Harvard Mark I - Wikipedia, the free encyclopedia
Harvard Mark I. From Wikipedia, the free encyclopedia. Jump to: navigation, search ... Harvard Mark I - IBM ASCC (US) 1944. Decimal. Electro-mechanical ...
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History of Computing Science: Harvard Mark I
Part of a multipage presentation on the history of computers. This page talks about the origin of the Harvard Mark I machine.
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Howard Aiken's Harvard Mark I (the IBM ASCC)
Many consider that the modern computer era commenced with the first large-scale automatic digital computer, the Harvard Mark 1, which was developed between 1939 and ...
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Howard Aiken and Grace Hopper - Inventors of the Mark I Computer
Howard Aiken and Grace Hopper computer inventors with the Mark I computer. ... In 1944, she started working with Aiken on the Harvard Mark I computer. ...
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Category:Harvard Mark I - Wikimedia Commons
Category:Harvard Mark I. From Wikimedia Commons, the free ... Media in category "Harvard Mark I" The following 8 files are in this category, out of 8 total. ...
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Harvard Mark I Summary and Analysis Summary
Harvard Mark I summary with 9 pages of encyclopedia entries, essays, summaries, research information, and more. ... Harvard-Ibm Automatic Sequence Controlled ...
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IBM Archives: IBM's ASCC (a.k.a. The Harvard Mark I)
IBM Archives: Exhibits: IBM's ASCC: IBM's ASCC (a.k.a. The Harvard Mark I) ... (a.k.a. The Harvard Mark I) Length: 51 feet. Height: eight feet. Weight: nearly ...
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IBM Archives: IBM's ASCC (a.k.a. The Harvard Mark I) - page 2
IBM Archives: Exhibits: IBM's ASCC: IBM's ASCC introduction 2 ... became known more popularly as the "Mark I" at Harvard -- brought Babbage's ...
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The History of Computers
... the Mark I, was put into operation in 1944 and was used until 1959 at Harvard. ... The Harvard Mark I computer could carry out five operations, addition, ...
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The IBM ASCC
Also called the Harvard Mark I. It was built in 1940-43 and remained operational ... Bloch, Richard M., "Mark I Calculator", Proceedings of a Symposium on Large ...
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The IBM Automatic Sequence Controlled Calculator (ASCC), called the Mark I by Harvard UniversityThe machine's name as actually displayed on the hardware itself is Aiken-IBM Automatic Sequence Controlled Calculator Mark I. An early photograph (Wilkes 1956:16 figure 1-7) displays the name as IBM Automatic Sequence Controlled Calculator. , was the first large-scale automatic digital computer in the USA. It is considered by some to be the first universal calculator.

The electromechanical ASCC was devised by Howard Aiken, created at IBM, shipped to Harvard in February 1944, and formally delivered there on August 7, 1944. The main advantage of the Mark I was that it was fully automatic—it didn't need any human intervention once it started. It was the first fully automatic computer to be completed. It was also very reliable, much more so than early electronic computers. It is considered to be "the beginning of the era of the modern computer" and "the real dawn of the computer age", page 5..

Design and Construction The building elements of the ASCC were switches, relays, rotating shafts, and clutches. It was built using 765,000 electronic components and hundreds of miles of wire, amounting to a size of 51 feet (16 m) in length, eight feet (2.4 m) in height, and two feet (~61 cm) deep. It had a weight of about 10,000 pounds (4500 kg). The basic calculating units had to be synchronized mechanically, so they were run by a 50 foot (~15.5 m) shaft driven by a five-horsepower (4 kW) electric motor. From the IBM Archives: The Automatic Sequence Controlled Calculator (Harvard Mark I) was the first operating machine that could execute long computations automatically. A project conceived by Harvard University's Dr. Howard Aiken, the Mark I was built by IBM engineers in Endicott, N.Y. A steel frame 51 feet long and eight feet high held the calculator, which consisted of an interlocking panel of small gears, counters, switches and control circuits, all only a few inches in depth. The ASSC used 500 miles of wire with three million connections, 3,500 multipole relays with 35,000 contacts, 2,225 counters, 1,464 tenpole switches and tiers of 72 adding machines, each with 23 significant numbers. It was the industry's largest electromechanical calculator IBM Archives: FAQ / Products and Services.

Operation The Mark I had 60 sets of 24 switches for manual data entry and could store 72 numbers, each 23 decimal digits long.Wilkes 1956:16-17 It could do three additions or subtractions in a second. A multiplication took six seconds, a division took 15.3 seconds, and a logarithm or a trigonometric function took over one minute.

The Mark I read its Instruction sets from a 24 channel punched tape and executed the current instruction and then read in the next one. It had no conditional branch instruction. This meant that complex programs had to be physically long. A loop was accomplished by joining the end of the paper tape containing the program back to the beginning of the tape (literally creating a loop). This separation of data and instructions is known as the Harvard architecture. The first programmers of the Mark I were Richard Milton Block, Robert Campbell, and computing pioneer Grace Hopper, respectively.Wexelblat, Richard L. (Ed.) (1981). History of Programming Languages, p. 20. New York: Academic Press. ISBN 0-12-745040-8

Instruction Format The 24 channels of the input tape were divided into 3 fields of 8 channels. Each Accumulator (computing), each set of switches, and the Hardware register associated with the Input/output, and Arithmetic logic unit were assigned a unique identifying index number. These numbers were represented in Binary numeral system on the control tape. The first field was the binary index of the result of the operation and the second, the source datum for the operation. The third field was a Opcode for the Instruction (computer science) to be performed.Wilkes 1956:17-18

Aiken and IBM At the dedication ceremony, Aiken failed to mention the involvement of IBM in designing and building the computer. IBM was not pleased with this, and parted ways with Aiken. IBM named the computer the ASCC but Harvard and Aiken renamed it the Mark I. IBM went on to build the IBM SSEC.

Successors The Mark I was followed by the Harvard Mark II (1947 or 1948), Harvard Mark III (September 1949), and Harvard Mark IV (1952) – all the work of Aiken. The Mark II was an improvement over the Mark I, but it also used electromechanical relays. The Mark III used some electronic components and the Mark IV was all-electronic, using solid state (electronics) components. The Mark III and Mark IV used Drum memory memory and the Mark IV also had magnetic core memory. The Mark II and Mark III went to the United States Navy base at Dahlgren, Virginia. The Mark IV was built for the United States Air Force, but it stayed at Harvard.

The Mark I was eventually disassembled, although portions of it remain at Harvard in the Science Center.

Myth on origins of "bugs" Grace Hopper popularized the story that the word "bug" (in the sense of a technical problem) was inspired by a moth crushed in a relay of the Mark I, but this is not true (see Computer bug#Etymology).

Comparison with other early computers Notes

See also

• History of computing hardware
• Harvard Mark II
• Harvard Mark III
• Harvard Mark IV
• Howard Aiken
• Other early computers:
• Z3 (Germany)
• Manchester Mark I (UK)
• Atanasoff–Berry Computer (USA)
• ENIAC (USA)
• Colossus computer (UK)
• IBM Selective Sequence Electronic Calculator (USA)

References

• {{cite web

| last = Cruz | first = Frank da | title = The IBM Automatic Sequence Controlled Calculator | publisher = Columbia University Computing History | date = Aug 2004 | url = http://www.columbia.edu/acis/history/mark1.html | accessdate = October 2006 -->

• {{cite book

| last = Campbell-Kelly | first = Martin | coauthors = Aspray, William | title = Computer: A History of the Information Machine | publisher = Basic Books | date = 1996 | url = | id = ISBN 0-465-02989-2 -->

• {{cite book

| last = Wilkes | first = M. V. | authorlink = Maurice Vincent Wilkes | coauthors = | title = Automatic Digital Computers | publisher = John Wiley & Sons | date = 1956 | location = New York | pages = 305 pages | url = | doi = | id = QA76.W5 1956 | isbn = -->

External links

• IBM Archive: IBM ASCC Reference Room
• ASCC operational manual (PDF)

Harvard Mark I - Wikipedia, the free encyclopedia
The IBM Automatic Sequence Controlled Calculator (ASCC), called the Mark I by Harvard University, [1] was the first large-scale automatic digital computer in the USA.

Howard Aiken's Harvard Mark I (the IBM ASCC)
Many consider that the modern computer era commenced with the first large-scale automatic digital computer, the Harvard Mark 1, which was developed between 1939 and 1944.

Harvard Mark II Machine from FOLDOC
Harvard Mark II Machine < computer, history > A relay-based computer designed and built by Howard Aiken, with support from IBM, for the United States Navy's Naval Proving Ground ...

IBM Archives: IBM's ASCC (a.k.a. The Harvard Mark I)
IBM Archives: Exhibits: IBM's ASCC: IBM's ASCC (a.k.a. The Harvard Mark I) ... Length: 51 feet. Height: eight feet. Weight: nearly five tons. An SUV on steroids?

Category:Harvard Mark I - Wikimedia Commons
Media in category "Harvard Mark I" The following 8 files are in this category, out of 8 total.

History of Computing Science: Harvard Mark I
Part of a multipage presentation on the history of computers. This page talks about the origin of the Harvard Mark I machine.

Harvard Divinity Bulletin - Mark I. Pinsky - Teflon Televangelists
Dialogue Teflon Televangelists . by Mark I. Pinsky. faith and forbearance can sometimes be insurmountable barriers for religion journalists. When it comes to some true believers ...

IEEEVM: Harvard Mark I
The Mark I computer, built at Harvard University in 1943, is one of the early landmarks of computer technology. The computer was the brainchild of Howard Aiken, a Harvard graduate ...

Harvard Graphics from FOLDOC
Harvard Graphics < graphics, tool > A presentation graphics product by Software ... hard-wired « Harris Semiconductor Ltd. « Harvard architecture « Harvard Graphics » Harvard Mark ...

Harvard Mark I - Wikipédia
L’ IBM ASCC (Automatic Sequence Controlled Calculator), appelé le Mark I par l’ Université Harvard [1], a été le premier ordinateur numérique aux États-Unis.