OOn my desk right now, sitting next to my ultra-modern gaming PC, is a strange device that looks like a spaceship control panel from a 1970s sci-fi movie. There’s no keyboard, no monitor, just a few lines of rows of colored switches below a cascade of flashing lights. If you thought the recent spate of retro video game consoles like the Mini SNES and Mega Drive Mini was a surprising development in tech nostalgia, meet the PiDP-10, a 2:3 scale replica of the PDP-10 mainframe computer. launched for the first time. by Digital Equipment Corporation (DEC) in 1966. Designed and built by an international group of computer enthusiasts known as Guaranteed Obsolescence, it’s a thing of beauty.
The origins of the project date back to 2015. Oscar Vermeulen, a Dutch economist and lifelong computer collector, wanted to build a single copy of a PDP-8 minicomputer, a machine he had been obsessed with since childhood. “I had a Commodore 64 and proudly showed it to a friend of my father’s,” he says. “He just sniffed and said the Commodore was a toy. A real computer was a PDP, specifically a PDP-8. So I started looking for discarded PDP-8 computers, but never found one. They are now collector’s items, extremely expensive and almost always broken. So I decided to make a copy for myself.”
As something of a perfectionist, Vermeulen decided he needed a professionally made front panel cover. “The company that could do it told me I would have to pay for a whole four square meter sheet of Perspex, enough for 50 of these panels,” he says. “So I made an extra 49, thinking I’d get 49 idiot friends. I had no idea that in the years that followed I would be making thousands on my dinner table.”
At the same time, Vermeulen began posting to various vintage computer groups on Google Groups, where people were already working on software emulators of pre-microprocessor computers. As word spread about his copy, it quickly became a group activity and now more than 100 people are involved. While Vermeulen focuses on designing the hardware reproduction—the front panel with its working switches and lights—others are tackling various aspects of the open-source software emulation, which has a complex history. At its core is SIMH, created by former DEC employee and megastar hacker Bob Supnik, which emulates a variety of classic computers. This was later modified by Richard Cornwell and Lars Brinkhoff adding driver support for the PDP-10’s ITS operating system and other Massachusetts Institute of Technology (MIT) projects. There were many other people involved along the way, some collecting and saving old backup tapes, others adding improvements and bug fixes, or providing documentation and schematics.
The attention to detail is outrageous. Front lights aren’t just for show. As in the original machine, they show the instructions being executed, a large number of CPU signals, the contents of memory. Vermeulen refers to it as watching the computer’s heartbeat. This element was taken very seriously. “Two people spent months on a particular problem,” says Vermeulen. “As you know, LEDs turn on and off, but incandescent bulbs glow. So a whole study was done to make the LEDs simulate the brightness of the original bulbs. And then we discovered that different bulbs from different years had a different lighting time. The measurements were made, the math was applied, but we added the brightness of the bulb. More CPU time is spent simulating it than simulating the original CPU!”
Why? Why go to all this trouble? First, there is the historical significance. Built from 1959 to the early 1970s, PDP cars were groundbreaking. Not only were they much cheaper than the giant mainframes used by the military and large corporations, but they were designed as multi-purpose, fully interactive machines. You didn’t have to produce programs on punch cards, which were then handed off to the IT department, which would run them through the computer, which would provide a printout, which you would correct maybe a day later. With PDPs, you can type directly into the computer and test the results immediately.
These factors led to a tremendous explosion of experimentation. Most modern programming languages, including C, began on DEC machines; a PDP-10 was the center of the MIT AI Lab, the room in which the term artificial intelligence was coined. “PDP-10 computers dominated the Arpanet, which was the predecessor of the Internet,” says Lars Brinkhoff. “Internet protocols were prototyped on the PDP-10, PDP-11 and other computers. The GNU Project was inspired by the free sharing of software and information on the PDP-10. Stephen Hawking’s artificial voice came from a DECtalk device, which came out of Dennis Klatt’s voice synthesis research started on a PDP-9.
PDPs were installed in university labs around the world, where they were embraced by an emerging generation of engineers, scientists, and coders—the original computer hackers. Steve Wozniak started coding on a PDP-8, a smaller, cheaper machine that sold to thousands of hobbyists – its operating system, OS/8, was the predecessor to MS-DOS. School teenagers Bill Gates and Paul Allen sneaked into the University of Washington to program the PCP-10. And it was on PDP computers that MIT student Steve Russell and a group of friends designed the shoot-’em-up, SpaceWar!, one of the first video games created on a computer.
This legendary game was not alone – there were many others at the time, because making games was a fun way to explore what was possible. “There’s Dazzle Dart, a four-player laser tennis game and Lunar Lander,” says Vermeulen. “Maze War was the first networked video game; people would connect two IMLAC minicomputers/graphics terminals over the Arpanet through a PDP-10 mainframe, and with that multi-million dollar pile of hardware they could chase around a maze and shoot each other.” It was also on PDP computers that the original text adventures like Colossal Cave and Zork were written, as well as the first online multiplayer games, including MUDs and Star Trek.
These machines, then, are a vital part of our digital culture – they are the furnace of the modern gaming and technology industries. But to be understood, they must be used. “The problem with the history of computing is that you can’t really show it by putting some old dead computers in a museum—that tells you almost nothing,” says Vermeulen. “You have to experience these machines, how they worked. And the problem with pre-1975 computers is that they are big, heavy and pretty much impossible to keep running. Paul Allen, the co-founder of Microsoft, had a deep love for the PDP-10, and with the means he had, he could afford a team of veteran technicians to repair and run one. But it turned out to be very expensive – unfortunately, his family decided to stop this after his death.”
The answer is emulation. The PDP replicas reproduce all the original terminal bezels, with their lights and switches, but the computation is handled by a Raspberry Pi microcomputer attached to the back via a serial port. To get it working at home, plug in your Raspberry Pi, plug in a keyboard and monitor, turn it on, and download the software. Next, flick a switch on the front of the PDP-10, reboot the Raspberry Pi, and you’re now in PDP mode, your monitor running a window that mimics the old Knight TV terminal screen. Using the command line interface (remember those?), you can then use a whole range of native programs – including games.
This is what I expected. We all understand SpaceWar’s seminal role in the birth of the modern gaming industry, but to play it, to actually control one of the spaceships battling it out amid vector explosions against a twinkling starscape… it feels like experience history.
Fifteen years after Vermeulen began work on his personal PDP-8 emulator, the Guaranteed Antiquity group has sold many hundreds of copies of it and is working on more, including MIT’s experimental Project Whirlwind computer from the 1950s (which had a simple version of tic-tac – toe). There is now a company, Chiriqui Electronic Design Studio, in Panama that builds the device. What started as a personal project has become something much bigger. “We just had the ‘official’ launch of the PiDP-10 replica at MIT in Boston, where the original machine was located. About 50 hackers from the 1970s joined us for a demo session. It was fun to see people playing a multiplayer Maze War game 50 years later!”
That’s another reason why the PiDP-10 is worth it: it’s fun. I never expected to see one of these things up close, let alone hook one up to my monitor at home and play with it. It has been an exciting, nostalgic and strange experience. Navigating the ITS drive system, with that bright green dot-matrix font, its lists of intriguing programs and games, the message above the terminal command line that reads “Happy hacking!”… is incredibly evocative. .
Meanwhile, coders who have bought PiDP machines are making new programs and games. They range in age from 80-year-old PDP veterans to 20-somethings eager to experience a bygone era of programming. Lack of memory and processing power meant you had to write slick, super-efficient code – there was no room for bloat. “Many universities use PiDP-11 and -8 in classrooms,” says Vermeulen. “Partly to show computer science students where we’ve come from, and also because the super-low-level programming you still have to do for microcontrollers or hardware drivers is the kind of coding you learn very well on these dinosaurs.”
Brinkhoff agrees that while there is nostalgia in these cars, they still have something to teach us. They are functional. “I love writing new software for 10; for example, a program to display fractals or generate QR codes,” he says.
“I hope this is something that more people will understand, because if you don’t do anything with PiDP, it’s mostly going to sit on a shelf, with its lights on. It’s a nice sight, but I think a computer isn’t really going to be happy if it doesn’t have users programming it.”
