Mr. Walden eventually enrolled at San Francisco State College (now University) and earned his BA in mathematics in 1964. His interest in computing grew in a numerical analysis course that included working on an IBM computer.
After college, he began working as a computer programmer in the Department of Space Communications at Massachusetts Institute of Technology’s Lincoln Laboratories.
He met education manager Sara Elizabeth Cowles in 1965 and they were married the following year. He was hired by Bolt Beranek and Newman in 1967. Soon the company won a contract to build the first IMP.
“It was a very small group working together all the time,” said Mr Walden. I said In a 1990 interview with the Charles Babbage Institute at the University of Minnesota, an archival and research center specializing in information technology.
“We were going in and out of each other’s offices and helping each other debug,” he added.
Each discovery aroused excitement. “We used to come running, ‘Look, I got this working!’ we would say,” he said.
Mr. Walden left Bolt Beranek in 1970 to work for Norsk Data, helping that company build a computer modeled after the IMP. In 1971 Bolt returned to Beranek and remained there until 1995. He later became an expert in management. An avid computer historian, he was the editor of the IEEE Annals of the History of Computing, originally published by the Institute of Electrical and Electronics Engineers.
Although Mr. Walden does not hold a master’s degree, he received an honorary doctorate from California State University in 2014 for his work on Arpanet. “He told me more than once that he didn’t think he would have such an honor,” Alex McKenzie, a former colleague of Mr. Walden’s, said in an interview.
In addition to his wife, Mr. Walden is survived by his son Luke; his brother Daniel; sister Velma Walden Hampson; and two grandchildren.