SEAC (''Standards Eastern Automatic Computer'' or ''Standards Electronic Automatic Computer'')
/ref> was a first-generation electronic computer, built in 1950 by the

U.S. The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

National Bureau of Standards The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...

(NBS) and was initially called the ''National Bureau of Standards Interim Computer'', because it was a small-scale computer designed to be built quickly and put into operation while the NBS waited for more powerful computers to be completed (the

DYSEAC DYSEAC was the second Standards Electronic Automatic Computer. (See SEAC.) DYSEAC was a first-generation computer built by the National Bureau of Standards for the U.S. Army Signal Corps. It was housed in a truck, making it one of the first m ...

). The team that developed SEAC was organized by Samuel N. Alexander. SEAC was demonstrated in April 1950 and was dedicated on June 1950; it is claimed to be the first fully operational stored-program electronic computer in the US.

Description

Based on EDVAC, SEAC used only 747

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as ...

s (a small number for the time) eventually expanded to 1,500 tubes. It had 10,500 germanium diodes which performed all of the logic functions (see the article

diode–transistor logic Diode–transistor logic (DTL) is a class of digital circuits that is the direct ancestor of transistor–transistor logic. It is called so because the logic gating function (e.g., AND) is performed by a diode network and the amplifying function ...

for the working principles of diode logic), later expanded to 16,000 diodes. It was the first computer to do most of its logic with solid-state devices. The tubes were used for amplification, inversion and storing information in dynamic

flip-flops Flip-flops are a type of light sandal, typically worn as a form of casual footwear. They consist of a flat sole held loosely on the foot by a Y-shaped strap known as a toe thong that passes between the first and second toes and around both side ...

. The machine used 64 acoustic delay lines to store 512 words of

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered ...

, with each word being 45

bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

s in size. The

clock rate In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...

was kept low (1

MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

). The computer's instruction set consisted of only 11 types of instructions: fixed-point addition, subtraction, multiplication, and division; comparison, and input & output. It eventually expanded to 16 instructions. The addition time was 864

microseconds A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available. A microsecond is equal to 1000 ...

and the multiplication time was 2,980 microseconds (i.e. close to 3 milliseconds). Weight: (central machine).

Applications

On some occasions SEAC was used by a remote

teletype A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Init ...

. This makes it one of the first computers to be used remotely. With many modifications, it was used until 1964. Some of the problems run on it dealt with: *

digital imaging Digital imaging or digital image acquisition is the creation of a digital representation of the visual characteristics of an object, such as a physical scene or the interior structure of an object. The term is often assumed to imply or include t ...

, led by

Russell A. Kirsch Russell A. Kirsch (June 20, 1929August 11, 2020) was an American engineer at the National Bureau of Standards (now known as the National Institute of Standards and Technology). He was recognized as the developer of the first digital image scanne ...

* computer animation of the city traffic simulation *

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

* linear programming * optical lenses * a program for

Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development laboratories of the United States Department of Energy (DOE), located a short distance northwest of Santa Fe, New Mexico, ...

* tables for

LORAN LORAN, short for long range navigation, was a hyperbolic radio navigation system developed in the United States during World War II. It was similar to the UK's Gee system but operated at lower frequencies in order to provide an improved range u ...

navigation * statistical sampling plans * wave function of the

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

atom * designing a proton synchrotron File:SEACComputer 008.jpg, SEAC block diagram File:SEACComputer 011.jpg, SEAC input/output diagram File:SEACComputer 030.jpg, Magnetic wire drives and cartridges File:SEACComputer 025.jpg, Offline magnetic wire to paper tape & print station File:SEACComputer 031.jpg, SEAC scanner File:NBSFirstScanImage.jpg, First image scanned into SEAC, son of

File:SEACComputer 018.jpg, Samuel N. Alexander with SEAC File:SEACComputer 047.jpg, Horace Joseph and George A. Moore using the SEAC image scanner to analyze metallurgical photographs in 1960. Moore was legally blind.Metallography--past, Present, and Future: 75th Anniversary Volume
Issue 1165, George F. Vander Voort, p.14 File:SEACComputer 039.jpg, SEAC wiring File:SEACComputer 024.jpg, Ethel Marden at the control console of SEAC in 1959

References

* Williams, Michael R. (1997). ''A History of Computing Technology''. IEEE Computer Society. * Metropolis, N; Howlett, J.; Rota, Gian-Carlo (editors) (1980). ''A History of Computing in the Twentieth Century''. Academic Press. (The chapter "Memories of the Bureau of Standards' SEAC", by Ralph J. Slutz.) * Astin, A. V. (1955)
''Computer Development (SEAC and DYSEAC) at the National Bureau of Standards, Washington D.C.''
National Bureau of Standards Circular 551, Issued January 25, 1955, U.S. Government Printing Office. Includes several papers describing SEAC, its technical details, and its operation. In particular, see "SEAC", by S. Greenwald, S. N. Alexander, and Ruth C. Haueter, on pp. 5–26, for an overview of the SEAC system.

External links

SEAC and the Start of Image Processing at the National Bureau of Standards(Archived)
– At the NIST virtual museum
Margaret R. Fox Papers, 1935-1976

Charles Babbage Institute The IT History Society (ITHS) is an organization that supports the history and scholarship of information technology by encouraging, fostering, and facilitating archival and historical research. Formerly known as the Charles Babbage Foundation, ...

, University of Minnesota. collection contains reports, including the original report on the ENIAC, UNIVAC, and many early in-house National Bureau of Standards (NBS) activity reports; memoranda on and histories of SEAC, SWAC, and DYSEAC; programming instructions for the UNIVAC, LARC, and MIDAC; patent evaluations and disclosures; system descriptions; speeches and articles written by Margaret Fox's colleagues; and correspondence of Samuel Alexander, Margaret Fox, and Samuel Williams. Boxes 6-8 of the Fox papers contain documents, reports, and analysis of the NBS's SEAC.
SEAC ("Standards Eastern Automatic Computer") (1950)
from ''History of Computing: An Encyclopedia of the People and Machines that Made Computer History'', Lexikon Services Publishing
Timeline of Computer History at CHM
{{Commons category, position=left, SEAC computer One-of-a-kind computers Vacuum tube computers 1950s computers Computer-related introductions in 1950 Serial computers

Description

Applications

See also

References

Further reading

External links