Oral History of Keith Diefendorff

Interviewed by Douglas Fairbairn on 2022-08-24 in Mountain View, CA
© Computer History Museum

Keith Diefendorff had a remarkable career as the lead architect for multiple microprocessors, including the Motorola 88110, the PowerPC, and a version of the MIPS processor. He played a leading role in the design of other microprocessors as well, including TI’s Lisp machine, the MicroExplorer. Keith grew up in Ohio where he attended Kent State and the University of Akron where he earned a Masters in EE. He went to work for Texas Instruments where he spent 13 years designing computer peripherals, and a variety of microprocessors from the TI 9900 family to the Explorer family of Lisp machines.

Keith then moved on to Motorola where he was asked to architect the next generation of the 88K family of microprocessors, the 88110. That project was eventually cancelled when Motorola, Apple, and IBM decided to collaborate on the design of the PowerPC family of chips. Diefendorff was the lead architect for Motorola.

After 7 years at Motorola, he moved to Silicon Valley and went to work for NexGen Microsystems, where he played a critical role in convincing the company to make their X86 processor compatible with Intel’s X86 family.
After AMD’s purchase of NexGen, he moved onto Apple where he again got to play the role of lead architect for the PowerPC, but this time from Apple’s perspective. His major contribution in this role was to get the AltiVec Vector processing instructions added to the architecture.

He later served stints as the editor-in-chief of the Microprocessor Report, CTO at ARC Cores, chief architect of MIPS’ proposed Sony Playstation processor, architect at Montalvo Systems, and finally back to Apple, from which he retired in 2011. Upon retirement, he moved back to Texas where he has a 100-acre ranch, cattle, horses, etc. and two houses – one for he and his wife, and one for his son and his family.

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Catalog Number: 102792765
Acquisition Number: 2022.0125