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42-471: The WiGig specification allows devices to communicate without wires at multi- gigabit speeds. It enables high-performance wireless data, display and audio applications that supplement the capabilities of previous wireless LAN devices. WiGig tri-band-enabled devices, which operate in the 2.4, 5 and 60 GHz bands, deliver data transfer rates up to 7  Gbit /s (for 11ad), about as fast as an 8-band 802.11ac transmission, and more than eleven times faster than

84-463: A binit as an arbitrary information unit equivalent to some fixed but unspecified number of bits. Unit of information In digital 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

126-409: A byte or word , is referred to, it is usually specified by a number from 0 upwards corresponding to its position within the byte or word. However, 0 can refer to either the most or least significant bit depending on the context. Similar to torque and energy in physics; information-theoretic information and data storage size have the same dimensionality of units of measurement , but there

168-540: A random access memory chip with a capacity of 2 bytes would be referred to as a 256-megabyte chip. The table below illustrates these differences. In the past, uppercase K has been used instead of lowercase k to indicate 1024 instead of 1000. However, this usage was not consistently applied. On the other hand, for external storage systems (such as optical discs ), the SI prefixes are commonly used with their decimal values (powers of 10). Many attempts have sought to resolve

210-509: A unit of information , the bit is also known as a shannon , named after Claude E. Shannon . The symbol for the binary digit is either "bit", per the IEC 80000-13 :2008 standard, or the lowercase character "b", per the IEEE 1541-2002 standard. Use of the latter may create confusion with the capital "B" which is the international standard symbol for the byte. The encoding of data by discrete bits

252-482: A Bell Labs memo on 9 January 1947 in which he contracted "binary information digit" to simply "bit". A bit can be stored by a digital device or other physical system that exists in either of two possible distinct states . These may be the two stable states of a flip-flop , two positions of an electrical switch , two distinct voltage or current levels allowed by a circuit , two distinct levels of light intensity , two directions of magnetization or polarization ,

294-429: A bit was represented by the polarity of magnetization of a certain area of a ferromagnetic film, or by a change in polarity from one direction to the other. The same principle was later used in the magnetic bubble memory developed in the 1980s, and is still found in various magnetic strip items such as metro tickets and some credit cards . In modern semiconductor memory , such as dynamic random-access memory ,

336-404: A byte, is sometimes called a nibble , nybble or nyble. This unit is most often used in the context of hexadecimal number representations, since a nibble has the same number of possible values as one hexadecimal digit has. Computers usually manipulate bits in groups of a fixed size, conventionally called words . The number of bits in a word is usually defined by the size of the registers in

378-456: 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 log b N . Changing the base of the logarithm from b to a different number c has the effect of multiplying the value of the logarithm by a fixed constant, namely log c N = (log c b ) log b N . Therefore,

420-422: A much lower data rate where the higher rates are not needed. 802.11ay has a transmission rate of 20 to 40 Gbit/s and an extended transmission distance of 300 to 500 meters. 802.11ay should not be confused with the similarly named 802.11ax that was released in 2019. The 802.11ay standard is designed to run at much higher frequencies. The lower frequency of 802.11ax enables it to penetrate walls, something that

462-404: A time in serial transmission , and by a multiple number of bits in parallel transmission . A bitwise operation optionally processes bits one at a time. Data transfer rates are usually measured in decimal SI multiples of the unit bit per second (bit/s), such as kbit/s. In the earliest non-electronic information processing devices, such as Jacquard's loom or Babbage's Analytical Engine , a bit

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504-486: Is in general no meaning to adding, subtracting or otherwise combining the units mathematically, although one may act as a bound on the other. Units of information used in information theory include the shannon (Sh), the natural unit of information (nat) and the hartley (Hart). One shannon is the maximum amount of information needed to specify the state of one bit of storage. These are related by 1 Sh ≈ 0.693 nat ≈ 0.301 Hart. Some authors also define

546-554: Is more compressed—the same bucket can hold more. For example, it is estimated that the combined technological capacity of the world to store information provides 1,300 exabytes of hardware digits. However, when this storage space is filled and the corresponding content is optimally compressed, this only represents 295 exabytes of information. When optimally compressed, the resulting carrying capacity approaches Shannon information or information entropy . Certain bitwise computer processor instructions (such as bit set ) operate at

588-555: Is obsolete and removed in 802.11-2020. ip based: port / cable standard for mobile equipment Gigabit The bit is the most basic unit of information in computing and digital communication . 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 represented as either " 1 " or " 0 " , but other representations such as true / false , yes / no , on / off , or + / − are also widely used. The relation between these values and

630-460: 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). In 1928, Ralph Hartley observed

672-410: The yottabit (Ybit). When the information capacity of a storage system or a communication channel is presented in bits or bits per second , this often refers to binary digits, which is a computer hardware capacity to store binary data ( 0 or 1 , up or down, current or not, etc.). Information capacity of a storage system is only an upper bound to the quantity of information stored therein. If

714-785: The 11ay standard struggles to do. The name WiGig comes from Wireless Gigabit Alliance , the original association being formed to promote the adoption of IEEE 802.11ad. However, it is now certified by Wi-Fi Alliance . The WiGig MAC and PHY Specification, version 1.1 includes the following capabilities: On November 3, 2010, WiGig Alliance announced the WiGig version 1.0 A/V and I/O protocol adaptation layer (PAL) specifications. The application specifications have been developed to support specific system interfaces including extensions for PC peripherals and display interfaces for HDTVs, monitors and projectors. WiGig Display Extension WiGig Bus Extension and WiGig Serial Extension. The WiGig Bus Extension (WBE)

756-449: The 1940s, computer builders experimented with a variety of storage methods, such as pressure pulses traveling down a mercury delay line , charges stored on the inside surface of a cathode-ray tube , or opaque spots printed on glass discs by photolithographic techniques. In the 1950s and 1960s, these methods were largely supplanted by magnetic storage devices such as magnetic-core memory , magnetic tapes , drums , and disks , where

798-409: The ambiguity of relying on the underlying hardware design, the unit octet was defined to explicitly denote a sequence of eight bits. Computers usually manipulate bits in groups of a fixed size, conventionally named " words ". Like the byte, the number of bits in a word also varies with the hardware design, and is typically between 8 and 80 bits, or even more in some specialized computers. In

840-424: The average. This principle is the basis of data compression technology. Using an analogy, the hardware binary digits refer to the amount of storage space available (like the number of buckets available to store things), and the information content the filling, which comes in different levels of granularity (fine or coarse, that is, compressed or uncompressed information). When the granularity is finer—when information

882-414: The capacities of computer memories and some storage units are often multiples of some large power of two, such as 2  = 268 435 456 bytes. To avoid such unwieldy numbers, people have often repurposed the SI prefixes to mean the nearest power of two, e.g., using the prefix kilo for 2  = 1024, mega for 2  = 1 048 576 , and giga for 2  = 1 073 741 824 , and so on. For example,

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924-564: The choice of the base b determines the unit used to measure information. In particular, if b is a positive integer, then the unit is the amount of information that can be stored in a system with b possible states. When b is 2, the unit is the shannon , equal to the information content of one "bit" (a portmanteau of binary digit ). A system with 8 possible states, for example, can store up to log 2 8 = 3 bits of information. Other units that have been named include: The trit, ban, and nat are rarely used to measure storage capacity; but

966-869: The computer's CPU , or by the number of data bits that are fetched from its main memory in a single operation. In the IA-32 architecture more commonly known as x86-32, a word is 32 bits, but other past and current architectures use words with 4, 8, 9, 12, 13, 16, 18, 20, 21, 22, 24, 25, 29, 30, 31, 32, 33, 35, 36, 38, 39, 40, 42, 44, 48, 50, 52, 54, 56, 60, 64, 72 bits or others. Some machine instructions and computer number formats use two words (a "double word" or "dword"), or four words (a "quad word" or "quad"). Computer memory caches usually operate on blocks of memory that consist of several consecutive words. These units are customarily called cache blocks , or, in CPU caches , cache lines . Virtual memory systems partition

1008-636: The computer's main storage into even larger units, traditionally called pages . Terms for large quantities of bits can be formed using the standard range of SI prefixes for powers of 10, e.g., kilo  = 10  = 1000 (as in kilobit or kbit), mega  = 10  = 1 000 000 (as in megabit or Mbit) and giga  = 10 = 1 000 000 000 (as in gigabit or Gbit). These prefixes are more often used for multiples of bytes, as in kilobyte (1 kB = 8000 bit), megabyte (1 MB = 8 000 000 bit ), and gigabyte (1 GB = 8 000 000 000 bit ). However, for technical reasons,

1050-415: The early 21st century, retail personal or server computers have a word size of 32 or 64 bits. The International System of Units defines a series of decimal prefixes for multiples of standardized units which are commonly also used with the bit and the byte. The prefixes kilo (10 ) through yotta (10 ) increment by multiples of one thousand, and the corresponding units are the kilobit (kbit) through

1092-440: The highest 802.11n rate, while maintaining compatibility with existing Wi-Fi devices. The 60 GHz millimeter wave signal cannot typically penetrate walls but can propagate by reflection from walls, ceilings, floors and objects using beamforming built into the WiGig system. When roaming away from 60 GHz coverage, the protocol can switch to make use of the other, lower bands, both of which can propagate through walls, with

1134-409: The level of manipulating bits rather than manipulating data interpreted as an aggregate of bits. In the 1980s, when bitmapped computer displays became popular, some computers provided specialized bit block transfer instructions to set or copy the bits that corresponded to a given rectangular area on the screen. In most computers and programming languages, when a bit within a group of bits, such as

1176-649: The nat, in particular, is often used in information theory, because natural logarithms are mathematically more convenient than logarithms in other bases. Several conventional names are used for collections or groups of bits. Historically, a byte was the number of bits used to encode a character of text in the computer, which depended on computer hardware architecture, but today it almost always means eight bits – that is, an octet . An 8-bit byte can represent 256 (2 ) distinct values, such as non-negative integers from 0 to 255, or signed integers from −128 to 127. The IEEE 1541-2002 standard specifies "B" (upper case) as

1218-408: The orientation of reversible double stranded DNA , etc. Bits can be implemented in several forms. In most modern computing devices, a bit is usually represented by an electrical voltage or current pulse, or by the electrical state of a flip-flop circuit. For devices using positive logic , a digit value of 1 (or a logical value of true) is represented by a more positive voltage relative to

1260-443: The physical states of the underlying storage or device is a matter of convention, and different assignments may be used even within the same device or 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

1302-517: The representation of 0 . Different logic families require different voltages, and variations are allowed to account for component aging and noise immunity. For example, in transistor–transistor logic (TTL) and compatible circuits, digit values 0 and 1 at the output of a device are represented by no higher than 0.4 V and no lower than 2.6 V, respectively; while TTL inputs are specified to recognize 0.8 V or below as 0 and 2.2 V or above as 1 . Bits are transmitted one at

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1344-424: The size of the byte is not strictly defined. Frequently, half, full, double and quadruple words consist of a number of bytes which is a low power of two. A string of four bits is usually a nibble . In information theory , one bit is the information entropy of a random binary variable that is 0 or 1 with equal probability, or the information that is gained when the value of such a variable becomes known. As

1386-511: The symbol for byte ( IEC 80000-13 uses "o" for octet in French, but also allows "B" in English). Bytes, or multiples thereof, are almost always used to specify the sizes of computer files and the capacity of storage units. Most modern computers and peripheral devices are designed to manipulate data in whole bytes or groups of bytes, rather than individual bits. A group of four bits, or half

1428-577: The thickness of alternating black and white lines. The bit is not defined in the International System of Units (SI). However, the International Electrotechnical Commission issued standard IEC 60027 , which specifies that the symbol for binary digit should be 'bit', and this should be used in all multiples, such as 'kbit', for kilobit. However, the lower-case letter 'b' is widely used as well and

1470-556: The two possible values of one bit of storage are not equally likely, that bit of storage contains less than one bit of information. If the value is completely predictable, then the reading of that value provides no information at all (zero entropic bits, because no resolution of uncertainty occurs and therefore no information is available). If a computer file that uses n  bits of storage contains only m  <  n  bits of information, then that information can in principle be encoded in about m  bits, at least on

1512-444: The two values of a bit may be represented by two levels of electric charge stored in a capacitor . In certain types of programmable logic arrays and read-only memory , a bit may be represented by the presence or absence of a conducting path at a certain point of a circuit. In optical discs , a bit is encoded as the presence or absence of a microscopic pit on a reflective surface. In one-dimensional bar codes , bits are encoded as

1554-451: Was also used in Morse code (1844) and early digital communications machines such as teletypes and stock ticker machines (1870). Ralph Hartley suggested the use of a logarithmic measure of information in 1928. Claude E. Shannon first used the word "bit" in his seminal 1948 paper " A Mathematical Theory of Communication ". He attributed its origin to John W. Tukey , who had written

1596-509: Was available to members in 2011. WiGig competes with other 60 GHz frequency band transmission standards like WirelessHD in some applications. Regional spectrum allocations vary by region limiting the available number of channels in some regions. As of October 2016 the US is the only region supporting all six channels, while other regions are considering to follow suit. The use of the OFDM mode

1638-460: Was often stored as the position of a mechanical lever or gear, or the presence or absence of a hole at a specific point of a paper card or tape . The first electrical devices for discrete logic (such as elevator and traffic light control circuits , telephone switches , and Konrad Zuse's computer) represented bits as the states of electrical relays which could be either "open" or "closed". When relays were replaced by vacuum tubes , starting in

1680-507: Was recommended by the IEEE 1541 Standard (2002) . In contrast, the upper case letter 'B' is the standard and customary symbol for byte. Multiple bits may be expressed and represented in several ways. For convenience of representing commonly reoccurring groups of bits in information technology, several units of information have traditionally been used. The most common is the unit byte , coined by Werner Buchholz in June 1956, which historically

1722-541: Was used in the punched cards invented by Basile Bouchon and Jean-Baptiste Falcon (1732), developed by Joseph Marie Jacquard (1804), and later adopted by Semyon Korsakov , Charles Babbage , Herman Hollerith , and early computer manufacturers like IBM . A variant of that idea was the perforated paper tape . In all those systems, the medium (card or tape) conceptually carried an array of hole positions; each position could be either punched through or not, thus carrying one bit of information. The encoding of text by bits

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1764-405: Was used to represent the group of bits used to encode a single character of text (until UTF-8 multibyte encoding took over) in a computer and for this reason it was used as the basic addressable element in many computer architectures . The trend in hardware design converged on the most common implementation of using eight bits per byte, as it is widely used today. However, because of

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