A replica of the first electronic digital computer, the Atanasoff-Berry Computer (ABC), which was built at Iowa State, is currently on display at the University of Colorado at Boulder.

The original was created at Iowa State by John Atanasoff and Clifford Berry during 1939-42.

“We think students will be interested in the history of it and how it was built,” said Carol Rowe, director of communications for the College of Engineering and Applied Sciences at CU-Boulder.

The replica, formally unveiled on Oct. 8, 1997, at the National Press Club in Washington, D.C., has been touring the state of Iowa for the past year. Boulder is the first stop on a three-site national tour. It will also travel to Long Beach, Calif., and San Jose, Calif.

CU-Boulder will have the computer on display for students and the public until Jan. 27. The university will also host a symposium Jan. 25, featuring John Atanasoff II.

Rowe said bringing the ABC to CU-Boulder was a suggestion from people in the Boulder community.

“A local businessman wanted to bring it here, and we were happy to go along with it,” she said.

The original ABC was never patented and eventually was dismantled for experiment parts, said Charles Derra, communication specialist for ISU University Relations.

“The original was built here on campus, and nobody understood the importance of what Atanasoff had done,” he said.

Derra said the replica was built to show how the ABC actually worked.

“The reason it was built was to prove that Atanasoff had built a working computer, and he did it here,” he said. “It was quite a scavenger hunt because they had to find parts for it from that time period.”

Gary Sleege, one of the principal electronics designers of the replica, said the only part left of the original ABC was the memory drum, which is now at the Smithsonian Institute in Washington, D.C.

Most of the replica design was done by looking at what few pictures were taken of the original ABC and interpreting photocopied documents belonging to Atanasoff.

“You know the saying, ‘A picture’s worth a thousand words?’ Well, we had to go by Berry’s words for most of the circuits, so you can imagine what we first came up with,” Sleege said.

Sleege said some things amazed him while building the replica. For example, the original part numbers for the vacuum tubes are still used today.

Also, the ABC had the ability to convert decimal numbers to binary numbers to do calculations and then give the answer in decimals, similar to modern computers.

Unlike computers today, the original ABC weighed 750 pounds and had unique features, including rotating drums for data storage and vacuum tubes that flickered.

“When you have a computer that looks like the first one, a lot of people notice,” Sleege said. “People take note of nostalgia.”

Atanasoff was a professor of physics and mathematics at Iowa State, and Berry was his graduate student.

All construction of the ABC replica was completed by a team of scientists, technicians and students at the Ames Laboratory, a U.S. Department of Energy facility at Iowa State.