About the Mark I

Click to view full size[ open image in a new tab ] Image courtesy of Popular Mechanics, October 1944

Mark I was designed in 1937 by a Harvard graduate student, Howard H. Aiken to solve advanced mathematical physics problems encountered in his research. Aiken’s ambitious proposal envisioned the use of modified, commercially-available technologies coordinated by a central control system.

Supported by Harvard faculty in the division that is today the School of Engineering and Applied Sciences, Aiken discussed his idea with several manufacturers, eventually finding interest at IBM, a company that specialized in calculating machines and punch card systems. Using company components, IBM engineers in Endicott, NY developed the machine’s working systems and directed its construction over five years. During that period America entered World War II. When Mark I was finally delivered to Harvard in 1944, it was operated by the U.S. Navy Bureau of Ships for military purposes, solving mathematical problems that until then required large teams of human “computers.”

Mark I was in operation between 1944 and 1959, at which point sections from each of its components were taken to IBM and the Smithsonian Institution, leaving the smaller version seen here. The original Mark I was about twice the current length.

Automatic Calculators,
Human Computers

Click to view full size[ open image in a new tab ] Image courtesy of The Library of Congress

Until the 1940s, mathematical problems and tables were worked by teams of dozens of human "computers" with mechanical calculating machines. Mathematicians were in charge of turning complex problems into distributed, simple operations for their teams.

Mark I was originally called the “Automatic Sequence Controlled Calculator” by IBM, and often referred to as the “Harvard Calculator” when first installed in Cambridge in 1944. It started to be known as Mark I as its successor machines were built.

Was it a Robot? a Calculator? or a Computer? Until 1945, “computer” was a job description for a person who performed mathematical operations for large-scale projects. The existence of new machines like Mark I created the need for a word to describe them. Around 1945, people started redefining such new machines as “computers.”

... By "calculator" or "calculating machine" we shall mean a device ... capable of accepting two numbers A and B, and of forming some or any of the combinations
A + B, A - B, A x B, A / B.

By "computer" we shall mean a machine capable of carrying out automatically a succession of operations of this kind and of storing the necessary intermediate results ... Human agents will be referred to as "operators" to distinguish them from "computers" (machines).

‒George Stibitz, Report for the National Defense Research Committee on Relay Computers (February 1945).


[ link ]  IBM Archives
Digital Exhibit on the Automatic Sequence Controlled Calculator (a.k.a. The Harvard Mark I)

[ link ]   National Museum of American History, Smithsonian Institution
Mark I Log Book With Computer Bug

Collection of Historical Scientific Instruments   © President and Fellows of Harvard College