Amdahl was born to immigrant parents in Flandreau, South Dakota. After serving in the Navy during WWII he completed a degree in engineering physics at South Dakota State University in 1948. He went on to study theoretical physics at the University of Wisconsin and completed his doctorate there in 1952, creating his first computer, the WISC. He then went straight from Wisconsin to a well paid position at IBM.

At IBM he worked on the IBM 704, the IBM 709, and then the Stretch project, the basis for the IBM 7030. He left IBM in 1956 but returned in 1960. On his return he worked on the System/360 family architecture and became an IBM fellow (1965) and head of the ACS Laboratory in Menlo Park, California. He left IBM again in 1970, after his ideas for computer development were rejected, and set up Amdahl Corporation in Sunnyvale, Calif with aid from Fujitsu. Competing with IBM in the mainframe market the company manufactured "plug compatible" mainframes, shipping its first machine in 1975 - the Amdahl 470 V6, a less expensive and faster replacement for the System 360/165. By purchasing an Amdahl 470 and plug compatible peripheral devices from third-party manufacturers, customers could now run S/360 applications without buying actual IBM hardware.

Amdahl left his company in 1980 to set up Trilogy Systems. With over US$200 million in funds Trilogy was aimed at designing an integrated chip for even cheaper mainframes. The chip development failed within months of the company's $60 million public offering; thereafter, the company focused on developing its VLSI technology and, when that project failed, in 1985 Trilogy merged into Elxsi Corporation. Elxsi also did poorly and Amdahl left in 1989, having already founded his next venture, Andor International, in 1987. Andor hoped to compete in the mid-sized mainframe market, using improved production techniques to make smaller, more efficient machines. Production problems and strong competition led the company into bankruptcy by 1995.

Ever determined, Amdahl co-founded Commercial Data Servers in 1996, again in Sunnyvale, and again developing mainframe-like machines but this time with new super-cooled processor designs and aimed at physically smaller systems. One such machine, from 1997, was the ESP/490 (Enterprise Server Platform/490), an enhancement of IBM's P/390 of the System/390 family.

Article update wanted: how is CDS doing now? What is Amdahl doing now, if alive and well and not retired?