DYSEAC was the second Standards Electronic Automatic Computer. (See SEAC.) DYSEAC was a first-generation computer built by the

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 ...

for the

U.S. Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cl ...

Signal Corps. It was housed in a truck, making it one of the first movable computers (perhaps the first). It went into operation in April 1954. DYSEAC used 900

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 and 24,500 crystal diodes. It had a

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 ...

of 512

word A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no conse ...

s of 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 each (plus 1 parity bit), using mercury

delay-line memory Delay-line memory is a form of computer memory, now obsolete, that was used on some of the earliest digital computers. Like many modern forms of electronic computer memory, delay-line memory was a refreshable memory, but as opposed to modern ran ...

. Memory access time was 48–384

microsecond 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 ...

s. The addition time was 48 microseconds, and the multiplication/division time was 2112 microseconds. These times are excluding the memory-access time, which added up to approximately 1500 microseconds to those times. DYSEAC weighed about .

References

External links

BRL report on computers, inc. DYSEAC
* 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. Fully viewable online. Includes several papers describing the technical details and operation of both DYSEAC and its predecessor SEAC, from which DYSEAC was derived. In particular, see "DYSEAC", by A. L. Leiner, S. N. Alexander, and R. P. Witt, on pp. 39–71, for an overview of DYSEAC and its differences from SEAC. One-of-a-kind computers Vacuum tube computers Portable computers Serial computers {{compu-hardware-stub

See also

References

External links