UMD student leads restoration of 50-year-old computer

On Dawson Rosell's father's resume, one line grabbed the attention of every interviewer he met with, from 3M to the nuclear navy -- his restoration of a classic car.

Peter Peterson (right), assistant professor of computer science at UMD, talks about the 50-year-old PDP-12 computer while Dawson Rosell, a UMD computer science and electrical engineerging undergraduate, fires up the machine. At left is Pete Willemsen, professor of computer science. They were involved in procuring the rare computer, which was produced somewhere between 1969 and 1972. (Bob King /

On Dawson Rosell's father's resume, one line grabbed the attention of every interviewer he met with, from 3M to the nuclear navy - his restoration of a classic car.

On Friday, Rosell unveiled his own classic restoration.

"In a way, this is kind of my Model A," the University of Minnesota Duluth senior said following a presentation on a 50-year-old computer he brought back to life this summer. "It's opening doors for me."

The 800-pound, refrigerator-shaped PDP-12 was the center of attention in a crowded classroom as Rosell demonstrated the fruits of his labor. The relic of computing was at once foreign and familiar, its noises and displays like something out of Star Trek, its myriad components like a modern computer under a microscope.

Because sure, even though today's devices have a million times more memory capacity and are 2,000 times lighter - that's no exaggeration - the 0s and 1s still run the show.


"Computers haven't really changed that much," said UMD computer science professor Peter Peterson.

That much was obvious as two kids took their turn staring into the oscilloscope playing the world's first video game, Spacewar!

A perfect opportunity

Rosell had come to Peterson looking for an undergraduate research project at about the same time the PDP-12 was in need of a new home after spending the last 40 years in a closet at the Twin Cities U of M campus.

"He said he was into old computers and assembly language," Peterson said. "I said, 'I think we have the right project for you.'"

Rosell, 21, has been performing surgery on the digital beast since June, digging through thousands of pages of schematics and getting intimately familiar with what goes where and why.

"I've learned more about electronics and circuits in the two months working on this than I had in a year of undergrad," he said.

Digital Equipment Corp. built its 12th-edition Programmed Data Processors between 1969 and 1972, offering an affordable option for those researchers and industries in need of the latest in mini-computing power. At $27,900, it would cost $186,000 in today's dollars.


About 725 of the hand-built units were sold, and about four others are in known working condition today in museums from Seattle to Germany.

"Aside form 'this is cool, and it's history' and all that, we hope to have our students working with the computer," Peterson said.

Volunteer boosted project

It turns out classic computers are a lot like classic cars. Beyond the appeal to aficionados and the fact the PDP-12 uses an actual ignition key to start, there's a community of collectors who have no problem sharing expertise, hard-to-find parts and, it turns out, their time.

Warren Stearns was eager to drive from South Dakota to UMD to help get the thing running this summer and, crucially, archive all that old magnetic tape the machine runs on.

"He had been through several restorations like this, and he could help us face-to-face as opposed to over email," Peterson said. "This guy really came and volunteered his time and expertise. We would have been able to do this demo sometime without him, but probably six months from now."

On Sunday, Stearns died after suffering a heart attack.

His family was grateful he spent his final weeks doing what he loved - and that his efforts were caught on video and posted to YouTube as Peterson documented the process.


"These things simply aren't being made anymore," Peterson said. "It's a lost art."

The lifeless machine has felt the breath of countless coders and mechanics, whose contributions will keep the computer in the public eye for, who knows, another 50, 500 years.

Eleven-year-old Matthew Fisch probably didn't grasp the weight of the human achievement in front of him on Friday, but as he waged space battle against his 8-year-old sister, Sabrina, the two left their own fingerprints on a piece of history.

Brooks Johnson was an enterprise/investigative reporter and business columnist at the Duluth News Tribune from 2016 to 2019.
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