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Howard Aiken - the Mark I Computer

Electrical engineer, physicist, and computing pioneer Howard Hathaway Aiken was born in 1900 in Hoboken, New Jersey. He spent most of his childhood in Indianapolis, Indiana and obtained a bachelor's degree in electrical engineering from the University of Wisconsin, Madison. While he studied, he also worked for the Madison Gas Company. After he graduated, the company promoted him to chief engineer.

In 1935, Aiken returned to school and received a Ph.D. from Harvard University in 1939. He became very interested in computers while working on his doctoral thesis in physics. He had ideas for a machine that could help with difficult calculations. He convinced IBM to fund a project to develop such a machine. A constructing team at Harvard was to use machine components that IBM already had in existence.

The inventor, Grace Murray Hopper, worked with Aiken on the computer, which was a priority undertaking in the Bureau of Ordinance's Computation Project at Harvard University to which Hopper had been assigned. It took seven years before Aiken and his team completed the computer, which they called the Mark I. The machine was very large at 51 feet long and 8 feet high, with 26 foot panels stretching out of the back. Its glass encasement exposed thousands of switches, relays, shafts, wheels and wires. It had the ability to carry out five operations, addition, subtraction, multiplication, division and reference to previous results. In 1944, the system, officially named the IBM Automatic Sequence Controlled Calculator, was demonstrated with uneventful response. But it was an important start.

Meanwhile, in 1942, the Navy had asked Aiken for a system for their Naval Proving Ground. That's when he began work on the Harvard Mark II. This system, which employed an electrical memory, was finished in 1947. One important advance in the second system was the concept of 'constants' - fixed values which are referenced by the program the machine is running. This was a new concept in programming at the time, but it is taken for granted in today's programming languages.

Aiken's third computer version, the Harvard Mark III, was finished in 1949. This was the first of Aiken's machines to run from a stored program. This version had a more comprehensive control system, which incorporated address registers and indirect addressing, which allows a program to get its data from an address stored in a register. This concept is virtually universal in computers today. Though the Harvard Mark III had greater storage capacity, it was extremely unreliable when it was turned on and off, as the components were very susceptible to heat changes.

The Harvard Mark IV, finished in 1952, was much the same as the Mark III, but had the addition of a magnetic core memory storing 200 registers. This advance made the computer much faster.

Aiken continued to teach at Harvard, working on computers and publishing numerous articles on electronics and switching theory, until his retirement in 1961. His early designs and research made an inestimable impact on today's powerful and indispensable machines. His 1944 founding of the Harvard Computation Laboratory was also the first establishment of an academic center for computer research.

In 1964, Aiken received the Harry M. Goode Memorial Award, a medal and $2,000 awarded by the Computer Society. He died in St. Louis, Missouri, in 1973.

[October 2002]

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