In 1966, computer memory was a nightmare. IBM's mainframes stored bits in hand-woven magnetic cores — tiny iron rings threaded on wires by (mostly) women workers in Asian factories. Each core held one bit. A megabyte weighed pounds, cost tens of thousands of dollars, and could not shrink much further. Semiconductor alternatives existed — the six-transistor SRAM cell — but each bit chewed up so much silicon that mainframe-scale memory was economically impossible.

Robert Dennard, an IBM researcher at the Watson Research Center in Yorktown Heights, went home one evening in 1966 turning the problem over in his head. That night, he sketched a radically simpler idea on a notepad. What if a bit could be stored in a single MOSFET transistor connected to a single tiny capacitor? The capacitor would hold a charge (a "1") or not (a "0"). The transistor would act as a switch, letting you read or write the charge. Six transistors became one transistor and one capacitor.

The catch: capacitors leak. The charge would drain in milliseconds. So the circuit had to refresh itself constantly — reading each bit and writing it back thousands of times per second. Hence the name: Dynamic Random-Access Memory, or DRAM.

Dennard filed U.S. Patent 3,387,286, "Field-Effect Transistor Memory," on July 14, 1967. It was granted June 4, 1968. The patent describes exactly what sits inside every laptop, phone, server, and gaming console today: an array of one-transistor cells arranged on a grid of word lines and bit lines, refreshed on a schedule.

IBM's initial reaction was tepid. It took Intel — a two-year-old startup — to commercialize the idea with the Intel 1103 in 1970, a 1-kilobit DRAM that quickly killed the magnetic core industry. By 1972, the 1103 was the world's best-selling semiconductor chip.

Dennard's second contribution was, if anything, more consequential. In a 1974 paper, he articulated what became known as Dennard Scaling: as you shrink a MOSFET's dimensions by a factor of k, its power consumption drops by k², so the power density of a chip stays constant even as you cram in more transistors. This principle, alongside Moore's Law, drove the entire computing revolution from 1975 to roughly 2005. Every faster, cooler, cheaper chip generation was Dennard Scaling in action.

Dennard Scaling finally broke down in the mid-2000s — leakage currents at nanometer scales made further voltage reduction impractical, which is why clock speeds plateaued around 3–4 GHz and the industry pivoted to multi-core designs. But his DRAM cell? Still there. The physical structure has been refined a thousand times — trench capacitors, stacked capacitors, high-k dielectrics — but the fundamental one-transistor-one-capacitor topology remains. A modern 16 GB DDR5 stick contains roughly 128 billion Dennard cells, each functionally identical to the one he sketched at his kitchen table in 1966.

The economics are staggering. In 1968, a bit of core memory cost about one dollar. Today, a bit of DRAM costs roughly a hundred-billionth of a cent — a price reduction of about 10¹³. It is arguably the largest sustained cost collapse of any manufactured product in human history, and it began with one drawing on one notepad.