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Harvard Mark I
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The Harvard Mark I, or IBM Automatic Sequence Controlled Calculator, was one of the earliest general-purpose electromechanical computers used in the war effort during the last part of World War II.
Closeup of input/output and control readers
Closeup of input/output and control readers
The left end consisted of electromechanical computing components.
The left end consisted of electromechanical computing components.
The right end included data and program readers, and automatic typewriters.
The right end included data and program readers, and automatic typewriters.
Card punch used to prepare programs
Card punch used to prepare programs
Harvard Mark II
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The Harvard Mark II, also known as the Aiken Relay Calculator, was an electromechanical computer built under the direction of Howard Aiken at Harvard University, completed in 1947. It was financed by
Harvard Mark I
…and was only retrospectively applied to the Harvard machines, and that the term could only be applied to the Mark III and IV, not to the Mark I or II. The main sequence mechanism was unidirectional. This meant that complex programs had to be physically lengthy. A program loop was accomplished by loop…
Logbook entry containing the "bug"
Logbook entry containing the "bug"