Byte

Byte ( eng. Byte ) (Russian designation: byte and B ; international: B , byte ) ^[1] - a unit for storing and processing digital information; a set of bits processed by a computer simultaneously. In modern computing systems, a byte consists of eight bits and, accordingly, can take one of 256 (2 ⁸ ) different values (states, codes ). However, in the history of computer technology there were solutions with different byte sizes (for example, 6, 32 or 36 bits), therefore sometimes in computer standards and official documents the term “ octet ” is used to uniquely identify a group of 8 bits ( lat. Octet ).

In most computing architectures, a byte is the smallest independently addressable dataset.

Content

History

The name “byte” was first used in June 1956 by W. Buchholz ( born Werner Buchholz ) when designing the first IBM 7030 Stretch supercomputer for a bunch of one to six bits simultaneously transmitted in input / output devices. Later, as part of the same project, the byte was expanded to eight bits. The word byte was chosen as the intentionally distorted word bite , pronounced in the same way ( English bite - “piece”; “part of something separated in one bite”; compare also the name that appeared later for the 4-bit unit “ nibble ” from English .nibble - "bite"). A modified spelling of byte through y instead of i was required to avoid confusion with the word “bit” ^[2] . In print, the word byte first appeared in June 1959 ^[3] .

A number of computers of the 1950s and 1960s ( BESM-6 , M-220 ) used 6-bit characters in 48-bit or 60-bit machine words . On some Burroughs Corporation (now Unisys ) computer models, the character size was 9 bits. In the Soviet computer Minsk-32 , a 7-bit byte was used.

Byte memory addressing was first used on the IBM System / 360 system . In earlier computers, it was possible to address only the whole machine word , which consisted of several bytes, which made it difficult to process text data.

8-bit bytes were adopted in System / 360, probably due to the use of the BCD format for representing numbers: one decimal digit (0-9) requires 4 bits ( tetrad ) for storage; one 8-bit byte can represent two decimal digits. Bytes of 6 bits can store only one decimal digit, two bits remain unused.

According to another version, the 8-bit byte size is associated with the 8-bit numeric representation of characters in EBCDIC encoding.

According to the third version, because of the binary coding system in computers, word lengths that are multiples of powers of two, including 1 byte = 2 ³ = 8 bits, are most advantageous for hardware implementation and convenient for data processing. Systems and computers with word lengths not divisible by 2 have disappeared due to disadvantage and inconvenience.

Gradually, 8-bit bytes became the de facto standard; since the beginning of the 1970s, on most computers, bytes have been composed of 8 bits , and the size of a machine word is a multiple of 8 bits .

The number of states (codes) in a byte

The number of states (codes, values) that can take 1 eight-bit byte with positional coding is determined in combinatorics . It is equal to the number of placements with repetitions and is calculated by the formula:

N_{p}={\bar {A}}(n,k)={\bar {A}}_{n}^{k}=n^{k}=2^{8}=256

{\ displaystyle N_ {p} = {\ bar {A}} (n, k) = {\ bar {A}} _ {n} ^ {k} = n ^ {k} = 2 ^ {8} = 256 }

possible states (codes, values), where

$N_{p}$ ${\ displaystyle N_ {p}}$ - the number of states (codes, values) in one byte;
${\bar {A}}(n,k)={\bar {A}}_{n}^{k}$ ${\ displaystyle {\ bar {A}} (n, k) = {\ bar {A}} _ {n} ^ {k}}$ - number of placements with repetitions ;
$n$ ${\ displaystyle n}$ - the number of states (codes, values) in one bit; bit 2 states ( n = 2 );
$k$ ${\ displaystyle k}$ - the number of bits in a byte; in 8-bit byte k = 8 .

Derived Units

Multiple and fractional prefixes for the formation of derived units for a byte are not used as usual. Diminishing prefixes are not used at all, and units of information smaller than a byte are called special words - nibble (tetrad, nibble) and bit . Magnifying prefixes are multiples of either 1024 = 2 ¹⁰ or 1000 = 10 ³ : 1 kibibyte is 1024 bytes , 1 mebibyte is 1024 kibytes or 1024 × 1024 = 1,048,576 bytes , etc. for gibi, teby, and pebibytes. In turn, 1 kilobyte is 1000 bytes , 1 megabyte is 1000 kilobytes or 1000 × 1000 = 1,000,000 bytes , etc. for gigabyte, tera, and petabytes . The difference between capacities (volumes), expressed in kilo = 10 ³ = 1000 and expressed in kibi = 2 ¹⁰ = 1024 , increases with the weight of the prefix. The IEC recommends the use of binary prefixes - kibibyte , mebibyte , yobibyte , etc.

Sometimes decimal prefixes are also used in the literal sense, for example, when specifying the capacity of hard drives : they have gigabytes (gibibytes) that can mean not 1,073,741,824 = 1,024 ³ bytes , but a million kilobytes (kibibytes) , i.e. 1,024,000,000 bytes , or even just a billion bytes.

Designation

The use of the Russian capital letter “B” to denote a byte is regulated by the Interstate ( CIS ) standard GOST 8.417-2002 ^[4] (“Units of quantities”) in “Appendix A” and Decree of the Government of the Russian Federation of October 31, 2009 No. 879. In addition, the tradition of using SI prefixes along with the name “bytes” to indicate multipliers that are powers of two ( 1 KB = 1024 bytes , 1 MB = 1024 KB , 1 GB = 1024 MB , etc., is used instead of the lowercase “k”. “K”), and it is mentioned that such use of SI prefixes is not is correct. According to GOST IEC 60027-2-2015, the lowercase “k” corresponds to 1000 and “Ki” - 1024, so 1 KiB = 1024 B, 1 kB = 1000 B.

The use of the capital letter “B” to designate a byte meets the requirements of GOST and avoids confusion between abbreviations from bytes and bits. A record with a lowercase letter in the form of “Kb” (Mb, GB) for a byte will not correspond to the international IEC standard (and the GOST localized by it). However, the authors of the spelling dictionary ^[5] give the lowercase form "b" (and "Kb", "Mb", "GB") for the byte, as not formed from the last name.

It should be borne in mind that in GOST 8.417, except for “bits,” there is no one-letter designation for a bit, so using a record like “Mb” as a synonym for “Mbps” does not meet this standard. But some documents use the abbreviation b for bit: IEEE 1541-2002, IEEE Std 260.1-2004, in lower case: GOST R IEC 80000-13—2016, GOST IEC 60027-2-2015.

In the international standard IEC IEC 60027-2 of 2005 ^[6] for use in the electrical and electronic fields, the following notations are recommended:

bit - for a bit;
o, B - for octet , byte. Moreover, o is the only indicated designation in French.

Declination

In addition to the usual form of the genitive case of the plural (bytes, kilobytes, bits), there is a countable form “bytes” ^[7] , which is used in combination with numerals: 8 bytes , 16 kilobytes . The accounting form is colloquial. In the same way, for example, with kilograms: the usual form of the genitive case is used if there is no numeral, and in combination with the numeral there can be options: 16 kilograms (stylistically neutral ordinary form) and 16 kilograms (colloquial counting form).

Notes

↑ Regulation on units allowed for use in the Russian Federation. Approved by Decree of the Government of the Russian Federation of October 31, 2009 No. 879 (unopened) (inaccessible link) . Date of treatment July 23, 2015. Archived November 2, 2013.
↑ Buchholz W. The Word 'Byte' Comes of Age ... (Eng.) // Byte Magazine . - 1977. - Vol. 2 , iss. 2 . - P. 144 .
↑ Blaauw GA, Brooks FP , Buchholz W. Processing Data in Bits and Pieces // IRE Transactions on Electronic Computers . - June 1959. - P. 121 .
↑ GOST 8.417-2002 (“Units of quantities”) “Appendix A” .
↑ Appendix 1 Basic generally accepted graphic abbreviations // Russian Spelling Dictionary: about 200,000 words / Russian Academy of Sciences . Institute of the Russian Language named after V.V. Vinogradov / Pod. ed. V.V. Lopatina O. E. Ivanova . - 4th, rev. and add. - M .: AST-PRESS BOOK, 2013 .-- S. 859-872. - 896 p. - (Fundamental dictionaries of the Russian language). - ISBN 978-5-462-01272-3 .
↑ fr. NORME INTERNATIONALE CEI, Troisième édition INTERNATIONAL STANDARD IEC, Third edition - 60027-2, from 2005-08, p. 5, 112-117.
↑ Russian Spelling Dictionary: about 180,000 words [Electronic version] / O. E. Ivanova , V. V. Lopatin (ed.), I. V. Nechaev , L. K. Cheltsova . - 2nd ed., Rev. and add. - M .: Russian Academy of Sciences . Institute of the Russian Language named after V.V. Vinogradov , 2004. - 960 p. - ISBN 5-88744-052-X .

Links

GOST 8.417-2002 (“Units of quantities”) “Appendix A”

[1] Regulation on units allowed for use in the Russian Federation. Approved by Decree of the Government of the Russian Federation of October 31, 2009 No. 879 (unopened) (inaccessible link) . Date of treatment July 23, 2015. Archived November 2, 2013.

[2] Buchholz W. The Word 'Byte' Comes of Age ... (Eng.) // Byte Magazine . - 1977. - Vol. 2 , iss. 2 . - P. 144 .

[3] Blaauw GA, Brooks FP , Buchholz W. Processing Data in Bits and Pieces // IRE Transactions on Electronic Computers . - June 1959. - P. 121 .

[4] GOST 8.417-2002 (“Units of quantities”) “Appendix A” .

[5] Appendix 1 Basic generally accepted graphic abbreviations // Russian Spelling Dictionary: about 200,000 words / Russian Academy of Sciences . Institute of the Russian Language named after V.V. Vinogradov / Pod. ed. V.V. Lopatina O. E. Ivanova . - 4th, rev. and add. - M .: AST-PRESS BOOK, 2013 .-- S. 859-872. - 896 p. - (Fundamental dictionaries of the Russian language). - ISBN 978-5-462-01272-3 .

[6] r. NORME INTERNATIONALE CEI, Troisième édition INTERNATIONAL STANDARD IEC, Third edition - 60027-2, from 2005-08, p. 5, 112-117.

[7] Russian Spelling Dictionary: about 180,000 words [Electronic version] / O. E. Ivanova , V. V. Lopatin (ed.), I. V. Nechaev , L. K. Cheltsova . - 2nd ed., Rev. and add. - M .: Russian Academy of Sciences . Institute of the Russian Language named after V.V. Vinogradov , 2004. - 960 p. - ISBN 5-88744-052-X .

Measurements in bytes
GOST 8.417 —2002			SI prefixes		IEC prefixes
Title	Designation	Power	Title	Power	Title	Symbol		Power
byte	B	10 ⁰	-	10 ⁰	byte	B	B	2 ⁰
kilobytes	KB	10 ³	kilo	10 ³	kibibyte	Kib	KiB	2 ¹⁰
megabyte	MB	10 ⁶	mega-	10 ⁶	mebibyte	MiB	MiB	2 ²⁰
gigabyte	GB	10 ⁹	giga	10 ⁹	gibibyte	Gib	GiB	2 ³⁰
terabyte	TB	10 ¹²	tera	10 ¹²	tebibyte	Tib	Tib	2 ⁴⁰
petabyte	Bytes	10 ¹⁵	peta	10 ¹⁵	pebibyte	PiB	PiB	2 ⁵⁰
exabyte	EBayt	10 ¹⁸	exa	10 ¹⁸	exbyte	Eib	EIB	2 ⁶⁰
zettabyte	Zb	10 ²¹	zetta	10 ²¹	zebibyte	Zib	ZiB	2 ⁷⁰
yottabyte	IByte	10 ²⁴	yotta	10 ²⁴	yobibyte	Yib	YiB	2 ⁸⁰