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Quantities of bits
SI prefixes Binary prefixes
Name
(Symbol)
Standard
SI
Rare
usage
Name
(Symbol)
Value
kilobit (kbit) 103 210 kibibit (Kibit) 210
megabit (Mbit) 106 220 mebibit (Mibit) 220
gigabit (Gbit) 109 230 gibibit (Gibit) 230
terabit (Tbit) 1012 240 tebibit (Tibit) 240
petabit (Pbit) 1015 250 pebibit (Pibit) 250
exabit (Ebit) 1018 260 exbibit (Eibit) 260
zettabit (Zbit) 1021 270 zebibit (Zibit) 270
yottabit (Ybit) 1024 280 yobibit (Yibit) 280

A bit is a binary digit, taking a value of either 0 or 1. For example, the number 10010111 is 8 bits long, or in most cases, one modern PC byte. Binary digits are a basic unit of information storage and communication in digital computing and digital information theory. Information theory also often uses the natural digit, called either a nit or a nat. Quantum computing also uses qubits, a single piece of information with a probability of being true. An SI prefix (also known as a metric prefix) is a name or associated symbol that precedes a unit of measure (or its symbol) to form a decimal multiple or submultiple. ... // In computing, binary prefixes can be used to quantify large numbers where powers of two are more useful than powers of ten (such as computer memory sizes). ... Look up si, Si, SI in Wiktionary, the free dictionary. ... // In computing, binary prefixes can be used to quantify large numbers where powers of two are more useful than powers of ten (such as computer memory sizes). ... A kilobit is a unit of information storage, abbreviated kbit or sometimes kb. ... A kibibit (a contraction of kilo binary digit) is a unit of information or computer storage, abbreviated Kibit, or sometimes Kib. ... The Megabit is a unit of information storage, abbreviated Mbit or sometimes Mb. ... A mebibit (a contraction of mega binary binary digit) is a unit of information or computer storage, abbreviated Mibit or sometimes Mib. ... A gigabit is a unit of information or computer storage, abbreviated Gbit or sometimes Gb. ... A gibibit is a unit of information or computer storage. ... A terabit 1 terabit = 1012 bits = 1,000,000,000,000 bits (one trillion, long scale: one billion) The terabit is closely related to the tebibit, which is equal to 240 bits. ... A tebibit is a unit of information or computer storage. ... A petabit is a unit of information or computer storage. ... A pebibit is a unit of information or computer storage. ... An exabit is a unit of information or computer storage. ... A exbibit is a unit of information or computer storage. ... A zettabit is a unit of information or computer storage. ... In computing, binary prefixes are often used to quantify large numbers where powers of two are more useful than powers of ten. ... A yottabit is a unit of information or computer storage, abbreviated Ybit or sometimes Yb. ... In computing, binary prefixes are often used to quantify large numbers where powers of two are more useful than powers of ten. ... Look up bit in Wiktionary, the free dictionary. ... The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... In mathematics and computer science, a numerical digit is a symbol, e. ... In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ... The ASCII codes for the word Wikipedia represented in binary, the numeral system most commonly used for encoding computer information. ... This article does not cite any references or sources. ... In telecommunications, transmission is the act of transmitting electrical messages (and the associated phenomena of radiant energy that passes through media). ... RAM (Random Access Memory) Look up computing in Wiktionary, the free dictionary. ... Not to be confused with information technology, information science, or informatics. ... It has been suggested that this article or section be merged with Nat (information). ... A nat (sometimes also nit or even nepit) is a logarithmic unit of information or entropy, based on natural logarithms and powers of e, rather than the powers of 2 and base 2 logarithms which define the bit. ... Molecule of alanine used in NMR implementation of error correction. ... To meet Wikipedias quality standards and make it more accessible, this article needs a better explanation of technical details or more context regarding applications or importance to make it more accessible to a general audience, or at least to technical readers outside this specialty. ...


The bit is also a unit of measurement, the information capacity of one binary digit. It has the symbol bit, or b (see discussion below). The unit is also known as the shannon, with symbol Sh. Claude Shannon Claude Elwood Shannon (April 30, 1916 – February 24, 2001), an American electrical engineer and mathematician, has been called the father of information theory, and was the founder of practical digital circuit design theory. ...

Contents

Binary digit

Claude E. Shannon first used the word bit in a 1948 paper. He attributed its origin to John W. Tukey, who had written a Bell Labs memo on 9 January 1947 in which he contracted "binary digit" to simply "bit".[verification needed] Interestingly, Vannevar Bush had written in 1936 of "bits of information" that could be stored on the punch cards used in the mechanical computers of that time. [1] Claude Elwood Shannon (April 30, 1916 - February 24, 2001) has been called the father of information theory, and was the founder of practical digital circuit design theory. ... John Wilder Tukey (June 16, 1915 - July 26, 2000) was a statistician. ... Vannevar Bush (March 11, 1890 – June 30, 1974) was an American engineer and science administrator, known for his political role in the development of the atomic bomb, and the idea of the memex—seen as a pioneering concept for the World Wide Web. ... Punched cards (or Hollerith cards, or IBM cards), are pieces of stiff paper that contain digital information represented by the presence or absence of holes in predefined positions. ...


A bit of storage is like a light switch; it can be either on (1) or off (0). A single bit is a one or a zero, a true or a false, a "flag" which is "on" or "off", or in general, the quantity of information required to distinguish two mutually exclusive equally probable states from each other. Gregory Bateson defined a bit as "a difference that makes a difference". [1] In information processing, a state is the complete set of properties (for example, its energy level, etc. ... Gregory Bateson (9 May 1904–4 July 1980) was a British anthropologist, social scientist, linguist and cyberneticist whose work intersected that of many other fields. ...


Representation

Bits can be represented in many forms. For example, in digital circuits in most computing devices, bits are represented as electrical levels. For some devices, a 1 (true value) is represented by a non-zero voltage, while a 0 (false value) is represented by a zero voltage. For other devices, zero volts is used to represent 1 (true value). A 1 is sometimes referred to as "high", and 0 as "low". Digital circuits are electric circuits based on a number of discrete voltage levels. ... The article on electrical energy is located elsewhere. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ...


On CD-ROMs, this is represented as "pits" or "grounds". Pits, as the name implies, refers to a small groove on the CD, which reflects away the laser that reads it. Ground, on the other hand, refers basically to the flat reflective surface. The light of the reading laser is reflected back into the laser, which then picks up that light with a sensor. The transition between a pit and a ground means a 1, and a short period of time on the same level is a 0. No more than 11 consequent zeros may occur, because the laser receives no state change during consequent zeros and has to rely on a timer to know the amount of zeros, whose accuracy is limited. The CD-ROM (an abbreviation for Compact Disc Read-Only Memory (ROM)) is a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. ... For other uses, see Laser (disambiguation). ... The term reflection (also spelt reflexion) can refer to several different concepts: In mathematics, reflection is the transformation of a space. ... The term reflection (also spelt reflexion) can refer to several different concepts: In mathematics, reflection is the transformation of a space. ...


CD-Rs work on the same theory, except that they use dyes instead of pits and ground. This article does not cite any references or sources. ... A dye can generally be described as a coloured substance that has an affinity to the substrate to which it is being applied. ...


Bits can also be represented magnetically, such as in magnetic tapes and cassettes. For other uses, see Magnet (disambiguation). ... Look up Tape in Wiktionary, the free dictionary. ... The Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply tape, is a magnetic tape sound recording format. ...


Unit

It is important to differentiate between the use of "bit" in referring to a discrete storage unit and the use of "bit" in referring to a statistical unit of information. The bit, as a discrete storage unit, can by definition store only 0 or 1. A statistical bit is the amount of information that, on average[citation needed], can be stored in a discrete bit. It is thus the amount of information carried by a choice between two equally likely outcomes. One bit corresponds to about 0.693 nats (ln(2)), or 0.301 hartleys (log10(2)). A nat (sometimes also nit or even nepit) is a logarithmic unit of information or entropy, based on natural logarithms and powers of e, rather than the powers of 2 and base 2 logarithms which define the bit. ... A ban, sometimes called a hartley, is a logarithmic unit which measures information or entropy, based on base 10 logarithms and powers of 10, rather than the powers of 2 and base 2 logarithms which define the bit. ...


Consider, for example, a computer file with one thousand 0s and 1s which can be losslessly compressed to a file of five hundred 0s and 1s (on average, over all files of that kind). The original file, although having 1,000 bits of storage, has at most 500 bits of information entropy, since information is not destroyed by lossless compression. A file can have no more information theoretical bits than it has storage bits. If these two ideas need to be distinguished, sometimes the name bit is used when discussing data storage while shannon is used for the statistical bit. However, most of the time, the meaning is clear from the context. This article is about computer files and file systems in general terms. ... Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data. ... Claude Shannon In information theory, the Shannon entropy or information entropy is a measure of the uncertainty associated with a random variable. ...


Abbreviation/symbol

No uniform agreement has been reached yet about what the official unit symbols for bit and byte should be. One commonly-quoted standard, the International Electrotechnical Commission's IEC 60027, specifies that "bit" should be the unit symbol for the unit bit (e.g. "kbit" for kilobit). In the same standard, the symbols "o" and "B" are specified for the byte. In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ... The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ... IEC 60027 (formerly IEC 27) is the International Electrotechnical Commissions standard on Letter symbols to be used in electrical technology. ... In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ...


The other commonly-quoted relevant standard, IEEE 1541, specifies "b" to be the unit symbol for bit and "B" to be that for byte. This convention is also widely used in computing, but has so far not been considered acceptable internationally for several reasons: IEEE 1541 is a standard issued by the Institute of Electrical and Electronics Engineers (IEEE) concerning the use of prefixes for binary multiples of units of measurement related to digital electronics and computing. ...

  • both these symbols are already used for other units: "b" for barn and "B" for bel;
  • "bit" is already short for "binary digit", so there is little reason to abbreviate it any further;
  • it is customary to start a unit symbol with an uppercase letter only if the unit was named after a person (see also Claude Émile Jean-Baptiste Litre);
  • instead of byte, the term octet (unit symbol: "o") is used in some fields and in some French-speaking countries, which adds to the difficulty of agreeing on an international symbol;
  • "b" is occasionally also used for byte, along with "bit" for bit.

The unit bel is rarely used by itself (only as decibel, "dB"), so the chances of conflict with "B" for byte are quite small, even though both units are very commonly used in the same fields (e.g., telecommunication). A barn (symbol b) is a unit of area. ... For other uses, see Decibel (disambiguation). ... Claude Émile Jean-Baptiste Litre is a fictional character created in 1978 by Kenneth Woolner of the University of Waterloo in order to justify the use of a capital L to denote litres. ... In computer technology and networking, an octet is a group of 8 bits. ...


More than one bit

A byte is a collection of bits, originally differing in size depending on the context but now almost always eight bits. Eight-bit bytes, also known as octets, can represent 256 values (28 values, 0–255). A four-bit quantity is known as a nybble, and can represent 16 values (24 values, 0–15). A rarely used term, crumb, can refer to a two-bit quantity, and can represent 4 values (2² values, 0–3). In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ... In computer technology and networking, an octet is a group of 8 bits. ... In computing, a nibble (often spelled nybble) is 4 bits, or half an octet (an 8-bit byte). ... Look up crumb in Wiktionary, the free dictionary. ...


"Word" is a term for a slightly larger group of bits, but it has no standard size. It represents the size of one register in a Computer-CPU. In the IA-32 architecture more commonly known as x86-32, 16 bits are called a "word" (with 32 bits being a double word or dword), but other architectures have word sizes of 8, 32, 64, 80 or others. In computing, word is a term for the natural unit of data used by a particular computer design. ... This article is about the machine. ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ... It has been suggested that this article or section be merged with X86 assembly language. ... In computing, word is a term for the natural unit of data used by a particular computer design. ...


Terms for large quantities of bits can be formed using the standard range of SI prefixes, e.g., kilobit (kbit), megabit (Mbit) and gigabit (Gbit). Note that much confusion exists regarding these units and their abbreviations (see above). Kilo (symbol: k) is a prefix in the SI system denoting 103 or 1000. ... A kilobit is a unit of information storage, abbreviated kbit or sometimes kb. ... mega- (symbol M) is an SI prefix in the SI system of units denoting a factor of 106, i. ... The megabit is a unit of information storage, abbreviated Mbit or sometimes Mb. ... Look up giga- in Wiktionary, the free dictionary. ... A gigabit is a unit of information or computer storage, abbreviated Gbit or sometimes Gb. ...


When a bit within a group of bits such as a byte or word is to be referred to, it is usually specified by a number from 0 (not 1) upwards corresponding to its position within the byte or word. However, 0 can refer to either the most significant bit or to the least significant bit depending on the context, so the convention being used must be known. The binary representation of decimal 149, with the MSB highlighted. ... The binary representation of decimal 149, with the lsb highlighted. ...


Certain bitwise computer processor instructions (such as bit set) operate at the level of manipulating bits rather than manipulating data interpreted as an aggregate of bits. In computer programming, a bitwise operation operates on one or two bit patterns or binary numerals at the level of their individual bits. ... CPU redirects here. ...


Telecommunications or computer network transfer rates are usually described in terms of bits per second (bps), not to be confused with baud. Telecommunication involves the transmission of signals over a distance for the purpose of communication. ... A computer network is a useless group of computers. ... In telecommunications and computing, bit rate (sometimes written bitrate) is the frequency at which bits are passing a given (physical or metaphorical) point. It is quantified using the bit per second (bit/s) unit. ... For the town in France, see Baud, Morbihan. ...


Cultural

Bits has also been adopted in the Art world. With many exhibits and works using them as reference. See the following article Bits as Art and artist work Images Animation.


See also

In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ... In computer science, the term integer is used to refer to any data type which can represent some subset of the mathematical integers. ... A bitstream or bit stream is a time series of bits. ... Claude Shannon In information theory, the Shannon entropy or information entropy is a measure of the uncertainty associated with a random variable. ... The binary or base-two numeral system is a system for representing numbers in which a radix of two is used; that is, each digit in a binary numeral may have either of two different values. ... Ternary or trinary is the base-3 numeral system. ...

Notes

  1. ^ Darwin among the machines: the evolution of global intelligence, George Dyson, 1997. ISBN 0-201-40649-7

  Results from FactBites:
 
Bit - Wikipedia, the free encyclopedia (961 words)
A single bit is a one or a zero, a true or a false, a "flag" which is "on" or "off", or in general, the quantity of information required to distinguish two mutually exclusive states from each other.
It is important to differentiate between the use of "bit" in referring to a discrete storage unit and the use of "bit" in referring to a statistical unit of information.
The combination of the symbols "bit" for bit and "B" for byte is also widely used in computing, and is perhaps least ambiguous.
  More results at FactBites »

 
 

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