When Gene Amdahl grew up on his family's South Dakota farm, there was no electricity until he was in his teens. He attended a one-room school and did some of his boyhood chores behind a horse-driven plow.
He went on to become a high-tech visionary who was the chief architect of IBM's mainframe computers and whose technological insights shaped the industry for decades to come.
Amdahl died Tuesday in a Palo Alto nursing facility. He was 92.
Amdahl, who had Alzheimer's disease, died of pneumonia, his son Carl said.
"He was an inventor and a very intense thinker," Carl Amdahl said. "He was really comfortable with a blank sheet of paper."
An entrepreneur who ended up running a series of start-ups, Amdahl began his career at IBM Corp. In the early 1960s, he designed a series of big, revolutionary mainframe computers known as the System/360.
The effort has been described by the Computer History Museum in Mountain View, Calif., as "a daring business and technical gamble that became one of the greatest success stories in the history of computing."
IBM backed it with $5 billion, much of it for five new factories to meet exploding demand.
The system represented a leap forward in data processing because it linked machines of different sizes and speeds with a common computing language — a feat that had not been achieved before.
"The impact of that development lives on," the San Jose Mercury News said. "Some IBM mainframes continue to run on the series, while Amdahl's achievements are integrally embedded into the smartphone and search-engine technologies of today."
Born in Flandreau, S.D., on Nov. 16, 1922, Amdahl never wanted to follow his parents and homesteading grandparents into farming. In high school, he was intrigued by science. He studied engineering physics at South Dakota State University and received a doctorate in theoretical physics from the University of Wisconsin.
His 1951 doctoral thesis was titled "The Logical Design of an Intermediate Speed Digital Computer." To support it, Amdahl built a pioneering computer.
IBM hired Amdahl straight out of school. He soon made his mark with designs for the company's 704 scientific mainframe computer. In the mid-1950s, he left for other companies but in 1960 returned to IBM, where he ran the Advanced Computing Systems Lab in Menlo Park.
By 1970, when he founded the Amdahl Computer Corp., he was a celebrity in the high-tech world, known not just for his IBM achievements but also for formulating "Amdahl's Law," a concept in parallel computing.
His new company, in the heart of Silicon Valley, made mainframes cheaper than IBM's and, at one point, captured 24% of the market. It was acquired by Fujitsu after Amdahl left it in 1979.
In 1980, he started Trilogy Systems, aiming to develop a supercomputer running on superchips. But the venture was ill-starred.
Two months after it started, Amdahl was involved in a traffic accident that killed a motorcyclist. He pleaded nolo contendere to misdemeanor manslaughter. A civil suit against him was settled out of court.
Then heavy rains turned a Trilogy site under construction into a swamp. An air conditioning system malfunctioned at its chip-making plant, ruining a "clean room." Other catastrophes followed, but the company, which ultimately folded, may have been on shaky ground at the outset.
"Analysts suggest that Trilogy's ambition was so overweening — to build not only a radically new chip but also a computer — and the technology so complex, that failure was inevitable for even a computer genius such as Mr. Amdahl," the New York Times said in 1984.
Months after he left Trilogy in 1987, Amdahl founded a computer company he called Andor.
In 1991, it was foundering but Amdahl's outlook was positive.
"I see opportunity gleaming in front of me," he told Forbes magazine.
In addition to his son Carl, Amdahl is survived by Marian, his wife since 1946; two daughters; and five grandchildren.