PDP12.ORG Logo

PDP-8 Minis
PDP-8 (0)
PDP-8/E (3)
PDP-8/M (2)
PDP-8/S (0)
PDP-11 Minis
PDP-12 Minis
PDP-12 Front View
Front View of HP-9100
Monroe 630
Tektronix 909
Test Equipment
Front View of HP-3440
Marconi 2955B
Front View of IBM 360 Front Panel
Help the Museum
Contact Us
Hosted by KRTEN.COM


2007 08 29 Initial Inspection of PDP-8/L

The 8/L arrived from Orange, CA, USA. I bought this one from a private collector. Here are the initial pictures immediately after unpacking.

Empty PDP-8/L cabinet S M L XL

The story with this 8/L is that the previous owner's company had used them as general "prototyping" modules long after the 8/L had been gutted by a scrapper (notice the sheared-off power connectors at the top left of the picture).

My mission, should I choose to accept it, is to find sufficient spare modules for this 8/L so that I can bring it back to life. (What I bought was the case, power supply, backplane, and front panel.) Luckily, as it turns out, I have most of the standard M-series modules in inventory. A few "odd ball" modules, like the 8/L-specific G785 power card were unobtainable, until the previous owner looked around in a storage area and found them. That is the next shipment which will be arriving.

I'm going to use a gentle compressed air source to do the initial cleanup (maybe vacuum it first), and then proceed to the power supply capacitor reformation.

When the box arrived, there was a small bit of damage to one of the fuseholders. I replaced it.

PDP-8/L backplane S M L XL

As you can see, the backplane is in excellent condition. The wood shown on the bottom of this picture, as well as the right-hand side of the picture above, is for protection during shipping. The box arrived wrapped in a few sheets of brown shipping paper. Talk about your package that "will arrive in a plain brown envelope" :-)

Keep in mind that the 8/L is "upside down" (like a PDP-11/20); the backplane is on top and the cards fight gravity. This makes it easier to get to pins on the backplane, but it doesn't look as nice.

The front panel is in the second part of the shipment, and a bunch of spare cards are in the third batch.

2007 08 31 Power Supply

PDP-8/L Power Supply before restoration S M L XL

You gotta love early DEC power supplies -- dead simple, and relatively easy to get to and work on.

This one is filthy -- there's a thick coating of dust on everything: the capacitors, the wires, the bridge rectifiers -- everything.

Organizing Screws S M L XL

Yes, I am retentive -- this way, however, I'm able to find where each and every screw goes. There are no leftover parts :-)

Also, a good shot of the dirty capacitors. Left to right, there's an 80mF @ 15V, a 22mF @ 50V, and an 18mF @ 25V (reminder, mF == milli Farad; these are big capacitors!)

PDP-8/L Disassembled Power Supply S M L XL

And this is what the power supply looks like after I pulled all the caps out and started reforming them, and cleaning the power supply. Another reason to take lots of pictures.

Inside a PDP-8/L with a new fan S M L XL

I had to replace one of the fans; it started up and made a hell of a racket. It was much easier to just drop in a used fan from the 40 or so Gould logic state analyzers I scrapped this winter (long story; executive summary, I bought them at auction for a total of $15, no probes. It took about two man-weeks of work to scrap them all, and I sold the individual pieces to a local recycler (mainly for the Al, Cu, and Au) involving three car trips with a fully loaded car! for around $600. Yay.)

A Mostly Populated PDP-8/L S M L XL

Well, it sure has been worthwhile picking up spare boards over the years! :-) This picture shows how much of the 8/L I was able to populate just from spare cards (approximatley 70 cards)! (The astute observer will notice a Yamaha DX-7 synthesizer and a TU56 tape canister in the background.)

Latest Updates
Master Reference
PDP-12 is alive!
New machine: PDP-8/L

Contact us This page was updated on Fri Feb 19 00:10:08 EST 2010 © 2000-2007 by Robert Krten.
All rights reserved.
Areas of expertise: 8044, 8051, ARC/CBS, ARCNet, ARM, ASM-86, Automated Disassembly, Avanza, Avionics Software, awk, bash, Bell 103, Bell 202, BITBus, Bootloaders, C, Call Processing, Caller ID, CF-UTTH, Clear Thinking and Common Sense, Client/Server, CMR-91, Code Analysis, Cold Standby, Computer Based Training, Course Developemnt, Course Presentation, CRS-1, curl, cvs, Czech Language, Databases, Data Acquisition, Data Recovery, Decompilation, Debugging, Distributed Processing, DMS-100, Documentation, Drivers, DSP, DTMF, E.164, Embedded Systems, Emulation, Equinox, expect, Fault Tolerance, FFT, Filesystems, Firewalls, Fractals, FreeBSD, FSK, Gammacell 40/1000/3000, Graphics, GSR-12000, Hardware, High Availability, Home Automation, Hot Standby, HTML, HTTP, IDA Pro, IIDS, Image Processing, In-Service Upgrade, Industrial Automation, Infrastructure, Internationalization, iRMX-86/286, ISBT-128, Kernels, ksh, Ladder Logic, Lexical Analyzers, Linux, Loggers, m4, make, Medical Devices, Memory Constrained Environments, Message Passing, Microcontrollers, MIDI, MIL-STD-2167A, NNTP, OpenBSD, Optimization, OrCAD, Oscilloscopes, PABX, Parallel Processing, Parsing, PDP-8, Photon, Porting, POSIX, POVRay, Powerpoint, PowerPC, Preprocessor, Process Control, Program Flow Analysis, Project Management, Prototyping, Public Speaking, QNET, QNX 2, QNX 4, QNX 6 (Neutrino), Radarsat, rcs, Realtime Techniques, Recursive Descent Parsers, Regression Testing, Regular Expressions, Requirements Analysis, Resource Managers, Restoration, Reverse Engineering, Scripting, Security Systems, sed, Serial Protocols, SGML, Simulation, SMDR, SMTP, Soldering, svn, SX-20, Synthesizers, System Architecture, T.4, T.30, TCL, TCP/IP, Technical Presentations, Technical Writing, Telecoms, Testcases, Testjigs, Text Processing, Threads, Tools, Traceability Matrices, TTL, UNIX, Utilities, UUCP, Validation Protocols, Vaulting, VAX/VMS, vi, Virtual Filesystems, Warm Standby, wget, Wirewrap, X-10, X.25, x86