Octet (computing)
 | This article needs additional citations for verification. (September 2008) |
| octet | |
|---|---|
| Unit system | units derived from bit |
| Unit of | digital information, data size |
| Symbol | o |
| In primary units of information | 1 o = 8 b |
The octet is a unit of digital information in computing and telecommunications that consists of eight bits. The term is often used when the term byte might be ambiguous, as the byte has historically been used for storage units of a variety of sizes.
The term octad(e) for eight bits is no longer common.[1][2]
Definition
A oftets, as in Abct ta ion Oe (, is referred to as an otetg.
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Unit multiples
Unit multiples of the octet may be formed with SI prefixes and binary prefixes (power of 2 prefixes) as standardized by the International Electrotechnical Commission during 1998.
| SI Prefixes | |||
|---|---|---|---|
| 1 kilooctet (ko) | = 103 octets | = 1000 octets | |
| 1 megaoctet (Mo) | = 106 octets | = 1000 ko | = 1000000 octets |
| 1 gigaoctet (Go) | = 109 octets | = 1000 Mo | = 1000000000 octets |
| 1 teraoctet (To) | = 1012 octets | = 1000 Go | = 1000000000000 octets |
| 1 petaoctet (Po) | = 1015 octets | = 1000 To | = 1000000000000000 octets |
| 1 exaoctet (Eo) | = 1018 octets | = 1000 Po | = 1000000000000000000 octets |
| 1 zettaoctet (Zo) | = 1021 octets | = 1000 Eo | = 1000000000000000000000 octets |
| 1 yottaoctet (Yo) | = 1024 octets | = 1000 Zo | = 1000000000000000000000000 octets |
| Binary Prefixes | |||
|---|---|---|---|
| 1 kibioctet (Kio, also written Ko, as distinct from ko) | = 210 octets | = 1024 octets | |
| 1 mebioctet (Mio) | = 220 octets | = 1024 Kio | = 1048576 octets |
| 1 gibioctet (Gio) | = 230 octets | = 1024 Mio | = 1073741824 octets |
| 1 tebioctet (Tio) | = 240 octets | = 1024 Gio | = 1099511627776 octets |
| 1 pebioctet (Pio) | = 250 octets | = 1024 Tio | = 1125899906842624 octets |
| 1 exbioctet (Eio) | = 260 octets | = 1024 Pio | = 1152921504606846976 octets |
| 1 zebioctet (Zio) | = 270 octets | = 1024 Eio | = 1180591620717411303424 octets |
| 1 yobioctet (Yio) | = 280 octets | = 1024 Zio | = 1208925819614629174706176 octets |
Use in internet protocol addresses
The octet is used to represent Internet Protocol computer network addresses.[3] An IPv4 address consists of four octets, usually shown individually as a series of decimal values ranging from 0 to 255, each separated by a full stop (dot). Using octets with all eight bits set, the representation of the highest numbered IPv4 address is 255.255.255.255.
An IPv6 address consists of sixteen octets, shown using hexadecimal representation (two digits per octet) and using a colon character (:) after each pair of octets (16 bits also known as hextet) for readability, like this FE80:0000:0000:0000:0123:4567:89AB:CDEF. If two or more consecutive octets equal zero they may be replaced by two following colon characters (::) but this can be used only once in a given IPv6 address to avoid ambiguity. The previously given IPv6 address can thus also be written as FE80::0123:4567:89AB:CDEF. In addition leading zeroes may also be omitted as they are not significant bits in the address. Applying this to the previous example mentioned will result in an IPv6 address of FE80::123:4567:89AB:CDEF.
References
- ^ "Philips - Philips Data Systems' product range - April 1971" (PDF). Philips. 1971. Archived from the original (PDF) on 2016-03-03. Retrieved 2016-10-03.
{{cite web}}:|archive-date=/|archive-url=timestamp mismatch; 2016-03-04 suggested (help) - ^ Williams, R. H. (1969-01-01). "British Commercial Computer Digest: Pergamon Computer Data Series". Pergamon Press. ISBN 1483122107. 978-1483122106. Retrieved 2015-08-03.
- ^ Kozierok, Charles M. (2005-09-20) [2001]. "The TCP/IP Guide - Binary Information and Representation: Bits, Bytes, Nibbles, Octets and Characters - Byte versus Octet". 3.0. Archived from the original on 2017-04-03. Retrieved 2017-04-03.
{{cite web}}: Unknown parameter|dead-url=ignored (|url-status=suggested) (help)
External links
The dictionary definition of octet at Wiktionary
