Building the PiDP-8 - An Amazing Replica of a Vintage Computer

In this video, I'm building the PiDP-8, a fully functional replica of the PDP-8 by Digital Equipment Corp. It's a rather long but also quite informative video, especially if you're planning to build one, too. Also, there's a cat.
PDP-8 Computer:
PDP-8 (Wikipedia) -- en.wikipedia.org/wiki/PDP-8
PDP-8/I (Dusty Old Computers) -- dustyoldcomputers.com/pdp8/pdp...
Building the PiDP-8:
Obsolescence Guaranteed -- obsolescence.wixsite.com/obsol...
Raspberry Pi Zero -- www.raspberrypi.org/products/...
Colossus - The Forbin Project (Wikipedia) -- en.wikipedia.org/wiki/Colossu...
Photo (PDP-8/I) -- www.vintagecomputer.net/digita...

[@alanb76]

When I was in high school a few of us were allowed to go over to the Junior College and learn programming on the PDP-8. Later I attended that Junior College and worked directly with that PDP-8 and an HP-3000. Then I went to college and worked with the PDP-11 and the CDC-6400. Later I built systems with LSI-11's and MicroVAXes and onward from there. Fun times and great memories. Either a PiDP-8 or PiDP-11 would be interesting to play with, especially the 11.

[@Greebstreebling]

I worked with PDP 8 and PDP 11 at Harwell in the early 70's - they were used as front end processors to control Neutron Spectrometers. A PDP8 was used as a command processor/ multiplexer for end users of the IBM system 360 mainframe. In those days end users were lucky if they had a teletype. These days the AVR 8 bit microcontrollers I use to control the dome of my astro observatory have much more memory, dozens of registers, internal oscillators and 20Mhz cpu clock if you need it, also 500 times smaller and cost next to nothing..... You could use one to simulate a PDP11 - now there's an idea -where's my box of awful red, white and black plastic....thanks for posting, - a nice nostalgia project :) :)

[@thiesenf]

Oh... "Colossus - The Forbin Project"... thanks for the title of that movie.... I had seen it as a kid in the 80's so wanteed to see it again§...

[@musicandblinkenlights8280]

You're welcome! It's a great movie. While the computer itself didn't age that well (blinkenlights and such...) the subject of the movie is as relevant as ever.

[@thiesenf]

@@musicandblinkenlights8280 Yup... what would happen if a sentience where told that it must be eliminated...

[@antihz]

I thoroughly enjoyed hearing Werner Herzog talk about his love for blinking lights, thank you!

[@musicandblinkenlights8280]

He sometimes narrates my videos...

[@Clarke-Walker]

Thanks. This was fascinating and wonderful. Similar to this model I wrote my first program on a PDP-8e. Eventually I was hired by Digital Equipment Corporation to support the PDP-8 Family on the East coast. Great times with a great company. I hope to build one when more kits are available.

[@squirlmy]

in Maynard, Massachusetts? I really don't have much connection to them or the PDP, but I've sometimes dream if Silicon Valley and the "PC revolution" didn't happen in Silicon Valley, and the center of computing remained around Rt 128 and Boston: DEC, Wang Inc, Symbolics and all the hackers from MIT, the inventors of Visicalc, and all a stone's throw from IBM in Armonk, New York. All the tech that started there could have stayed there, but it wasn't to be.

[@timdolan4591]

hey Clarke - how you doing? me? basically 7000

[@alanb76]

Very nice job. I might 3d print some guides for the LEDs if I was building this kit. Plus perhaps some 3d printed mounting parts with brass heat-set nuts instead of wood scraps.

[@juliangedzierski2546]

Takes me right back i must get one. Wish it had the correct keys though.

[@baretoon]

That's a great video. I learned a few tricks that would have been handy when I build my PiDP-8/i. Thanks for sharing!

[@musicandblinkenlights8280]

Thanks!

[@wa4aos]

Very Well done video. Thanks!!

[@aphexteknol]

I agree, the intended method of installing the PCB into the case isn’t the best. I still haven’t mounted the front panel permanently on mine either, but otherwise its a great kit. I wish I had mounted the PCB in a different way in mine, and I just might revise it to be similar to yours now. Thanks for the video!

[@musicandblinkenlights8280]

I think it's perfectly fine to friction-mount the front panel into the case. If you don't shake it too vigorously, the panel shouldn't fall out.

[@jeffstanton1009]

What power supply did you use for the PiDP? Was it a generic 5V supply, or one specifically rated for the Raspberry Pi?

[@musicandblinkenlights8280]

It was a generic one, sufficient for the demands of the Pi Zero. However, depending on the raspi variant you use (and what you intend to run on it) I'd check the power rating of the "recommended" (branded...) supply and try to match it with a cheaper, generic one ;-)

[@cwilsonpa]

I really liked this video and found it very helpful. I finished assembling the 2019 version of this kit just this week. I have yet to mount the PCB in the case because I was weighing my options for running power. I used a Raspberry Pi 3 but I may remove it and use a Pi Zero W instead and route the power the way that you did. Your method seems like a cleaner implementation than the slot that I was about to cut in the box. I have one question: How did you attach the front panel to the case ? Did you use Velcro ? Thanks again for recording your assembly process.

[@musicandblinkenlights8280]

You can press the acrylic panel into the case. It'll hold by friction. Just don't shake the case with the panel facing down...

[@irgski]

Is your lead forming tool a commercially available part?

[@musicandblinkenlights8280]

Yes! Google "resistor lead bending gauge" and you'll find tools like this (www.sparkfun.com/products/13114) or that (www.musikding.de/Bending-gauge). Cheers!

[@Kevin_Kennelly]

PIP baby.

[@tylerdean980]

What operating systems can this run? I know the piDP-11 has a bunch of UNIX variants, but does this?

[@thomasw2509]

Hallo, schön gemacht. Möchte ich auch machen. Leider reagiert der Schöpfer des Emulators auf Anfragen, Bestellungswünsche SEHR langsam, imo gar nicht. Würden sie die Hardware Dokumente (Stand 2015, eigentlich auf Anfrage von seiner Google-Speicher) bereitstellen? Wäre schön. Die Hardware auf dem Frontpanel-PCB ist nicht so schwer. Ein Paar Widerstände, Schalter, LED, Verbinder, UDN LED-Treiber. Ausserdem ist das Panel recht gross geraten. Das Briel pcb (Altair) war deutlich kompakter. K.A. , warum alle ein Geheimnis daraus machen. LG

[@musicandblinkenlights8280]

Es dauert eine Weile, aber Oscar antwortet schliesslich doch. Auch bei mir hat es einen Moment gedauert. Die Schaltpläne -- und ich glaube auch auch die Produktionsdateien -- sind auf der obsolescence Seite.

[@thomasw2509]

@@musicandblinkenlights8280 Hallo, danke. Die Dokumente sind eingesperrt auf seiner Google-Disk. Google/KZbin sperrt mich mal wieder aus. Kommentare verschwinden. Egal, der Altair8800 ist auf dem Weg zu mir. Es gibt immer was zu tun. LG

[@gastrodus]

Hi Ralph, du bist in der Schweiz zuhause? Ich habe Probleme mit meinem PiDP8i, wäre froh für etwas Hilfe ...

[@musicandblinkenlights8280]

Momoll, bin ich. Wo liegt denn das Problem?

[@gastrodus]

Wie könnte ich mit dir in Kontakt treten? Hier ist wohl etwas mühsam ... ;-)

[@JohnDlugosz]

a fancy box connected to an emulator -- not what I expected. I thought you would build a gate-level reproduction without using a microcontroller.

[@musicandblinkenlights8280]

In a way it's cheating, I agree, but unless you "clone" the whole computer using original parts (or modern compatible ones), you'll have to compromise one way or another. I don't necessarily mind emulating obsolete (i.e. unobtainable) hardware. Perhaps I would have preferred an emulator running on an Arduino or something, in other words "small", instead of a full, "real" Linux computer (the raspberry pi).

[@JohnDlugosz]

Have you seen the various projects building 8-bit from scratch (e.g. using 74000 series chips) or the MOnSter 6502? I saw an Apple 1 clone that used a propeller microcontroller to emulate the unavailable chips (specifically the terminal controller), but was not an emulation of the whole thing on a modern CPU.

[@musicandblinkenlights8280]

Yes, I've seen many of them, although I'm sure I missed the best ones. I know that you can still get 6502 processors (compatibles). And I already bought a Z80, 64K of RAM, blank EEPROMS, ...

[@donporter8432]

Love it! I bought an 8/I back in '72 and programmed in Fortran, running a commercial mailing list maintenance and labelling company for several years. Now, as an oldie, gotta build me one of these pronto! THANKS!

[@andrewwasson6153]

I realize this is an old post but regarding John’s critique about using a small but powerful modern computer to emulate this older classic, I built one of the 1st run in 2015 (with the latest simh PDP8 emulation software) and it is quite convincing. If you didn’t know it was a Linux box pretending to be a PDP8, you wouldn’t know, except that is might run faster than you expect. The Digital Corp eventually moved the PDP8 onto silicon and if you’ve got deep pockets and some time on your hands, you could track down the Digital Corps 6120 chipset and put together a real Digital Corp PDP8 and use Oscar’s kit as the front end. Another less costly option would be to build a PDP8 processor on a FPGA device and then use the kit for the front end. Lots of options. I prefer the kit with the Raspberry pi myself because it took an afternoon to build and has been running flawlessly since. Rather than wrestle with hardware, I can tinker with code old school style.

[@griftereck]

blink and you'll miss it