page_title: Grace Hopper
section_title: World War II
hierarchical_section_title: Grace Hopper / Career / World War II
caption_attribution_description: English: Duty officer signup sheet for the U.S. Navy Bureau of Ships Computation Project at Harvard University, which built and operated the w:Harvard Mark I, one of the earliest digital computers. The Mark I was in operation from 1944 to 1959. During that period, the days of the week and dates on the form, e.g. Monday, 23 April, match up for the following years: 1945, 1951 and 1957. Grace Hopper, noted computer pioneer, worked on the project from 1944 to 1949.
context_page_description: Grace Brewster Murray Hopper was an American computer scientist and United States Navy rear admiral. One of the first programmers of the Harvard Mark I computer, she was a pioneer of computer programming who invented one of the first linkers. She popularized the idea of machine-independent programming languages, which led to the development of COBOL, an early high-level programming language still in use today.
  Prior to joining the Navy, Hopper earned a Ph.D. in mathematics from Yale University and was a professor of mathematics at Vassar College. Hopper attempted to enlist in the Navy during World War II but was rejected because she was 34 years old. She instead joined the Navy Reserves. Hopper began her computing career in 1944 when she worked on the Harvard Mark I team led by Howard H. Aiken. In 1949, she joined the Eckert–Mauchly Computer Corporation and was part of the team that developed the UNIVAC I computer. At Eckert–Mauchly she began developing the linker. She believed that a programming language based on English was possible. Her linker converted English terms into machine code understood by computers.
context_section_description: Hopper had tried to enlist in the Navy early in World War II. She was rejected for a few reasons. At age 34, she was too old to enlist, and her weight to height ratio was too low. She was also denied on the basis that her job as a mathematician and mathematics professor at Vassar College was valuable to the war effort. During the war in 1943, Hopper obtained a leave of absence from Vassar and was sworn into the United States Navy Reserve; she was one of many women who volunteered to serve in the WAVES. She had to get an exemption to enlist; she was 15 pounds (6.8 kg) below the Navy minimum weight of 120 pounds (54 kg). She reported in December and trained at the Naval Reserve Midshipmen's School at Smith College in Northampton, Massachusetts. Hopper graduated first in her class in 1944, and was assigned to the Bureau of Ships Computation Project at Harvard University as a lieutenant, junior grade. She served on the Mark I computer programming staff headed by Howard H. Aiken. Hopper and Aiken co-authored three papers on the Mark I, also known as the Automatic Sequence Controlled Calculator. Hopper's request to transfer to the regular Navy at the end of the war was declined due to her advanced age of 38. She continued to serve in the Navy Reserve. Hopper remained at the Harvard Computation Lab until 1949, turning down a full professorship at Vassar in favor of working as a research fellow under a Navy contract at Harvard.
caption: Hopper's signatures on a duty officer signup sheet for the Bureau of Ships Computation Project at Harvard, which built and operated the Mark I
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