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Harvard Mark I

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Harvard Mark I
Closeup of input/output and control readers
Also known asIBMAutomatic Sequence Controlled Calculator (ASCC)
DeveloperHoward Aiken/IBM
Release dateAugust 7, 1944;79 years ago(1944-08-07)
Power5 hp (3.7 kW)
Dimensions
  • 816 cu ft (23.1 m3):
  • Width: 51 ft (16 m)
  • Height: 8 ft (2.4 m)
  • Depth: 2 ft (0.61 m)
Mass9,445 lb (4,284 kg)
SuccessorHarvard Mark II
The left end consisted of electromechanical computing components.
The right end included data and program readers, and automatic typewriters.

TheHarvard Mark I,orIBMAutomatic Sequence Controlled Calculator(ASCC), was one of the earliest general-purposeelectromechanicalcomputersused in the war effort during the last part ofWorld War II.

One of the first programs to run on the Mark I was initiated on 29 March 1944[1]byJohn von Neumann.At that time, von Neumann was working on theManhattan Project,and needed to determine whetherimplosionwas a viable choice to detonate the atomic bomb that would be used a year later. The Mark I also computed and printed mathematical tables, which had been the initial goal of British inventorCharles Babbagefor his "analytical engine"in 1837.

According toEdmund Berkeley,the operators of the Mark I often called the machine “Bessy, the Bessel engine,” afterBessel functions.[2]

The Mark I was disassembled in 1959; part of it was given to IBM, part went to theSmithsonian Institution,and part entered theHarvard Collection of Historical Scientific Instruments.For decades, Harvard's portion was on display in the lobby of the Aiken Computation Lab. About 1997, it was moved to theHarvard Science Center.In 2021, it was moved again, to the lobby of Harvard's new Science and Engineering Complex inAllston, Massachusetts.[3]

Origins

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The original concept was presented to IBM byHoward Aikenin November 1937.[4]After a feasibility study by IBM engineers, the company chairmanThomas Watson Sr.personally approved the project and its funding in February 1939.

Howard Aiken had started to look for a company to design and build his calculator in early 1937. After two rejections,[5]he was shown a demonstration set thatCharles Babbage’s son had given to Harvard University 70 years earlier. This led him to study Babbage and to add references to theAnalytical Engineto his proposal; the resulting machine "brought Babbage’s principles of the Analytical Engine almost to full realization, while adding important new features."[6]

The ASCC was developed and built by IBM at theirEndicottplant and shipped toHarvardin February 1944. It began computations for the US Navy Bureau of Ships in May and was officially presented to the university on August 7, 1944.[7]

Although not thefirst working computer,the machine was the first to automate the execution of complex calculations, making it a significant step forward for computing.[8]

Design and construction

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The ASCC was built fromswitches,relays,rotating shafts,andclutches.It used 765,000electromechanicalcomponents and hundreds of miles of wire, comprising a volume of 816 cubic feet (23 m3) – 51 feet (16 m) in length, 8 feet (2.4 m) in height, and 2 feet (0.61 m) deep. It weighed about 9,445 pounds (4.7 short tons; 4.3 t).[9]The basic calculating units had to be synchronized and powered mechanically, so they were operated by a 50-foot (15 m)drive shaftcoupled to a 5 horsepower (3.7 kW) electric motor, which served as the main power source andsystem clock.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 8 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 ASCC used 500 miles (800 km) 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.[10]

The enclosure for the Mark I was designed by futuristic Americanindustrial designerNorman Bel Geddesat IBM's expense. Aiken was annoyed that the cost ($50,000 or more according toGrace Hopper) was not used to build additional computer equipment.[11]

Operation

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The Mark I had 60 sets of 24 switches for manual data entry and could store 72 numbers, each 23 decimal digits long.[12]It could do 3 additions or subtractions in a second. A multiplication took 6 seconds, a division took 15.3 seconds, and a logarithm or a trigonometric function took over one minute.[13]

The Mark I read itsinstructionsfrom a 24-channelpunched paper tape.It executed the current instruction and then read the next one. A separate tape could contain numbers for input, but the tape formats were not interchangeable. Instructions could not be executed from the storage registers. Because instructions were not stored in working memory, it is widely claimed that the Harvard Mark I was the origin of theHarvard architecture.However, this is disputed inThe Myth of the Harvard Architecturepublished in theIEEE Annals of History of Computing,[14]which shows the term 'Harvard architecture' did not come into use until the 1970s (in the context of microcontrollers) and was only retrospectively applied to the Harvard machines, and that the term could only be applied to theMark IIIandIV,not to the Mark I orII.

The main sequence mechanism was unidirectional. This meant that complex programs had to be physically lengthy. A program loop was accomplished byloop unrollingor by joining the end of the paper tape containing the program back to the beginning of the tape (literally creating aloop). At first,conditional branchingin Mark I was performed manually. Later modifications in 1946 introduced automatic program branching (bysubroutinecall).[15][16][17][18][19]The first programmers of the Mark I were computing pioneersRichard Milton Bloch,Robert Campbell, andGrace Hopper.[20]There was also a small technical team whose assignment was to actually operate the machine; some had been IBM employees before being required to join the Navy to work on the machine.[21]This technical team was not informed of the overall purpose of their work while at Harvard.

  • Tape punch used to prepare programs
    Tape punch used to prepare programs
  • Program tape with visible programming patches
    Program tape with visibleprogramming patches
  • Rotary switches used to enter program data constants
    Rotary switches used to enter program data constants
  • Sequence indicators and switches
    Sequence indicators and switches
  • Rear view of the computing section
    Rear view of the computing section

Instruction format

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The 24 channels of the input tape were divided into three fields of eight channels. Each storage location, each set of switches, and theregistersassociated with theinput, output,andarithmetic unitswere assigned a unique identifying index number. These numbers were represented inbinaryon the control tape. The first field was the binary index of the result of the operation, the second was the sourcedatumfor the operation and the third field was acodefor theoperationto be performed.[12]

Contribution to the Manhattan Project

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In 1928L.J. Comriewas the first to turn IBM "punched-card equipment to scientific use: computation of astronomical tables by the method of finite differences, as envisioned by Babbage 100 years earlier for his Difference Engine".[22]Very soon after, IBM started to modify its tabulators to facilitate this kind of computation. One of these tabulators, built in 1931, was The Columbia Difference Tabulator.[23]

John von Neumannhad a team at Los Alamos that used "modified IBM punched-card machines"[24]to determine the effects of the implosion. In March 1944, he proposed to run certain problems regarding implosion of the Mark I, and in 1944 he arrived with two mathematicians to write a simulation program to study the implosion of the firstatomic bomb.[1]

The Los Alamos group completed its work in a much shorter time than the Cambridge group. However,the punched-card machine operation computed values to six decimal places, whereas the Mark I computed values to eighteen decimal places.Additionally, Mark Iintegrated the partial differential equation at a much smaller interval size [or smaller mesh] and so...achieved far greater precision.[24]

"Von Neumann joined theManhattan Projectin 1943, working on the immense number of calculations needed to build the atomic bomb. He showed that the implosion design, which would later be used in the Trinity and Fat Man bombs, was likely faster and more efficient than the gun design. "[25]

Aiken and IBM

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Aiken published a press release announcing the Mark I listing himself as the sole “inventor”.James W. Brycewas the only IBM person mentioned, even though several IBM engineers including Clair Lake and Frank Hamilton had helped to build various elements. IBM chairmanThomas J. Watsonwas enraged, and only reluctantly attended the dedication ceremony on August 7, 1944.[26][page needed][27]Aiken, in turn, decided to build further machines without IBM's help, and the ASCC came to be generally known as the "Harvard Mark I". IBM went on to build itsSelective Sequence Electronic Calculator(SSEC) to both test new technology and provide more publicity for the company's efforts.[26][page needed]

Successors

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The Mark I was followed by theHarvard Mark II(1947 or 1948),Mark III/ADEC(September 1949), andHarvard Mark IV(1952) – all the work of Aiken. The Mark II was an improvement over the Mark I, although it still was based on electromechanicalrelays.The Mark III used mostlyelectronic components—vacuum tubesandcrystal diodes—but also included mechanical components: rotatingmagnetic drumsfor storage, plus relays for transferring data between drums. The Mark IV was all-electronic, replacing the remaining mechanical components withmagnetic core memory.The Mark II and Mark III were delivered to theUS Navybase atDahlgren, Virginia.The Mark IV was built for theUS Air Force,but it stayed at Harvard.[citation needed]

The Mark I was disassembled in 1959, and portions of it went on display in theScience Center,as part of theHarvard Collection of Historical Scientific Instruments.It was relocated to the newScience and Engineering ComplexinAllstonin July 2021.[28]Other sections of the original machine had much earlier been transferred to IBM and theSmithsonian Institution.[29]

See also

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References

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Notes
  1. ^abCohen (2000),p. 164.
  2. ^Berkeley, Edmund Callis. Giant Brains, or, Machines That Think (Classics To Go) (p. 6). Otbebookpublishing. Kindle Edition.
  3. ^Powell, Alvin (July 23, 2021)."Harvard's Mark 1 finds its new home".Harvard Gazette.RetrievedAugust 17,2023.
  4. ^Cohen (2000),p. 53.
  5. ^Cohen (2000),p. 39: It was first rejected by theMonroe Calculator Companyand then by Harvard University.
  6. ^"IBM's ASCC introduction 2".January 23, 2003.RetrievedDecember 14,2013.
  7. ^"Proposed automatic calculating machine (Abstract)".IEEE Spectrum.1(8). IEEE Xplore: 62–69. August 1964.doi:10.1109/MSPEC.1964.6500770.ISSN0018-9235.S2CID51652725.
  8. ^"The History of Harvard Mark 1: A Complete Guide".September 21, 2021.
  9. ^"IBM Archives: Feeds, speeds and specifications ASCC Statistics".www-03.ibm.com.January 23, 2003.
  10. ^IBM Archives: FAQ / Products and Services
  11. ^"Grace Murray Hopper Interview"(PDF).Computer Oral History Collection, 1969-1973, 1977. Archives Center, National Museum of American History. January 7, 1969. pp. 7–8. Archived fromthe original(PDF)on February 23, 2012.RetrievedOctober 21,2012.
  12. ^abMaurice Vincent Wilkes(1956).Automatic Digital Computers.New York: John Wiley & Sons. pp. 16–20.
  13. ^Campbell (1999),p. 43.
  14. ^Pawson, Richard (September 30, 2022)."The Myth of the Harvard Architecture".IEEE Annals of the History of Computing.44(3): 59–69.doi:10.1109/MAHC.2022.3175612.S2CID252018052.
  15. ^Beyer, Kurt W. (2015).Grace Hopper and the Invention of the Information Age.BookBaby. pp. 78–79.ISBN9781483550497.[permanent dead link]
  16. ^Bloch, Richard (February 22, 1984).Oral history interview with Richard M. Bloch.pp. 9–10.hdl:11299/107123.
  17. ^"The Erwin Tomash Library on the History of Computing: An Annotated and Illustrated Catalog".www.cbi.umn.edu.CBI Hosted Publications. 1948. Image:Harvard.Vol 16.1948.subsiderary sequence mechanism,description:H Chapter,pp. 577-578.RetrievedMay 8,2018.
  18. ^A Manual of Operation (1946):subsidiary sequence control,pp. 22, 50, 57, 73, 91
  19. ^Campbell (1999),p. 53.
  20. ^Wexelblat, Richard L. (Ed.) (1981).History of Programming Languages,p. 20. New York: Academic Press.ISBN0-12-745040-8
  21. ^Williams, Kathleen (November 10, 2012).Grace Hopper: Admiral of the Cyber Sea.Naval Institute Press. pp. 33–34.ISBN9781612512655.RetrievedAugust 7,2019.
  22. ^"Columbia University Computing History: L.J. Comrie".RetrievedDecember 15,2013.
  23. ^"The Columbia Difference Tabulator - 1931".RetrievedDecember 15,2013.
  24. ^abCohen (2000),p. 166
  25. ^"Atomic Heritage Foundation: John von Neumann".RetrievedMay 12,2019.
  26. ^abEmerson W. Pugh (1995).Building IBM: Shaping an Industry and Its Technology.MIT Press.ISBN978-0-262-16147-3.
  27. ^Martin Campbell-Kelly;William Aspray (1996).Computer: A History of the Information Machine.Basic Books.p. 74.ISBN0-465-02989-2.
  28. ^Powell, Alvin."Mark 1, rebooted".Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS).Cambridge, Massachusetts: President and Fellows of Harvard College.RetrievedJuly 28,2021.
  29. ^"Collection of Historical Scientific Instruments Mark I".Atlas Obscura.RetrievedMay 24,2016.
Publications

Further reading

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