Editing 8b/10b encoding (section)

== Technologies that use 8b/10b ==
After the above-mentioned IBM patent expired, the scheme became even more popular and was chosen as a DC-free line code for several communication technologies.

Among the areas in which 8b/10b encoding finds application are the following:
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* [[Aurora (protocol)|Aurora]]
* [[Camera Serial Interface]]
* [[CoaXPress]]
* [[Common Public Radio Interface]] (CPRI)
* [[DVB]] [[Asynchronous serial interface]] (ASI)
* [[DVI]] and [[HDMI]] Video Island ([[transition-minimized differential signaling]])
* [[DisplayPort]] 1.x
* [[ESCON]] (Enterprise Systems Connection)
* [[Fibre Channel]]
* [[Gigabit Ethernet]] (except for the [[twisted pair]]&ndash;based [[1000BASE-T]])
* [[IEEE 1394b]] (FireWire and others)
* [[InfiniBand]]
* [[JESD204B]]
* [[Open Base Station Architecture Initiative|OBSAI RP3]] interface
* [[PCI Express]] 1.x and 2.x
* [[Serial RapidIO]]
* [[SD UHS-II]]
* [[Serial ATA]]
* [[Serial Attached SCSI|SAS]] 1.x, 2.x and 3.x
* [[Serial Storage Architecture|SSA]]
* [[ServerNet]] (starting with ServerNet2)
* [[SGMII]]
* [[UniPro M-PHY]]<ref>{{cite web|url=http://www.mipi.org/specifications/physical-layer#MPHY |title=Physical Layer Specifications |publisher=MIPI Alliance |work=Mipi.org |access-date=2014-04-20}}</ref>
* [[USB 3.0]]
* [[Thunderbolt (interface)|Thunderbolt]] 1.x and 2.x
* [[XAUI]]
* SLVS-EC
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=== Fibre Channel (4GFC and 8GFC variants only) ===
{{Main|Fibre Channel}}

The FC-0 standard defines what encoding scheme is to be used (8b/10b or 64b/66b) in a Fibre Channel system<ref>Fibre Channel
Framing and Signaling - 3
(FC-FS-3) Rev 1.1 Sections 5.2.1 and 5.3.1 [http://www.t11.org/index.html]</ref>{{snd}} higher speed variants typically use 64b/66b to optimize bandwidth efficiency (since bandwidth overhead is 20% in 8b/10b versus approximately 3% (~&nbsp;2/66) in 64b/66b systems). Thus, 8b/10b encoding is used for 4GFC and 8GFC variants; for 10GFC and 16GFC variants, it is 64b/66b.<ref>FIBRE CHANNEL
Physical Interface-5
(FC-PI-5)
REV 6.10 Section 5.7 [http://www.t11.org/index.html]</ref> The Fibre Channel ''FC1'' data link layer is then responsible for implementing the 8b/10b encoding and decoding of signals.

The Fibre Channel 8b/10b coding scheme is also used in other telecommunications systems.  Data is expanded using an algorithm that creates one of two possible 10-bit output values for each input 8-bit value.  Each 8-bit input value can map either to a 10-bit output value with odd disparity, or to one with even disparity.  This mapping is usually done at the time when parallel input data is converted into a serial output stream for transmission over a fibre channel link.  The odd/even selection is done in such a way that a long-term zero disparity between ones and zeroes is maintained.  This is often called "DC balancing".

The 8-bit to 10-bit conversion scheme uses only 512 of the possible 1024 output values. Of the remaining 512 unused output values, most contain either too many ones (or too many zeroes) and therefore are not allowed. This still leaves enough spare 10-bit odd+even coding pairs to allow for at least 12 special non-data characters.

The codes that represent the 256 data values are called the data (D) codes.  The codes that represent the 12 special non-data characters are called the control (K) codes.

All of the codes can be described by stating 3 octal values.  This is done with a naming convention of "Dxx.x" or "Kxx.x".  (Note that the tables in earlier sections are using decimal, rather than octal, values for Dxx.x or Kxx.x) 

'''Example:'''

:Input Data Bits:     ABCDEFGH
:Data is split:       ABC DEFGH
:Data is shuffled:    DEFGH ABC

Now these bits are converted to decimal in the way they are paired.

Input data

 C3 (HEX) = 11000011
          = 110 00011
          = 00011 110
          =   3    6
'''E 8B/10B  = D03.6'''

=== Digital audio ===
Encoding schemes 8b/10b have found a heavy use in digital audio storage applications, namely
* [[Digital Audio Tape]], US Patent 4,456,905, June 1984 by K. Odaka.
* [[Digital Compact Cassette]] (DCC), US Patent 4,620,311, October 1986 by [[Kees Schouhamer Immink]].
A differing but related scheme is used for [[Compact Disc Digital Audio|audio CDs]] and [[CD-ROM]]s:
* [[Compact disc]] [[Eight-to-fourteen modulation]]