{{Short description|Symbol placed before units of digital information to indicate multiplication by a power of two}}
{{About|unit prefixes, notably prefixes of units of digital information like bit and byte|the syntactical elements used to declare the radix of a given integer literal in program code|Integer literal#Affixes}}
{{Use dmy dates|date=May 2019|cs1-dates=y}}
{{Bit and byte prefixes}}
A '''binary prefix''' is a [[prefix (linguistics)|prefix]] to indicate [[multiple (mathematics)|multiples]] of a [[units of measurement|unit of measurement]] by an integer [[powers of two|power of two]]. The most commonly used ones are '''kibi''' (symbol '''Ki''', meaning 210= 1024), '''mebi''' ('''Mi''', 220 = {{val|1048576}}), and '''gibi''' ('''Gi''', 230 = {{val|1073741824}}). Binary prefixes are most often used in [[information technology]] as multipliers of [[bit]] and the [[byte]], when expressing the capacity of [[storage device]]s or the size of computer [[file (computer)|files]].
Binary prefixes were defined in 1998 by the [[International Electrotechnical Commission]] (IEC), in the [[ISO/IEC 80000#Part 13: Information science and technology|ISO/IEC 80000]] standard, as precise alternatives to the [[International System of Units|metric (SI)]] [[powers of 10|decimal power]] prefixes, such as "kilo" ("k" or "K", 103 = 1000), "mega" ("M", 106 = {{val|1000000}}) and "giga" ("G", 109 = {{val|1000000000}}), that were commonly used in the computer industry to indicate the nearest powers of two. For example, a hard disk whose capacity was specified by the manufacturer as "500 gigabytes" or "500 GB" would probably hold hold 500 × 230 = {{val|536870912000}} bytes, or maybe even 29 × 230 ≈ {{val|550000000000}} bytes, instead of 500 × 109 = {{val|500000000000}}. On the other hand, a file whose size was listed as "2.3 GB" may have a size closer to 2.3 × 230 ≈ {{val|2470000000}} or to 2.3 × 109 = {{val|2300000000}}, depending on the [[program (computer)|program]] or [[operating system]] providing that measurement. This ambiguity was often confusing to computer system users and even resulted in [[lawsuit]]s.[
Prior to the 1998 IEC [[standard]], there were some attempts by industry organizations, such as [[JEDEC memory standards#Unit prefixes for semiconductor storage capacity|Joint Electron Device Engineering Council]] (JEDEC), to redefine the terms ''kilobyte'', ''megabyte'', and ''gigabyte'', and the corresponding symbols ''KB'', ''MB'', and ''GB'' in the binary sense, for use in storage capacity masurements. However, the ambiguity persisted. Since 1998, several standards organizations, including the [[International Bureau of Weights and Measures|BIPM]] (which defines the SI system), the [[United States|US]] [[National Institute of Standards and Technology|NIST]],][ the [[Society of Automotive Engineers|SAE]], and the [[European Union]] have expressly prohibited the use of SI prefixes to denote binary multiples, and recommended or mandated the use of the IEC prefixes for that purpose. However, the misuse of decimal prefixes for binary multiples persists to this day.
==History==
{{See also|Timeline of binary prefixes}}
===Early prefixes===
The original [[metric system]] adopted by France in 1795 included two binary prefixes named ''[[double (metric prefix)|double]]-'' (2×) and ''[[demi (metric prefix)|demi]]-'' ({{sfrac|1|2}}×).][ However, these were not retained when the [[SI prefix]]es were internationally adopted by the 11th [[Conférence générale des poids et mesures|CGPM conference]] in 1960.
===Main memory===
Early computers used one of two addressing methods to access the system memory; binary (base 2) or decimal (base 10).][ For example, the [[IBM 701]] (1952) used binary and could address 2048 [[Word (data type)|words]] of 36 [[bit]]s each, while the [[IBM 702]] (1953) used decimal and could address ten thousand 7-bit words.
By the mid-1960s, binary addressing had become the standard architecture in most computer designs, and main memory sizes were most commonly powers of two. This is the most natural configuration for memory, as all combinations of their [[address line]]s map to a valid address, allowing easy aggregation into a larger block of memory with contiguous addresses.
Early computer system documentation would specify the memory size with an exact number such as 4096, 8192, or {{val|16384}} words of storage. These are all [[Power of two|powers of two]], and furthermore are small multiples of 210, or 1024. As storage capacities increased, several different methods were developed to abbreviate these quantities.
The method most commonly used today uses prefixes such as kilo, mega, giga, and corresponding symbols K, M, and G, which the computer industry originally adopted from the [[metric system]]. The prefixes ''kilo-'' and ''mega-'', meaning 1000 and {{val|1000000}} respectively, were commonly used in the electronics industry before World War II.][ Along with ''giga-'' or G-, meaning {{val|1000000000}}, they are now known as [[SI prefixes]]][ after the [[International System of Units]] (SI), introduced in 1960 to formalize aspects of the metric system.
The International System of Units does not define units for digital information but notes that the SI prefixes may be applied outside the contexts where base units or derived units would be used. But as computer main memory in a
binary-addressed system is manufactured in sizes that were easily expressed as multiples of 1024, ''kilobyte'', when applied to computer memory, came to be used to mean 1024 bytes instead of 1000. This usage is not consistent with the SI. Compliance with the SI requires that the prefixes take their 1000-based meaning, and that they are not to be used as placeholders for other numbers, like 1024.][{{rp|p.121}}
The use of K in the binary sense as in a "32K core" meaning {{nowrap|32 × 1024}} words, i.e., {{val|32768}} words, can be found as early as 1959.][
[[Gene Amdahl]]'s seminal 1964 article on [[IBM System/360]] used "1K" to mean 1024.][ This style was used by other computer vendors, the [[CDC 7600]] ''System Description'' (1968) made extensive use of K as 1024.][
Another style was to truncate the last three digits and append K, essentially using K as a decimal prefix similar to [[SI prefixes|SI]], but always truncating to the next lower whole number instead of rounding to the nearest. The exact values {{val|32768}} words, {{val|65536}} words and {{val|131072}} words would then be described as "32K", "65K" and "131K".][ (If these values had been rounded to nearest they would have become 33K, 66K, and 131K, respectively.) This style was used from about 1965 to 1975.
These two styles (K = 1024 and truncation) were used loosely around the same time, sometimes by the same company. In discussions of binary-addressed memories, the exact size was evident from context. (For memory sizes of "41K" and below, there is no difference between the two styles.) The [[HP 2100|HP 21MX]] real-time computer (1974) denoted {{val|196608}} (which is 192×1024) as "196K" and {{val|1048576}} as "1M",][ while the [[HP 3000]] business computer (1973) could have "64K", "96K", or "128K" bytes of memory.][ The "truncation" method gradually waned. Capitalization of the letter K became the ''de facto'' standard for binary notation, although this could not be extended to higher powers, and use of the lowercase k did persist.][ Nevertheless, the practice of using the SI-inspired "kilo" to indicate 1024 was later extended to "megabyte" meaning 10242 ({{val|1048576}}) bytes, and later "gigabyte" for 10243 ({{val|1073741824}}) bytes. For example, a "512 megabyte" RAM module is {{nowrap|512 × 10242}} bytes (512 × {{val|1048576}}, or {{val|536870912}}), rather than {{val|512000000}}.
The symbols Kbit, Kbyte, Mbit and Mbyte started to be used as "binary units"—"bit" or "byte" with a multiplier that is a power of 1024—in the early 1970s.][ For a time, memory capacities were often expressed in K, even when M could have been used: 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."][
Megabyte was used to describe the 22-bit addressing of DEC [[PDP-11]]/70 (1975)][
and gigabyte the 30-bit addressing DEC [[VAX-11/780]] (1977).
In 1998, the [[International Electrotechnical Commission]] IEC introduced the binary prefixes kibi, mebi, gibi, etc., to mean 1024, 10242, 10243 etc., so that 1048576 bytes could be referred to unambiguously as 1 [[mebibyte]]. The IEC prefixes were defined for use alongside the [[International System of Quantities]] (ISQ) in [[ISO 80000-1|2009]].
===Disk drives===
The disk drive industry has followed a different pattern. Disk drive capacity is generally specified with unit prefixes with decimal meaning, in accordance to SI practices. Unlike computer main memory, disk architecture or construction does not mandate or make it convenient to use binary multiples. Drives can have any practical number of platters or surfaces, and the count of tracks, as well as the count of sectors per track may vary greatly between designs.
The first commercially sold disk drive, the [[IBM 350]], had fifty physical disk platters containing a total of {{val|50000}} sectors of 100 characters each, for a total quoted capacity of 5 million characters.][ It was introduced in September 1956.
In the 1960s most disk drives used IBM's variable block length format, called [[Count Key Data]] (CKD).][ Any block size could be specified up to the maximum track length. Since the block headers occupied space, the usable capacity of the drive was dependent on the block size. Blocks ("records" in IBM's terminology) of 88, 96, 880 and 960 were often used because they related to the fixed block size of 80- and 96-character punch cards. The drive capacity was usually stated under conditions of full track record blocking. For example, the 100-megabyte 3336 disk pack only achieved that capacity with a full track block size of {{val|13030}} bytes.
[[Floppy disk#3½-inch floppy disk|Floppy disks]] for the IBM PC and compatibles quickly [[List of floppy disk formats#Known disk logical formats|standardized on 512-byte sectors]], so two sectors were easily referred to as "1K". The 3.5-inch "360 KB" and "720 KB" had 720 (single-sided) and 1440 sectors (double-sided) respectively. When the High Density "1.44 MB" floppies came along, with 2880 of these 512-byte sectors, that terminology represented a hybrid binary-decimal definition of "1 MB" = 210 × 103 = 1 024 000 bytes.
In contrast, [[hard disk]] drive manufacturers used ''megabytes'' or ''MB'', meaning 106 bytes, to characterize their products as early as 1974.][ By 1977, in its first edition, Disk/Trend, a leading hard disk drive industry marketing consultancy segmented the industry according to MBs (decimal sense) of capacity.][
One of the earliest hard disk drives in personal computing history, the Seagate [[ST-412]], was specified as ''Formatted: 10.0 Megabytes''.][ The drive contains four heads and active surfaces (tracks per cylinder), 306 cylinders. When formatted with a sector size of 256 bytes and 32 sectors/track it has a capacity of {{val|10027008|u=bytes}}. This drive was one of several types installed in the [[IBM PC/XT]]][ and extensively advertised and reported as a "10 MB" (formatted) hard disk drive.][ The cylinder count of 306 is not conveniently close to any power of 1024; operating systems and programs using the customary binary prefixes show this as 9.5625 MB. Many later drives in the personal computer market used 17 sectors per track; still later, [[zone bit recording]] was introduced, causing the number of sectors per track to vary from the outer track to the inner.
The hard drive industry continues to use decimal prefixes for drive capacity, as well as for transfer rate. For example, a "300 GB" hard drive offers slightly more than {{val|300|e=9}}, or {{val|300000000000}}, bytes, not {{nowrap|300 × 230}} (which would be about {{val|322|e=9}}). Operating systems such as [[Microsoft Windows]] that display hard drive sizes using the customary binary prefix "GB" (as it is used for RAM) would display this as "279.4 GB" (meaning {{nowrap|279.4 × 10243}} bytes, or {{nowrap|279.4 × {{val|1073741824|u=B}}}}). On the other hand, [[macOS]] has since version 10.6 shown hard drive size using decimal prefixes (thus matching the drive makers' packaging). (Previous versions of Mac OS X used binary prefixes.)
Disk drive manufacturers sometimes use ''both'' IEC and SI prefixes with their standardized meanings. Seagate has specified data transfer rates in select manuals of some hard drives with both units, with the conversion between units clearly shown and the numeric values adjusted accordingly.][
"Advanced Format" drives uses the term "4K sectors", which it defines as having size of "4096 (4K) bytes".][
===Information transfer and clock rates===
Computer [[Clock signal|clock]] frequencies are always quoted using SI prefixes in their decimal sense. For example, the internal clock frequency of the original [[IBM PC]] was 4.77 MHz, that is {{val|4770000|u=Hz}}. Similarly, digital information transfer rates are quoted using decimal prefixes:
* The ATA-100 disk interface refers to {{val|100000000}} bytes per second
* A "56K" modem refers to {{val|56000}} bits per second
* SATA-2 has a raw bit rate of 3 Gbit/s = {{val|3000000000}} bits per second
* PC2-6400 [[random-access memory|RAM]] transfers {{val|6400000000}} bytes per second
* Firewire 800 has a raw rate of {{val|800000000}} bits per second
* In 2011, Seagate specified the sustained transfer rate of some hard disk drive models with both decimal and IEC binary prefixes.][
===Historical standardization of dual definitions===
By the mid-1970s it was common to see K meaning 1024 and the occasional M meaning {{val|1048576}} for words or bytes of main memory (RAM) while K and M were commonly used with their decimal meaning for disk storage. In the 1980s, as capacities of both types of devices increased, the SI prefix G, with SI meaning, was commonly applied to disk storage, while M in its binary meaning, became common for computer memory. In the 1990s, the prefix G, in its binary meaning, became commonly used for computer memory capacity. The first terabyte (SI prefix, {{val|1000000000000}} bytes) hard disk drive was introduced in 2007.][
The dual usage of the kilo (K), mega (M), and giga (G) prefixes as both powers of 1000 and powers of 1024 has been recorded in standards and dictionaries. For example, the obsolete standard ANSI/IEEE Std 1084-1986][ defined dual uses for kilo and mega. {{Blockquote| 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 1048576.}} The binary units Kbyte and Mbyte were formally defined in the obsolete standard ANSI/IEEE Std 1212-1991.][
Many dictionaries have noted the practice of using customary prefixes to indicate binary multiples.][
Oxford online dictionary historically defined, for example, megabyte as: "Computing: a unit of information equal to one million or (strictly) {{val|1048576}} bytes."][
The units Kbyte, Mbyte, and Gbyte were found in the trade press and in IEEE journals. Gigabyte was formally defined in obsolete standard IEEE Std 610.10-1994 as either {{val|1000000000}} or 230 bytes.][ Kilobyte, Kbyte, and KB were all defined in the obsolete standard IEEE 100–2000.][
The hardware industry measures system memory (RAM) using the binary meaning while magnetic disk storage uses the SI definition. However, many exceptions exist. Labeling of one type of [[diskette]] uses the megabyte to denote {{nowrap|1024 × 1000}} bytes.][ In the optical disks market, [[compact disc]]s use ''MB'' to mean 10242 bytes while [[DVD]]s use ''GB'' to mean 10003 bytes.][
In the personal computing era, one source of consumer confusion is the difference in the way many operating systems display hard drive sizes, compared to the way hard drive manufacturers describe them. [[#Disk drives|Hard drives]] are specified and sold using "GB" and "TB" in their decimal meaning: one [[billion]] and one trillion bytes. Many operating systems and other software, however, display hard drive and file sizes using "MB", "GB" or other SI-looking prefixes in their binary sense, just as they do for displays of RAM capacity. For example, many such systems display a hard drive marketed as "1 TB" as "931 GB". The earliest known presentation of hard disk drive capacity by an operating system using "KB" or "MB" in a binary sense is 1984;][ earlier operating systems generally presented the hard disk drive capacity as an exact number of bytes, with no prefix of any sort, for example, in the output of the [[DOS]] command '[[CHKDSK]]'.
===Legal disputes===
The different interpretations of disk size prefixes has led to class action lawsuits against digital storage manufacturers. These cases involved both flash memory and hard disk drives.
====Early cases====
Early cases (2004–2007) were settled prior to any court ruling with the manufacturers admitting no wrongdoing but agreeing to clarify the storage capacity of their products on the consumer packaging. Accordingly, many flash memory and hard disk manufacturers have disclosures on their packaging and web sites clarifying the formatted capacity of the devices or defining MB as 1 million bytes and 1 GB as 1 billion bytes.][
The parties agreed that manufacturers could continue to use the decimal definition so long as the definition was added to the packaging and web sites.][ The consumers could apply for "a discount of ten percent off a future online purchase from Defendants' Online Stores Flash Memory Device".][
====''Orin Safier v. Western Digital Corporation''====
On 7 July 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.][
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 in March 2006 with 14 June 2006 as the Final Approval hearing date.][
Western Digital offered to compensate customers with a free download of backup and recovery software valued at US$30. They also paid ${{val|500000}} in fees and expenses to San Francisco lawyers Adam Gutride and Seth Safier, who filed the suit. The settlement called for Western Digital to add a disclaimer to their later packaging and advertising.][
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."][
==== ''Cho v. Seagate Technology (US) Holdings, Inc.'' ====
A lawsuit (''Cho v. Seagate Technology (US) Holdings, Inc.'', San Francisco Superior Court, Case No. CGC-06-453195) was filed against [[Seagate Technology]], alleging that Seagate overrepresented the amount of usable storage by 7% on hard drives sold between 22 March 2001 and 26 September 2007. The case was settled without Seagate admitting wrongdoing, but agreeing to supply those purchasers with free backup software or a 5% refund on the cost of the drives.][
==== ''Dinan et al. v. SanDisk LLC'' ====
On 22 January 2020, the district court of the Northern District of California ruled in favor of the defendant, SanDisk, upholding its use of "GB" to mean {{val|1000000000|u=bytes}}.][
==Unique binary prefixes==
===Early suggestions===
While early computer scientists typically used k to mean 1000, some recognized the convenience that would result from working with multiples of 1024 and the confusion that resulted from using the same prefixes for two different meanings.
Several proposals for unique binary prefixes][ were made in 1968. Donald Morrison proposed to use the Greek letter kappa ([[κ]]) to denote 1024, κ2 to denote 10242, and so on.][ (At the time, memory size was small, and only K was in widespread use.) [[Wallace Givens]] responded with a proposal to use bK as an abbreviation for 1024 and bK2 or bK2 for 10242, though he noted that neither the Greek letter nor lowercase letter b would be easy to reproduce on computer printers of the day.][ [[Bruce Alan Martin]] of [[Brookhaven National Laboratory]] further proposed that the prefixes be abandoned altogether, and the letter [[binary scientific notation|B]] be used for base-2 exponents, similar to [[E notation|E]] in [[decimal scientific notation]], to create shorthands like 3B20 for {{nowrap|3 × 220}},][ a convention still used on some calculators to present binary floating point-numbers today.][ None of these gained much acceptance, and capitalization of the letter K became the ''de facto'' standard for indicating a factor of 1024 instead of 1000, although this could not be extended to higher powers.
As the discrepancy between the two systems increased in the higher-order powers, more proposals for unique prefixes were made. In 1996, [[Markus Kuhn (computer scientist)|Markus Kuhn]] proposed a system with ''di'' prefixes, like the "dikilobyte" (K2B or K2B).][ [[Donald Knuth]], who uses decimal notation like 1 MB = 1000 kB,][ proposed that the powers of 1024 be designated as "large kilobytes" and "large megabytes", with abbreviations KKB and MMB.][ [[Metric prefix#Double prefixes|Double prefixes]] were already abolished from SI, however, having a multiplicative meaning ("MMB" would be equivalent to "TB"), and this proposed usage never gained any traction.
==={{anchor|kibi|mebi|gibi|tebi|pebi|exbi|zebi|yobi|IEC standard prefixes}}IEC prefixes===
{{redirect|Gibi}}
The set of binary prefixes that were eventually adopted, now referred to as the "IEC prefixes",][ were first proposed by the [[International Union of Pure and Applied Chemistry]]'s (IUPAC) Interdivisional Committee on Nomenclature and Symbols (IDCNS) in 1995. At that time, it was proposed that the terms kilobyte and megabyte be used only for 103 bytes and 106 bytes, respectively. The new prefixes ''kibi'' (kilobinary), ''mebi'' (megabinary), ''gibi'' (gigabinary) and ''tebi'' (terabinary) were also proposed at the time, and the proposed symbols for the prefixes were kb, Mb, Gb and Tb respectively, rather than Ki, Mi, Gi and Ti.][ The proposal was not accepted at the time.
The [[Institute of Electrical and Electronics Engineers]] (IEEE) began to collaborate with the [[International Organization for Standardization]] (ISO) and [[International Electrotechnical Commission]] (IEC) to find acceptable names for binary prefixes. IEC proposed ''kibi'', ''mebi'', ''gibi'' and ''tebi'', with the symbols Ki, Mi, Gi and Ti respectively, in 1996.][
The names for the new prefixes are derived from the original SI prefixes combined with the term ''binary'', but contracted, by taking the first two letters of the SI prefix and "bi" from binary. The first letter of each such prefix is identical to the corresponding SI prefix, except that "k" is capitalised to "K".
The IEEE decided that their standards would use the prefixes ''kilo'', etc. with their metric definitions, but allowed the binary definitions to be used in an interim period as long as such usage was explicitly pointed out on a case-by-case basis.][
====Adoption by IEC, NIST and ISO====
In January 1999, the IEC published the first international standard ([[IEC 60027-2]] Amendment 2) with the new prefixes, extended up to ''pebi'' (Pi) and ''exbi'' (Ei).][
The IEC 60027-2 Amendment 2 also states that the IEC position is the same as that of BIPM (the body that regulates the SI system); the SI prefixes retain their definitions in powers of 1000 and are never used to mean a power of 1024.
In usage, products and concepts typically described using powers of 1024 would continue to be, but with the new IEC prefixes. For example, a memory module of {{val|536870912}} bytes ({{nowrap|512 × {{val|1048576}}}}) would be referred to as 512 MiB or 512 mebibytes instead of 512 MB or 512 megabytes. Conversely, since hard drives have historically been marketed using the SI convention that "giga" means {{val|1000000000}}, a "500 GB" hard drive would still be labeled as such. According to these recommendations, operating systems and other software would also use binary and SI prefixes in the same way, so the purchaser of a "500 GB" hard drive would find the operating system reporting either "500 GB" or "466 GiB", while {{val|536870912}} bytes of RAM would be displayed as "512 MiB".
The second edition of the standard, published in 2000,][ defined them only up to ''exbi'',][ but in 2005, the third edition added prefixes ''zebi'' and ''yobi'', thus matching all then-defined SI prefixes with binary counterparts.][
The harmonized [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] [[IEC 80000-13]]:2008 standard cancels and replaces subclauses 3.8 and 3.9 of IEC 60027-2:2005 (those defining prefixes for binary multiples). The only significant change is the addition of explicit definitions for some quantities.][ In 2009, the prefixes kibi-, mebi-, etc. were defined by [[ISO 80000-1]] in their own right, independently of the kibibyte, mebibyte, and so on.
The BIPM standard JCGM 200:2012 "International vocabulary of metrology – Basic and general concepts and associated terms (VIM), 3rd edition" lists the IEC binary prefixes and states "SI prefixes refer strictly to powers of 10, and should not be used for powers of 2. For example, 1 kilobit should not be used to represent {{val|1024}} bits (210 bits), which is 1 kibibit."][
{| style="margin:auto;" class="wikitable"
|+ Specific units of IEC 60027-2 A.2 and ISO/IEC 80000:13-2008
|-
!colspan="2"|IEC prefix
!colspan="4"|Representations
|-
! Name
! Symbol
! Base 2
! Base 1024
! Value
! Base 10
|-
| kibi
| Ki
| 210
| 10241
|align="right"| {{val|1024}}
| = {{val|1.024|e=3}}
|- style="background:#eee;"
| mebi
| Mi
| 220
| 10242
|align="right"| {{val|1048576}}
| ≈ {{val|1.049|e=6}}
|-
| gibi
| Gi
| 230
| 10243
|align="right"| {{val|1073741824}}
| ≈ {{val|1.074|e=9}}
|- style="background:#eee;"
| tebi
| Ti
| 240
| 10244
|align="right"| {{val|1099511627776}}
| ≈ {{val|1.100|e=12}}
|-
| pebi
| Pi
| 250
| 10245
|align="right"| {{val|1125899906842624}}
| ≈ {{val|1.126|e=15}}
|- style="background:#eee;"
| exbi
| Ei
| 260
| 10246
|align="right"| {{val|1152921504606846976}}
| ≈ {{val|1.153|e=18}}
|-
| zebi
| Zi
| 270
| 10247
|align="right"| {{val|1180591620717411303424}}
| ≈ {{val|1.181|e=21}}
|- style="background:#eee;"
| yobi
| Yi
| 280
| 10248
|align="right"| {{val|1208925819614629174706176}}
| ≈ {{val|1.209|e=24}}
|}
{{anchor|robi|quebi}}The additional decimal prefixes ''[[ronna-]]'' for 10009 and ''[[quetta-]]'' for 100010 were adopted by the [[International Bureau of Weights and Measures]] (BIPM) in 2022.][ The natural binary counterparts to ''ronna-'' and ''quetta-'' were suggested in a consultation paper of the [[International Committee for Weights and Measures]]' Consultative Committee for Units (CCU) as ''robi-'' (Ri, 10249) and ''quebi-'' (Qi, 102410).][ {{As of|2022}}, no corresponding binary prefixes have been adopted by the IEC and ISO.][
====Other standards bodies and organizations====
The IEC standard binary prefixes are now supported by other standardization bodies and technical organizations.
The United States [[National Institute of Standards and Technology]] (NIST) supports the ISO/IEC standards for
"Prefixes for binary multiples" and has a web page][ documenting them, describing and justifying their use. NIST suggests 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''.][ NIST has stated the SI prefixes "refer strictly to powers of 10" and that the binary definitions "should not be used" for them.][
The microelectronics industry standards body [[JEDEC]] describes the IEC prefixes in its online dictionary with a note: "The definitions of kilo, giga, and mega based on powers of two are included only to reflect common usage."][ The JEDEC standards for semiconductor memory use the customary prefix symbols K, M and G in the binary sense.][
On 19 March 2005, the IEEE standard [[IEEE 1541-2002]] ("Prefixes for Binary Multiples") was elevated to a full-use standard by the IEEE Standards Association after a two-year trial period.][ However, {{As of|2008|4|lc=on}}, the IEEE Publications division does not require the use of IEC prefixes in its major magazines such as ''Spectrum''][ or ''Computer''.][{{Cite journal |last1=Gschwind |first1=Michael |title=An Open Source Environment for Cell Broadband Engine System Software |journal=Computer |volume=40 |issue=6 |pages=37–47 |publisher=IEEE Computer Society |date=June 2007 |doi = 10.1109/MC.2007.192 |last2=Erb |first2=David |last3=Manning |first3=Sid |last4=Nutter |first4=Mark |s2cid=10877922 |url=http://www.research.ibm.com/people/m/mikeg/papers/2007_ieeecomputer.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.research.ibm.com/people/m/mikeg/papers/2007_ieeecomputer.pdf |archive-date=2022-10-09 |url-status=live }} "The processor has a memory subsystem with separate first-level 32-Kbyte instruction and data caches, and a 512-Kbyte unified second-level cache." Authors are with IBM.]
The [[International Bureau of Weights and Measures]] (BIPM), which maintains the [[International System of Units]] (SI), expressly prohibits the use of SI prefixes to denote binary multiples, and recommends the use of the IEC prefixes as an alternative since units of information are not included in SI.[
The [[Society of Automobile Engineers|Society of Automotive Engineers]] (SAE) prohibits the use of SI prefixes with anything but a power-of-1000 meaning, but does not recommend or otherwise cite the IEC binary prefixes.][
The European Committee for Electrotechnical Standardization ([[CENELEC]]) adopted the IEC-recommended binary prefixes via the harmonization document HD 60027-2:2003-03.][ The European Union (EU) has required the use of the IEC binary prefixes since 2007.][
==Current practice in information technology==
Most computer hardware uses [[SI prefixes]]][ to state capacity and define other performance parameters such as data rate. [[Main memory|Main]] and [[cache memory|cache]] memories are notable exceptions.
Capacities of [[main memory]] and [[cache memory]] are usually expressed with customary binary prefixes][ On the other hand, [[flash memory]], like that found in solid state drives, mostly uses [[SI prefixes]]][ to state capacity.
Some operating systems and other software continue to use the customary binary prefixes in displays of memory, disk storage capacity, and file size, but SI prefixes][ in other areas such as network communication speeds and processor speeds.
In the following subsections, unless otherwise noted, examples are first given using the common prefixes used in each case, and then followed by interpretation using other notation where appropriate.
===Operating systems===
Prior to the release of [[Classic Mac OS|Macintosh System Software]] (1984), file sizes were typically reported by the operating system without any prefixes.{{Citation needed|date=August 2008}} Today, most operating systems report file sizes with prefixes.
* The [[Linux kernel]] uses standards-compliant decimal and binary prefixes when booting up.][ However, many [[Unix-like]] system utilities, such as the [[ls]] command, use powers of 1024 indicated as K/M (customary binary prefixes) if called with the "{{Mono|-h}}" option. They give the exact value in bytes otherwise. The GNU versions will also use powers of 10 indicated with k/M if called with the "{{Mono|--si}}" option.
** The [[Ubuntu (operating system)|Ubuntu]] [[Linux distribution]] uses the IEC prefixes for base-2 numbers as of the 10.10 release.][
* [[Microsoft Windows]] reports file sizes and disk device capacities using the customary binary prefixes or, in a "Properties" dialog, using the exact value in bytes.
* iOS 10 and earlier, Mac OS X Leopard and earlier and watchOS use the binary system (1 GB = {{val|1073741824|u=bytes}}). Apple product specifications, iOS and macOS (including [[Mac OS X Snow Leopard]]: version 10.6) now report sizes using [[SI prefix|SI decimal prefixes]] (1 GB = {{val|1000000000}} bytes).][
===Software===
Since the IEC 1998 standard, computer software has been gradually evolving to either use the IEC binary prefixes and symbols, or use the decimal prefixes with the proper power of 10 meaning. However, many programs still use the decimal prefixes and symbols to mean the similar powers of 2.
[[file|GParted 0.3.5 -- 2008, 06.png|[[Linux]] [[GNOME]]'s partition editor uses IEC prefixes to display partition sizes. The total capacity of the 120×109-byte disk is displayed as "111.79 GiB]]
[[File|GNOME System Monitor memory size and network rate.png|GNOME's system monitor uses IEC prefixes to show memory size and networking data rate.]]
===Computer hardware===
Hardware types that use powers-of-1024 multipliers, such as memory, continue to be marketed with customary binary prefixes.
====Computer memory====
[[File:Elixir M2U51264DS8HC3G-5T 20060320.jpg|thumb|The {{val|536870912}} byte ({{gaps|512|base=2|e=20}}) capacity of these RAM modules is stated as "512 MB" on the label.]]
Measurements of most types of electronic [[computer memory|memory]] such as [[random-access memory|RAM]] and [[Read-only memory|ROM]] are given using customary binary prefixes (kilo, mega, and giga). This includes some [[flash memory]], like [[EEPROM]]s. For example, a "512-megabyte" memory module is {{gaps|512|base=2|e=20}} bytes (512 × {{val|1048576}}, or {{val|536870912}}).
JEDEC Solid State Technology Association, the semiconductor engineering standardization body of the Electronic Industries Alliance (EIA), continues to include the customary binary definitions of kilo, mega and giga in their ''Terms, Definitions, and Letter Symbols'' document,][
====Flash drives====
[[USB flash drive]]s, flash-based memory cards like [[CompactFlash]] or [[Secure Digital]], and flash-based [[solid-state drive]]s (SSDs) use [[SI prefixes]];][
for example, a "256 MB" flash card provides at least 256 million bytes ({{val|256000000}}), not 256×1024×1024 ({{val|268435456}}).][
The earlier "1200 KB" ({{nowrap|1200 × 1024}} bytes) 5.25-inch diskette sold with the [[PC AT|IBM PC AT]] was marketed as "1.2 MB" ({{val|1.171875|u=MiB}}). The largest 8-inch diskette formats could contain more than a megabyte, and the capacities of those devices were often irregularly specified in megabytes, also without controversy.
Older and smaller diskette formats were usually identified as an accurate number of (binary) KB, for example the [[Disk II|Apple Disk II]] described as "140KB" had a {{nowrap|140 × 1024}}-byte capacity, and the original "360KB" double sided, double density disk drive used on the IBM PC had a {{nowrap|360 × 1024}}-byte capacity.
In many cases diskette hardware was marketed based on unformatted capacity, and the overhead required to format sectors on the media would reduce the nominal capacity as well (and this overhead typically varied based on the size of the formatted sectors), leading to more irregularities.
====Optical discs====
The capacities of most [[optical disc]] storage media like [[DVD]], [[Blu-ray Disc]], [[HD DVD]] and [[Magneto-optical drive|magneto-optical (MO)]] are given using SI decimal prefixes. A "4.7 GB" DVD has a nominal capacity of about 4.38 [[GiB]].][
====Data transmission and clock rates====
{{Unreferenced section|date=January 2023}}
Certain units are always used with SI decimal prefixes even in computing contexts.
Two examples are [[hertz]] (Hz), which is used to measure the [[clock rate]]s of electronic components, and to bit/s and B/s, which are used to measure [[bit rate|data transmission speed]].
* A 1 GHz processor receives {{val|1000000000}} clock ticks per second.
* A sound file sampled at {{val|44.1|u=kHz}} has {{val|44100}} samples per second.
* A {{val|128|u=kbit/s}} [[MP3]] stream consumes {{val|128000}} bits (16 kilobytes, {{val|15.6|u=KiB}}) per second.
* A {{val|1|u=Mbit/s}} Internet connection can transfer {{val|1000000}} bits per second ({{val|125000}} bytes per second ≈ {{val|122|u=KiB/s}}, assuming an 8-bit byte and no overhead)
* A {{val|1|u=Gbit/s}} Ethernet connection can transfer at nominal speed of {{val|1000000000}} bits per second ({{val|125000000}} bytes per second ≈ {{val|119|u=MiB/s}}, assuming an 8-bit byte and no overhead)
* A [[56k]] modem transfers {{val|56000}} bits per second ≈ {{val|6.8|u=KiB/s}}.
[[Computer bus|Bus]] clock speeds and therefore bandwidths are both quoted using SI decimal prefixes.
* [[DDR SDRAM|PC3200]] memory on a [[double data rate]] bus, transferring 8 bytes per cycle with a clock speed of {{val|200|u=MHz}} ({{val|200000000}} cycles per second) has a bandwidth of {{nowrap|{{val|200000000}} × 8 × 2}} = {{val|3200000000}} B/s = {{val|3.2|u=GB/s}} (about {{val|3.0|u=GiB/s}}).
* A [[PCI-X]] bus at {{val|66|u=MHz}} ({{val|66000000}} cycles per second), 64 bits per transfer, has a bandwidth of {{val|66000000}} transfers per second × 64 bits per transfer = {{val|4224000000}} bit/s, or {{val|528000000}} B/s, usually quoted as {{val|528|u=MB/s}} (about {{val|503|u=MiB/s}}).
===Use by industry===
IEC prefixes are used by [[Toshiba]],][ [[IBM]], [[Hewlett-Packard|HP]] to advertise or describe some of their products. According to one HP brochure, [http://h20566.www2.hp.com/portal/site/hpsc/template.BINARYPORTLET/public/kb/docDisplay/resource.process/?spf_p.tpst=kbDocDisplay_ws_BI&spf_p.rid_kbDocDisplay=docDisplayResURL&javax.portlet.begCacheTok=com.vignette.cachetoken&spf_p.rst_kbDocDisplay=wsrp-resourceState%3DdocId%253Demr_na-c02022732-1%257CdocLocale%253D&javax.portlet.endCacheTok=com.vignette.cachetoken]{{dead link|date=May 2023|bot=medic}}{{cbignore|bot=medic}} "[t]o reduce confusion, vendors are pursuing one of two remedies: they are changing SI prefixes to the new binary prefixes, or they are recalculating the numbers as powers of ten." The [[IBM Data Center]] also uses IEC prefixes to reduce confusion.][ The IBM Style Guide reads][ ]To help avoid inaccuracy (especially with the larger prefixes) and potential ambiguity, the International Electrotechnical Commission (IEC) in 2000 adopted a set of prefixes specifically for binary multipliers (See IEC 60027-2). Their use is now supported by the United States National Institute of Standards and Technology (NIST) and incorporated into ISO 80000. They are also required by EU law and in certain contexts in the US.
However, most documentation and products in the industry continue to use SI prefixes when referring to binary multipliers. In product documentation, follow the same standard that is used in the product itself (for example, in the interface or firmware). Whether you choose to use IEC prefixes for powers of 2 and SI prefixes for powers of 10, or use SI prefixes for a dual purpose ... be consistent in your usage and explain to the user your adopted system.
==Other uses==
The international standard [[ISO 80000-1]] defines the prefixes kibi-, mebi-, gibi- ... without limiting their application to [[information technology]]. Uses of binary prefixes for quantities other than bits or bytes include their use to indicate binary multiples of the frequency unit [[Hertz (unit)|hertz]] (Hz), for example the [[kibihertz]] (symbol KiHz) is 1024 Hz.[
==See also==
* [[Binary engineering notation]]
* [[B notation (scientific notation)]]
* [[ISO/IEC 80000]]
* [[Nibble]]
* [[Octet (computing)|Octet]]
== References ==
][{{cite web | url = https://www.courthousenews.com/wp-content/uploads/2020/01/flashdrives.pdf | title = Order Granting Motion to Dismiss | publisher = [[United States District Court for the Northern District of California]] | access-date = 2020-01-24 }}]
[See also Dinan v. SanDisk LLC, No. 20-15287 (9th Cir. Feb. 11, 2021) https://scholar.google.com/scholar_case?case=16989791406584358656]
[{{cite web | url=http://physics.nist.gov/cuu/Units/prefixes.html | title = SI prefixes |author= | website = The NIST Reference on Constants, Units, and Uncertainty: International System of Units (SI) | publisher = [[National Institute of Standards and Technology]] | access-date = 2017-04-03}}]
[{{cite web |title=La Loi Du 18 Germinal An 3: Décision de tracer le mètre, unité fondamentale, sur une règle de platine. Nomenclature des " mesures républicaines ". Reprise de la triangulation. |language=fr |trans-title=The Law of 18 [[Germinal (month)|Germinal]], Year 3: Decision to draw the fundamental unit metre on a platinum ruler. Nomenclature of "Republican measures". Resumption of the triangulation. |work=L'Histoire Du Mètre [The history of the metre] |publisher=histoire.du.metre.free.fr |url=http://histoire.du.metre.free.fr/fr/Pages/Sommaire/06.htm |access-date=2015-10-12 |url-status=live |archive-url=https://web.archive.org/web/20221126164814/http://histoire.du.metre.free.fr/fr/Pages/Sommaire/06.htm |archive-date=2022-11-26 |quote=Art. 8. Dans les poids et mesures de capacité, chacune des mesures décimales de ces deux genres aura son double et sa moitié, afin de donner à la vente des divers objets toute la commodité que l'on peut désirer. Il y aura donc le double-litre et le demi-litre, le double-hectogramme et le demi-hectogramme, et ainsi des autres. |trans-quote=Art. 8. In the weights and measures of capacity, each of the decimal measures of these two kinds will have its double and its half, in order to give to the sale of the various articles all the convenience that one can desire. There will therefore be the double-litre and the half-litre, the double-hectogram and the half-hectogram, and so on.}}]
[{{cite journal |title = A Third Survey of Domestic Electronic Digital Computing Systems: Chapter III Analysis and Trends |quote = Of 187 different relevant systems, 131 utilize a straight binary system internally, whereas 53 utilize the decimal system (primarily binary coded decimal) and 3 systems utilize a binary coded alphanumeric system of notation. |journal = Ballistic Research Laboratories Report No. 1115 | first = Martin H. |last = Weik |date=March 1961 |page = 1027 |url = http://ed-thelen.org/comp-hist/BRL61analysis.html#STORAGE }} This lengthy report describes many of the early computers.]
[Hunting Trouble on 28 Megacycles, A. L. Blais, QST, January 1930.]
[{{Cite journal | last = Real | first = P. | title = A generalized analysis of variance program utilizing binary logic. | journal = ACM '59: Preprints of Papers Presented at the 14th National Meeting of the Association for Computing Machinery | pages = 78–1–78–5 |date=September 1959 | doi = 10.1145/612201.612294 | publisher = ACM Press | s2cid = 14701651 | quote = On a 32K core size 704 computer, approximately {{val|28000}} data may be analyzed, ... without resorting to auxiliary tape storage.}} Note: the IBM 704 core memory units had 4096 36-bit words. Up to {{val|32768}} words could be installed]
[{{Cite journal | last1 =Gruenberger | first1 =Fred | title =Letters to the Editor | journal =Communications of the ACM | volume =3 | issue =10 |date=October 1960 | doi = 10.1145/367415.367419 | last2 =Burgess | first2 =C. R. | last3 =Gruenberger | first3 =Fred| s2cid =3199685 }} "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.]
[{{Cite journal | last =Amdahl | first = Gene M. | author-link = Gene Amdahl | title = Architecture of the IBM System/360 | journal =IBM Journal of Research and Development | volume =8 | issue =2 | publisher = IBM | year = 1964 | url = http://www.research.ibm.com/journal/rd/441/amdahl.pdf | doi = 10.1147/rd.82.0087 | pages=87–101}} Figure 1 gives storage (memory) capacity ranges of the various models in "Capacity 8-bit bytes, 1 K = 1024"]
[{{Cite book | author = Control Data Corporation | title = Control Data 7600 Computer System: Preliminary System Description |date=November 1968 | url = http://archive.computerhistory.org/resources/text/CDC/CDC.7600.1968.102646087.pdf |quote = 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). }}]
[{{Cite book |author = Control Data Corporation |title = Control Data 6400/6500/6600 Computer Systems Reference Manual |year = 1965–1967 |pages = 2–1 |edition = Pub No. 60100000 |url = http://ed-thelen.org/comp-hist/CDC-6600-R-M.html#TOC/ |quote = Central Memory is organized into 32K, 65K, or 131K words (60-bit) in 8, 16, or 32 banks of 4096 words each. |access-date = 2013-11-07 |archive-url = https://web.archive.org/web/20140102194752/http://ed-thelen.org/comp-hist/CDC-6600-R-M.html#TOC/ |archive-date = 2014-01-02 }}]
[{{Cite journal |last = Frankenberg |first = Robert |title = All Semiconductor Memory Selected for New Minicomputer Series |journal = Hewlett-Packard Journal |volume = 26 |issue = 2 |pages = 15–20 |publisher = Hewlett-Packard |date = October 1974 |url = http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1974-10.pdf |access-date = 2007-06-18 |quote = 196K-word memory size |archive-date = 2007-11-29 |archive-url = https://web.archive.org/web/20071129060208/http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1974-10.pdf |url-status = dead }}]
[{{Cite journal | last = Hewlett-Packard | title =HP 3000 Configuration Guide | journal = HP 3000 Computer System and Subsystem Data | page = 59 |date = November 1973 | url = http://www.bitsavers.org/pdf/hp/3000/hp3000/5952-4500_optionsBrochure_Nov73.pdf |access-date=2010-01-22}}]
[{{cite book|title=Webster's New World Telecom Dictionary|author=Ray Horak|page=271|publisher=[[John Wiley & Sons]]|year=2008|isbn=9780471774570|quote=In computing and storage systems, a kB (kiloByte) is actually 1,024 (2^10) bytes, since the measurement is based on a base 2, or binary, number system. The term kB comes from the fact that 1,024 is nominally, or approximately, 1,000.}}]
[{{cite book |title=The ACS style guide: a manual for authors and editors|author=Janet S. Dodd|page=124|publisher=[[American Chemical Society]]|year=1997|isbn=9780841234611|quote=kB (kilobyte; actually 1024 bytes) KB (kilobyte; kB is preferred)}}]
[{{cite book |title=Information Technology: Agent of Change|author=F. J. M. Laver|date=11 May 1989|page=35|publisher=[[Cambridge University Press]]|isbn=978-0521350358|quote=when describing the performance of IT systems the larger units 'kilobytes' (kB) [...] Strictly speaking, k means the 'binary thousand' 1024}}]
[{{Cite journal|last1=Lin |first1=Yeong |title=Cost-performance evaluation of memory hierarchies |journal=IEEE Transactions on Magnetics |volume=8 |issue=3 |pages=390–392 |publisher=IEEE |date=September 1972 |quote=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. |doi=10.1109/TMAG.1972.1067329 |last2=Mattson |first2=R. |bibcode=1972ITM.....8..390L}}]
[{{Cite book | last =IBM| title = System/370 Model 158 brochure | publisher = IBM | year = 1972 | url = http://archive.computerhistory.org/resources/text/IBM/IBM.370Mod158.1972.102646258.pdf | quote = 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. | id = G520-261871 }}]
[{{Cite journal | last = Bell | first = Gordon | title = Computer structures: What have we learned from the PDP-11? | journal = ISCA '76: Proceedings of the 3rd Annual Symposium on Computer Architecture | pages = 1–14 | publisher = ACM Press |date=November 1975 | url = http://research.microsoft.com/~gbell/Digital/Bell_Strecker_What_we%20_learned_fm_PDP-11c%207511.pdf | doi = 10.1145/800110.803541 | s2cid = 14496112 | quote = memory size (8k bytes to 4 megabytes). }}]
[{{cite web |url=http://www-03.ibm.com/ibm/history/exhibits/storage/storage_350.html |work=IBM Archives |title=IBM 350 disk storage unit |author=IBM Corporation|date=23 January 2003 }}]
[IBM invented the disk drive in 1956 and until the late 1960s its drives and their clones were dominant. See, e.g. [http://www.hagley.lib.de.us/1980.htm US vs. IBM antitrust litigation (Jan 1969)] {{webarchive |url=https://web.archive.org/web/20080507065825/http://www.hagley.lib.de.us/1980.htm |date=7 May 2008 }}, especially IBM analyses of Memorex and other disk drive companies.]
[The [http://www.bitsavers.org/pdf/cdc/discs/brochures/ProductLine_Oct74.pdf CDC Product Line Card] unambiguously uses MB to characterize HDD capacity in millions of bytes]
[1977 Disk/Trend Report – Rigid Disk Drives, published June 1977]
[{{cite book |url = http://maben.homeip.net/static/S100/seagate/disks/Seagate%20ST412%20OEM%20Manual%201982.pdf |title = ST506/412 OEM Manual |author = Seagate Corporation |date = April 1982 |page = 3 |access-date = 2016-09-06 |archive-url = https://web.archive.org/web/20161008003923/http://maben.homeip.net/static/S100/seagate/disks/Seagate%20ST412%20OEM%20Manual%201982.pdf |archive-date = 2016-10-08 }}]
[IBM Tells MiniScribe It Is Cutting Back On Winchester Orders, Computer System News, 1 Jan 1984, p. 1]
[{{cite web|last=Mellor |first=Chris |url=https://www.theregister.co.uk/2011/04/06/oldest_seagate_drive_in_uk/ |title=It's the oldest working Seagate drive in the UK |publisher=Theregister.co.uk |date=2011-04-06 |access-date=2012-01-26}}]
[ [http://www.seagate.com/staticfiles/support/docs/manual/enterprise/seag2011/10K.5/100628561d.pdf Seagate Seag2011 10K.5 SAS Product Manual], 100628561, Rev D, March 2011, sec 5.2.3, p. 10 (18th page of the pdf), states the drive's sustained transfer speed as "89 to 160 [[MiB]]/s" on one line, and "93 to 168 MB/s" on the next line.]
[{{cite web|title=Marketing Bulletin: Advanced Format 4K Sector Transition Frequently Asked Questions|url=http://www.seagate.com/docs/pdf/whitepaper/mb604_4k_transition_faq.pdf|publisher=[[Seagate Technology]]|archive-url=https://web.archive.org/web/20100715030704/http://www.seagate.com/docs/pdf/whitepaper/mb604_4k_transition_faq.pdf|archive-date=15 July 2010}}]
[{{cite web |url=http://www.pcworld.com/article/id,128400-page,1/article.html |title=Hitachi Introduces 1-Terabyte Hard Drive |work=PC World |date=2007-01-04 |access-date=2010-02-04 |archive-date=2007-01-12 |archive-url=https://web.archive.org/web/20070112044932/http://www.pcworld.com/article/id,128400-page,1/article.html }}]
[{{Cite book|date=30 October 1986 |quote=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 1048576. |doi=10.1109/IEEESTD.1986.79649 |isbn=0-7381-4541-6 |title=IEEE Standard Glossary of Mathematics of Computing Terminology }}]
[{{Cite book|date=22 July 1992 |quote=Kbyte. Kilobyte. Indicates 210 bytes. Mbyte. Megabyte. Indicates 220bytes. Gbyte is used in the Foreword. |doi=10.1109/IEEESTD.1992.106981 |isbn=0-7381-4336-7 |title=IEEE Standard Control and Status Register (CSR) Architecture for Microcomputer Buses }}]
[{{cite web|url=http://www.m-w.com/dictionary/Megabyte|title=Definition of megabyte|website=M-w.com|access-date=30 December 2017}}]
[{{cite web|url=http://dictionary.reference.com/browse/Megabyte|title=Definitions of Megabyte|website=Dictionary.reference.com|access-date=30 December 2017}}]
[{{cite web|url=http://www.askoxford.com/concise_oed/megabyte?view=uk|archive-url=https://web.archive.org/web/20050525164142/http://www.askoxford.com/concise_oed/megabyte?view=uk|url-status=dead|archive-date=25 May 2005|title=AskOxford: megabyte|website=Askoxford.com|access-date=30 December 2017}}]
[{{Cite book | date=24 June 1994 | quote= gigabyte (gig, GB). This term may mean either a) {{val|1000000000}} 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.|doi=10.1109/IEEESTD.1995.79522 |isbn=1-55937-492-6 | title=IEEE Standard Glossary of Computer Hardware Terminology }}]
[{{Cite book|author=Institute of Electrical and Electronics Engineers |title=100-2000 |author-link=Institute of Electrical and Electronics Engineers |publisher=IEEE Computer Society Press |year=2000 |isbn=978-0-7381-2601-2 |doi=10.1109/IEEESTD.2000.322230 |url=https://repositorio.unal.edu.co/handle/unal/79391 }} "kB See kilobyte." "Kbyte Kilobyte. Indicates 210 bytes." "Kilobyte Either 1000 or 210 or 1024 bytes." The standard also defines megabyte and gigabyte with a note that an alternative notation for base 2 is under development.]
[{{cite web|url=http://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP2075.html |title=System/360 Model 75 |publisher=[[IBM]]|access-date=2015-03-10|work=IBM Archives|date=23 January 2003 |quote=up to 1,048,576 characters of information}}]
[Apple [[Macintosh]] which began using "KB" in a binary sense to report HDD capacity beginning 1984.]
[{{cite web | url = http://www.wdc.com/en/products/Products.asp?DriveID=301 | title = WD Caviar SE16 SATA Hard Drives | work = Western Digital: Products | publisher = [[Western Digital Corporation]] | access-date = 2007-09-09 | archive-url = https://web.archive.org/web/20070902080558/http://www.wdc.com/en/products/products.asp?driveid=301 | archive-date = 2007-09-02 }}]
[{{cite web | url = http://forum.corsair.com/v3/showthread.php?t=33071 | title = Jack Flash F.A.Q. | publisher = [[Corsair Gaming|Corsair]] | access-date = 2014-06-20 | quote = [...] the industry-standard definition of a megabyte (MByte) for flash devices is one million (1,000,000) bytes, where the operating system uses two to the twentieth power, or 1,048,576 bytes. Similarly, for a gigabyte (GByte), the number is 1,000,000,000 and 1,073,741,824 respectively. | archive-date = 2016-03-05 | archive-url = https://web.archive.org/web/20160305080304/http://forum.corsair.com/v3/showthread.php?t=33071 }}]
[{{cite web |url=http://www.sandisk.com/media/416788/80-11-01707_rev1_datasheet_ultracf_r1.pdf |title=SanDisk Ultra® CompactFlash® cards |publisher=[[SanDisk Corporation]] |access-date=2014-06-20 |archive-url=https://web.archive.org/web/20130810032314/http://www.sandisk.com/media/416788/80-11-01707_rev1_datasheet_ultracf_r1.pdf |archive-date=2013-08-10 }}]
[{{cite web|date=10 March 2005 |url=https://www.pddocs.com/FlashMemory/Documents/Vroegh%20Third%20Amended%20Complaint.pdf |title=Vreogh Third Amended Complaint (Case No. GCG-04-428953) |work=pddocs.com |publisher=Poorman-Douglas Corporation |access-date=2007-09-09 |archive-url=https://web.archive.org/web/20080309143513/https://www.pddocs.com/FlashMemory/Documents/Vroegh%20Third%20Amended%20Complaint.pdf |archive-date=9 March 2008 }}]
[{{cite web |title=Why is the capacity of my Secure Digital memory card (as reported by many operating systems) different than the capacity that is listed on its label? |url=http://www.sandisk.com/Assets/Categories/Products/sd_capacitydisclaimer.pdf|archive-url=https://web.archive.org/web/20120413100902/http://www.sandisk.com/Assets/Categories/Products/sd_capacitydisclaimer.pdf|archive-date=13 April 2012|date=13 April 2012|website=Sandisk.com|access-date=30 December 2017}}]
[{{cite web|last=Safier |first=Seth A. |url=https://www.pddocs.com/FlashMemory/faq.aspx |title=Frequently Asked Questions |work=Flash Memory Settlement |publisher=Poorman-Douglas Corporation |access-date=2007-09-09 |archive-url=https://web.archive.org/web/20070928013731/https://www.pddocs.com/FlashMemory/faq.aspx |archive-date=28 September 2007 }}]
[{{cite web | last = Gutride | first = Adam | author2 = Seth A. Safier | date = 29 March 2006 | url = http://www.wdc.com/settlement/docs/complaint.htm | title = Class Action Complaint | work = Orin Safier v. Western Digital Corporation | publisher = [[Western Digital Corporation]] | access-date = 2007-09-09 | archive-url = https://web.archive.org/web/20071016171124/http://wdc.com/settlement/docs/complaint.htm | archive-date = 16 October 2007 }}]
[{{cite web | last = Zimmerman | first = Bernard | year = 2006 | url = http://www.wdc.com/settlement/docs/longform.htm | title = Notice of Class Action and Proposed Settlement | work = Orin Safier v. Western Digital Corporation | publisher = [[Western Digital Corporation]] | access-date = 2007-09-09 | archive-url = https://web.archive.org/web/20070922234210/http://www.wdc.com/settlement/docs/longform.htm | archive-date = 2007-09-22 }}]
[{{cite web|url=http://www.betanews.com/article/Western_Digital_Settles_Capacity_Suit/1151510648|title=Western Digital Settles Capacity Suit|website=Betanews.com|access-date=30 December 2017|date=28 June 2006}} ]
[{{cite web |url=https://arstechnica.com/old/content/2006/06/7174.ars |title=Western Digital settles drive size lawsuit |author=Jeremy Reimer |date=2006-06-30 |publisher=Ars Technica LLC |access-date=2010-02-10 }}]
[{{cite web |url=http://www.wdc.com/settlement/docs/longform.htm |title=NOTICE OF CLASS ACTION AND PROPOSED SETTLEMENT ("NOTICE") |author=Western Digital Corporation |year=2006 |access-date=2010-02-10 |archive-url=https://web.archive.org/web/20100507132711/http://www.wdc.com/settlement/docs/longform.htm |archive-date=2010-05-07 }}]
[{{cite web | last = Baskin | first = Scott D. | date = 1 February 2006 | url = http://www.wdc.com/settlement/docs/document20.htm | title = "Defendant Western Digital Corporation's Brief in Support of Plaintiff's Motion for Preliminary Approval" | work = ''Orin Safier v. Western Digital Corporation'' | publisher = [[Western Digital Corporation]] | access-date = 2007-09-09 }}]
[{{cite web | url = http://www.harddrive-settlement.com | title = Settlement Website for Cho v. Seagate Technology (US) Holdings, Inc. | access-date = 2011-04-12 | archive-url = https://web.archive.org/web/20190118155341/http://www.harddrive-settlement.com/ | archive-date = 18 January 2019 }}]
[{{cite web | url = https://www.courthousenews.com/wp-content/uploads/2020/01/flashdrives.pdf | title = Order Granting Motion to Dismiss | publisher = [[United States District Court for the Northern District of California]] | access-date = 2020-01-24 }}]
[A '''binary prefix''' is a prefix that denotes a power of 1024. For example, in the computer industry's customary practice, one "megabyte" of RAM is 10242 bytes of RAM, one "gigabyte" of RAM is 10243 bytes of RAM, and so on. In the IEC system, these would be expressed as one "mebibyte" and one "gibibyte", respectively. Both are "binary prefixes" in these usages.]
[{{Cite journal |title=Letters to the editor: Abbreviations for computer and memory sizes |author= Donald R. Morrison, [[Sandia National Laboratories|Sandia Corporation]] |journal= Communications of the ACM |volume=11 |issue=3 |date=March 1968 |page=150 |doi=10.1145/362929.362962|s2cid= 22934466 |doi-access=free}}]
[{{Cite journal |title=Letters to the editor: proposed abbreviation for 1024: bK |author= Wallace Givens, Applied National Lab |journal= Communications of the ACM |volume=11 |issue=6 |date=June 1968 |page=391 |doi=10.1145/363347.363351|s2cid= 22205692 |doi-access=free}}]
[{{cite journal | title=Letters to the editor: On binary notation | first=Bruce Alan | last=Martin | publisher=[[Associated Universities Inc.]] | journal=[[Communications of the ACM]] | volume=11 | issue=10 | date=October 1968 | page=658 | doi=10.1145/364096.364107| s2cid=28248410 }}]
[{{cite book|title=HP16C Emulator Library for the HP48S/SX|first1=Jake|last1=Schwartz|first2=Rick|last2=Grevelle|date=2003-10-20|orig-date=1993|edition=1|version=1.20|url=http://www.pahhc.org/mul8r.htm|access-date=2015-08-15}}]
[{{cite web |url=http://www.cl.cam.ac.uk/~mgk25/information-units.txt |title=Standardized units for use in information technology |author-first=Markus |author-last=Kuhn|author-link=Markus Kuhn (computer scientist) |date=29 December 1996}} ]
[''[https://www-cs-faculty.stanford.edu/~knuth/fasc1.ps.gz The Art of Computer Programming] {{webarchive|url=https://web.archive.org/web/20160305014709/http://www-cs-staff.stanford.edu/~knuth/fasc1.ps.gz |date=2016-03-05 }}'' Volume 1, [[Donald Knuth]], pp. 24 and 94]
[{{cite web|url=https://www-cs-faculty.stanford.edu/~knuth/news99.html |title=Knuth: Recent News (1999) |publisher=Cs-staff.stanford.edu |access-date=2012-01-26}}]
[The term '''IEC binary prefix''' or '''IEC prefix''' refers to the prefixes such as kibi, mebi, gibi, etc., or their corresponding symbols Ki, Mi, Gi, etc., first adopted by the [[International Electrotechnical Commission]] (IEC). Such prefixes are commonly used with the units bits or bytes (or less commonly, compound units derived from them such as bytes/second) and always denote powers of 1024; that is, they are always used as binary prefixes. Thus 1 mebibyte of RAM is 10242 bytes of RAM, one gibibyte or 1 GiB of RAM is 10243 bytes, and so on.]
[{{cite web |title=IUCr annual report for 1995 |publisher=[[International Union of Crystallography]] |author=IUCr IUPAC Interdivisional Committee on Nomenclature and Symbols (IDCNS) |type=Report |date=1997-02-13 |orig-date=1995 |url=http://ww1.iucr.org/cexec/rep95/idcns.htm |access-date=2012-01-26 |url-status=dead |archive-url=https://web.archive.org/web/20090827091437/http://ww1.iucr.org/cexec/rep95/idcns.htm |archive-date=2009-08-27}}]
[{{cite web |title=(IUCr) 1996 Report - IUPAC Interdivisional Committee on Nomenclature and Symbols (IDCNS) |type=Report |publisher=[[International Union of Crystallography]] |date=1997-02-14 |orig-date=1996 |url=http://www.chester.iucr.org/iucr-top/cexec/rep96/idcns.htm |access-date=2012-01-26 |url-status=dead |archive-url=https://web.archive.org/web/20130613121942/http://www.chester.iucr.org/iucr-top/cexec/rep96/idcns.htm |archive-date=2013-06-13}}]
[{{cite journal |author-first=Bruce |author-last=Barrow |title=A Lesson in Megabytes |journal=IEEE Standards Bearer |volume=11 |date=January 1997 |orig-date=1996 |publisher=[[IEEE]] |page=5 |url=https://www.thierry-lequeu.fr/data/PELS/Comm/Publications/Newsletter/9704/STORY18.HTML |access-date=2022-12-24 |url-status=live |archive-url=https://web.archive.org/web/20220528124411/https://www.thierry-lequeu.fr/data/PELS/Comm/Publications/Newsletter/9704/STORY18.HTML |archive-date=2022-05-28}}]
["These prefixes for binary multiples, which were developed by IEC Technical Committee (TC) 25, Quantities and units, and their letter symbols, with the strong support of the International Committee for Weights and Measures (CIPM) and the IEEE, were adopted by the IEC as Amendment 2 to IEC International Standard IEC 60027-2: Letter symbols to be used in electrical technology – Part 2: Telecommunications and electronics."]
[{{cite journal|url=http://journals.iucr.org/a/issues/2000/06/00/es0288/es0288bdy.html#SEC15.1 |title=IUCR 1999 report on IUPAC Interdivisional Committee on Nomenclature and Symbols |journal=Acta Crystallographica Section A: Foundations of Crystallography |date=November 2000 |volume=56 |issue=6 |pages=609–642 |publisher=Journals.iucr.org |doi=10.1107/S0108767300012873 |pmid=11058849 |access-date=2012-01-26}}]
[IEC 60027-2 (2000-11) Ed. 2.0 ]
[{{Cite journal |title=Prefixes for binary multiples |author=A.J.Thor |journal=Metrologia |year=2000 |volume=37 |issue=81 |url=http://ej.iop.org/links/rDo33k,Nb/lrUHtuYE3BGiff6cav5vpA/me0112.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://ej.iop.org/links/rDo33k,Nb/lrUHtuYE3BGiff6cav5vpA/me0112.pdf |archive-date=2022-10-09 |url-status=live |doi=10.1088/0026-1394/37/1/12 |page=81 |bibcode=2000Metro..37...81T |s2cid=250774728 }}{{dead link|date=July 2017 |bot=InternetArchiveBot |fix-attempted=yes }}]
[{{cite press release|date=2005-08-15 |title=HERE COME ZEBI AND YOBI |publisher=International Electrotechnical Commission |url=http://www.iec.ch/news_centre/release/nr2005/nr2005.htm |archive-url=https://archive.today/20070611071833/http://www.iec.ch/news_centre/release/nr2005/nr2005.htm |archive-date=11 June 2007 }}]
[{{cite web |url=http://www.niso.org/publications/newsline/2008/newslinemay2008.htm#Spec4 |title=niso, New Specs and Standards |publisher=Niso.org |access-date=2012-01-26 |archive-url=https://web.archive.org/web/20081208131408/http://www.niso.org/publications/newsline/2008/newslinemay2008.htm#Spec4 |archive-date=2008-12-08 }}]
[{{cite web|url=http://www.bipm.org/utils/common/documents/jcgm/JCGM_200_2012.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.bipm.org/utils/common/documents/jcgm/JCGM_200_2012.pdf |archive-date=2022-10-09 |url-status=live|title=International vocabulary of metrology - Basic and general concepts and associated terms (VIM)|edition=3rd|website=Bipm.org|access-date=30 December 2017}}]
[{{cite web |title=List of Resolutions for the 27th meeting of the General Conference on Weights and Measures |url=https://www.bipm.org/documents/20126/64811223/Resolutions-2022.pdf |archive-url=https://web.archive.org/web/20221118153958/https://www.bipm.org/documents/20126/64811223/Resolutions-2022.pdf |archive-date=2022-11-18 |url-status=live |date=2022-11-18 |access-date=2022-11-18 }}]
[{{cite journal |title=How many yottabytes in a quettabyte? Extreme numbers get new names |author-last=Gibney |author-first=Elizabeth |date=2022-11-18 |journal=[[Nature (journal)|Nature]] |volume= |issue= |pages= |doi=10.1038/d41586-022-03747-9 |pmid=36400954 |s2cid=253671538 |url=https://www.nature.com/articles/d41586-022-03747-9 |access-date=2022-11-21}}]
[{{cite journal |title=A further short history of the SI prefixes |journal=[[Metrologia]] |department=Letter to the editor |author-first=Richard J. C. |author-last=Brown |date=2023 |orig-date=2022-02-08, 2022-04-01, 2022-11-24 |volume=60 |issue=1 |page=013001 |publisher=[[BIPM]] & [[IOP Publishing Ltd]] |id=013001 |doi=10.1088/1681-7575/ac6afd |bibcode=2023Metro..60a3001B |s2cid=253966045 |doi-access=free }} (1+4 pages)]
[{{cite journal |title=Reply to 'Facing a shortage of the Latin letters for the prospective new SI symbols: alternative proposal for the new SI prefixes' |author-last=Brown |author-first=Richard J. C. |date=2022-04-27 |journal={{ill|Accreditation and Quality Assurance|de}} |volume=27 |issue= 3|pages=143–144 |doi=10.1007/s00769-022-01499-7|s2cid=248397680 }}]
[[http://physics.nist.gov/cuu/Units/binary.html The NIST Reference on Constants, Units, and Uncertainty]]
[{{cite web | url = http://physics.nist.gov/cuu/Units/binary.html | title = International System of Units (SI): Prefixes for binary multiples | work = The NIST Reference on Constants, Units, and Uncertainty | publisher = [[National Institute of Science and Technology]] | access-date = 2007-09-09 }}]
[{{Cite book |author=Barry N. Taylor & Ambler Thompson Ed. |title=The International System of Units (SI) |url=http://physics.nist.gov/Pubs/SP330/sp330.pdf |access-date=2010-04-27 |publisher=National Institute of Standards and Technology |location=Gaithersburg, MD |page=29 |year=2008 |archive-date=2018-12-25 |archive-url=https://web.archive.org/web/20181225010952/https://physics.nist.gov/Pubs/SP330/sp330.pdf }}]
[{{cite web|title=mega (M) (as a prefix to units of semiconductor storage capacity)|url=http://www.jedec.org/standards-documents/dictionary/terms/mega-m-prefix-units-semiconductor-storage-capacity|website=JEDEC - Global Standards for the Microelectronics Industry|access-date=14 April 2021}}]
[{{cite book | title = Low Power Double Data Rate 4 (LPDDR4) JESD209-4 | publisher = JEDEC Solid State Technology Association | date = August 2014 | page = 7 | url = http://www.jedec.org/standards-documents/results/jesd79-4%20ddr4 | quote = These devices contain the following number of bits: 4Gb has 4,294,967,296 bits ... 32Gb has 34,359,738,368 bits}} Free registration required to download the standard.]
[{{Cite book|doi=10.1109/IEEESTD.2003.94236 |url=http://ieeexplore.ieee.org/servlet/opac?punumber=8450 |archive-url=https://web.archive.org/web/20121014151530/http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?reload=true&punumber=8450 |archive-date=2012-10-14 |access-date=2007-07-29 |date=12 February 2003 |version=Reaffirmed 27 March 2008 |quote=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. |isbn=978-0-7381-3385-0 |title=1541-2002 }}]
[{{cite web|url=http://standards.ieee.org/board/rev/305agenda.html |title=IEEE-SA Standards Board Standards Review Committee (RevCom) Meeting Agenda |access-date=2007-02-25 |date=2005-03-19 |quote='''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. |archive-url=https://web.archive.org/web/20070922215418/http://standards.ieee.org/board/rev/305agenda.html |archive-date=22 September 2007 }}]
[{{Cite journal |last=Wallich |first=Paul |title=Tools & toys: Hacking the Nokia N800 |journal=IEEE Spectrum |volume=45 |issue=4 |page=25 |date=April 2008 |doi=10.1109/MSPEC.2008.4476441 |s2cid=20129812 }} ''"A lot can happen in a decade. You can hold the Nokia N800 in your hand, yet it's a near-exact match for a high-end desktop PC from 10 years ago. It has a 320-megahertz processor, 128 megabytes of RAM, and a few gigabytes of available mass storage."'']
[{{cite web |url=http://www.bipm.org/en/si/prefixes.html |title=BIPM – SI prefixes|website=Bipm.org|access-date=30 December 2017}}]
[{{Cite book |title=The International System of Units (SI) |chapter-url=http://www1.bipm.org/utils/common/pdf/si_brochure_8.pdf |archive-url=https://web.archive.org/web/20060813144253/http://www.bipm.org/utils/common/pdf/si_brochure_8.pdf |archive-date=2006-08-13 |url-status=live |access-date=2007-02-25 |edition=8th |year=2006 |publisher=STEDI Media |location=Paris |language=fr, en |isbn=978-92-822-2213-3 |page=127 |chapter=§3.1 SI prefixes |quote=[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. |author=Bureau International des Poids et Mesures.}}]
[{{cite web|url=http://www.sae.org/standardsdev/tsb/tsb003.pdf#page=33 |archive-url=https://ghostarchive.org/archive/20221009/http://www.sae.org/standardsdev/tsb/tsb003.pdf#page=33 |archive-date=2022-10-09 |url-status=live|format=PDF|title=Rules for SAE Use of SI (Metric) Units] – Section C.1.12 – SI prefixes|website=Sae.org|access-date=30 December 2017}}]
[{{Cite web|url=http://www.cenelec.eu/dyn/www/f?p=104:110:1546953662480229::::FSP_PROJECT,FSP_LANG_ID:15306,25|archive-url=https://archive.today/20130213052907/http://www.cenelec.eu/dyn/www/f?p=104:110:1546953662480229::::FSP_PROJECT,FSP_LANG_ID:15306,25|archive-date=2013-02-13|title = CENELEC - Standards Development - List of Technical Bodies -}}]
[{{Cite web|url=http://www.cenelec.eu/dyn/www/f?p=104:110:6177007965168887::::FSP_PROJECT,FSP_LANG_ID:20776,25|archive-url=https://archive.today/20120722151947/http://www.cenelec.eu/dyn/www/f?p=104:110:6177007965168887::::FSP_PROJECT,FSP_LANG_ID:20776,25|archive-date=2012-07-22|title = CENELEC - Standards Development - List of Technical Bodies -}}]
[As used in this article, the term '''customary binary prefix''' or similar refers to prefixes such as kilo, mega, giga, etc., borrowed from the similarly named [[SI prefix]]es but used to denote a power of 1024.]
[{{cite web|url=http://welcome.hp.com/country/us/en/welcome.html |title=Hewlett-Packard |publisher=Welcome.hp.com |access-date=2012-01-26}}]
[{{cite web|url=http://www.sonystyle.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10551&storeId=10151&langId=-1&categoryId=16155&SR=nav:shop:computers:desktops:ss&ref=http://www.sony.com/index.php|title=Consumer Electronics - Sony US|website=Sonystyle.com|access-date=30 December 2017|archive-date=2011-06-16 |archive-url=https://web.archive.org/web/20110616080047/http://www.sonystyle.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10551&storeId=10151&langId=-1&categoryId=16155&SR=nav%3Ashop%3Acomputers%3Adesktops%3Ass&ref=http%3A%2F%2Fwww.sony.com%2Findex.php}}]
[{{cite web|url=http://www.4allmemory.com/index.cfm?fuseaction=search.rdram_rambus_pc1066 |title=4AllMemory.com |publisher=4AllMemory.com |access-date=2012-01-26}}]
[The term '''SI prefix''' or similar refers to prefixes such as kilo, mega, giga, etc., defined by the [[International System of Units|SI system]] of units and ''always'' used to denote a power of 1000; in other words, always as decimal prefixes.]
[{{cite web |url=http://www.annodex.net/cgi-bin/man/man2html?units+7 |title=Units |access-date=2007-05-20 |date=2001-12-22 |work=[[Manual page (Unix)|Linux Programmer's Manual]] |quote=When the Linux kernel boots and says ]hda: 120064896 sectors (61473 MB) w/2048KiB Cache the MB are megabytes and the KiB are kibibytes. |archive-url=https://web.archive.org/web/20070902124532/http://www.annodex.net/cgi-bin/man/man2html?units+7 |archive-date=2 September 2007 }}
[{{cite web|url=https://lwn.net/2002/0103/a/esr-kibi.php3 |title=ESR post on LKML |publisher=Lwn.net |access-date=2012-01-26}}]
[{{cite web|url=http://www.neowin.net/news/ubuntu-implements-units-policy-will-switch-to-base-10-units-in-future-release |title=Ubuntu implements units policy, will switch to base-10 units in future release |publisher=Neowin.net |access-date=2012-01-26}}]
[{{cite web|url=https://wiki.ubuntu.com/UnitsPolicy |title=UnitsPolicy – Ubuntu Wiki |publisher=Wiki.ubuntu.com |access-date=2012-01-26}}]
[{{cite magazine |url=http://www.macworld.co.uk/mac/news/index.cfm?RSS&NewsID=27034 |title=Snow Leopard's new maths |magazine=Macworld |date=2009-08-28 |access-date=2011-04-13 }}{{Dead link|date=May 2021 |bot=InternetArchiveBot |fix-attempted=yes }}]
[{{cite web |url=https://support.apple.com/en-ca/HT201402 |title=How iOS and macOS report storage capacity |publisher=Apple Inc |date=2018-02-27 |access-date=2021-06-27}}]
[{{cite web | author = JEDEC Solid State Technology Association | title = JEDEC Standard No. 100B.01 – Terms, Definitions, and Letter Symbols for Microcomputers, Microprocessors, and Memory Integrated Circuits | date = December 2002 | page = 8 | url = http://www.jedec.org/download/search/JESD100B01.pdf | access-date = 2010-03-07 | quote = The definitions of kilo, giga, and mega based on powers of two are included only to reflect common usage. IEEE/ASTM SI 10-1997 states "This practice frequently leads to confusion and is deprecated." }} (Requires free registration and login.)]
[{{cite web |title=DDR3 SDRAM Standard |author=JEDEC |date = September 2009|access-date=2010-02-04 |url=http://www.jedec.org/standards-documents/docs/jesd-79-3d }} ]
[ {{cite web |title=DDR2 SDRAM Standard |author=JEDEC |date = November 2009|access-date=2010-02-04 |url=http://www.jedec.org/standards-documents/docs/jesd-79-2e }} ]
[ {{cite web |title=Memory Configurations |author=JEDEC |access-date=2010-02-04 |url=http://www.jedec.org/standards-documents/technology-focus-areas/memory-configurations-jesd21-c }} ]
[ {{cite web |title=Memory Configurations Table of Contents |author=JEDEC |access-date=2010-02-04 |url=http://www.jedec.org/sites/default/files/21C_TOCR18.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.jedec.org/sites/default/files/21C_TOCR18.pdf |archive-date=2022-10-09 |url-status=live }} ]
[ {{cite web |title=Terms and Definitions |author=JEDEC |access-date=2010-02-04 |url=http://www.jedec.org/sites/default/files/2_00R19.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.jedec.org/sites/default/files/2_00R19.pdf |archive-date=2022-10-09 |url-status=live }} ]
[[http://www.hitachigst.com/tech/techlib.nsf/techdocs/B259B4A73296DA628625751600058A80/$file/ProductBrochureMarch2009.pdf]{{dead link|date=October 2015}}{{cbignore}}]
[{{cite web|url=http://www.samsung.com/global/business/hdd/faqView.do?b2b_bbs_msg_id=167 |archive-url=https://web.archive.org/web/20110616021347/http://www.samsung.com/global/business/hdd/faqView.do?b2b_bbs_msg_id=167 |archive-date=2011-06-16 |title=FAQs|website=Samsung.com |access-date=30 December 2017}}]
[{{cite web |url=http://www.seagate.com/docs/pdf/whitepaper/storage_solutions_guide.pdf |title=Storage Solutions Guide |website=Seagate |access-date=2010-03-04 |archive-url=https://web.archive.org/web/20100331115539/http://www.seagate.com/docs/pdf/whitepaper/storage_solutions_guide.pdf |archive-date=2010-03-31 }}]
[{{cite press release |url=http://sdd.toshiba.com/techdocs/MKxx33GSG_MK1235GSL_r1.pdf |archive-url=https://web.archive.org/web/20091122075109/http://sdd.toshiba.com/techdocs/MKxx33GSG_MK1235GSL_r1.pdf |archive-date=22 November 2009 |title=Toshiba Introduces Two 1.8-inch Hard Disk Drive Families For Both High Performance and Long Battery Life in Mobile Computing Applications |publisher=Toshiba |date=4 November 2009 |access-date=30 December 2017}}]
[{{cite web |title=WD Model and Order Numbers |url=http://www.wdc.com/en/library/2579-001028.pdf |archive-url=https://web.archive.org/web/20050824091308/http://www.wdc.com/en/library/2579-001028.pdf |archive-date=2005-08-24 }}]
[{{cite web |url=http://www.sandisk.com/Assets/Categories/Products/card_capacitydisclaimer.pdf |title=Secure Digital Capacity Disclaimer |work=sandisk.com |publisher=[[SanDisk|SanDisk Corporation]] |access-date=2014-06-20 |archive-url=https://web.archive.org/web/20130227015453/http://www.sandisk.com/Assets/Categories/Products/card_capacitydisclaimer.pdf |archive-date=2013-02-27 }}]
[{{cite web |last=Microsoft |title=Determining Actual Disk Size: Why 1.44 MB Should Be 1.40 MB |work=Article ID: 121839 |publisher=Microsoft |date=2003-05-06 |url=http://support.microsoft.com/kb/121839 |access-date=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."]
[[http://www.osta.org/technology/pdf/dvdqa.pdf#page=20 Understanding Recordable and Rewritable DVD] {{webarchive |url=https://web.archive.org/web/20110102065839/http://www.osta.org/technology/pdf/dvdqa.pdf#page=20 |date=2 January 2011 }}]
[{{cite web |url=http://www.videohelp.com/forum/userguides/135642.php |title=Data capacity of CDs |publisher=Videohelp.com |access-date=2012-01-26 |archive-date=2006-07-15 |archive-url=https://web.archive.org/web/20060715075021/http://www.videohelp.com/forum/userguides/135642.php |url-status=dead }}]
[[ftp://ftp.software.ibm.com/common/ssi/pm/sp/n/tsd00063usen/TSD00063USEN.PDFIBM]{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}]
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==Further reading==
* {{cite web|url=http://www.iec.ch/zone/si/si_bytes.htm|archive-url=https://web.archive.org/web/20090403051731/http://www.iec.ch/zone/si/si_bytes.htm|archive-date=2009-04-03|title=When is a kilobyte a kibibyte? And an MB an MiB?|publisher=International Electrotechnical Commission|date=2007-02-12}} – An introduction to binary prefixes
* {{cite web|url=http://physics.nist.gov/cuu/Units/binary.html|title=Prefixes for binary multiples|publisher=[[NIST]]}}
* {{Cite press release|url=https://www.nist.gov/public_affairs/techbeat/tb9903.htm#Information%20Technology|title=Get Ready for the mebi, gibi and tebi|publisher=[[NIST]]|date=1999-03-02|access-date=2017-07-13 |archive-date=2016-08-20 |archive-url=https://web.archive.org/web/20160820141603/http://www.nist.gov/public_affairs/techbeat/tb9903.htm#Information%20Technology}}
* {{cite web|url=http://www.cl.cam.ac.uk/~mgk25/information-units.txt|title=What is a Megabyte ...?|author-first=Markus |author-last=Kuhn|author-link=Markus Kuhn (computer scientist)|date=1996-12-29}}—a 1996–1999 paper on bits, bytes, prefixes and symbols
* {{cite web|url=http://jdebp.eu./FGA/1mb44-is-not-a-standard-floppy-disc-size.html|author-first=Jonathan|author-last=de Boyne Pollard|title=There is no such thing as a 1.44 MB standard format floppy disc|work=Frequently Given Answers|archive-url=https://web.archive.org/web/20161007222128/https://jdebp.eu/FGA/1mb44-is-not-a-standard-floppy-disc-size.html|archive-date=2016-10-07}}
* {{cite web|url=http://www.quinion.com/words/turnsofphrase/tp-kib1.htm|title=Kibibyte|date=1999-08-21|author=Michael Quinion|work=World Wide Words|access-date=2002-11-13 |archive-date=2004-06-12 |archive-url=https://web.archive.org/web/20040612044148/http://www.quinion.com/words/turnsofphrase/tp-kib1.htm}}—Another description of binary prefixes
* {{Cite press release |url=http://www.wiebetech.com/pressreleases/BillionEqualBillion.pdf|title=When One Billion does not equal One Billion, or: Why your computer's disk drive capacity doesn't appear to match the stated capacity |website=WiebeTech |author=James Wiebe|date=2003-10-09|access-date=2010-01-22|journal=|archive-date=2013-12-04 |archive-url=https://web.archive.org/web/20131204100206/http://www.wiebetech.com/pressreleases/BillionEqualBillion.pdf}}—White-paper on the controversy over drive capacities
==External links==
* [http://lpar.ath0.com/2008/07/15/si-unit-prefixes-a-plea-for-sanity/ A plea for sanity]
* [https://alexey.chernyak.id.au/prefBin.xhtml A summary of the organizations, software, and so on that have implemented the new binary prefixes]
* [http://www.lyberty.com/encyc/articles/kb_kilobytes.html KiloBytes vs. kilobits vs. Kibibytes (Binary prefixes)]
* [http://converter.50webs.com/ SI/Binary Prefix Converter]
* [http://knowledge.seagate.com/articles/en_US/FAQ/002046en?language=en_US Storage Capacity Measurement Standards] {{Webarchive|url=https://web.archive.org/web/20150102192754/http://knowledge.seagate.com/articles/en_US/FAQ/002046en?language=en_US |date=2015-01-02 }}
{{Computer Storage Volumes}}
{{DEFAULTSORT:Binary Prefix}}
[[Category:Measurement]]
[[Category:Naming conventions]]
[[Category:Binary prefixes| ]]
[[Category:Units of information]]
[[Category:Numeral systems]]