When Lockheed Martin shuttered its corporate campus in Eagan in 2010, it left behind a 60 year legacy of computing — and thousands of artifacts to document it.

"A lot of people think the computer industry started in Silicon Valley," said Lynn Gruber, executive director of the Dakota County Historical Society. "We would say … it had its beginnings here in St. Paul first and later in Eagan."

Lockheed Martin this year delivered about two semitrailer tucks full of prototype computers, photographs, documents and company memorabilia dating back to Engineering Resource Associates, which opened in 1946. The historical society recruited an area retiree group to help sort through it all, and the resulting exhibit, "From ERA to Lockheed Martin: Minnesota's Computer Industry," opened this month at the Lawshe Memorial Museum in South St. Paul.

The exhibit contains early prototypes of computers that became standard in American and Japanese naval vessels over decades, said collections assistant Andrew Fox. These computers, pioneered by a number of engineering firms in the area, were built to withstand the daily stresses of warships.

"They're built to be very strong and to withstand all kinds of extreme conditions," Fox said. "Because of that they're incredibly reliable machines, so actually even some of the early computers that they had were still going strong 20, 30 years later."

The early computers were also much larger than modern devices. One photo shows engineers working with a memory unit in the 1950s. The hard drive precursor is roughly the same size and shape as an oil drum.

The historical society has cataloged more than 1,000 computers, discs, parts, promotional items and other objects from Lockheed's donation, Fox said, but still has tens of thousands of photographs and documents to sort though.

To help catalog the donations and create the new exhibit, Fox enlisted the VIP Retiree Club, a group of mostly retired engineers Lockheed Martin had originally tasked with preparing artifacts to be donated to Dakota County and the University of Minnesota.

Before the exhibit opened, the historical society held a reception for the nearly 60 volunteers who had helped catalog the donations since March. Fox said the retirees' perspective was invaluable to the process. Because of their long careers at multiple companies in the area, many of the volunteers were like "walking encyclopedias."

"I really had no idea in the beginning what kind of journey I was going to be going on," Fox said. "I've learned a great deal."

Harvey Taipale, a club member who helped prepare the exhibit and the original donation, said the process brought back memories of his 40-year career and illuminated a branch of computing history not widely known outside of Lockheed Martin.

Over decades of mergers, acquisitions and management changes of different companies, Taipale said Minnesota's defense and computing industry born out of ERA has remained self-contained and uniquely Minnesotan.

Coastal transplants have been unwilling to leave the state with their companies in the past, and Taipale said Lockheed Martin could face resistance if they attempt to relocate the nearly 200 air traffic control employees still operating in Eagan.

"They are truly the wizards of the world when it comes to air traffic control," Taipale said. "They realize if they try to move them … they'll lose [employees]."

Minnesota's computing industry has seen about a dozen companies come and go, often operating under different names over time, including Remington Rand, UNISYS, Loral, Sperry and most recently Lockheed. However, most owe their existence to the ERA, a group of businessmen and former Navy code crackers who worked on some of the earliest computers after World War II on the same site recently vacated by Lockheed Martin.

"You can argue about who was most important in the early days, but they were really one of the key companies in launching the computer business," Taipale said. "Nobody knows about them because their programs early days were classified … There's a huge untold story there about what these people really did."

Tony Wagner is a Twin Cities freelance writer.