She built the first compiler, helped invent COBOL — and carried nanoseconds in her purse.
Grace Hopper (1906–1992) was the US Navy rear admiral and computer scientist who built the first compiler in 1952 — letting programmers write in words instead of machine code — and drove the creation of COBOL, the business language that still runs much of the world's finance.
A Vassar mathematics professor who joined the Navy in 1943, she worked on the Harvard Mark I under Howard Aiken, then spent four decades dragging the industry, by force of personality, toward programming languages humans could read.
Grace Brewster Murray was born in 1906 in New York City and earned a PhD in mathematics from Yale in 1934 — rare for a woman then. Teaching at Vassar, she tried to enlist after Pearl Harbor; at 34 she was considered too old and too slight, until a waiver let her into the WAVES in 1943.
Assigned to Harvard's Computation Laboratory, she became the third person to program the Mark I, a 51-foot electromechanical giant. She wrote its 561-page manual and stayed up nights coaxing it through ballistics calculations for the war effort.
In 1952, at Remington Rand working on the UNIVAC, Hopper built the A-0 system — the first compiler, translating human-readable instructions into machine code. 'Nobody believed that,' she recalled. 'I had a running compiler and nobody would touch it.' She was right: compilers became the foundation of all software.
Her FLOW-MATIC language used English-like commands, proving business data processing could be programmed in words. When the industry met in 1959 to design a common business language, her ideas shaped COBOL — still processing trillions of dollars of transactions today.
She popularized the term 'debugging': in 1947 a moth was found taped into the Harvard Mark II logbook with the note 'first actual case of bug being found' — the logbook survives at the Smithsonian. She carried pieces of wire cut to 11.8 inches — the distance light travels in a nanosecond — to explain why engineers must think small.
Famous for 'it's easier to ask forgiveness than it is to get permission' and 'humans are allergic to change', she retired from the Navy as a rear admiral in 1986 at 79, the oldest serving officer. The destroyer USS Hopper bears her name.
