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Grace Hopper
1906–1992 · Computer Scientist & Naval Admiral
Rear Admiral Grace Hopper was a pioneering computer scientist who helped make programming easier through early compilers and word-based programming languages.
“Humans are allergic to change. They love to say, 'We've always done it this way.' I try to fight that. That's why I have a clock on my wall that runs counter-clockwise.”
Why is this scientist famous?
Developing one of the earliest compilers and pioneering word-based programming languages that helped make computers easier to program.
Grace Hopper developed A-0, often described as one of the earliest compilers, and became a leading advocate for programming languages that were easier for people to use. Her later work on FLOW-MATIC helped demonstrate that programs could use word-based commands and strongly influenced the development of COBOL.
Grace's story
Early Life
Born in New York City, Grace Brewster Murray was a curious child who took apart alarm clocks to see how they worked — she had seven in pieces before she understood one. She earned a doctorate in mathematics from Yale in 1934, one of the first women to do so, and taught at Vassar College.
World War II
At 37, Hopper tried to join the Navy but was deemed too old and too light. She persisted, joined the WAVES, and was assigned to the Bureau of Ships Computation Project at Harvard, where she worked on the Mark I — one of the first programmable computers. In 1947, a team working on the Harvard Mark II found a moth trapped in a relay and taped it into the computer logbook as the ‘first actual case of bug being found’. The word ‘bug’ for a technical fault already existed, but Hopper later helped make the story famous.
The Compiler
After leaving Harvard, Hopper joined the Eckert-Mauchly Computer Corporation, where she worked on the Universal Automatic Computer (UNIVAC). In 1952 she developed A-0, often considered one of the earliest compilers — software that helped turn higher-level instructions into forms a computer could use.
Hopper continued developing easier ways to program computers. Her team created FLOW-MATIC, an influential language that used English-like word commands for business data processing. In 1959 she participated in the CODASYL effort to create COBOL, a standard business programming language. COBOL was developed collaboratively by a committee of many people, but Hopper’s ideas, FLOW-MATIC work and later promotion of COBOL were important influences on its development and adoption.
Legacy
Hopper remained in the Naval Reserve and returned to active duty after an earlier retirement. She finally retired from the Navy in 1986 as a rear admiral at age 79, when she was the oldest serving officer in the U.S. armed forces. She became a legendary teacher and speaker, famous for handing out “nanosecond” lengths of wire to show how fast data travels.
What did they discover?
Early Compiler Development
Developed the A-0 system in 1952, often considered one of the earliest compilers and an important step toward making programming more automatic and accessible.
COBOL
Her FLOW-MATIC work and advocacy for word-based programming strongly influenced COBOL. Hopper participated in the CODASYL effort that developed the language and later worked to promote and standardise its use.
Popularising the "Bug"
In 1947, a team working on the Harvard Mark II found a moth trapped in a relay and recorded it as the ‘first actual case of bug being found’. The term ‘bug’ was already used for technical faults, but Hopper later helped popularise the famous story.
Amazing facts
She helped make famous the 1947 story of a moth found in a Harvard Mark II relay, although engineers were already using the word ‘bug’ for technical faults.
She was the oldest serving officer in the U.S. Navy when she retired at 79.
She held a PhD in mathematics from Yale, earned in 1934.
She proposed using word-based programming commands and was initially told that the idea would not work.
She used to hand out 11.8-inch pieces of wire to represent how far light travels in a nanosecond.
The U.S. Navy destroyer USS Hopper was named in her honour, and a NASA-supported lunar hopping robot called Grace was also named after her.
Timeline
Born in New York City
Earned PhD in mathematics from Yale
Begins working on the Harvard Mark I after entering the U.S. Naval Reserve in December 1943
Developed A-0, often considered one of the earliest compilers
Participated in the CODASYL effort that developed COBOL, which drew important ideas from her earlier FLOW-MATIC work
Retired from the Navy as a rear admiral at age 79
Died and was buried at Arlington National Cemetery
Awards & honours
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