Adding Linux To A PDP-11

The UNIBUS architecture for DEC’s PDPs and Vaxxen was a stroke of genius. If you wanted more memory in your minicomputer, just add another card. Need a drive? Plug it into the backplane. Of course, with all those weird cards, these old UNIBUS PDPs are hard to keep running. The UniBone is the solution to this problem. It puts Linux on a UNIBUS bridge, allowing this card to serve as a memory emulator, a test console, a disk emulator, or any other hardware you can think of.

The key to this build is the BeagleBone, everyone’s second-favorite single board computer that has one feature the other one doesn’t: PRUs, or a programmable real-time unit, that allows you to blink a lot of pins very, very fast. We’ve seen the BeagleBone be used as Linux in a terminal, as the rest of the computer for an old PDP-10 front panel and as the front end for a PDP-11/03.

In this build, the Beaglebone’s PRU takes care of interfacing to the UNIBUS backplane, sending everything to a device emulator running as an application. The UniBone can be configured as memory or something boring, but one of these can emulate four RL02 drives, giving a PDP-11 an amazing forty megabytes of storage. The real killer app of this implementation is giving these emulated drives a full complement of glowing buttons for load, ready, fault, and write protect, just like the front of a real RL02 drive. This panel is controlled over the I2C bus on the Beaglebone, and it’s a work of art. Of course, emulating the drive means you can’t use it as the world’s largest thumb drive, but that’s a small price to pay for saving these old computers.

VCF West: Homebrew Lisp Machines And Injection Molded PDPs

Someone walks into the Vintage Computer Festival and asks, ‘what’s new?’. It’s a hilarious joke, but there is some truth to it. At this year’s Vintage Computer Festival West, the exhibit hall wasn’t just filled to the brim with ancient computers from the Before Time. There was new hardware. There was hardware that would give your Apple IIgs even more memory. There was new hardware that perfectly emulated 40-year-old functionality. There’s always something new at the Vintage Computer Festival.

Some of the more interesting projects are just coming off the assembly line. If you want a modern-day Lisp machine, that one won’t be assembled until next week, although there was a working prototype at VCF. If you want the greatest recreation of the most beautiful hardware, VCF has your back. Check out these amazing builds below.

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Hackaday Links: May 20, 2018

One of the more interesting pieces of tech from Hollywood that never seems to become a reality is a location tracker. Remember the ‘movement tracker’ in Alien that found the cat in the locker? Yeah, like that. Something that reports the direction and distance to a target, kind of like a PKE Meter from Ghostbusters. I think there was something like this in Predator. On Indiegogo, there’s a device that tracks other devices. It’s called the Lynq, and it’s a small, handheld device that tells you the distance and bearing of other paired devices. Hand them out to your friends, and you’ll be able to find each other at Coachella. While the device and use case is interesting, we’re wondering how exactly this thing works. Our best guess is that each device has a GPS module inside, and communicates with other paired devices over the 900MHz band. It’s a bit pricey at $80 per unit (although you need at least two to be useful), but this is a really interesting project.

The SDRPlay SDR1 and SDR2 are — as you would guess — software defined radio receivers, that retail for $2-300. Problem: a few of these units were stolen from a warehouse, and are winding up on eBay. Solution: SDRPlay has decided to disable the specific receivers ‘via the serial number’. In a move just slightly reminiscent of FTDIgate, a manufacturer has decided to brick products that are stolen or infringe on IP. It’s a solution, but I wouldn’t want to be on the customer service team at SDRPlay.

A few years ago, [Oscar] created the PiDP-8/I, a computer kit that miniaturized the venerable PDP-8/I into a desktop form factor, complete with blinkenlights and clicky switches. It’s a full simulation of a PDP-8 running on a Raspberry Pi, and if you took the PiDP-8/I back to 1975, you could, indeed, connect it to other computers. But the PDP-8/I isn’t the most beautiful minicomputer ever created. That honor goes to the PDP-11/70, a beast of a machine wrapped in injection molded plastic and purple toggle switches. Now, after years of work, [Oscar] has miniaturized this beast of a machine. The PiDP-11/70 is a miniature remake of the PDP-11/70, runs a Raspberry Pi, and is everything you could ever want in a minimainframe. The price will be around $250 — expensive, but have you ever tried to find a PDP-11 front panel on eBay?

The Nvidia TX2 is a credit card-sized computer with a powerful ARM processor and a GPU. The TX2 is a module designed for ‘AI at the edge’, or something along those lines, meaning you can take a trained data set, load it onto an SD card, and the TX2 will do all the fancy image processing and OpenCV without a connection to the Internet. The obvious application for the TX2 is something like an ‘AI camera’, and now this is finally a product. The DNNCam is a 4k, 60FPS camera attached to a TX2 and stuffed into an IP67-rated enclosure. If you’re thinking of building anything like a security camera attached to a GPU, this is the all-in-one solution. It’s pricey, yes, but the TX2 module isn’t exactly cheap.

A Mini-ITX PDP-11

The PDP-11 is perhaps the most important computer in history. This was the king of all minicomputers, and once you get past the amazing front panels of the 11/20, 11/40, and 11/70, you’ll find PDP-11s everywhere. Heathkit sold one. It was the smallest computer that could run Unix. There were desktop versions sold as DEC Professionals. I have been told Ticketmaster — the entire backend of all event ticket sales in the United States — still runs on PDP-11s.

One of the interesting bits of the PDP-11 is the miniaturization that happened over the course of its development. Over time, the Unibus processor cards of the earlier models were shrunk down into a single chip. This PDP-on-a-chip was then cloned by the Soviets, and like most vintage Eastern European electronics, they’re all readily available on eBay.

For his Hackaday Prize entry, [SHAOS] is taking one of these chips and turning it into a modern machine. The PDPii is a project to bring the PDP-11 back to life in the form of an Open Source motherboard with a Mini-ITX motherboard. Is it game-changing? No, not really; you could buy a desktop PDP-11 thirty years ago. This project, though, is taking new old stock chips you can buy for ten dollars and turning it into something resembling a modern system. Finally, Ticketmaster can upgrade.

The design of this project doesn’t quite meet the spec for the Mini-ITX form factor; it’s based off the RC2014 backplane Z80 computer, but desktop computer cases are cheap, as are power supplies, and I’m sure someone out there knows how to fit an eight inch floppy in a five and a quarter inch hole.

The key feature for this Mini-ITX backplane PDP-11 is a redesign of the Q-bus found in later PDPs to something that’s a bit smaller, a bit cheaper to manufacture, and still has all the relevant pins accessible. With some reconfiguring of the baroque DEC standards, [SHAOS] came up with the Bread-Board Friendly Q-bus Extended, or BBQ-Bus+. The next step for this project is gathering up a few PDP-11 compatible Russian КР1801ВМ2 CPUs and going to town on the architecture of what is probably the most replicated computer design ever.

Turning a Pi Into a PDP

There’s no better way to learn how to program a computer than assembly, and there’s no better way to do assembly than with a bunch of blinkenlights and switches. Therefore, the best way to learn programming is with a PDP-11. It’s a shame these machines are locked up in museums and the garages of very cool people, but you can build your own PDP-11 with a Raspberry Pi and just a few extra components.

[jonatron] built his own simulated version of the PDP-11 with a lot of LEDs, a ton of switches, and a few 16-bit serial to parallel ICs. Of course the coolest part of any blinkenlight simulator are the front panel graphics, and here [jonatron] didn’t skimp. He put those switches and LEDs on a piece of laser cut acrylic with a handsome PDP11 decal. The software comes with a load of compiler warnings and doesn’t run anything except for very simple machine code programs. That’s really all you can do with a bunch of toggle switches and lights, though.

If this project looks familiar, your memory does not deceive you. The PiDP-8/I was an entry in this year’s Hackaday Prize and ended up being one of the top projects in the Best Product category. We ran into [Oscar], the creator of the PiDP-8, a few times this year. The most recent was at the Hackaday SuperConferece where he gave a talk. He’s currently working on a replica of the king of PDPs, the PDP-11/70.

Video below.

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Vintage Computer Fest: Berlin 2015

Berlin was a good city to be a geek in last weekend. Alongside the Berlin Maker Faire, there was the 2015 meeting of the Vintage Computing Festival: Berlin (VCFB). Each VCFB has a special theme, and this year it was analogue computers, but there was no lack of old computers large and small, teletext machines, vintage video game consoles, and general nerdy nostalgia.

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VCF East X: The Mega Mix

The Vintage Computer Festival East was last weekend, and now it’s time to wrap everything up. We’re going to start this off with a video of the biggest, most intolerable jerk on the planet walking around the boardwalk at Ashbury Park. Thanks to [Fran] for filming it.

That video, despite the wretched casting director, included the reveal of the PDP Straight-8, the 50-year-old minicomputer that was repaired and refurbished by [David Gesswein] just this year. You can see some pictures of that and more below, and a little more on [David]’s website.

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