pahp
Experienced Member
Hi, my name is Peter Peterson -- I'm an Associate Professor of CS at the University of Minnesota Duluth. We have a PDP-12 that is functional thanks to the hard work of students alongside the help of many in the community, including the late greats Warren Stearns and Charles Lasner along with Mike Thompson at RICM, Vince Slyngstad, Jack Rubin, Jim Mahaffey, and many others. We have a (currently neglected) blog, YouTube playlist, an Instagram (the PDP-12 is beautiful and deserves some glamour shots!), and I tend to post snippets about our work on my Twitter Mastodon feed. I've been meaning (for months!) to start posting more here on the VCF forums since this is where the community is.
Our specific machine (PDP-12 #435) was purchased in the early 1970s by the University of Minnesota for a grant with PI Dr. Albert Yonas of the Institute for Child Development for use in cognition experiments. Al used the PDP-12's hardware to great effect back in the 70s in classic LINC-style biomedical research -- moving dots on a screen and sampling muscle signals in very young children to track visual response time and other effects.
Although the PDP-12 became outmoded, Dr. Yonas couldn't bring himself to scrap the beautiful behemoth, so he stored it in a closet in his climate-controlled lab for almost 40 years. When Dr. Yonas came to retirement, he looked to pass on the PDP-12 to someone at the Twin Cities campus, but they weren't interested. Dr. Yonas was a collaborator with Dr. Pete Willemsen here at UMN Duluth. He asked Pete if he might be "interested in an old computer." Thinking the machine might be an unremarkable Gateway 2000 or somesuch, Pete asked Al for a picture. When he saw the PDP-12, he knew he was interested! Pete and I hatched a plan to bring the PDP-12 to Duluth. By a stroke of luck we found someone in the Cities who was able to crate and ship the '12 up to Duluth -- he was not only the most affordable, but he also had a PDP-8 of his own at home, so he knew exactly how to take care of it. We found a pathway through the labyrinthine hallways and elevators of UMD that could get #435 safely to my lab.
Then, I started to look for someone who could take on the restoration project. A student in my OS class, Dawson Rosell, came by looking for a research project. I asked him what he was interested in, and he said "Old computers and 6502 assembly." I said: "Have I got a project for you!" Dawson followed the excellent blog posts and instructions of the folks at RICM and they patiently answered our questions. The good condition of the machine due to its storage meant that besides reforming the capacitors, very little was necessary to get the machine into an operational (if not quite correct) state.
Through Mike at RICM, we met Warren Stearns, who came to Duluth from South Dakota and spent a big chunk of the summer working with us and helping to (i.e., showing us how to) restore the machine. He was an excellent teacher and friend who very generously donated his time and money to our project, including getting us in touch with Jim Mahaffey who donated a 4K core to our project (one of our machine's cores had been pilfered at some point in the last 40 years). Warren was planning to come back to help us more in the Fall, but his sudden death due to a heart attack ended those plans. Nevertheless, his hard work with Dawson paid off, getting our machine into a very functional state. Extensive work by others, especially student Julian Nowaczek further improved the state of the machine and helped build up our set of tools and skills for debugging.
We have continued to work on the machine on and off. I'm creating this thread as a place to document our work for posterity and for others in the community. I'll save more discussion of those matters for future posts.
We are so grateful to everyone who has helped our project -- we absolutely would not have been able to do this without you all and our hope is that we can return the favor to others through documentation, videos, posts, and more.
Stay tuned for more updates!
Our specific machine (PDP-12 #435) was purchased in the early 1970s by the University of Minnesota for a grant with PI Dr. Albert Yonas of the Institute for Child Development for use in cognition experiments. Al used the PDP-12's hardware to great effect back in the 70s in classic LINC-style biomedical research -- moving dots on a screen and sampling muscle signals in very young children to track visual response time and other effects.
Although the PDP-12 became outmoded, Dr. Yonas couldn't bring himself to scrap the beautiful behemoth, so he stored it in a closet in his climate-controlled lab for almost 40 years. When Dr. Yonas came to retirement, he looked to pass on the PDP-12 to someone at the Twin Cities campus, but they weren't interested. Dr. Yonas was a collaborator with Dr. Pete Willemsen here at UMN Duluth. He asked Pete if he might be "interested in an old computer." Thinking the machine might be an unremarkable Gateway 2000 or somesuch, Pete asked Al for a picture. When he saw the PDP-12, he knew he was interested! Pete and I hatched a plan to bring the PDP-12 to Duluth. By a stroke of luck we found someone in the Cities who was able to crate and ship the '12 up to Duluth -- he was not only the most affordable, but he also had a PDP-8 of his own at home, so he knew exactly how to take care of it. We found a pathway through the labyrinthine hallways and elevators of UMD that could get #435 safely to my lab.
Then, I started to look for someone who could take on the restoration project. A student in my OS class, Dawson Rosell, came by looking for a research project. I asked him what he was interested in, and he said "Old computers and 6502 assembly." I said: "Have I got a project for you!" Dawson followed the excellent blog posts and instructions of the folks at RICM and they patiently answered our questions. The good condition of the machine due to its storage meant that besides reforming the capacitors, very little was necessary to get the machine into an operational (if not quite correct) state.
Through Mike at RICM, we met Warren Stearns, who came to Duluth from South Dakota and spent a big chunk of the summer working with us and helping to (i.e., showing us how to) restore the machine. He was an excellent teacher and friend who very generously donated his time and money to our project, including getting us in touch with Jim Mahaffey who donated a 4K core to our project (one of our machine's cores had been pilfered at some point in the last 40 years). Warren was planning to come back to help us more in the Fall, but his sudden death due to a heart attack ended those plans. Nevertheless, his hard work with Dawson paid off, getting our machine into a very functional state. Extensive work by others, especially student Julian Nowaczek further improved the state of the machine and helped build up our set of tools and skills for debugging.
We have continued to work on the machine on and off. I'm creating this thread as a place to document our work for posterity and for others in the community. I'll save more discussion of those matters for future posts.
We are so grateful to everyone who has helped our project -- we absolutely would not have been able to do this without you all and our hope is that we can return the favor to others through documentation, videos, posts, and more.
Stay tuned for more updates!