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Encyclopedia > Binary prefix

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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). Each successive prefix is multiplied by 1024 (210) rather than the 1000 (103) used by the SI prefix system. Binary prefixes are often written and pronounced identically to the SI prefixes, despite the resulting ambiguity. The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... Look up prefix in Wiktionary, the free dictionary. ... The terms storage (U.K.) or memory (U.S.) refer to the parts of a digital computer that retain physical state (data) for some interval of time, possibly even after electrical power to the computer is turned off. ... 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. ...


History

Early computers used one of two addressing methods to access the system memory; binary (base-2) or decimal (base-10). The IBM 701 (1952) used binary and could address 2048 36-bit words. The IBM 702 (1953) used decimal and could address 10,000 7-bit words. One of the most successful early computers was the IBM 1401. It was introduced in 1959 and by 1961 one out every four electronic stored-program computers was an IBM 1401. It used decimal addressing and could have 1400, 2000, 4000, 8000, 12000 or 16000 characters of 8-bit core storage.[1] A reference to a "4k IBM 1401" meant 4000 characters of storage (memory).[2] The use of K in the binary sense as in a "32K store" can be found as early as 1960.[3] The IBM 701, known as the Defense Calculator while in development, was announced to the public on April 29, 1952, and was IBM’s first commercial scientific computer. ... The IBM 700/7000 series was a series of incompatible large scale (mainframe) computer systems made by IBM through the 1950s and early 1960s. ... IBM 1401 (Card system) The IBM 1401, the first member of the IBM 1400 series, was a variable wordlength decimal computer that was announced by IBM on October 5, 1959. ... A 16×16 cm area core memory plane of 128×128 bits, i. ...


By the mid 1960s binary addressing was the standard architecture in computer design. The computer system documentation would specify the memory size with an exact number such as 32,768, 65,536 or 131,072 words of storage. There were several methods used to abbreviate these quantities. Gene Amdahl's seminal 1964 article on IBM System/360 used 1K to mean 1024.[4] This style was used by other computer vendors, the CDC 7600 System Description (1968) made extensive use of K as 1024.[5] Another style was to truncate the last 3 digits and append K. The exact values 32,768, 65,536 and 131,072 would become 32K, 65K and 131K.[6] If 32,768 were rounded off it would be 33K. This style was used from about 1965 to 1975. Gene Myron Amdahl (born November 16, 1922) is an American computer architect and hi-tech entrepreneur of Norwegian descent, chiefly known for his work on mainframe computers at International Business Machines (IBM) and later his own companies. ... System 360 Model 65 operators console, with register value lamps and toggle switches (middle of picture) and emergency pull switch (upper right). ... The CDC 7600 was the Seymour Cray-designed successor to the CDC 6600, extending Control Datas dominance of the supercomputer field into the 1970s. ...


The use of the 1024 K was more common than the truncated K. Both were used, sometimes by the same company. The HP 21MX real-time computer (1974) denoted 196,608 as 196K and 1,048,576 as 1 M.[7] The HP 3000 business computer (1973) could have 64K, 96K, or 128K bytes of memory.[8] Hewlett-Packards first computer, the 2116A of the HP-2100 series, was developed in the late 1960s. ... The HP 3000 series is a family of minicomputers released by Hewlett-Packard in 1973 after a difficult development project. ...


The terms Kbit, Kbyte, Mbit and Mbyte started to be used as binary units in the early 1970s.[9] Most memory capacities were expressed in K. The IBM System/370 Model 158 brochure (1972) had the following: "Real storage capacity is available in 512K increments ranging from 512K to 2,048K bytes."[10] Megabyte was used to describe the 22-bit addressing of DEC PDP-11/70 (1975)[11] and gigabyte the 30-bit addressing DEC VAX11/780 (1977). The PDP-11 was a 16-bit minicomputer sold by Digital Equipment Corp. ... VAX is a 32-bit computing architecture that supports an orthogonal instruction set (machine language) and virtual addressing (i. ...


By the mid 1970s it was common to see K (or Kbyte) as 1024 and the occasional M (or MByte) as 1,048,576 for words or bytes of memory (RAM). K and M were also used with their decimal meaning for disk storage. The dual use of these prefixes as both decimal and binary was defined in early standards and dictionaries. The ANSI/IEEE Std 1084-1986[12] is still available for reference and defined kilo and mega. The term "computer storage" means system memory.[4]

"kilo (K). (1) A prefix indicating 1000. (2) In statements involving size of computer storage, a prefix indicating 210, or 1024."

"mega (M). (1) A prefix indicating one million. (2) In statements involving size of computer storage, a prefix indicating 220, or 1,048,576."

In the 1980s the terms kilobyte, megabyte, and gigabyte became popular along with the abbreviations KB, MB, and GB. The binary units Kbyte and Mbyte were formally defined in ANSI/IEEE Std 1212-1991.[13] The terms Kbyte, Mbyte, and Gbyte are found in the trade press and in IEEE journals. A kilobyte (derived from the SI prefix kilo-, meaning 1000) is a unit of information or computer storage equal to the decimal 1024 bytes (2 to the 10th power, or 1,024 bytes based in the binary system). ... ReBoot character, see Megabyte (ReBoot). ... A gigabyte (derived from the SI prefix giga-) is a unit of information or computer storage equal to 1000³ bytes or 1024³ bytes (1000³ = one billion). ...


Gigabyte was formally defined in IEEE Std 610.10-1994 as either 1,000,000,000 or 230 bytes.[14] Kilobyte, Kbyte, and KB are equivalent units and all are defined in current standard, IEEE 100-2000.[15]


The industry has coped with the dual definitions because system memory (RAM) typically uses the binary meaning while disk storage uses the decimal meaning. (There are exceptions especially with disks.) There are no SI units for computer storage capacity but the decimal meanings of KB, MB, and GB are often referred to as SI prefixes. Cover of brochure The International System of Units. ...


In January 1999, the International Electrotechnical Commission introduced the prefixes kibi-, mebi-, gibi-, etc., and the symbols Ki, Mi, Gi, etc. to specify binary multiples of a quantity and eliminate this ambiguity.[16] The names for the new standard are derived from the first two letters of the original SI prefixes followed by bi, short for "binary". The new standard also clarifies that, from the point of view of the IEC, the SI prefixes will henceforth only have their base-10 meaning and never have a base-2 meaning. Year 1999 (MCMXCIX) was a common year starting on Friday (link will display full 1999 Gregorian calendar). ... The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ...


The second edition of the standard[17] defined them only up to exbi-[18], but in 2005, the third edition added prefixes zebi- and yobi-, thus matching all standard SI prefixes with their binary counterparts.[19] Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...


On March 19, 2005 the IEEE standard IEEE 1541-2002 (Prefixes for Binary Multiples) has been elevated to a full-use standard by the IEEE Standards Association after a two-year trial period.[20] is the 78th day of the year (79th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... 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. ...


Consumer confusion

This hard disk can hold 160×109 bytes, and is marketed using standard SI prefixes as "160 GB"
This hard disk can hold 160×109 bytes, and is marketed using standard SI prefixes as "160 GB"
Linux's fdisk uses standard SI prefixes to display a 160×109 byte disk as "160.0 GB"
Linux's fdisk uses standard SI prefixes to display a 160×109 byte disk as "160.0 GB"

In the early days of computers there was little or no consumer confusion because of the sophisticated nature of the consumers and the practice of the computer manufacturers to specify (as opposed to advertise) their products with decimal digits of sufficient places, e.g., the 1968 IBM stated System 360 "Model 91s can accommodate up to 6,291,496 bytes of main storage."[21] Hard disk drive manufacturers began using MB, i.e. 106 bytes, to characterize their products as early as 1974[22]. By 1977, in its first edition, Disk/Trend[23], a leading hard disk drive industry marketing consultancy segmented the industry according to MB's (decimal sense) of capacity. The presentation of hard disk drive capacity by an operating system using MB in a binary sense appears no earlier than Macintosh Finder after 1984. Prior to that, on the systems that had a hard disk drive, capacity was presented in decimal digits with no prefix of any sort (e.g., MS/PC DOS CHKDSK command). Later, Microsoft Windows 3.11, for example, would report the space available on a 41,959,424 byte hard disk drive as 40 MB. Image File history File links Metadata Size of this preview: 800 × 578 pixelsFull resolution (1748 × 1262 pixel, file size: 282 KB, MIME type: image/jpeg) All of these images are derived from the same physical hard drive: File history Legend: (cur) = this is the current file, (del) = delete this old... Image File history File links Metadata Size of this preview: 800 × 578 pixelsFull resolution (1748 × 1262 pixel, file size: 282 KB, MIME type: image/jpeg) All of these images are derived from the same physical hard drive: File history Legend: (cur) = this is the current file, (del) = delete this old... 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. ... Image File history File links Size of this preview: 800 × 500 pixelsFull resolution (827 × 517 pixel, file size: 61 KB, MIME type: image/png) All of these images are derived from the same physical hard drive: (I think fdisk is GPL, but I cant find this information anywhere. ... Image File history File links Size of this preview: 800 × 500 pixelsFull resolution (827 × 517 pixel, file size: 61 KB, MIME type: image/png) All of these images are derived from the same physical hard drive: (I think fdisk is GPL, but I cant find this information anywhere. ... This article or section includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... 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. ... Generally speaking, advertising is the paid promotion of goods, services, companies and ideas by an identified sponsor. ... The Finder is the default application program used on the Mac OS and Mac OS X operating systems that is responsible for the overall user-management of files, disks, network volumes and the launching of other applications. ... This article does not cite any references or sources. ...


Binary prefixes using SI symbols

Name Symbol Value Base 16 Base 10
kilo k/K 210 = 1,024 = 162.5 > 103
mega M 220 = 1,048,576 = 165 > 106
giga G 230 = 1,073,741,824 = 167.5 > 109
tera T 240 = 1,099,511,627,776 = 1610 > 1012
peta P 250 = 1,125,899,906,842,624 = 1612.5 > 1015
exa E 260 = 1,152,921,504,606,846,976 = 1615 > 1018
zetta Z 270 = 1,180,591,620,717,411,303,424 = 1617.5 > 1021
yotta Y 280 = 1,208,925,819,614,629,174,706,176  = 1620 > 1024

The one-letter symbols are identical to SI prefixes, except for "K", which is used interchangeably with "k" (in SI, the upper-case or capital "K" stands for kelvin, and only the lower-case "k" represents 1,000). Kilo (symbol: k) is a prefix in the SI system denoting 103 or 1000. ... mega- (symbol M) is an SI prefix in the SI system of units denoting a factor of 106, i. ... Look up giga- in Wiktionary, the free dictionary. ... tera- (symbol: T) is a prefix in the SI system of units denoting 1012, or 1 000 000 000 000. ... In physics and mathematics, peta- (symbol: P) is a prefix in the SI (system of units) denoting 1015, or 1 000 000 000 000 000. ... In the X Window System, in the X.Org Server, EXA is a graphics acceleration architecture to make the XRender extension more usable, with only minor changes needed to adapt XFree86 video drivers written to use XAA (the XFree86 Acceleration Architecture). ... Zetta (symbol Z) is a SI prefix in the SI (system of units) denoting 1021 or 1 000 000 000 000 000 000 000. ... Yotta (symbol Y) is a SI prefix in the SI (system of units) denoting 1024 or 1 000 000 000 000 000 000 000 000. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ...


These prefixes are in common use in contexts such as file and memory sizes. The names and values of the SI prefixes were defined in the 1960 SI standard, with powers-of-1000 values. Standard dictionaries do recognize the binary meanings for these prefixes.[24][25] Oxford online dictionary define, for example, megabyte as: "Computing a unit of information equal to one million or (strictly) 1,048,576 bytes."[26] An SI prefix is a prefix which can be applied to any unit of the International System of Units (SI) to give subdivisions and multiples of that unit. ...


BIPM (the International Bureau of Weights and Measures which maintains SI) expressly prohibits the binary prefix usage, and recommends the use of the IEC prefixes as an alternative since computing units are not included in SI.[27] The Bureau International des Poids et Mesures (International Bureau of Weights and Measures, or BIPM) is a standards organization, one of the three organizations established to maintain the SI system under the terms of the Metre Convention. ... Look up si, Si, SI in Wiktionary, the free dictionary. ...


Some have suggested that "k" be used for 1,000, and "K" for 1,024, but this cannot be extended to the higher order prefixes and has never been widely recognised.


Although the SI prefixes denoting fractions of a bit or byte might theoretically find application in areas such as cryptography, data compression, and data transfer rates, they are not used in practice. The German Lorenz cipher machine, used in World War II for encryption of very high-level general staff messages Cryptography (or cryptology; derived from Greek κρυπτός kryptós hidden, and the verb γράφω gráfo write or λεγειν legein to speak) is the study of message secrecy. ... In computer science and information theory, data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an unencoded representation would use through use of specific encoding schemes. ...


Informally, the prefixes are often used on their own. Thus one might hear about a "256K DRAM" (256 binary kilobytes), "a 160 MB HDD" (160 decimal megabytes) or "a 2M Internet connection" (2 decimal megabits per second). What units are being used, and whether the multipliers are decimal or binary, depends on context and cannot be determined by the units alone.

IEC standard prefixes

Name Symbol Base 2 Base 16 Base 10
kibi Ki 210 162.5 400(16) = 1,024 > 103
mebi Mi 220 165 10 0000(16) = 1,048,576 > 106
gibi Gi 230 167.5 4 000 0000(16) = 1,073,741,824 > 109
tebi Ti 240 1610 100 0000 0000(16) = 1,099,511,627,776 > 1012
pebi Pi 250 1612.5 4 0000 0000 0000(16) = 1,125,899,906,842,624 > 1015
exbi Ei 260 1615 1000 0000 0000 0000(16) = 1,152,921,504,606,846,976 > 1018
zebi Zi 270 1617.5 40 0000 0000 0000 0000(16) = 1,180,591,620,717,411,303,424 > 1021
yobi Yi 280 1620 1 0000 0000 0000 0000 0000(16) = 1,208,925,819,614,629,174,706,176 > 1024

Example: 300 GB ≅ 279.5 GiB.


Approximate ratios between binary and decimal prefixes

As the order of magnitude increases, the percentage difference between the binary and decimal values of a prefix increases, from 2.4% (with the kilo prefix) to over 20% (with the yotta prefix). This makes differentiating between the two increasingly important as larger and larger data storage and transmission technologies are developed.

Name Bin ÷ Dec Dec ÷ Bin Example Percentage difference
kilobyte : kibibyte 1.024 0.976 100 kB ≅ 97.6 KiB +2.4% or −2.3%
megabyte : mebibyte 1.049 0.954 100 MB ≅ 95.4 MiB +4.9% or −4.6%
gigabyte : gibibyte 1.074 0.931 100 GB ≅ 93.1 GiB +7.4% or −6.9%
terabyte : tebibyte 1.100 0.909 100 TB ≅ 90.9 TiB +10% or −9.1%
petabyte : pebibyte 1.126 0.888 100 PB ≅ 88.8 PiB +12.6% or −11.2%
exabyte : exbibyte 1.153 0.867 100 EB ≅ 86.7 EiB +15.3% or −13.3%
zettabyte : zebibyte 1.181 0.847 100 ZB ≅ 84.7 ZiB +18.1% or −15.3%
yottabyte : yobibyte 1.209 0.827 100 YB ≅ 82.7 YiB +20.9% or −17.3%

A kilobyte (derived from the SI prefix kilo-, meaning 1000) is a unit of information or computer storage equal to the decimal 1024 bytes (2 to the 10th power, or 1,024 bytes based in the binary system). ... A kibibyte (a contraction of kilo binary byte) is a unit of information or computer storage, commonly abbreviated KiB (never kiB). 1 kibibyte = 210 bytes = 1,024 bytes The kibibyte is closely related to the kilobyte, which can be used either as a synonym for kibibyte or to refer to... ReBoot character, see Megabyte (ReBoot). ... A mebibyte (a contraction of mega binary byte) is a unit of information or computer storage, abbreviated MiB. 1 MiB = 220 bytes = 1,048,576 bytes = 1,024 kibibytes 1 MiB = 1024 (= 210) kibibytes (KiB), and 1024 MiB equal one gibibyte (GiB). ... A gigabyte (derived from the SI prefix giga-) is a unit of information or computer storage equal to 1000³ bytes or 1024³ bytes (1000³ = one billion). ... A gibibyte is a unit of information or computer storage. ... This article is about a measurement term for data storage capacity. ... A tebibyte is a unit of information or computer storage, commonly abbreviated TiB. 1 tebibyte = 240 bytes = 1,099,511,627,776 bytes The tebibyte is closely related to the terabyte, which can either be a synonym for tebibyte, or refer to 1012 bytes = 1,000,000,000,000 bytes... A petabyte (derived from the SI prefix peta- ) is a unit of information or computer storage equal to one quadrillion bytes. ... A pebibyte is a unit of information or computer storage. ... An exabyte (derived from the SI prefix exa-) is a unit of information or computer storage equal to approximately one quintillion bytes. ... An exbibyte (a contraction of exa binary byte) is a unit of information or computer storage, abbreviated EiB. 1 exbibyte = 260 bytes = 1,152,921,504,606,846,976 bytes = 1,024 pebibytes The exbibyte is closely related to the exabyte, which can either be a synonym for exbibyte, or... A zettabyte (derived from the SI prefix zetta-) is a unit of information or computer storage equal to one sextillion (one long scale trilliard) bytes. ... A zettabyte (derived from the SI prefix zetta-) is a unit of information or computer storage equal to one sextillion (one long scale trilliard) bytes. ... A yottabyte (derived from the SI prefix yotta-) is a unit of information or computer storage equal to one septillion (one long scale quadrillion or 1024) bytes. ... This article or section does not cite any references or sources. ...

Adoption

As of 2007, the IEC binary naming convention is not widespread. Most publications, computer manufacturers and software companies are still using the traditional binary units defined in IEEE 100, The Authoritative Dictionary of IEEE Standards Terms, Seventh Edition, 2000. [15] 2007 is a common year starting on Monday of the Gregorian calendar. ... The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ...


It is strongly supported by many standardization bodies and technical organizations, such as IEEE, CIPM, NIST, and SAE.[28][27][29][30] The new binary prefixes have also been adopted by the European Committee for Electrotechnical Standardization (CENELEC) as the harmonization document HD 60027-2:2003-03.[31] This document will be adopted as a European standard.[32] The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ... The Comité international des poids et mesures or The International Committee for Weights and Measures (CIPM) consists of eighteen persons from Member States of the Metre Convention. ... As a non-regulatory agency of the United States Department of Commerce’s Technology Administration, the National Institute of Standards (NIST) develops and promotes measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life. ... SAE may refer to: Soviet Antarctic Expeditions Scientific Audio Electronics Society of Automotive Engineers SAE Institute (formerly the School of Audio Engineering) Sigma Alpha Epsilon fraternity Stichting Academisch Erfgoed Standard American Equivalent (in relation to tool sizing see Standard and Imperial; different from Metric tool sizing but pertaining to same... CENELEC (French: Comité Européen de Normalisation Electrotechnique) is the European Committee for Electrotechnical Standardization. ... CEN, the European Committee for Standardization, is a private non-profit organization whose mission is to foster the European economy in global trading, the welfare of European citizens and the environment by providing an efficient infrastructure to interested parties for the development, maintenance and distribution of coherent sets of standards...


The prefixes are beginning to be used in technical articles and software where it is important to avoid ambiguity. Examples of software that use IEC standard prefixes (along with standard SI prefixes) include the Linux kernel,[33] GNU Core Utilities,[34] Launchpad, GParted,[35] ifconfig,[36] Deluge (BitTorrent client), [37] and BitTornado. Other programs like fdisk and apt-get use SI prefixes with their decimal meaning. The Linux kernel is a Unix-like operating system kernel. ... The GNU Core Utilities or coreutils is a package of GNU software containing many of the basic tools such as cat, ls, and rm needed for Unix-like operating systems. ... Launchpad is a web application and web site supporting software development, particularly that of free software. ... GParted stands for GNOME Partition Editor. ... Sample output from ifconfig on Linux The Unix command ifconfig is a tool used to configure a network interface for TCP/IP. It was originally released as part of the BSD TCP/IP suite - so in effect, its part of the original internet toolkit. ... Deluge is a BitTorrent client, created using Python and GTK+ (through PyGTK). ... BitTornado in Ubuntu Linux BitTornado is a BitTorrent client. ... This article or section includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... Advanced Packaging Tool, or APT, is a package management system used by the Debian project. ...


It can be argued that the main purpose of the binary prefixes is to clarify that, according to national and international standards, the traditional SI prefixes always refer to powers of ten, even in the context of information technology. Therefore, rather than measuring the success of the binary prefixes based on how commonly they appear in technical and marketing literature, it may be more appropriate to judge them by their success in restoring the original power-of-ten meaning of the standard SI prefixes in information technology. Binary prefixes are only convenient for a small number of information-technology quantities, most notably the size of address spaces (e.g., of RAM chips). They provide no practical advantage for quantities where powers-of-two times a small integer are not preferred numbers, such as file sizes, download speeds, line rates, symbol rates, clock frequencies, tape or disk capacities. There, decimal prefixes are far more convenient for mental arithmetic. In industrial design, product developers must choose numerous lengths, distances, diameters, volumes, and other characteristic quantities. ...

Usage notes

The phrase "decimal unit" will be used to denote "SI designation understood in its standard, decimal, power-of-1000 sense" and "binary unit" will mean "SI designation understood in its binary, power-of-1024 sense." B will be used as the symbol for byte as per computer-industry standard (IEEE 1541 and IEC 60027; B is also the symbol for bel, a common non-SI unit used for ratio measurement). 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. ... IEC 60027 (formerly IEC 27) is the International Electrotechnical Commissions standard on Letter symbols to be used in electrical technology. ... The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power) relative to a specified or implied reference level. ...


Certain units are always understood as decimal even in computing contexts. For example, hertz (Hz), which is used to measure clock rates of electronic components, and bit/s, used to measure bit rate. So a 1 GHz processor performs 1,000,000,000 clock ticks per second, a 128 kbit/s MP3 stream consumes 128,000 bits (16 kB, 15.625 KiB) per second, and a 1 Mbit/s Internet connection can transfer 1,000,000 bits (125 kB, approx 122 KiB) per second, assuming an 8-bit byte, and no overhead.[38] MHZ redirects here. ... It has been suggested that this article or section be merged into Clock signal. ... 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. ... MPEG-1 Audio Layer 3, more commonly referred to as MP3, is an audio encoding format. ...


Pronunciation

It is suggested that in English, the first syllable of the name of the binary-multiple prefix should be pronounced in the same way as the first syllable of the name of the corresponding SI prefix, and that the second syllable should be pronounced as "bee." [29]


Computer memory

Measurements of most types of electronic memory such as RAM and ROM and Flash (large scale disk-like flash is sometimes an exception) are given in binary units, as they are made in power-of-two sizes. This is the most natural configuration for memory, as all combinations of their address lines map to a valid address, allowing easy aggregation into a larger contiguous block of memory. It has been suggested that this article or section be merged with JEDEC. (Discuss) The JEDEC Solid State Technology Association is the semiconductor engineering standardization body of the Electronic Industries Alliance (EIA). ... The terms storage (U.K.) or memory (U.S.) refer to the parts of a digital computer that retain physical state (data) for some interval of time, possibly even after electrical power to the computer is turned off. ... Random access memory (usually known by its acronym, RAM) is a type of data storage used in computers. ... Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. ... A USB flash drive. ...


JEDEC Solid State Technology Association, the semiconductor engineering standardization body of the Electronic Industries Alliance (EIA) in Standard 100B.01[6][39] defines in the binary sense K, M and G as prefixes to units of semiconductor memory, noting that these definitions are “only included to reflect common usage” and noting that ‘IEEE/ASTM SI 10-1997 state “This practice frequently leads to confusion and is deprecated.” ’. All standards published by JEDEC are still using the common usage, including end-user packaging recommendations for memory chips.


Many computer programming tasks naturally reference memory in terms of powers of two. For example, a 16-bit pointer can reference at most 65,536 items (bytes, words, or other objects), or an operating system might map memory in terms of 4,096-byte pages, in which case exactly 8,192 pages could be allocated within 33,554,432 bytes of hardware memory. It is convenient to informally express these numbers, respectively, as 64K items, or as 8K pages of 4 Kbytes (KiB) each within 32 MBytes (MiB) of memory. A programmer can easily mentally calculate that "8K × 4K is 32 meg" and get it exactly right, within this powers-of-two context. This convenience is likely one source of originally adapting "kilo" and "mega" from SI as shorthand for 1,024 and 1,048,576, as specialized jargon within a segment of the industry. In mathematics, a power of two is any of the nonnegative integer powers of the number two; in other words, two times itself a certain number of times. ... In computer science, a pointer is a programming language data type whose value refers directly to (or “points to”) another value stored elsewhere in the computer memory using its address. ...


Almost all computer user tasks (and many high-level programming tasks) have no natural affinity or need for explicit powers of two. The consumer confusion between powers of 1000 and powers of 1024 may derive largely from some operating systems and applications that were originally written by and for programmers, and which thus reported quantities such as file sizes in familiar (to programmers) powers of 1024 while using SI (powers of 1000) abbreviations. Without such reporting, most users might not have been substantially exposed to powers of 1024, as the net memory available to users after various overheads is rarely a power of two. This legacy behavior of operating systems reporting sizes in powers of 1024 has continued to this day (in 2007) even in many GUI oriented operating systems intended mainly for non-programmers.


Hard disk drives

HDD manufacturers state capacity in decimal units. This usage has a long tradition, even predating the SI system of decimal prefixes adopted in 1960, as follows: Typical hard drives of the mid-1990s. ... An SI prefix is a prefix which can be applied to any unit of the International System of Units (SI) to give subdivisions and multiples of that unit. ...

  • The first disk drive the IBM 350 (1950s) had 5,000,000 6 bit characters organized in 100 character sectors (i.e., blocks). This predates the SI system.
  • In the 1960s virtually all disk drives used IBM's variable block length format (called, Count Key Data or "CKD[40]"). Any block size could be specified up to the maximum track length. Blocks ("records" in IBM's terminology) of 88, 96, 880 and 960 were often used because they related to the fixed block size of punch cards. The drive capacity was usually stated in full track record blocking, for example, the 100 Megabyte 3336 disk pack only achieved that capacity with a full track block size of 13,030 bytes.
  • CKD continued into the 1990s and perhaps into this day. In the 1970s and 1980s most drives were specified with unformatted tracks (the unformatted capacity) with the particular block size and formatted capacity a function of the controller design. For example, the ST412 of IBM PC/XT fame had an unformatted capacity of 12.75 MB (not MiB) and with the Xebec controller and 512 byte blocks it formatted to and was advertised as a 10.0 MB (not MiB) HDD. Other controllers supported other block sizes resulting in other formatted capacities.
  • The advent of intelligent interfaces (SCSI and IDE) in the early 1990s took the block size decision into the drive and virtually all chose 512 bytes, for no reason other than that was what IBM had chosen when they picked the Xebec controller for the PC/XT. Capacity continued to be specified by the HDD manufacturers with SI prefix definitions.

Regardless of the HDD manufacturers' continuous practice of specifying with conventional SI prefixes, some systems' GUIs took the HDD capacity, reported by the operating system as a binary number without prefixes, and reported the HDD capacity in a mixed decimal number/binary prefix[citation needed] leading to some confusion. As of January 2007, most, if not all, HDD manufacturers continue to use decimal prefixes to identify capacity.[41] RAMAC is an IBM trademark for mass storage products. ... This article or section does not cite any references or sources. ... This article does not cite any references or sources. ... The Bulgarian political party Citizens for European Development of Bulgaria, which had only been founded on 2006-12-03 by Sofia mayor Boyko Borisov, instantly comes second in a public poll on party support, trailing only the Bulgarian Socialist Party. ...


Flash drives

USB Flash Drive and Flash-based memory cards like CompactFlash and Secure Digital are typically classified in "powers of two" multiples of decimal megabytes; for example, a "256 MB" card would hold 256 million bytes.[2] Although the devices usually have at least the expected byte capacity, each manufacturer allocates different portions of the device's ultimate capacity for such things as wear levelling. A USB flash drive, shown with a 24 mm U.S. quarter coin for scale. ... A 64 MB CompactFlash Type I card A 32 MB High Speed CompactFlash Type I card CompactFlash (CF) was originally developed as a type of data storage device used in portable electronic devices. ... 16Mb SD Card Secure Digital, or SD, is a flash memory data storage device based on Toshibas earlier Multi Media Cards (MMC). ... Wear levelling (also written -levelling) is a technique for prolonging the service life of some kinds of eraseable computer storage media, e. ...


Floppy drives

Floppy disk drive and media manufacturers use decimal units for unformatted recording capacity while most computer operating systems use binary units to measure the formatted capacity. The original IBM Personal Computer (1981) used a Tandon TM100 5¼ inch floppy disk drive. The single sided drive was rated at 250 kilobytes (unformatted) and the double sided version was rated at 500 kilobytes. [42] IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... Image File history File links Metadata Size of this preview: 750 × 600 pixelsFull resolution (2000 × 1600 pixel, file size: 398 KB, MIME type: image/jpeg) IBM PC 5 1/4 inch Diskette Drive shown with DOS 1. ...


A 5¼ inch diskette recorded at double density (MFM) will hold 6,250 bytes per track and has 40 tracks per side, yielding 250,000 bytes per side. To make it practical to record smaller blocks of data, the tracks are formatted into sectors with gaps between them. The gaps allow individual sectors to be recorded without overwriting adjacent sectors. Each sector also has additional header bytes to identify the sector. Modified Frequency Modulation, commonly MFM, is a line coding scheme used to encode information on most floppy disk formats, which include the floppy disk formats used in most CP/M machines as well as PCs running DOS. MFM is a modification to the original FM (frequency modulation) scheme for encoding...


With IBM PC-DOS 1.0 and 1.1, each track has 8 sectors of 512 bytes and this provides 163,840 bytes per side (8 × 512 × 40). The IBM user documentation referred to this as "160KB" for single sided diskette and "320KB" for double sided diskette.[43] Starting with PC-DOS 2.0 (1983), each track had 9 sectors of 512 bytes. The formatted capacity was increased to 184,320 bytes per side or 368,640 bytes per diskette. The IBM documentation referred to these as "180KB" and "360KB" diskettes. The same drives and media can have different capacities depending on format.[44] IBM PC-DOS was one of three major operating systems that dominated the personal computer market from about 1985 to 1995. ...


On all diskettes the capacity available to the user will be smaller that the total number of sectors because some are reserved by the operating system for boot records or directory tables.


The IBM Personal Computer/AT (1984) had a new 5¼ inch disk drive that had 80 tracks per side, rotated at 360 rpm (versus 300 rpm) and had a new diskette media. The formatted capacity was 1,228,800 bytes or 1200 KiB. (80 tracks × 15 sectors × 512 bytes × 2 sides) The IBM Personal Computer/AT (IBM 5170), more commonly known as the IBM AT and also sometimes called the PC AT or PC/AT, was IBMs second-generation PC, designed around the Intel 80286 microprocessor running at 6 MHz and released in 1984. ...


The IBM PC Convertible (1986) used the 3½ inch diskettes. These were similar in recording technology to the original 5¼ inch drives except they had 80 tracks per side. The formatted capacity was 737,280 bytes or 720 KiB. Apple used the same disk with a different recording technology, GRC, that gave a formatted capacity of 819,200 bytes or 800 KiB. Apple referred to this as an "800K" disk.[45] IBM PC Convertible The IBM PC Convertible, released April 3, 1986, was IBMs first laptop computer and was also the first IBM computer to utilize the now-standard 3. ... Group Code Recording (GCR) is a floppy disk data encoding format used by the Apple II and Commodore Business Machines in the 5¼ disk drives for their 8-bit computers (the best-known drives being the Disk II for the Apple II family and the Commodore 1541, used with the...


The last widely adopted diskette was the 3½ inch high density. This has twice the capacity as the 720 KiB diskettes, 1,474,560 bytes or 1440 KiB. The drive was marketed as 1.44 MB when a more accurate value would have been 1.4 MiB (1.40625 MiB). Some users have noticed the missing 0.04 MiB and both Apple and Microsoft have support bulletins referring to them as 1.4 MB.[46] [45] The 1200 KiB 5½ inch diskette was marketed as 1.2 MB (1.171875 MiB) without any controversy.


CD and DVD

CD capacities are always given in binary units. A "700 MB" (or "80 minute") CD has a nominal capacity of about 700 MiB (approx 730MB).[47] But DVD capacities are given in decimal units. A "4.7 GB" DVD has a nominal capacity of about 4.38 GiB.[48] A Compact Disc or CD is an optical disc used to store digital data, originally developed for storing digital audio. ... The three-letter acronym MIB may refer to any of several concepts: Management information base, a computing information repository used (for example) by SNMP In marbles, any marble, but esp. ... Size comparison: A 12 cm Sony DVD+RW and a 19 cm Dixon Ticonderoga pencil. ... The term gib may refer to: a castrated male cat or ferret an abbreviation for gibibyte (GiB) or gibibit (Gib) an abbreviation for Gibraltar an abbreviation for Gib Board, itself an abbreviation of Gibraltar Board, all Winston Wallboards[1] tradenames for drywall (plasterboard). ...


Buses

Bus bandwidth is given in decimal units. This is not because hard drive capacities use the decimal versions, nor because bit rates do, but because clock speeds do. For example, "PC3200" memory runs on a double pumped 200 MHz bus, transferring 8 bytes per cycle, and hence has a bandwidth of 200,000,000×2×8 = 3,200,000,000 byte/s. In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ... DDR SDRAM or double-data-rate synchronous dynamic random access memory is a type of memory integrated circuit used in computers. ... In computing, a computer bus operating with double data rate transfers data on both the rising and falling edges of the clock signal, effectively nearly doubling the data transmission rate without having to deal with the additional problems of timing skew that increasing the number of data lines would introduce. ...


Legal disputes

There have been two significant class action lawsuits against digital storage manufactures. One case involved flash memory and the other involved hard disk drives. Both were settled with the manufactures agreeing to clarify the storage capacity of their products on the consumer packaging.


On February 20, 2004, Willem Vroegh filed a lawsuit against Lexar Media, Dane–Elec Memory, Fuji Photo Film USA, Eastman Kodak Company, Kingston Technology Company, Inc., Memorex Products, Inc.; PNY Technologies Inc., SanDisk Corporation, Verbatim Corporation, and Viking InterWorks alleging that their descriptions of the capacity of their flash memory cards were false and misleading. is the 51st day of the year in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... // Willem Vroegh v. ... Fujifilm Holdings Corporation, or Fujifilm, is a Japanese company known for its photographic film and cameras. ... Eastman Kodak Company (NYSE: EK) is an American multinational public company. ... Established in 1961 in Silicon Valley, Memorex is today a consumer electronics brand of Imation specializing in recordable media (CD & DVD Drives), travel drives, flash storage, computer accessories and other electronics. ... PNY Technologies, Inc. ... SanDisk Corporation (NASDAQ: SNDK), formerly SunDisk, is an American multinational corporation which designs and markets flash memory card products. ... The Verbatim Corporation is a US company. ... A USB flash drive. ...


Vroegh claimed that a 256 MB Flash Memory Device had only 244 MB of accessible memory. "Plaintiffs allege that Defendants marketed the memory capacity of their products by assuming that one megabyte equals one million bytes and one gigabyte equals one billion bytes." The plaintiffs wanted to use the binary values 220 for megabyte and 230 for gigabyte. The plaintiffs acknowledged that the IEC and IEEE standards define a MB as one million bytes but stated that the industry has largely ignored the IEC standards.[3]


The manufactures agreed to clarify the flash memory card capacity on the packaging and web sites. [4] The consumers could apply for "a discount of ten percent off a future online purchase from Defendants' Online Stores Flash Memory Device."[5] The law firms Gutride Safier, LLP and Milberg Weiss received $2.4 million.


On July 7, 2005, an action entitled Orin Safier v. Western Digital Corporation, et al., was filed in the Superior Court for the City and County of San Francisco, Case No. CGC-05-442812. The case was subsequently moved to the Northern District of California, Case No. 05-03353 BZ. [6] is the 188th day of the year (189th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Western Digital Corporation (NYSE: WDC) (often abbreviated to WD) is a manufacturer of a large proportion of the worlds hard disks, and has a long history in the electronics industry as an IC maker and a storage products company. ...


Although Western Digital maintained that their usage of units is consistent with "the indisputably correct industry standard for measuring and describing storage capacity", and that they "cannot be expected to reform the software industry", they agreed to settle[7] in March 2006 with June 14, 2006 as the Final Approval hearing date. June 14 is the 165th day of the year (166th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday (link displays full 2006 calendar) of the Gregorian calendar. ...


Western Digital offered to compensate customers with a free download of backup and recovery software valued at US$30. They also paid $500,000 in fees and expenses to San Francisco lawyers Adam Gutride and Seth Safier, who filed the suit.[8]


Western Digital had this footnote in their settlement. "Apparently, Plaintiff believes that he could sue an egg company for fraud for labeling a carton of 12 eggs a “dozen,” because some bakers would view a “dozen” as including 13 items."[9]


The flash memory and hard disk manufactures now have disclaimers on their packaging and web sites clarifying the formatted capacity of the flash memory[10] or defining MB as 1 million bytes and 1 GB as 1 billion bytes.[11]


Also the Class Action Fairness Act of 2005 requires greater scrutiny on coupon settlements. One of the plaintiff law firms in the Vroegh case, Milberg Weiss & Bershad, was indicted for fraud in unrelated class action cases.[12] The U.S. Class Action Fairness Act of 2005, 28 U.S.C. Sections 1332(d), 1453, and 1711-1715, grants federal courts original jurisdiction over certain mass actions and class actions (forms of civil action) in which the amount in controversy exceeds $5 million, and any of the members...


See also

In computer science, the term integer is used to refer to any data type which can represent some subset of the mathematical integers. ... This article is about the unit of information. ... A nibble (or less commonly but more accurately, nybble) is the computing term for a four-bit aggregation, or half an octet (an octet being an 8-bit byte). ... 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 information technology there is sometimes confusion about measurement of bits and bytes. ... 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. ... 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. ...

Specific units of IEC 60027-2 A.2

These units have individual articles:

Bit rates
Decimal prefixes (SI)
Name Symbol Multiple
kilobit per second kbit/s 103
megabit per second Mbit/s 106
gigabit per second Gbit/s 109
terabit per second Tbit/s 1012
Binary prefixes
(IEC 60027-2)
kibibit per second Kibit/s 210
mebibit per second Mibit/s 220
gibibit per second Gibit/s 230
tebibit per second Tibit/s 240
v  d  e
Quantities of bytes
SI prefixes Historical
Use
Binary prefixes
Symbol
(Name)
Value Symbol Value Symbol
(Name)
Value
kB (kilobyte) 10001 = 103 KB 10241 = 210 KiB (kibibyte) 210
MB (megabyte) 10002 = 106 MB 10242 = 220 MiB (mebibyte) 220
GB (gigabyte) 10003 = 109 GB 10243 = 230 GiB (gibibyte) 230
TB (terabyte) 10004 = 1012 TB 10244 = 240 TiB (tebibyte) 240
PB (petabyte) 10005 = 1015 PB 10245 = 250 PiB (pebibyte) 250
EB (exabyte) 10006 = 1018 EB 10246 = 260 EiB (exbibyte) 260
ZB (zettabyte) 10007 = 1021 ZB 10247 = 270 ZiB (zebibyte) 270
YB (yottabyte) 10008 = 1024 YB 10248 = 280 YiB (yobibyte) 280
v  d  e
Quantities of bits
SI prefixes Binary prefixes
Name
(Symbol)
Standard
SI
Rare
usage
Name
(Symbol)
Value
kilobit (kb) 103 210 kibibit (Kibit) 210
megabit (Mb) 106 220 mebibit (Mibit) 220
gigabit (Gb) 109 230 gibibit (Gibit) 230
terabit (Tb) 1012 240 tebibit (Tibit) 240
petabit (Pb) 1015 250 pebibit (Pibit) 250
exabit (Eb) 1018 260 exbibit (Eibit) 260
zettabit (Zb) 1021 270 zebibit (Zibit) 270
yottabit (Yb) 1024 280 yobibit (Yibit) 280

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. ... 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. ... Look up si, Si, SI in Wiktionary, the free dictionary. ... A kilobit per second (kbit/s or kbps or kBaud) is a unit of data transfer rate equal to 1,000 bits per second. ... Look up one thousand in Wiktionary, the free dictionary. ... A megabit per second (Mbps or Mbit/s or Mb/s) is a unit of data transmission equal to 1,024 kilobits per second or 1048576 bits per second. ... (Redirected from 1 E6) One million (1000000), one thousand thousand, is the natural number following 999999 and preceding 1000001. ... A gigabit per second (Gbps or Gbit/s) is a unit of data transmission equal to 1,000 megabits per second or 1,000,000 kilobits per second or 1,000,000,000 bits per second. ... To help compare orders of magnitude this page lists dimensionless numbers between 109 and 1012. ... A terabit per second (Tbps or Tbit/s) is a unit of data transfer equal to 1,000 gigabits per second, 1,000,000 megabits per second, 1,000,000,000 kilobits per second, or 1,000,000,000,000 bits per second. ... To help compare orders of magnitude this page lists dimensionless numbers between 1012 and 1015: See also Orders of magnitude (numbers) Categories: Stub | Orders of magnitude (numbers) ... In information technology there is sometimes confusion about measurement of bits and bytes. ... A kibibit per second (Kibps or Kibit/s) is a unit of data transmission equal to 1,024 bits per second. ... A mebibit per second (Mibps or Mibit/s) is a unit of data transmission equal to 1,024 kibibits per second or 1,048,576 bits per second. ... A gibibit per second (Gibps or Gibit/s) is a unit of data transmission equal to 1,024 mebibits per second or 1,048,576 kibibits per second or 1,073,741,824 bits per second. ... A tebibit per second (Tibps or Tibit/s) is a unit of data transmission equal to 1,024 tebibits per second, 1,048,576 mebibits per second, 1,073,741,824 kibibits per second, or 1,099,511,627,776 bits per second. ... In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ... 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). ... A kilobyte (derived from the SI prefix kilo-, meaning 1000) is a unit of information or computer storage equal to the decimal 1024 bytes (2 to the 10th power, or 1,024 bytes based in the binary system). ... A kibibyte (a contraction of kilo binary byte) is a unit of information or computer storage, commonly abbreviated KiB (never kiB). 1 kibibyte = 210 bytes = 1,024 bytes The kibibyte is closely related to the kilobyte, which can be used either as a synonym for kibibyte or to refer to... ReBoot character, see Megabyte (ReBoot). ... A mebibyte (a contraction of mega binary byte) is a unit of information or computer storage, abbreviated MiB. 1 MiB = 220 bytes = 1,048,576 bytes = 1,024 kibibytes 1 MiB = 1024 (= 210) kibibytes (KiB), and 1024 MiB equal one gibibyte (GiB). ... A gigabyte (derived from the SI prefix giga-) is a unit of information or computer storage equal to 1000³ bytes or 1024³ bytes (1000³ = one billion). ... A gibibyte is a unit of information or computer storage. ... This article is about a measurement term for data storage capacity. ... A tebibyte is a unit of information or computer storage, commonly abbreviated TiB. 1 tebibyte = 240 bytes = 1,099,511,627,776 bytes The tebibyte is closely related to the terabyte, which can either be a synonym for tebibyte, or refer to 1012 bytes = 1,000,000,000,000 bytes... A petabyte (derived from the SI prefix peta- ) is a unit of information or computer storage equal to one quadrillion bytes. ... A pebibyte is a unit of information or computer storage. ... An exabyte (derived from the SI prefix exa-) is a unit of information or computer storage equal to approximately one quintillion bytes. ... An exbibyte (a contraction of exa binary byte) is a unit of information or computer storage, abbreviated EiB. 1 exbibyte = 260 bytes = 1,152,921,504,606,846,976 bytes = 1,024 pebibytes The exbibyte is closely related to the exabyte, which can either be a synonym for exbibyte, or... A zettabyte (derived from the SI prefix zetta-) is a unit of information or computer storage equal to one sextillion (one long scale trilliard) bytes. ... A zettabyte (derived from the SI prefix zetta-) is a unit of information or computer storage equal to one sextillion (one long scale trilliard) bytes. ... A yottabyte (derived from the SI prefix yotta-) is a unit of information or computer storage equal to one septillion (one long scale quadrillion or 1024) bytes. ... This article or section does not cite any references or sources. ... This article is about the unit of information. ... 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. ... 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 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 (derived from the SI prefix yotta) is a unit of measurement in computers of one million million million million (American septillion, European quadrillion) bits. ... In computing, binary prefixes are often used to quantify large numbers where powers of two are more useful than powers of ten. ...

References

  1. ^ IBM (April 1962). IBM 1401 Data Processing System: Reference Manual, A24-1403-5, pg 9. 
  2. ^ Sonquiest, John A. (December 1962). "Fixed-word-length arrays in variable-word-length computers". Communications of the ACM 5 (12): pg 602. “The following scheme for assigning storage for fixed-word-length arrays seems to meet these criteria and has been used successfully in working with linear arrays on a 4k IBM 1401.” 
  3. ^ Gruenberger, Fred (October 1960). "Letters to the Editor". Communications of the ACM 3 (10).  "The 8K core stores were getting fairly common in this country in 1954. The 32K store started mass production in 1956; it is the standard now for large machines and at least 200 machines of the size (or its equivalent in the character addressable machines) are in existence today (and at least 100 were in existence in mid-1959)." Note: The IBM 1401 was a character addressable computer.
  4. ^ a b Amdahl, Gene M.; Gerrit Blaauw; Fred Brooks (1964). "Architecture of the IBM System/360". IBM Journal of Research and Development 8 (2).  Figure 1 gives storage (memory) capacity ranges of the various models in "Capacity 8 bit bytes, 1 K = 1024"
  5. ^ Control Data Corporation (November 1968). Control Data 7600 Computer System: Preliminary System Description. “One type, designated as the small core memory (SCM) is a many bank coincident current type memory with a total of 64K words of 60 bit length (K=1024).” 
  6. ^ Control Data Corporation (1965-1967). Control Data 6400/6500/6600 Computer Systems Reference Manual, Pub No. 60100000, pg 2-1. “Central Memory is organized into 32K, 65K, or 131K words (60-bit) in 8, 16, or 32 banks of 4096 words each.” 
  7. ^ Frankenberg, Robert (October 1974). "All Semiconductor Memory Selected for New Minicomputer Series". Hewlett-Packard Journal 26 (2): pg 15-20. Retrieved on 2007-06-18. “196K-word memory size” 
  8. ^ Hewlett-Packard (November 1973), "HP 3000 Configuration Guide", HP 3000 Computer System and Subsystem Data: pg 59
  9. ^ Lin, Yeong; Mattson, Richard (September 1972). "Cost-performance evaluation of memory hierarchies". Magnetics, IEEE Transactions on 8 (3): pg 390-392. “Also, random access devices are advantageous over serial access devices for backing store applications only when the memory capacity is less than 1 Mbyte. For capacities of 4 Mbyte and 16 Mbyte serial access stores with shift register lengths of 256 bit and 1024 bit, respectively, look favorable.” 
  10. ^ IBM (1972). "System/370 Model 158 brochure". “All-monolithic storage ... (1024-bit NMOS) This new improvement of processor storage makes system expansion more economical. Real storage capacity is available in 512K increments ranging from 512K to 2,048K bytes.” 
  11. ^ Bell, Gordon; Strecker, William (November 1975). "Computer structures: What have we learned from the PDP-11?". ISCA '76: Proceedings of the 3rd annual symposium on Computer architecture: pg 1-14. “memory size (8k bytes to 4 megabytes).” 
  12. ^ (October 30, 1986) ANSI/IEEE Std 1084-1986 IEEE Standard Glossary of Mathematics of Computing Terminology. “kilo (K). (1) A prefix indicating 1000. (2) In statements involving size of computer storage, a prefix indicating 210, or 1024. mega (M). (1) A prefix indicating one million. (2) In statements involving size of computer storage, a prefix indicating 220, or 1,048,576.” 
  13. ^ (July 22, 1992) ANSI/IEEE Std 1212-1991 IEEE Standard Control and Status Register (CSR) Architecture for Microcomputer Buses. “Kbyte. Kilobyte. Indicates 210 bytes. Mbyte. Megabyte. Indicates 220bytes. Gbyte is used in the Foreword.” 
  14. ^ (June 24, 1994) IEEE Std 610.10-1994 IEEE Standard Glossary of Computer Hardware Terminology. “gigabyte (gig, GB). This term may mean either a) 1,000,000,000 bytes or b) 230 bytes. … As used in this document, the terms kilobyte (kB) means 210 or 1024 bytes, megabyte (MB) means 1024 kilobytes, and gigabyte (GB) means 1024 megabytes.” 
  15. ^ a b Institute of Electrical and Electronics Engineers (2000). The Authoritative Dictionary of IEEE Standards Terms. IEEE Computer Society Press. ISBN 0-7381-2601-2.  "kB See kilobyte." "Kbyte Kilobyte. Indicates 210 bytes." "Kilobyte Either 1000 or 210 or 1024 bytes." The standard also defines megabyte and gigabyte. There is a note that an alternative notation for base-2 is under development.
  16. ^ Amendment 2 to IEC International Standard IEC 60027-2: Letter symbols to be used in electrical technology — Part 2: Telecommunications and electronics [1]
  17. ^ IEC 60027-2 (2000-11) Ed. 2.0
  18. ^ A.J.Thor (2000). "Prefixes for binary multiples" (PDF). Metrologica 37 (81). 
  19. ^ International Electrotechnical Commission (2005-08-15). HERE COME ZEBI AND YOBI. Press release.
  20. ^ IEEE-SA STANDARDS BOARD STANDARDS REVIEW COMMITTEE (RevCom) MEETING AGENDA (2005-03-19). Retrieved on 2007-02-25. “1541-2002 (SCC14) IEEE Trial-Use Standard for Prefixes for Binary Multiples [No negative comments received during trial-use period, which is now complete; Sponsor requests elevation of status to full-use.] Recommendation: Elevate status of standard from trial-use to full-use. Editorial staff will be notified to implement the necessary changes. The standard will be due for a maintenance action in 2007.”
  21. ^ System/360 Model 91
  22. ^ The |CDC Product Line Cardunambiguously uses MB to characterize HDD capacity in millions of bytes
  23. ^ 1977 Disk/Trend Report - Rigid Disk Drives, published June 1977
  24. ^ Definition of megabyte (html).
  25. ^ Definitions of Megabyte on Dictionnary.com" (html).
  26. ^ AskOxford: megabyte (html).
  27. ^ a b (2006) "§3.1 SI prefixes", The International System of Units (SI) (PDF), 8th edition (in French/English), Paris: STEDI Media, p. 127. ISBN 92-822-2213-6. Retrieved on 2007-02-25. “[Side note:] These SI prefixes refer strictly to powers of 10. They should not be used to indicate powers of 2 (for example, one kilobit represents 1000 bits and not 1024 bits). The IEC has adopted prefixes for binary powers in the international standard IEC 60027-2: 2005, third edition, Letter symbols to be used in electrical technology — Part 2: Telecommunications and electronics. The names and symbols for the prefixes corresponding to 210, 220, 230, 240, 250, and 260 are, respectively: kibi, Ki; mebi, Mi; gibi, Gi; tebi, Ti; pebi, Pi; and exbi, Ei. Thus, for example, one kibibyte would be written: 1 KiB = 210 B = 1024 B, where B denotes a byte. Although these prefixes are not part of the SI, they should be used in the field of information technology to avoid the incorrect usage of the SI prefixes.” 
  28. ^ (2003-02-12) IEEE Trial-Use Standard for Prefixes for Binary Multiples (PDF). ISBN 0-7381-3386-8. Retrieved on 2007-02-25. “This standard is prepared with two goals in mind: (1) to preserve the SI prefixes as unambiguous decimal multipliers and (2) to provide alternative prefixes for those cases where binary multipliers are needed. The first goal affects the general public, the wide audience of technical and nontechnical persons who use computers without much concern for their construction or inner working. These persons will normally interpret kilo, mega, etc., in their proper decimal sense. The second goal speaks to specialists—the prefixes for binary multiples make it possible for persons who work in the information sciences to communicate with precision.” 
  29. ^ a b Prefixes for Binary Multiples — The NIST Reference on Constants, Units, and Uncertainty
  30. ^ Rules for SAE Use of SI (Metric) Units — Section C.1.12 — SI prefixes
  31. ^ HD 60027-2:2003 Information about the harmonization document (obtainable on order)
  32. ^ prEN 60027-2:2006 Information about the EN standardization process
  33. ^ UNITS. Linux Programmer's Manual (2001-12-22). Retrieved on 2007-05-20. “When the Linux kernel boots and says hda: 120064896 sectors (61473 MB) w/2048KiB Cache the MB are megabytes and the KiB are kibibytes.”
  34. ^ 2.2 Block size. GNU Core Utilities manual. Free Software Foundation (2002-12-28). Retrieved on 2007-05-20. “Integers may be followed by suffixes that are upward compatible with the SI prefixes for decimal multiples and with the IEC 60027-2 prefixes for binary multiples.”
  35. ^ gparted-0.2 changelog. SourceForge (2006-01-30). Retrieved on 2007-05-20. “changed KB/MB/GB/TB to KiB/MiB/GiB/TiB after reading http://www.iec.ch/zone/si/si_bytes.htm”
  36. ^ IFCONFIG. Linux Programmer's Manual (2005-06-30). Retrieved on 2007-05-20. “Since net-tools 1.60-4 ifconfig is printing byte counters and human readable counters with IEC 60027-2 units. So 1 KiB are 2^10 byte.”
  37. ^ Deluge changeset. Retrieved on 2007-06-13. “proper prefix for size”
  38. ^ Binary vs. Decimal Measurements
  39. ^ JEDEC Solid State Technology Association (December 2002), "Terms, Definitions, and Letter Symbols for Microcomputers, Microprocessors, and Memory Integrated Circuits", JESD 100B.01
  40. ^ http://www.answers.com/topic/ckd
  41. ^ On January 6, 2007, a check of the websites of Fujitsu, HGST, Samsung, Seagate, Toshiba and Western Digital showed these companies (representing virtually all of the HDD industry by unit volume) specify capacity with the SI prefix definitions.
  42. ^ Tandon (Janurary1984). TM100-1, TM100-2 Flexible Disk Drives: Product Specification and User's Manual. Tandon Corporation, pg 2-4. 
  43. ^ IBM (May 1982). Disk Operating System by Microsoft (Version 1.1). IBM Corporation, G-1.  Some software applications "used with DOS 1.10, will operate with either two 160KB drives or two 320KB drives. Both drives MUST be of the same type…"
  44. ^ IBM (January 1983). Disk Operating System by Microsoft (Version 2.0). IBM Corporation, A-2.  "Beginning with DOS Version 2.00, DOS formats diskettes at 9 sectors per track, which increases capacity from 163,840 to 184,320 characters of information for single-sided diskettes and from 327,680 to 368,640 characters for dual-sided diskettes. The smaller capacity diskettes created by DOS Version 1.00 or DOS Version 1.10 (8 sectors per track) are also usable with DOS Version 2.00."
  45. ^ a b Apple Inc. (August 22, 1991). Double-Density Versus High-Density Disks. Article ID: 3802. Apple Inc.. Retrieved on 2007-07-07. "This article gives the specifications for the 800K floppy disks and the1.4MB floppy disks." 800K Disk has 1600 sectors and 1.4MB Disk has 2880 sectors. A sector is 512 bytes.
  46. ^ Microsoft (May 6, 2003). Determining Actual Disk Size: Why 1.44 MB Should Be 1.40 MB. Article ID: 121839. Microsoft. Retrieved on 2007-07-07. "The 1.44-megabyte (MB) value associated with the 3.5-inch disk format does not represent the actual size or free space of these disks. Although its size has been popularly called 1.44 MB, the correct size is actually 1.40 MB."
  47. ^ Data capacity of CDs
  48. ^ Understanding Recordable and Rewritable DVD

Gene Myron Amdahl (born November 16, 1922) is an American computer architect and hi-tech entrepreneur of Norwegian descent, chiefly known for his work on mainframe computers at International Business Machines (IBM) and later his own companies. ... Gerrit Anne Blaauw (male, b. ... Frederick Phillips Brooks, Jr. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 169th day of the year (170th in leap years) in the Gregorian calendar. ... The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-e) is an international non-profit, professional organization for the advancement of technology related to electricity. ... IEC 60027 (formerly IEC 27) is the International Electrotechnical Commissions standard on Letter symbols to be used in electrical technology. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 227th day of the year (228th in leap years) in the Gregorian calendar. ... A press release (sometimes known as a news release or press statement) is a written or recorded communication directed at members of the news media for the purpose of announcing something claimed as having news value. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 78th day of the year (79th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 56th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 56th day of the year in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... February 12 is the 43rd day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 56th day of the year in the Gregorian calendar. ... The man page on man Almost all substantial UNIX and Unix-like operating systems have extensive documentation known as man pages (short for manual pages). The Unix command used to display them is man. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... December 22 is the 356th day of the year (357th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 140th day of the year (141st in leap years) in the Gregorian calendar. ... The GNU Core Utilities or coreutils is a package of GNU software containing many of the basic tools such as cat, ls, and rm needed for Unix-like operating systems. ... The Free Software Foundation (FSF) is a non-profit corporation founded in October 1985 by Richard Stallman to support the free software movement (free as in freedom), and in particular the GNU project. ... Also see: 2002 (number). ... is the 362nd day of the year (363rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 140th day of the year (141st in leap years) in the Gregorian calendar. ... SourceForge is a collaborative revision control and software development management system. ... Year 2006 (MMVI) was a common year starting on Sunday (link displays full 2006 calendar) of the Gregorian calendar. ... is the 30th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 140th day of the year (141st in leap years) in the Gregorian calendar. ... The man page on man Almost all substantial UNIX and Unix-like operating systems have extensive documentation known as man pages (short for manual pages). The Unix command used to display them is man. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 181st day of the year (182nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 140th day of the year (141st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 164th day of the year (165th in leap years) in the Gregorian calendar. ... is the 6th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 188th day of the year (189th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 188th day of the year (189th in leap years) in the Gregorian calendar. ...

Further reading

  • When is a kilobyte a kibibyte? And an MB an MiB?. International Electrotechnical Commission (2007-02-12). — An introduction to binary prefixes
  • Prefixes for binary multiples. NIST.
  • NIST (1999-03-02). Get Ready for the mebi, gibi and tebi. Press release.
  • Markus Kuhn (1996-12-29). What is a Megabyte ...?. — a 1996–1999 paper on bits, bytes, prefixes and symbols
  • Jonathan de Boyne Pollard. There is no such thing as a 1.44 MB standard format floppy disc.
  • Michael Quinion (1999-08-21). Kibibyte. World Wide Words. — Another description of binary prefixes
  • James Wiebe (2003-10-09). "When One Billion does not equal One Billion, or: Why your computer's disk drive capacity doesn’t appear to match the stated capacity" (PDF). — White-paper on the controversy over drive capacities

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... February 12 is the 43rd day of the year in the Gregorian calendar. ... As a non-regulatory agency of the United States Department of Commerce’s Technology Administration, the National Institute of Standards (NIST) develops and promotes measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life. ... As a non-regulatory agency of the United States Department of Commerce’s Technology Administration, the National Institute of Standards (NIST) develops and promotes measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life. ... Year 1999 (MCMXCIX) was a common year starting on Friday (link will display full 1999 Gregorian calendar). ... is the 61st day of the year (62nd in leap years) in the Gregorian calendar. ... A press release (sometimes known as a news release or press statement) is a written or recorded communication directed at members of the news media for the purpose of announcing something claimed as having news value. ... Year 1996 (MCMXCVI) was a leap year starting on Monday (link will display full 1996 Gregorian calendar). ... is the 363rd day of the year (364th in leap years) in the Gregorian calendar. ... Year 1999 (MCMXCIX) was a common year starting on Friday (link will display full 1999 Gregorian calendar). ... is the 233rd day of the year (234th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... is the 282nd day of the year (283rd in leap years) in the Gregorian calendar. ...

External links

  • Tool to convert to/from the binary and standard units (up to yobibytes)
  • A summary of the organizations, software, and so on that have implemented the new binary prefixes
  • A plea for sanity
  • KiloBytes vs. kilobits vs. Kibibytes (Binary prefixes)
  • Decimal-to-Binary Prefixes and Binary-to-Decimal Prefixes Converter
  • JavaScript SI/Binary Prefix Converter

  Results from FactBites:
 
Definitions of the SI units: The binary prefixes (562 words)
In December 1998 the International Electrotechnical Commission (IEC), the leading international organization for worldwide standardization in electrotechnology, approved as an IEC International Standard names and symbols for prefixes for binary multiples for use in the fields of data processing and data transmission.
It is suggested that in English, the first syllable of the name of the binary-multiple prefix should be pronounced in the same way as the first syllable of the name of the corresponding SI prefix, and that the second syllable should be pronounced as "bee."
It is important to recognize that the new prefixes for binary multiples are not part of the International System of Units (SI), the modern metric system.
Bambooweb: Binary prefix (757 words)
Binary prefixes are often used to quantify large amounts of bytes, bits, or bits per second (bit/s, bps), and are derived, but slightly different, from the SI prefixes such as kilo-, mega-, giga- and so on.
As popularly used, these prefixes often indicate multiples that are similar, but not equal, to factors denoted by their SI counterparts.
These are identical to SI prefixes, except for "K", which corresponds to "k"; in SI (K stands for Kelvin in SI).
  More results at FactBites »

 
 

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