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Inventors of the Modern Computer
The Harvard MARK I Computer - Howard Aiken and Grace Hopper
Harvard Mark 1 Computer
Harvard Mark 1 Computer

Grace Hopper - Howard Aiken
Grace Hopper
Howard Aiken
Inventors of the Modern Computer Series
Table of Contents
Next Chapter
John Presper Eckert & John W. Mauchly - ENIAC 1 computer
ENTER
More on Grace Hopper
and Howard Aiken
Complete Biography of Grace Hopper and Howard Aiken
Looking Back:
Grace Hopper's Younger Years
Remembering
Grace Hopper A Legend in Her Own Time

By Mary Bellis

Howard Aiken and Grace Hopper designed the MARK series of computers at Harvard University. The MARK series of computers began with the Mark I in 1944. Imagine a giant roomful of noisy, clicking metal parts, 55 feet long and 8 feet high. The 5-ton device contained almost 760,000 separate pieces. Used by the US Navy for gunnery and ballistic calculations, the Mark I was in operation until 1959.

The computer, controlled by pre-punched paper tape, could carry out addition, subtraction, multiplication, division and reference to previous results. It had special subroutines for logarithms and trigonometric functions and used 23 decimal place numbers. Data was stored and counted mechanically using 3000 decimal storage wheels, 1400 rotary dial switches, and 500 miles of wire. Its electromagnetic relays classified the machine as a relay computer. All output was displayed on an electric typewriter. By today's standards, the Mark I was slow, requiring 3-5 seconds for a multiplication operation.

Howard Aiken

Born: 9 March 1900 in Hoboken, New Jersey, USA
Died: 14 March 1973 in St. Louis, Missouri, USA
Howard Aiken was an electrical engineer and physicist who first conceived of an electro-mechanical device like the Mark I in 1937. After completing his doctorate at Harvard in 1939, Aiken stayed on to continue the computer's development. IBM funded his research. Aiken headed a team of three engineers including Grace Hopper.
The Mark I reached completion in 1944.
In 1947, Howard Aiken completed the Mark II, an electronic computer. The same year he founded the Harvard Computation Laboratory.
He later published numerous articles on electronics and switching theory and started Aiken Industries.
Howard Aiken loved computers, but even he had no idea of their eventual widespread appeal. "Only six electronic digital computers would be required to satisfy the computing needs of the entire United States," he said in 1947.

Grace Hopper

Born: 9 Dec 1906 in New York, USA
Died: 1 Jan 1992 in Arlington, Virginia, USA
Grace Hopper studied at Vassar College and Yale and then joined the Naval Reserve in 1943. In 1944, she started working with Aiken on the Harvard Mark I computer.
Grace Hopper is responsible for the term 'bug' for a computer fault. The original 'bug' was a moth, which caused a hardware fault in the Mark I. Hopper was the first person to 'debug' a computer.
In 1949, Grace Hopper started research for the Eckert-Mauchly Computer Corporation where she designed an improved compiler and was part of the team which developed Flow-Matic, the first English-language data processing compiler.
She invented the language APT and verified the language COBOL.
Grace Hopper was the first computer science "Man of the Year" in 1969.
In 1991, Grace Hopper received the National Medal of Technology.

Next Chapter > The ENIAC 1 Computer

artwork©marybellis
original photos©"army photos"

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