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‘The first large-scale general-purpose automatic digital computer’

The Mark 1 dedication at Harvard was on 07 August 1944.

It was 51 feet long and eight feet high. It weighed about five tons (10,000 pounds) and consisted of about 750,000 parts.

If you’ve heard of it, you probably know the IBM Automatic Sequence Controlled Calculator (ASCC) by a more colloquial name, the Mark 1. At the time, it was “the largest electromechanical calculator ever built.”

On 07 August 1944, IBM president Thomas J. Watson Sr. and Harvard University president James B. Conant dedicated it, “the first large-scale general-purpose automatic digital computer.” From an IBM brochure:

The IBM Automatic Sequence Controlled Calculator, an algebraic mechanism employing a unique automatic sequence control, is designed to solve, rapidly and accurately, practically any known problem in applied mathematics.


When this calculator returns to civilian use, it will be of the greatest importance in astronomy, atomic physics, radio research, investigations of the ionosphere, actuarial work, optics, and electronics.

According to the National Museum of American History:

One publication named the “Mathematical Robot” among the 10 most important scientific advancements of that year—along with penicillin, jet propulsion, the development of silicone, and the insecticide DDT.

Beginning in May 1944, the U.S. Navy Bureau of Ships began using the computer exclusively. It was “supported by a technical staff that include[d] former IBMers then serving in the Navy.”

In 1944, the Navy had assigned Grace Hopper to the Bureau of Ships Computation Project at Harvard University. At age 37, “she reported to active Navy duty in the basement of the Cruft Laboratory at Harvard” where she would work with Aiken and the Mark 1.

From Grace Hopper and the Invention of the Information Age:

Aiken, a difficult man who would be classified as a “male chauvinist” by today’s standards, found a kinship with Hopper … [such that] she became the most prominent person in the Harvard Computational Laboratory apart from the fiery Aiken.

Hopper wrote the first computer manual describing how to program the Mark 1. Her notes provide background for many of the terms used in computing today (emphasis added):

A repeating “loop” for the Mark I was an actual loop of punched paper instructions that fed into the machine continuously. A software “patch” for the Mark I referred to the paper patches applied over erroneously punched holes on a program tape or card. Once patched, it could be repunched with the correct instruction. The Mark I’s “library” was where all the punched paper tapes and cards that held the Mark I’s programming instructions were stored. And, though the term “bug” was already in use for hard-to-find mechanical problems, the Mark I saw it applied to computers, Schechner said. Hopper’s notebook contains a tongue-in-cheek reference to the term, an actual moth that was the cause of a malfunction in the next generation machine, the Mark II. Hopper taped the dead insect to the page, noting that the mythical “bug” had been observed at last.

Physicist John von Neumann also utilized the Mark 1 while working with the Manhattan Project in order “to calculate the potential effects of imploding the first atomic bomb.”

The Mark I operated at Harvard for 15 years. Because it used “punched cards and punched paper tape to store data and instructions,” it could solve a variety of mathematical problems, not just one specific type.

The Cruft Laboratory was also integral to World War I efforts.

Seven years in the making

In 1937, Howard H. Aiken, then a graduate student in theoretical physics at Harvard, was attempting to solve nonlinear equations. His proposal to faculty for a “large-scale digital calculator” met with a “nope.” So he turned to IBM’s James W. Bryce. His goal?

To discuss “the possibilities of designing a machine of a very complex nature for solving equations pertaining to the ionosphere to work on television and also equations pertaining to astronomy.”

On 16 February 1939, Watson agreed to support a proposal developed by Aiken, Bryce and other IBM engineers. In March, the IBM Board of Directors approved building an “Automated Computing Plant” at IBM’s North Street Laboratory in Endicott, N.Y.

World War II was proceeding apace in Europe but the United States would remain neutral for almost another two years. IBM shipped the computer to Harvard in February 1944. IBM invested about $200,000 (about $3.4 million in 2022 dollars) in the project and donated $100,000 for operating expenses.

The Mark I was a gigantic calculator that could perform four fundamental arithmetic operations on numbers up to 23 decimal digits in length. The scale of its mechanical operation is boggling:

It had 60 switch registers for constants, 72 storage counters for intermediate results, a central multiplying-dividing unit, functional counters for computing transcendental functions, and three interpolators for reading functions punched into perforated tape. Numerical input was in the form of punched cards, paper tape or manually set switches. The output was printed by electric typewriters or punched into cards. Sequencing of operations was accomplished by a perforated tape.

Beginning in May 1944, the U.S. Navy Bureau of Ships began using the computer exclusively. It was “supported by a technical staff that include[d] former IBMers then serving in the Navy.”

During the dedication ceremony on 07 August 1944:

Watson says, in part: “Dr. [James B.] Conant [Harvard’s President], I ask you to accept this IBM Automatic Sequence Controlled Calculator for Harvard University in the name of the International Business Machine Corporation. It is my earnest hope that the results accomplished by this machine and the future cooperation of our two institutions will contribute to further scientific development and will prove mutually satisfactory.”

Conant, in accepting the ASCC, expresses the hope that its usefulness will be extended to those engaged in scientific and technical work outside as well as within Harvard. He also says: “Mr. Watson and the International Business Machines Corporation, by employing their inventions of the past many years in the development and construction of this new, powerful instrument for mathematical work, have given Harvard not only a splendid gift but have presented the University with an opportunity so great as to constitute a challenge.”

According to the Computer History Museum:

IBM learned about large calculator development with the Mark I and applied these skills in its own Selective Sequence Controlled Calculator (SSEC), another Giant Brain project undertaken when Aiken snubbed IBM by claiming he had invented the ASCC.

Linking the Mark 1 and Charles Babbage

What I didn’t realize until now is this: the Mark 1 “brought Babbage’s principles of the analytical engine almost to full realization.” According to the Computer History Museum, “Babbage’s vast mechanical computing engines rank as one of the startling intellectual achievements of the 19th century.”

His youngest son, Henry Prevost Babbage, “acquired a sound grasp” of his father’s Difference and Analytical Engines.

Babbage bequeathed his drawings, workshop and the surviving physical relics of the engines to Henry who tried to continue his father’s work and to publicize the engines after Babbage’s death. He was at his father’s bedside when Babbage died in 1871.

There is no continuous line of development from Babbage to the electronic era and Henry is one of the bridging figures. From 1872 Henry continued diligently with his father’s work and then intermittently in retirement in 1875. He assembled about six small demonstration pieces for Difference Engine No. 1 one of which he sent to Harvard.

Aiken credited seeing that artifact at Harvard as inspiration for his engineering designs. Aiken wrote that “he felt that Babbage was addressing him personally from the past.”

#scitech, #computing, #war (199/365)
Daily posts, 2022-2023

By Kathy E. Gill

Digital evangelist, speaker, writer, educator. Transplanted Southerner; teach newbies to ride motorcycles! @kegill

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