Grace Hopper

Grace Hopper the American computer scientist and United States Navy rear admiral (1906-1992) who pioneered the development of programming languages and helped to make computers accessible to non-specialists. She wrote one of the first compilers, championed machine-independent languages, and played a leading role in the creation of COBOL, becoming one of the most influential figures in the early history of computing.

Early Life and Education

Grace Brewster Murray was born on 9 December 1906 in New York City, the daughter of an insurance broker and a homemaker. Curious and mechanically inclined, she took apart alarm clocks as a child to understand how they worked, a habit that her mother allowed on condition that she reassemble them. She studied at Vassar College, graduating in 1928 with a degree in mathematics and physics, and then earned master's and doctoral degrees in mathematics at Yale University, completing her doctorate in 1934.

She taught mathematics at Vassar for a decade, rising to associate professor, and married Vincent Foster Hopper in 1930; the couple later divorced. When the United States entered the Second World War she was determined to contribute, and despite being below the weight requirement and older than most recruits, she obtained a waiver and joined the United States Navy Reserve in 1943. She was assigned to the Bureau of Ordnance Computation Project at Harvard University.

The Harvard Mark I and Early Programming

At Harvard, Hopper worked on the Mark I, an electromechanical computer designed by Howard Aiken and used for wartime calculations. She learned to program it by writing sequences of instructions on paper tape, and she became one of the first people to write programs for a large automatic calculator. She co-authored a manual for the machine and helped to document and extend its use.

She later worked on the Mark II and Mark III computers and remained at Harvard after the war as a research fellow. It was on the Mark II, according to the story she often told, that a moth was found trapped in a relay and taped into the logbook with the note that it was the first actual case of a bug being found, an anecdote that popularized the term debugging. The episode, whether literal or apocryphal in its details, became part of computing folklore.

The First Compiler and Programming Languages

Hopper became convinced that programming should not require mathematicians to translate every problem into machine code by hand. Working at the Eckert-Mauchly Computer Corporation and later at Remington Rand, she developed the A-0 system in 1952, a program that translated symbolic mathematical notation into machine instructions. It was among the first compilers, and the idea that a machine could do the translation met with scepticism from those who doubted that computers could write programs.

She extended these ideas in the A-2 and A-3 systems and in the programming language that became known as FLOW-MATIC, an early language that used English-like statements to process business data. Her insistence that programs could be written in something closer to human language, and that such programs could run on more than one kind of machine, was a foundational insight of software engineering. It made possible the portable high-level languages that followed.

COBOL and Standards

Hopper was influential in the effort to create a common business language that would run across the computers of different manufacturers. She served on committees that shaped the specifications of COBOL, the common business-oriented language introduced in 1960, and her FLOW-MATIC work provided an important precedent for its English-like syntax. COBOL became one of the most widely used languages in the world and remained central to business and government computing for decades.

Beyond COBOL, she campaigned for standards and for the reuse of tested software. She argued that programming should build on verified components rather than begin from scratch every time, and she promoted the idea of a library of routines that could be shared. These principles, once controversial, became fundamental to modern software practice. She also taught and lectured widely, training a generation of programmers in her methods.

Navy Career and Legacy

Hopper retired from the Navy in 1966 but was recalled to active duty in 1967 and served for many more years, working on the standardization of programming languages for the service. In 1983 she was promoted to commodore and in 1985 to rear admiral, becoming at her retirement in 1986 one of the oldest officers on active duty. She continued to speak and consult into her final years, and she died on 1 January 1992.

She received the National Medal of Technology and the Presidential Medal of Freedom, and a Navy destroyer and a computing conference were named in her honour. She was renowned for her wit and for popular explanations of technical ideas, including her habit of handing out lengths of wire to illustrate how far light travels in a nanosecond. She is remembered as a founder of the software discipline and a tireless advocate for making computers serve human purposes.

See also

• COBOL
• Compiler
• Harvard Mark I
• Debugging