Robert H. Dennard

Robert H. Dennard invented dynamic random-access memory (DRAM) in 1966 while working as an engineer at IBM's Thomas J. Watson Research Center. His design used a single transistor and a single capacitor per memory cell, a radical simplification over the magnetic-core memory then in use.

Dennard Scaling is the principle Dennard articulated in the early 1970s stating that as transistors shrink, power density stays roughly constant—meaning smaller chips could run faster without using more power per unit area. This scaling law drove the microprocessor industry's rapid advances for roughly three decades before it began breaking down around the mid-2000s.

Dennard spent his entire industrial career at IBM, joining the company in 1958. He worked at IBM's research division in Yorktown Heights, New York, where he both invented DRAM and co-developed the scaling theory that bears his name.

Dennard did not receive a Nobel Prize, but he has been honored with many of engineering's highest awards. He received the National Medal of Technology from President Reagan in 1988 and the IEEE Medal of Honor in 2009, among others.

Before DRAM, computers relied primarily on magnetic-core memory, which was bulky, expensive, and slow. Dennard's insight was to store each bit of data as a charge on a tiny capacitor accessed through a single transistor, making memory dramatically cheaper, smaller, and higher-density.

No, Dennard Scaling largely broke down around the mid-2000s as transistor dimensions shrank below roughly 90 nanometers. Once leakage current and threshold-voltage limits could no longer be controlled, power density began rising with each new process node, forcing the industry toward multi-core designs instead of simply cranking up clock speeds.