Portion of the Harvard-IBM Mark 1, left side.

Right side.

Detail of Input/Output and control.

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. It is considered by some to be the first universal calculator. Image File history File links Download high resolution version (2560x1718, 1003 KB) Harvard-IBM Mark I Computer, left side of the computer. ... Image File history File links Download high resolution version (2560x1718, 1003 KB) Harvard-IBM Mark I Computer, left side of the computer. ... Image File history File links Download high resolution version (2560x1709, 987 KB) Harvard-IBM Mark I Computer, right side of the computer. ... Image File history File links Download high resolution version (2560x1709, 987 KB) Harvard-IBM Mark I Computer, right side of the computer. ... Image File history File links Download high resolution version (2560x1920, 1007 KB) Harvard-IBM Mark I Computer, detail of Input/Output and control. ... Image File history File links Download high resolution version (2560x1920, 1007 KB) Harvard-IBM Mark I Computer, detail of Input/Output and control. ... For other uses, see IBM (disambiguation) and Big Blue. ... Harvard University (incorporated as The President and Fellows of Harvard College) is a private university in Cambridge, Massachusetts, USA and a member of the Ivy League. ... This article is about the machine. ...

The electromechanical ASCC was devised by Howard H. 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"^[2] and "the real dawn of the computer age"^[3]. Harvard Mark I / IBM ASCC, left side. ... Harvard University is a private university in Cambridge, Massachusetts, USA, and a member of the Ivy League. ... 1944 (MCMXLIV) was a leap year starting on Saturday. ... is the 219th day of the year (220th in leap years) in the Gregorian calendar. ... 1944 (MCMXLIV) was a leap year starting on Saturday. ...

Design and Construction

The building elements of the ASCC were switches, relays, rotating shafts, and clutches. It was built using 765,000 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: Electrical switches. ... Automotive style miniature relay A relay is an electrical switch that opens and closes under the control of another electrical circuit. ... For other uses, see Clutch (disambiguation). ... Various components An electronic component is a basic electronic element usually packaged in a discrete form with two or more connecting leads or metallic pads. ...

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^[4].

Operation

The Mark I could store 72 numbers, each 23 decimal digits long. 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 instructions from a 24 channel punched paper 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.^[5] It has been suggested that some sections of this article be split into a new article entitled instruction set architecture. ... A roll of punched tape Punched tape is an old-fashioned form of data storage, consisting of a long strip of paper in which holes are punched to store data. ... A conditional branch is a basic logical structure. ... The term Harvard architecture originally referred to computer architectures that used physically separate storage and signal pathways for their instructions and data (in contrast to the von Neumann architecture). ... Rear Admiral Grace Murray Hopper (December 9, 1906 – January 1, 1992) was an American computer scientist and United States Navy officer. ...

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 SSEC. The IBM Selective Sequence Electronic Calculator (SSEC), also called Poppa, was an electomechanical computer built by IBM, finished in January 1948. ...

Successors

The Mark I was followed by the Harvard Mark II (1947 or 1948), Mark III/ADEC (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 components. The Mark III and Mark IV used magnetic drum memory and the Mark IV also had magnetic core memory. The Mark II and Mark III went to the US Navy base at Dahlgren, Virginia. The Mark IV was built for the US Air Force, but it stayed at Harvard. The Harvard Mark II was an electromechanical computer built at Harvard University under the direction of Howard Aiken and was finished in 1947. ... The Harvard Mark III, also known as ADEC (for Aiken Dahlgren Electronic Calculator) was an early computer that was parially electomechanical and partially electronic. ... The Harvard Mark IV was an electronic stored-program computer built by Harvard University under the supervision of Howard Aiken for the United States Air Force. ... In electronics, solid state circuits are those that do not contain vacuum tubes. ... hi i am cool xbox is all most as cool as me hi again ... A 16×16 cm area core memory plane of 128×128 bits, i. ... USN redirects here. ... Dahlgren is a census-designated place located in King George County, Virginia. ... “The U.S. Air Force” redirects here. ...

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). A computer bug is an error, flaw, mistake, failure, or fault in a computer program that prevents it from working as intended, or produces an incorrect result. ...

Comparison with other early computers

The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... This article is about the engineering discipline. ... A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ... For the usage of this term in Turing reductions, see Turing complete set. ... Statue in Bad Hersfeld Konrad Zuse (June 22, 1910 Berlin - December 18, 1995 Hünfeld) was a German engineer and computer pioneer. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... Film stock is the term for photographic film on which films are recorded. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... Atanasoff–Berry Computer replica at 1st floor of Durham Center, Iowa State University The Atanasoff–Berry Computer (ABC) was the first electronic digital computing device. ... A Colossus Mark II computer. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... ENIAC ENIAC, short for Electronic Numerical Integrator And Computer,[1] was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems,[2] although earlier computers had been built with some of these properties. ... Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. ...

Notes

1. ^ The machine's name as actually displayed on the hardware itself is Aiken-IBM Automatic Sequence Controlled Calculator Mark I.
2. ^ Stoll, E. L. (1983), "Mark I", in Ralston, Anthony & Edwin D. Reilly, Encyclopedia of computer science and engineering (2nd ed.), New York: Van Nostrand Reinhold Company Inc., pp. 916-917, ISBN 0-442-24496-7
3. ^ Pylyshyn, Zenon W. (1970), Perspectives on the computer revolution, Englewood Cliffs,N.J.: Prentice-Hall, Inc., page 5.
4. ^ IBM Archives: FAQ / Products and Services
5. ^ Wexelblat, Richard L. (Ed.) (1981). History of Programming Languages, p. 20. New York: Academic Press. ISBN 0-12-745040-8

See also

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

Computing hardware has been an important component of the process of calculation and data storage since it became useful for numerical values to be processed and shared. ... The Harvard Mark II was an electromechanical computer built at Harvard University under the direction of Howard Aiken and was finished in 1947. ... The Harvard Mark III, also known as ADEC (for Aiken Dahlgren Electronic Calculator) was an early computer that was parially electomechanical and partially electronic. ... The Harvard Mark IV was an electronic stored-program computer built by Harvard University under the supervision of Howard Aiken for the United States Air Force. ... Harvard Mark I / IBM ASCC, left side. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... Manchester Mark 1 was the worlds first stored program computer, which made its first successful run of a program on 21st June 1948 The Manchester Mark I was one of the earliest electronic computers, built at the University of Manchester in England, in 1949. ... Atanasoff–Berry Computer replica at 1st floor of Durham Center, Iowa State University The Atanasoff–Berry Computer (ABC) was the first electronic digital computing device. ... ENIAC ENIAC, short for Electronic Numerical Integrator And Computer,[1] was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems,[2] although earlier computers had been built with some of these properties. ... A Colossus Mark II computer. ... The IBM Selective Sequence Electronic Calculator (SSEC), also called Poppa, was an electromechanical computer built by IBM, finished in January 1948. ...

References

• Cruz, Frank da (Aug 2004). The IBM Automatic Sequence Controlled Calculator. Columbia University Computing History. Retrieved on October 2006.
• Campbell-Kelly, Martin; Aspray, William (1996). Computer: A History of the Information Machine. Basic Books. ISBN 0-465-02989-2. 

October 2006 is the tenth month of that year and has yet to occur. ...

External links

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