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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 movable computers (perhaps the first). It went into operation in April 1954. DYSEAC used 900 vacuum tubes and 24,500 crystal diodes. It had a memory of 512 words of 45 bits 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 ra .... Memory access time was 48–384 microseconds. 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& ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DYSEAC Van 2
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 movable computers (perhaps the first). It went into operation in April 1954. DYSEAC used 900 vacuum tubes and 24,500 crystal diodes. It had a memory of 512 words of 45 bits each (plus 1 parity bit), using mercury delay-line memory. Memory access time was 48–384 microseconds. 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 . See also * SEAC * List of vacuum-tube computers Vacuum-tube computers, now called first-generation computers, are programmable digital computers using vacuum-tube logic circuitry. They were preced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SEAC (computer)
SEAC (''Standards Eastern Automatic Computer'' or ''Standards Electronic Automatic Computer'') was a first-generation electronic computer, built in 1950 by the U.S. National Bureau of Standards (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). 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 tubes (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 for the working principles of diode logic), later expanded to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portable Computers
A portable computer is a computer designed to be easily moved from one place to another and included a display and keyboard together, with a single plug, much like later desktop computers called '' all-in-ones'' (AIO), that integrate the system's internal components into the same case as the display. The first commercially sold portable might be the MCM/70, released 1974. The next major portables were the IBM 5100 (1975), Osborne's CP/M-based Osborne 1 (1981) and Compaq's , advertised as 100% IBM PC compatible Compaq Portable (1983). These luggable computers still required a continuous connection to an external power source; this limitation was later overcome by the laptop. Laptops were followed by lighter models, so that in the 2000s mobile devices and by 2007 smartphones made the term almost meaningless. The 2010s introduced wearable computers such as smartwatches. Portable computers, by their nature, are generally microcomputers. Larger portable computers were com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Vacuum-tube Computers
Vacuum-tube computers, now called first-generation computers, are programmable digital computers using vacuum-tube logic circuitry. They were preceded by systems using electromechanical relays and followed by systems built from discrete transistors. Some later computers on the list had both vacuum tubes and transistors. This list of vacuum-tube computers is sorted by date put into service: }) are identical, except input-output equipment. Both were used internally. , - , The Wegematic 1000 , , 1960 , , , Improved version of the ALWAC III-E , - , ZRA 1 , , 1960 , , , Built by VEB Carl Zeiss, Jena, German Democratic RepublicSiegmar Gerber: ''Einsatz von Zeiss-Rechnern für Forschung, Lehre und Dienstleistung in Informatik in der DDR – eine Bilanz''. GI-Edition, Bonn 2006, p. 310–318 , - , Minsk-1 , , 1960 , , , Built in Minsk , - , Odra 1001 , , 1960 , , , First computer built by Elwro, Wroclaw, Poland , - , Minsk-1 , , 1960 , , , Built in Minsk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Tube Computers
Vacuum-tube computers, now called first-generation computers, are programmable digital computers using vacuum-tube logic circuitry. They were preceded by systems using electromechanical relays and followed by systems built from discrete transistors. Some later computers on the list had both vacuum tubes and transistors. This list of vacuum-tube computers is sorted by date put into service: }) are identical, except input-output equipment. Both were used internally. , - , The Wegematic 1000 , , 1960 , , , Improved version of the ALWAC III-E , - , ZRA 1 , , 1960 , , , Built by VEB Carl Zeiss, Jena, German Democratic RepublicSiegmar Gerber: ''Einsatz von Zeiss-Rechnern für Forschung, Lehre und Dienstleistung in Informatik in der DDR – eine Bilanz''. GI-Edition, Bonn 2006, p. 310–318 , - , Minsk-1 , , 1960 , , , Built in Minsk , - , Odra 1001 , , 1960 , , , First computer built by Elwro, Wroclaw, Poland , - , Minsk-1 , , 1960 , , , Built in Minsk , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Institute Of Standards And Technology
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 science laboratory programs that include nanoscale science and technology, engineering, information technology, neutron research, material measurement, and physical measurement. From 1901 to 1988, the agency was named the National Bureau of Standards. History Background The Articles of Confederation, ratified by the colonies in 1781, provided: The United States in Congress assembled shall also have the sole and exclusive right and power of regulating the alloy and value of coin struck by their own authority, or by that of the respective states—fixing the standards of weights and measures throughout the United States. Article 1, section 8, of the Constitution of the United States, ratified in 1789, granted these powers to the new Con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 a thermionic tube or thermionic valve utilizes thermionic emission of electrons from a hot cathode for fundamental electronic functions such as signal amplification and current rectification. Non-thermionic types such as a vacuum phototube, however, achieve electron emission through the photoelectric effect, and are used for such purposes as the detection of light intensities. In both types, the electrons are accelerated from the cathode to the anode by the electric field in the tube. The simplest vacuum tube, the diode (i.e. Fleming valve), invented in 1904 by John Ambrose Fleming, contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through the device—from the cathode to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diode
A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode and a plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most commonly used type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. Semiconductor diodes were the first semiconductor electronic devices. The discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other semiconducting materials such as gallium arsenide and germanium are also used. Among many uses, diodes are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Word (data Type)
In computing, a word is the natural unit of data used by a particular processor design. A word is a fixed-sized datum handled as a unit by the instruction set or the hardware of the processor. The number of bits or digits in a word (the ''word size'', ''word width'', or ''word length'') is an important characteristic of any specific processor design or computer architecture. The size of a word is reflected in many aspects of a computer's structure and operation; the majority of the registers in a processor are usually word-sized and the largest datum that can be transferred to and from the working memory in a single operation is a word in many (not all) architectures. The largest possible address size, used to designate a location in memory, is typically a hardware word (here, "hardware word" means the full-sized natural word of the processor, as opposed to any other definition used). Documentation for older computers with fixed word size commonly states memory sizes in words ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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), although they can also be applied separately to an entire message string of bits. The parity bit ensures that the total number of 1-bits in the string is even or odd. Accordingly, there are two variants of parity bits: even parity bit and odd parity bit. In the case of even parity, for a given set of bits, the bits whose value is 1 are counted. If that count is odd, the parity bit value is set to 1, making the total count of occurrences of 1s in the whole set (including the parity bit) an even number. If the count of 1s in a given set of bits is already even, the parity bit's value is 0. In the case of odd parity, the coding is reversed. For a given set of bits, if the count of bits with a value of 1 is even, the parity bit value is set ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum ( ) from the Greek words, ''hydor'' (water) and ''argyros'' (silver). A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature. Mercury occurs in deposits throughout the world mostly as cinnabar ( mercuric sulfide). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide. Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 random-access memory, delay-line memory was sequential-access. Analog delay line technology had been used since the 1920s to delay the propagation of analog signals. When a delay line is used as a memory device, an amplifier and a pulse shaper are connected between the output of the delay line and the input. These devices recirculate the signals from the output back into the input, creating a loop that maintains the signal as long as power is applied. The shaper ensures the pulses remain well-formed, removing any degradation due to losses in the medium. The memory capacity is determined by dividing the time taken to transmit one bit into the time it takes for data to circulate through the delay line. Early delay-line memory systems had ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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