Binary prefix
The most commonly used binary prefixes are kibi (symbol Ki, meaning 210 = 1024), mebi (Mi, 220 = 1048576), and gibi (Gi, 230 = 1073741824).
They are most often used in information technology as multipliers of bit and byte, when expressing the capacity of storage devices or the size of computer files.
Prior to the 1999 IEC standard, some industry organizations, such as the Joint Electron Device Engineering Council (JEDEC), attempted to redefine[citation needed] the terms kilobyte, megabyte, and gigabyte, and the corresponding symbols KB, MB, and GB in the binary sense, for use in storage capacity measurements.
The original metric system adopted by France in 1795 included two binary prefixes named double- (2×) and demi- (1/2×).
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.
[citation needed] In other documents, however, the metric prefixes and their symbols were used to denote powers of 10, but usually with the understanding that the values given were approximate, often truncated down.
The correct meaning was often clear from the context; for instance, in a binary-addressed computer, the true memory size had to be either a power of 2, or a small integer multiple thereof.
[32] Some programs and operating systems, such as Microsoft Windows, still use "MB" and "GB" to denote binary prefixes even when displaying disk drive capacities and file sizes, as did Classic Mac OS.
Some operating systems, such as Mac OS X,[33] Ubuntu,[34] and Debian,[35] have been updated to use "MB" and "GB" to denote decimal prefixes when displaying disk drive capacities and file sizes.
Some manufacturers, such as Seagate Technology, have released recommendations stating that properly-written software and documentation should specify clearly whether prefixes such as "K", "M", or "G" mean binary or decimal multipliers.
On the other hand, the quoted capacity of "1.44 MB" of the High Density ("HD") version was again a hybrid decimal and binary notation, since it meant 1440 pairs of 512-byte sectors, or 1440 × 210 = 1474560 bytes.
User complaints forced both Apple[citation needed] and Microsoft[42] to issue support bulletins explaining the discrepancy.
Seagate specified the sustained transfer rate of some hard disk drive models with both decimal and IEC binary prefixes.
A PC3200 memory on a double data rate bus, transferring 8 bytes per cycle with a clock speed of 200 MHz has a bandwidth of 200000000 × 8 × 2 = 3200000000 B/s, which would be quoted as 3.2 GB/s.
[56] Bruce Alan Martin of Brookhaven National Laboratory proposed that, instead of prefixes, binary powers of two were indicated by the letter B followed by the exponent, similar to E in decimal scientific notation.
[60] The ambiguous meanings of "kilo", "mega", "giga", etc., has caused significant consumer confusion, especially in the personal computer era.
The different interpretations of disk size prefixes led to class action lawsuits against digital storage manufacturers.
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.
[61][62][63][64] On 20 February 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.
[67] 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.
They also paid $500000 in fees and expenses to San Francisco lawyers Adam Gutride and Seth Safier, who filed the suit.
The case was settled without Seagate admitting wrongdoing, but agreeing to supply those purchasers with gratis backup software or a 5% refund on the cost of the drives.
[75] In 1995, the International Union of Pure and Applied Chemistry's (IUPAC) Interdivisional Committee on Nomenclature and Symbols (IDCNS) proposed the prefixes "kibi" (short for "kilobinary"), "mebi" ("megabinary"), "gibi" ("gigabinary") and "tebi" ("terabinary"), with respective symbols "kb", "Mb", "Gb" and "Tb",[76] for binary multipliers.
The proposal suggested that the SI prefixes should be used only for powers of 10; so that a disk drive capacity of "500 gigabytes", "0.5 terabytes", "500 GB", or "0.5 TB" should all mean 500×109 bytes, exactly or approximately, rather than 500 × 230 (= 536870912000) or 0.5 × 240 (= 549755813888).
The prefixes "kibi", "mebi", "gibi" and "tebi" were retained, but with the symbols "Ki" (with capital "K"), "Mi", "Gi" and "Ti" respectively.
[89][90] as of April 2008[update], the IEEE Publications division does not require the use of IEC prefixes in its major magazines such as Spectrum[91] or Computer.
[94] The European Committee for Electrotechnical Standardization (CENELEC) adopted the IEC-recommended binary prefixes via the harmonization document HD 60027-2:2003-03.
[96] Some computer industry participants, such as Hewlett-Packard (HP),[97] and IBM[98][99] have adopted or recommended IEC binary prefixes as part of their general documentation policies.
[115] The decimal meaning of SI prefixes is usually also intended in measurements of data transfer rates, and clock speeds.
[citation needed] Some operating systems and other software use either the IEC binary multiplier symbols ("Ki", "Mi", etc.
