SWAC (computer)

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SWAC. Williams tube memory is in center rear. SWAC 001.jpg
SWAC. Williams tube memory is in center rear.
SWAC Williams tube memory unit Museum of Science, Boston, MA - IMG 3160.JPG
SWAC Williams tube memory unit
Memory pattern on SWAC Williams tube CRT SWAC 003.jpg
Memory pattern on SWAC Williams tube CRT

The SWAC (Standards Western Automatic Computer) was an early electronic digital computer built in 1950 by the U.S. National Bureau of Standards (NBS) in Los Angeles, California. It was designed by Harry Huskey. [1] [ self-published source ] Like the SEAC which was built about the same time, the SWAC was a small-scale interim computer designed to be built quickly and put into operation while the NBS waited for more powerful computers to be completed (in particular, the RAYDAC by Raytheon).

A computer is a device that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. Modern computers have the ability to follow generalized sets of operations, called programs. These programs enable computers to perform an extremely wide range of tasks. A "complete" computer including the hardware, the operating system, and peripheral equipment required and used for "full" operation can be referred to as a computer system. This term may as well be used for a group of computers that are connected and work together, in particular a computer network or computer cluster.

United States federal republic in North America

The United States of America (USA), commonly known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico. The State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean. The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The extremely diverse geography, climate, and wildlife of the United States make it one of the world's 18 megadiverse countries.

The National Institute of Standards and Technology (NIST) is a physical sciences laboratory, and a non-regulatory agency of the United States Department of Commerce. Its mission is to promote innovation and industrial competitiveness. NIST's activities are organized into laboratory programs that include nanoscale science and technology, engineering, information technology, neutron research, material measurement, and physical measurement.


The machine used 2,300 vacuum tubes. It had 256 words of memory, using Williams tubes, with each word being 37 bits. It had only seven basic operations: add, subtract, and multiply (single precision and double precision versions); comparison, data extraction, input and output. Several years later drum memory was added. [2]

Vacuum tube device that controls electric current between electrodes in an evacuated container

In electronics, a vacuum tube, an electron tube, or valve or, colloquially, a tube, is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.

Williams tube elektronka

The Williams tube, or the Williams–Kilburn tube after inventors Freddie Williams and Tom Kilburn, is an early form of computer memory. It was the first random-access digital storage device, and was used successfully in several early computers.

The bit is a basic unit of information used in computing and digital communications. A binary digit can only have one of two values, and may be physically represented with a two-state device. These state values are most commonly represented as either a 0or1.

When the SWAC was completed in August 1950, [3] it was the fastest computer in the world. It continued to hold that status until the IAS computer was completed a year later. It could add two numbers and store the result in 64 microseconds. A similar multiplication took 384 microseconds. It was used by the NBS until 1954 when the Los Angeles office was closed, and then by UCLA until 1967 (with modifications). It was charged out there for $40 per hour.

IAS machine

The IAS machine was the first electronic computer to be built at the Institute for Advanced Study (IAS) in Princeton, New Jersey. It is sometimes called the von Neumann machine, since the paper describing its design was edited by John von Neumann, a mathematics professor at both Princeton University and IAS. The computer was built from late 1945 until 1951 under his direction. The general organization is called Von Neumann architecture, even though it was both conceived and implemented by others. The computer is in the collection of the Smithsonian National Museum of American History but is not currently on display.

University of California, Los Angeles Public research university in Los Angeles, California

The University of California, Los Angeles (UCLA) is a public research university in Los Angeles. It became the Southern Branch of the University of California in 1919, making it the second-oldest undergraduate campus of the 10-campus University of California system. It offers 337 undergraduate and graduate degree programs in a wide range of disciplines. UCLA enrolls about 31,000 undergraduate and 13,000 graduate students and had 119,000 applicants for Fall 2016, including transfer applicants, the most applicants for any American university.

In January 1952, Raphael M. Robinson used the SWAC to discover five Mersenne primes—the largest prime numbers known at the time, with 157, 183, [4] 386, 664 and 687 digits.

Raphael M. Robinson American mathematician

Raphael Mitchel Robinson was an American mathematician.

In mathematics, a Mersenne prime is a prime number that is one less than a power of two. That is, it is a prime number of the form Mn = 2n − 1 for some integer n. They are named after Marin Mersenne, a French Minim friar, who studied them in the early 17th century.

Largest known prime number Number

The largest known prime number is 282,589,933 − 1, a number with 24,862,048 digits. It was found by Patrick Laroche of the Great Internet Mersenne Prime Search (GIMPS) in 2018.

Additionally, the SWAC was vital in doing the intense calculation required for the X-ray analysis of the structure of vitamin B12 done by Dorothy Hodgkin. [5] This was fundamental in Hodgkin receiving the Nobel Prize in Chemistry in 1964.

Vitamin B<sub><small>12</small></sub> several chemical forms of vitamin B12

Vitamin B12, also called cobalamin, is a water-soluble vitamin that is involved in the metabolism of every cell of the human body: it is a cofactor in DNA synthesis, and in both fatty acid and amino acid metabolism. It is particularly important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the maturation of developing red blood cells in the bone marrow.

Dorothy Hodgkin British chemist

Dorothy Mary Crowfoot Hodgkin was a British chemist who developed protein crystallography, for which she won the Nobel Prize in Chemistry in 1964.

Nobel Prize in Chemistry One of the five Nobel Prizes established in 1895 by Alfred Nobel

The Nobel Prize in Chemistry is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of chemistry. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outstanding contributions in chemistry, physics, literature, peace, and physiology or medicine. This award is administered by the Nobel Foundation, and awarded by Royal Swedish Academy of Sciences on proposal of the Nobel Committee for Chemistry which consists of five members elected by Academy. The award is presented in Stockholm at an annual ceremony on December 10, the anniversary of Nobel's death.

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Samuel N. Alexander American computer scientist

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  1. McMurran, Marshall William (2008). ACHIEVING ACCURACY: A Legacy of Computers and Missiles. Xlibris Corporation. p. 49. ISBN   9781462810659.
  2. Oral history interview with Alexandra Forsythe, Charles Babbage Institute, University of Minnesota.
  3. "6. National Bureau of Standards Western Automatic Computer (SWAC)". Digital Computer Newsletter. 2 (4): 3. December 1950.
  4. "4. The SWAC". Digital Computer Newsletter. 4 (2): 3. April 1952.
  5. Hodgkin, D.C.; Pickworth, J.; Robertson, J.H; Trueblood, K.N.; Prosen, R.J; White, J.G. Nature. 1955. 176. 325.

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