字節

位元組的次方單位
十進位字首; (SI)
二進位字首; (IEC 60027-2)

位元組（英語：Byte），通常用作電腦及手機及手錶等資訊計量單位，不分資料型態。是通信和資料儲存的概念。一個位元組代表八個位元。從歷史的觀點上，「位元組」表示用於編碼單個字元所需要的位元數量。歷史上位元組長度曾基於硬體為1-48位元不等，最初通常使用6位元或9位元為一位元組。今日標準以8位元作為一位元組，因8為二進位整數。八個位元在一些規範（例如工業標準、電腦網路、電信技術等）中常被稱為八位組。位元組（Byte）可縮寫成B，例如MB表示Megabyte；位元（Bit）可縮寫成b，例如Mb表示Megabit。

歷史

位元組一詞是Werner Buchholz於1956年6月在IBM Stretch電腦的早期設計階段發明的，該電腦的定址為位和可變欄位長度（VFL）指令，指令中編碼了位元組大小。這是為了避免意外突變為位元而特意重寫的。

參考資料

^ Blaauw, Gerrit Anne; Brooks, Jr., Frederick Phillips; Buchholz, Werner, 4: Natural Data Units, Buchholz, Werner (編), Planning a Computer System – Project Stretch (PDF), McGraw-Hill Book Company, Inc. / The Maple Press Company, York, PA.: 39–40, 1962 [2017-04-03], LCCN 61-10466, （原始內容 (PDF)存檔於2017-04-03）, […] Terms used here to describe the structure imposed by the machine design, in addition to bit, are listed below.
Byte denotes a group of bits used to encode a character, or the number of bits transmitted in parallel to and from input-output units. A term other than character is used here because a given character may be represented in different applications by more than one code, and different codes may use different numbers of bits (i.e., different byte sizes). In input-output transmission the grouping of bits may be completely arbitrary and have no relation to actual characters. (The term is coined from bite, but respelled to avoid accidental mutation to bit.)
A word consists of the number of data bits transmitted in parallel from or to memory in one memory cycle. Word size is thus defined as a structural property of the memory. (The term catena was coined for this purpose by the designers of the Bull fr computer.)
Block refers to the number of words transmitted to or from an input-output unit in response to a single input-output instruction. Block size is a structural property of an input-output unit; it may have been fixed by the design or left to be varied by the program. […]
^ Bemer, Robert William, A proposal for a generalized card code of 256 characters, Communications of the ACM, 1959, 2 (9): 19–23, doi:10.1145/368424.368435

延伸閱讀

Tafel, Hans Jörg. 寫於RWTH, Aachen, Germany. Einführung in die digitale Datenverarbeitung [Introduction to digital information processing]. Munich, Germany: Carl Hanser Verlag. 1971: 300. ISBN 3-446-10569-7 （德語）. Byte = zusammengehörige Folge von i.a. neun Bits; davon sind acht Datenbits, das neunte ein Prüfbit (NB. Defines a byte as a group of typically 9 bits; 8 data bits plus 1 parity bit.)
Programming with the PDP-10 Instruction Set (PDF). PDP-10 System Reference Manual 1. Digital Equipment Corporation (DEC). August 1969 [2017-04-05]. （原始內容存檔 (PDF)於2017-04-05）.
Computer History Museum – Exhibits – Internet History – 1964: Internet History 1962 to 1992. Computer History Museum. 2017 [2015] [2017-04-03]. （原始內容存檔於2017-04-03）.
Jaffer, Aubrey. Metric-Interchange-Format. 2011 [2008] [2017-04-03]. （原始內容存檔於2017-04-03）.
Kozierok, Charles M. The TCP/IP Guide – Binary Information and Representation: Bits, Bytes, Nibbles, Octets and Characters – Byte versus Octet. 3.0. 2005-09-20 [2001] [2017-04-03]. （原始內容存檔於2017-04-03）.

參閲

八位元組（Octet）

外部連結

ГОСТ 8.417-2002 | Страница 19 （俄文）

[Buchholz_1962-1] Blaauw, Gerrit Anne; Brooks, Jr., Frederick Phillips; Buchholz, Werner, 4: Natural Data Units, Buchholz, Werner (編), Planning a Computer System – Project Stretch (PDF), McGraw-Hill Book Company, Inc. / The Maple Press Company, York, PA.: 39–40, 1962 [2017-04-03], LCCN 61-10466, （原始內容 (PDF)存檔於2017-04-03）, […] Terms used here to describe the structure imposed by the machine design, in addition to bit, are listed below.
Byte denotes a group of bits used to encode a character, or the number of bits transmitted in parallel to and from input-output units. A term other than character is used here because a given character may be represented in different applications by more than one code, and different codes may use different numbers of bits (i.e., different byte sizes). In input-output transmission the grouping of bits may be completely arbitrary and have no relation to actual characters. (The term is coined from bite, but respelled to avoid accidental mutation to bit.)
A word consists of the number of data bits transmitted in parallel from or to memory in one memory cycle. Word size is thus defined as a structural property of the memory. (The term catena was coined for this purpose by the designers of the Bull fr computer.)
Block refers to the number of words transmitted to or from an input-output unit in response to a single input-output instruction. Block size is a structural property of an input-output unit; it may have been fixed by the design or left to be varied by the program. […]

[Bemer_1959-2] Bemer, Robert William, A proposal for a generalized card code of 256 characters, Communications of the ACM, 1959, 2 (9): 19–23, doi:10.1145/368424.368435