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Bit (other)
The bit is the most basic Units of information, unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a truth value, logical state with one of two possible value (computer science), values. These values are most commonly represented as either , but other representations such as ''true''/''false'', ''yes''/''no'', ''on''/''off'', or ''+''/''−'' are also widely used. The relation between these values and the physical states of the underlying Data storage device, storage or computing device, device is a matter of convention, and different assignments may be used even within the same device or computer program, program. It may be physically implemented with a two-state device. A contiguous group of binary digits is commonly called a ''bit string'', a bit vector, or a single-dimensional (or multi-dimensional) ''bit array''. A group of eight bits is called one ''byte'', but historically the size of the byte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Units Of Information
In computing and telecommunications, a unit of information is the capacity of some standard data storage system or communication channel, used to measure the capacities of other systems and channels. In information theory, units of information are also used to measure information contained in messages and the entropy of random variables. The most commonly used units of data storage capacity are the bit, the capacity of a system that has only two states, and the byte (or octet), which is equivalent to eight bits. Multiples of these units can be formed from these with the SI prefixes (power-of-ten prefixes) or the newer IEC binary prefixes (power-of-two prefixes). Primary units In 1928, Ralph Hartley observed a fundamental storage principle, which was further formalized by Claude Shannon in 1945: the information that can be stored in a system is proportional to the logarithm of ''N'' possible states of that system, denoted . Changing the base of the logarithm from ''b'' to a diff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shannon (unit)
The shannon (symbol: Sh) is a unit of information named after Claude Shannon, the founder of information theory. IEC 80000-13 defines the shannon as the information content associated with an event when the probability of the event occurring is . It is understood as such within the realm of information theory, and is conceptually distinct from the bit, a term used in data processing and storage to denote a single instance of a binary signal. A sequence of ''n'' binary symbols (such as contained in computer memory or a binary data transmission) is properly described as consisting of ''n'' bits, but the information content of those ''n'' symbols may be more or less than ''n'' shannons according to the ''a priori'' probability of the actual sequence of symbols. The shannon also serves as a unit of the information entropy of an event, which is defined as the expected value of the information content of the event (i.e., the probability-weighted average of all potential events). Given a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stock Ticker Machine
Ticker tape was the earliest electrical dedicated financial communications medium, transmitting stock price information over telegraph lines, in use from around 1870 through 1970. It consisted of a paper strip that ran through a machine called a stock ticker, which printed abbreviated company names as alphabetic symbols followed by numeric stock transaction price and volume information. The term "ticker" came from the sound made by the machine as it printed. The ticker tape revolutionized financial markets, as it relayed information from trading floors continuously and simultaneously across geographical distances. Paper ticker tape became obsolete in the 1960s, as television and computers were increasingly used to transmit financial information. The concept of the stock ticker lives on, however, in the scrolling electronic tickers seen on brokerage walls and on news and financial television channels. Ticker tape stock price telegraphs were invented in 1867 by Edward A. Calahan, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teleprinter
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. Initially they were used in telegraphy, which developed in the late 1830s and 1840s as the first use of electrical engineering, though teleprinters were not used for telegraphy until 1887 at the earliest. The machines were adapted to provide a user interface to early mainframe computers and minicomputers, sending typed data to the computer and printing the response. Some models could also be used to create punched tape for data storage (either from typed input or from data received from a remote source) and to read back such tape for local printing or transmission. Teleprinters could use a variety of different communication media. These included a simple pair of wires; dedicated non-switched telephone circuits (leased lines); switched network ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morse Code
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of the inventors of the telegraph. International Morse code encodes the 26 basic Latin letters through , one accented Latin letter (), the Arabic numerals, and a small set of punctuation and procedural signals ( prosigns). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of ''dits'' and ''dahs''. The ''dit'' duration is the basic unit of time measurement in Morse code transmission. The duration of a ''dah'' is three times the duration of a ''dit''. Each ''dit'' or ''dah'' within an encoded character is followed by a period of signal absence, called a ''space'', equal to the ''dit'' duration. The letters of a word are separated by a space of duration equal to three ''dits'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paper Tape
Five- and eight-hole punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data storage that consists of a long strip of paper in which holes are punched. It developed from and was subsequently used alongside punched cards, differing in that the tape is continuous. Punched cards, and chains of punched cards, were used for control of looms in the 18th century. Use for telegraphy systems started in 1842. Punched tape was used throughout the 19th and for much of the 20th centuries for programmable looms, teleprinter communication, for input to computers of the 1950s and 1960s, and later as a storage medium for minicomputers and CNC machine tools. During the Second World War, high-speed punched tape systems using optical readout methods were used in code breaking systems. Punched tape was used to transmit data for manufacture o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herman Hollerith
Herman Hollerith (February 29, 1860 – November 17, 1929) was a German-American statistician, inventor, and businessman who developed an electromechanical tabulating machine The tabulating machine was an electromechanical machine designed to assist in summarizing information stored on punched cards. Invented by Herman Hollerith, the machine was developed to help process data for the 1890 U.S. Census. Later models w ... for punched cards to assist in summarizing information and, later, in accounting. His invention of the punched card tabulating machine, patented in 1884, marks the beginning of the era of mechanized binary code and semiautomatic data processing systems, and his concept dominated that landscape for nearly a century. Hollerith founded a company that was amalgamated in 1911 with several other companies to form the Computing-Tabulating-Recording Company. In 1924, the company was renamed "International Business Machines" (IBM) and became one of the largest and mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Babbage
Charles Babbage (; 26 December 1791 – 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer. Babbage is considered by some to be " father of the computer". Babbage is credited with inventing the first mechanical computer, the Difference Engine, that eventually led to more complex electronic designs, though all the essential ideas of modern computers are to be found in Babbage's Analytical Engine, programmed using a principle openly borrowed from the Jacquard loom. Babbage had a broad range of interests in addition to his work on computers covered in his book ''Economy of Manufactures and Machinery''. His varied work in other fields has led him to be described as "pre-eminent" among the many polymaths of his century. Babbage, who died before the complete successful engineering of many of his designs, including his Difference Engine and Analytical Eng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semyon Korsakov
Semyon Nikolaevich Korsakov (russian: Семён Николаевич Корсаков, ) (14 January 1787 – 1 December 1853 OS) was a Russian government official, noted both as a homeopath and an inventor who was involved with an early version of information technology. Biography Korsakov was born in 1787 in what is now Kherson, Ukraine (then part of the Russian empire). His father was a military engineer. The family had migrated from Lithuania in the 14th century. He was married to Sofia Mordvinova and they had four daughters and six sons, one of whom, Mikhail Semyonovich (russian: Михаил Семёнович Корсаков, ) (1826–1871), became famous in his own right as governor-general of Eastern Siberia and was the namesake of the town of Korsakov in Sakhalin Oblast and several Russian geological features. From 1812 to 1814, Semyon Korsakov took part in the Napoleonic Wars with the Russian Army. He later was to serve as an official in the statistics d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Marie Jacquard
Joseph Marie Charles ''dit'' (called or nicknamed) Jacquard (; 7 July 1752 – 7 August 1834) was a French weaver and merchant. He played an important role in the development of the earliest programmable loom (the " Jacquard loom"), which in turn played an important role in the development of other programmable machines, such as an early version of digital compiler used by IBM to develop the modern day computer. Sa Vie In his grandfather's generation, several branches of the Charles family lived in Lyon's Couzon-Au-Mont d’Or suburb (on Lyon’s north side, along the Saône River). To distinguish the various branches, the community gave them nicknames; Joseph’s branch was called “Jacquard” Charles. Thus, Joseph's grandfather was Bartholomew Charles ''dit'' alledJacquard. Joseph Marie Charles ''dit'' Jacquard was born into a conservative Catholic family in Lyon, France, on 7 July 1752. He was one of nine children of Jean Charles ''dit'' Jacquard, a master weaver of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basile Bouchon
Basile Bouchon () was a textile worker in the silk center in Lyon who invented a way to control a loom with a perforated paper tape in 1725. The son of an organ maker, Bouchon partially automated the tedious setting up process of the drawloom in which an operator lifted the warp threads using cords. This development is considered to be the first industrial application of a semi-automated machine. The cords of the warp were passed through the eyes of horizontal needles arranged to slide in a box. These were either raised or not depending on whether there was not or was a hole in the tape at that point. This was similar to the piano roll developed at the end of the 19th century and may have been inspired by the patterns that were traditionally drawn on squared paper. Three years later, his assistant Jean-Baptiste Falcon expanded the number of cords that could be handled by arranging the holes in rows and using rectangular cards that were joined together in an endless loop. Thou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Punched Card
A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to directly control automated machinery. Punched cards were widely used through much of the 20th century in the data processing industry, where specialized and increasingly complex unit record equipment, unit record machines, organized into semiautomatic data processing systems, used punched cards for data input, output, and storage. The IBM 12-row/80-column punched card format came to dominate the industry. Many early digital computers used punched cards as the primary medium for input of both computer programs and Data (computing), data. While punched cards are now obsolete as a storage medium, as of 2012, some voting machines still used punched cards to record votes. They also had a significant cultural impact. History The idea of contr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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