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

computer A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...

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 sc ...

for the U.S. Army

Signal Corps A signal corps is a military branch, responsible for military communications (''signals''). Many countries maintain a signal corps, which is typically subordinate to a country's army. Military communication usually consists of radio, telephone, ...

. 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, thermionic 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 voltage, potential difference has been applied. It ...

s and 24,500 crystal

diode A diode is a two-Terminal (electronics), terminal electronic component that conducts electric current primarily in One-way traffic, one direction (asymmetric electrical conductance, conductance). It has low (ideally zero) Electrical resistance ...

s. 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 remembe ...

of 512

word A word is a basic element of language that carries semantics, 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 consensus among linguist ...

s of 45 bits each (plus one

parity bit A parity bit, or check bit, is a bit added to a string of binary code. Parity bits are a simple form of error detecting code. Parity bits are generally applied to the smallest units of a communication protocol, typically 8-bit octets (bytes) ...

), using mercury

delay-line memory Delay-line memory is a form of computer memory, mostly obsolete, that was used on some of the earliest Digital data, digital computers, and is reappearing in the form of #Optical_delay_lines, optical delay lines. Like many modern forms of electro ...

. 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 to one second, ...

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 may have been the first computer to implement

interrupt In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted ...

s for I/O. 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