PiDP-11: RECREATING THE PDP-11/70
The PiDP-11 is a modern replica of the PDP-11/70.
Introduced in 1975, the 11/70 was top of the line in the famed PDP-11 range, and the very last system with a proper front panel. Tragically, DEC field service often removed the front panel in a later upgrade, leaving us staring at dull blank panels ever since..
The PiDP-11 wants to bring back the experience of PDP-11 Blinkenlights, with its pretty 1970s Rose & Magenta color scheme. On a more modest (living room compatible) scale 6:10, with faithfully reproduced case and switches.
The tabs above describe the PiDP in more detail. The web already contains lots of PDP-11 information, so these pages just focus on the practical PiDP aspects: how to build, operate and possibly hack the PiDP-11. The 'why' question will not be addressed here, only fools would think that PDP-11s are somehow obsolete. Here's a PiDP-11 serving a web page (remember - on a hardware design from the early 70s).
Compatible with the Pi 4, 3, 2, B+, A+, and Zero (W)
Recommended: Pi 4, 3 or 2.
In 2015, I made a replica of the PDP-8 for myself, as the Real Thing was above budget. The panel manufacturer asked me if I wanted just the one panel, or 50. Same price, just a bit more for shipping. So I looked around for 49 fellow-fools - but found 2000! I decided to spend the proceeds on a professionally made, no-compromise PiDP-11. Injection molded case, exact replica switches and whatnot. It was a steep learning curve (story here), the project got completely out of hand over the next two years. Never mind - it's done, you're looking at it!
So what is it?
You could look at this as a smallish PDP-11/70, built with modern parts.
Or alternatively, and equally valid, as a fancy front panel case for a Raspberry Pi.
Because inside is simply a Pi running the excellent simh emulator in the BlinkenBone variety.
It will happily run any other Pi applications concurrently with the PDP-11, so you are not necessarily constrained to just PDP-11 software. Although really, there's not much of interest that does not run on an 11.
Just like the PiDP-8, because it uses simh, the PiDP-11 will run pretty much all the original operating systems. This time, I did add a second (optional) ambition: a prototyping area has been added to the circuit board, with the hope that people will add hardware projects onto it. Here is an example (link). That hopefully gives a lot of hands-on motivation to dig in to this most venerable of computer architectures, and opens up the mad prospect of a PDP-11 controlled home automation system to name but one idea. A wall-mounted PDP-11 home automation console... Why not?
There are other possibilities on the horizon: If you have old PDP-11 peripherals, you could hook them up using the UniBone expansion card. Teletype, RL02 drives, RK05 disk packs, even using old core memory of a real but dead PDP-11... nuts.
And the creator of the PDP2011 (link) is looking into making an FPGA PDP-11 to fit the PiDP, replacing the Pi. Stay tuned for that. Lots of hacking is going on.
Proper Credit Where It's Due
It should be clear from the above that the PiDP owes its features to SimH, the emulation project fine-tuned over decades by Bob Supnik, Mark Pizzolato and many collaborators.
Making a PDP-11/70 front panel behave 100% faithful to the original is not trivial. We even ended up with a custom test program behind Miss Piggy, the old Microsoft 11/70 at the LCM for many off-hours to hone this to perfection. We? Well, it was Jörg who made that happen.
As Seen On TV
Well, OK, Youtube actually. I owe a lot to Steve Gibson and Leo Laporte from SecurityNow for getting the word out on my silly project. In the video, Steve gives a bit of historical background on the PDP-11 and its glorious, glorious predecessor: the PDP-8.
Beige-O-Vision (a member of the U.K. TNMOC) also did a great introductory video, followed up by very efficient build instructions.
MagPi magazine review
PJ Evans wrote a review of the PiDP-11 for the Raspbery Pi's magazine the MagPi in their January 2019 issue, reproduced here under the Creative Commons (BY-SA-NC 3.0) licence.
Thank you for the article - and for being pretty much the only Open Source published magazine on the planet... (click picture to zoom)
The Living in the Future Podcast
An audio podcast about the history of PDP minicomputers and why I thought the world needed more of them: