A very sad PDP-8/S

Guy Dunphy guykd at optusnet.com.au
Sat Nov 3 03:00:18 CDT 2018

At 01:29 AM 3/11/2018 -0400, you wrote:
>yes... the I/O for a tty is on a separate  mounting outside the cpu I recall for some reason...   I need to pull out or S and another classic 8 from storage.   as I recall there is a spare cLassic 8  front panel... snd it can find a new home.

If that's an offer that would be amazing! 
I only received this machine on Thursday, opened the box properly on Friday and found it was missing such
such major parts. It belongs to the ACMS (Australian Computer Museum Society) but with the way things are
going with them and their storage space ongoing misfortunes, I may be 'looking after it for them' indefinitely.

I had expected finding an existing spare front panel would be impossible.  Was just begging for sympathy.

Next question - is a classic 8 panel the same as an 8/S panel?

>The S I want to.put in museum display next to our classic in there and the spare one will display off site...
>it is in a blue Dec 8 rack... one in museum has plexiglass card surrounds.
> Ed#

My one will definitely be getting a case of some kind made. With no bottom shell, the wire-wrap plane
pins are exposed and on the bottom. Very high risk of damage. A few pins are bent, but nothing that can't
be fixed. No visible damage to the actual wire wrapping.

The way they managed to get such a dominant and regular theme of 45 degree wire wrap runs is beautiful.

>On Friday, November 2, 2018 Lyle Bickley via cctalk <lbickley at bickleywest.com; cctalk at classiccmp.org> wrote:
>On Sat, 03 Nov 2018 15:13:16 +1100
>Guy Dunphy via cctalk <cctalk at classiccmp.org> wrote:
>> This is rather sad.
>> I've received a PDP-8/S. It turns out to be missing so much, that
>> it's probably beyond restoration. Anyone who can think of potential
>> ways to find the missing parts, please speak up.
>> http://everist.org/pics/PDP-8S/
>> Missing:
>> - Front panel PCB, 
>> - Case top AND bottom, 
>> - Power supply.
>> - Some flip-chip slots are empty. Not sure if supposed to be.
>I have a restored and running PDP-8/S.
>It looks to me that you're not missing modules - the open slots are
>for the I/O cables.

Ah ha! I hadn't yet had a moment to go hunting bitsavers etc for data.
It also came with four ring binders of software manuals. I'll list their
contents tomorrow (going out tonight, will be a long night I suspect.)

>The P/S is a standard DEC linear P/S and can be easily substituted until
>you come across the real thing.

Good. Was the power supply external? I can't visualise where it fitted inside
this machine, unless it was in the case lid space above the flip chips cards.

>You need to get the schematics for the version of the PDP-8/S you have
>and check the modules in your system against the module chart.

Next question - in this pic http://everist.org/pics/PDP-8S/20181102_1567.jpg
is the "700" some kind of model number, or a serial number?

>When you say the front panel PCB is missing - do you mean that there
>is not a large circuit board with incandescent lamps in the system?
>That would seem unusual to me - given that all the switches are on the
>front panel.

See pic. There is a machined insulating panel with holes for the lights and
screw mounts for the LEDs PCB, but no PCB.

I am guessing the lights were all filament bulbs not LEDs? Maybe  modifying for
LEDs may be a good idea. Or doing a subsitute PCB layout.

>> Also there's no sign of any I/O circuitry.
>There is NO I/O on a PDP-8/S. The I/O cables connected to any I/O that
>Please get a PDP-8/S service manual and schematics...

Yes, next up.

>> A curse on slack people who remove stuff from a machine for servicing
>> or whatever, then never got around to putting it back. Resulting in
>> this kind of tragedy.
>I may not be as you think...

No, re the case, power supply and missing front panel, it is.
It's a general curse, based on many years of 'ebay stuff' found missing critical bits.
This is not from ebay, but same effect.


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