines in your neck of the woods.


April 20th, 2011, 06:20 PM
they were using it to check for the amount of led they were sending up the smoke stack

anyhow someone pointed me to something called the greenkey mailing list notr sure how a mailing list works ecatly

so i have 3 teletype manuals and 3 for the jarrell-ash witch has more drawings and info on the cards in the pdp

my googleing of the machean found it came with aple 2e in latter versions

April 20th, 2011, 11:18 PM
Heh, Inside the Jarell Ash machine there is another PDP-8/a or a PDP-11/34 (I can tell from the low resolution picture)

April 21st, 2011, 12:42 AM
aww thats the one i got

April 21st, 2011, 01:35 PM
1-4k mem test now scanned now 24pages into 200 page DKCA-AA OPTION CARD TEST#1

Mike Chambers
April 21st, 2011, 02:06 PM
holy resistors! that's an amazing haul.

April 21st, 2011, 02:34 PM
holy resistors! that's an amazing haul.

haha indeed only thing is i broke thee golden rule in urban exploration to do this witch i fallow to the teeth so this actualy made me feel really conflicted but after finding out the bit of extra stuff i rescued will fill a whole makes it worth that much more to me

allmost 100pages in now


now doing cpu test 1

April 21st, 2011, 04:20 PM
cpu test
https://docs.google.com/leaf?id=0Bwfh3w-st3iPNGNhNGYyYjYtODkwMC00OGFkLTg2YzUtOTMzNDM2NmExN mIy&sort=name&layout=list&num=50

still figuring out google docs

hows one make this stuff into pdf's?

April 22nd, 2011, 05:45 PM
WOW, I am super jealous of this find, you did an amazing job taking what you could!

April 23rd, 2011, 02:08 PM
got the one unit in the house now fired it up took some time to figure out how to load the paper apears i need a new ribbin and it prolly does need servicing but works none the less just gotta figure out how to use it and such

also when i was looking at the other unit as i had to pull it out to get it out of my way apears some sorta gear was taken off it from the motor looked it over and found an envilope with drawings in it and a modem
someone prolly bought the 2nd one for parts



May 3rd, 2011, 05:51 PM
Had the asr33power up it types dose the page feed not sure how to go to next line though as it's stuck on the far right? Prolly need an oiling have to go through the green key mailing list for that info I imagin anyhow turned the pdp8 on no smoke fans ran good so now just matter of getting my asr up and learning how to boot a pdp least I got the diagnostic software for it

May 11th, 2011, 04:26 PM
so buried in the documents i have the bill of sale


May 11th, 2011, 10:38 PM
and then i went back and found 3 bundles of dec eltrical drawings and another set of teletype drawings


and the missing parts from the second teletype and a pile of ribins for it

May 14th, 2011, 09:12 PM
the pdp8a apears to be working had it fired up still learning as i go here but i was back at the location and found a operators manual sweetness so played with the display panel apears to be working so now i am making copies of the tapes i have to run the diag tests and see what i get.


August 27th, 2011, 01:43 AM
found another 7 tapes i had missed on a shelf to my amazement
so now i have a boot strap

i've had it runing a counter program succefully that i manualy entered. but still can't get the teletype to engage the reader must be something sticking somewhere as it does receve a signal from the computer and trys to do something.

ii can now say i have a pdp8 in my bedroom lol

November 14th, 2011, 01:42 PM
picked this upgrade of ebay

DR-118A Dataram Memory Board 16k

Lou - N2MIY
November 14th, 2011, 02:33 PM
Yeah, I had seen that on there for a while. Did it come with the core stack?


November 14th, 2011, 06:44 PM
aww stak? feels like an idiot now

November 14th, 2011, 11:01 PM
looks like it could have the core stack sandwiched in there.

Lou - N2MIY
November 15th, 2011, 02:49 AM
Stand the card on edge and take a side view picture for us (that way we can see if the core stack is there or not.)


November 15th, 2011, 03:39 AM
soon as i have the card i shall

December 20th, 2011, 10:38 AM
video of the card


nige the hippy
December 21st, 2011, 03:15 PM
Looking good! - it's certainly a stack!

Lou - N2MIY
December 21st, 2011, 04:36 PM
Agreed. Now put it in the 8/a and fire it up!!

Did you find an RX8E or RL8A for any mass storage?


December 21st, 2011, 05:35 PM
before i install it i wana know witch slot should it go in? or does it matter what order i have it in with the other cards?
see here whats already pressent

not yet would like to also find a rl02 drive
but did nab 2 of those really cheap rl02 platers i found on ebay and then posted on the classiccmp mailing list so others could join in on the crazy deal as i nabed 2 of the 10 avail . the lister had them listed as rlo2 instead of rl02 lol

January 2nd, 2012, 07:29 PM
i duno if i just wasted my money on this or not

January 18th, 2012, 06:31 PM
seems to be alive duno what other stuff i can do to test?
my fans started to make a noise i see hmm

and my rl02 platters came in

and my asr is prolly due for some oiling?