View source for Transcode (character encoding)

'''Six-Bit Transcode''', or '''Six-Bit Transmission Code''', was, for a few years, one of the three [[Character encoding|character sets]] used by [[Company:IBM|IBM]] for [[Binary Synchronous Communications]]. Transmission using 6-bit Transcode had higher throughput than transmission using 8-bit EBCDIC or ASCII, provided that the data to be transmitted used a limited set of 48 characters.

The IBM 2780 data transmission terminal was announced with Transcode support in 1967. Its successor, the IBM 3780 [[Data communication|data communication]] terminal, announced in 1972, dropped Transcode support and added a "space compression" option.

Transcode is a [[Six-bit character code|six-bit character code]]. It relates to IBM's punched card code but, like [[Software:EBCDIC|EBCDIC]], it is not [[BCD (character encoding)|BCD]]. Its 64 values consist of the 26 uppercase letters, 10 numbers, 11 symbols, space, and 16 control characters. Its 48 printable characters are <code>ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 .'-/@#$%&*⌑</code>; it cannot represent <code>,:;!?"()[]<>+^=_\`{}|~</code>. Characters are transmitted with odd parity. The 2780 cannot use the 16 control characters as data characters in Transcode mode.<ref>{{cite book |last=IBM Corporation |title=Component Description: IBM 2780 Communications Terminal |year=1971 |url=http://www.bitsavers.org/pdf/ibm/2780/GA27-3005-3-2780_Data_Terminal_Description_Aug71.pdf |url-status=live |archive-url=https://web.archive.org/web/20200726231256/http://www.bitsavers.org/pdf/ibm/2780/GA27-3005-3-2780_Data_Terminal_Description_Aug71.pdf |archive-date=2020-07-26}}</ref>

==Code table==

{|{{chset-table-header1|Six-Bit Transcode}}
|-
|{{chset-ctrl1|U+0001 START OF HEADING|{{Control code link|SOH}}}}
|{{chset-cell1|U+0041 LATIN CAPITAL LETTER A|A|1}}
|{{chset-cell1|U+0042 LATIN CAPITAL LETTER B|B|2}}
|{{chset-cell1|U+0043 LATIN CAPITAL LETTER C|C|3}}
|{{chset-cell1|U+0044 LATIN CAPITAL LETTER D|D|4}}
|{{chset-cell1|U+0045 LATIN CAPITAL LETTER E|E|5}}
|{{chset-cell1|U+0046 LATIN CAPITAL LETTER F|F|6}}
|{{chset-cell1|U+0047 LATIN CAPITAL LETTER G|G|7}}
|{{chset-cell1|U+0048 LATIN CAPITAL LETTER H|H|8}}
|{{chset-cell1|U+0049 LATIN CAPITAL LETTER I|I|9}}
|{{chset-ctrl1|U+0002 START OF TEXT|{{Control code link|STX}}}}
|{{chset-cell1|U+002E FULL STOP|.}}
|{{chset-cell1|U+2311 SQUARE LOZENGE|[[Lozenge (shape)|⌑]]}}
|{{chset-ctrl1|U+0007 BELL|{{Control code link|BEL}}}}
|{{chset-ctrl1|U+001A SUBSTITUTE|{{Control code link|SUB}}}}
|{{chset-ctrl1|U+0017 END OF TRANSMISSION BLOCK|{{Control code link|ETB}}}}
|-
|{{chset-cell1|U+0026 AMPERSAND|[[Ampersand|&amp;]]}}
|{{chset-cell1|U+004A LATIN CAPITAL LETTER J|J}}
|{{chset-cell1|U+004B LATIN CAPITAL LETTER K|K}}
|{{chset-cell1|U+004C LATIN CAPITAL LETTER L|L}}
|{{chset-cell1|U+004D LATIN CAPITAL LETTER M|M}}
|{{chset-cell1|U+004E LATIN CAPITAL LETTER N|N}}
|{{chset-cell1|U+004F LATIN CAPITAL LETTER O|O}}
|{{chset-cell1|U+0050 LATIN CAPITAL LETTER P|P}}
|{{chset-cell1|U+0051 LATIN CAPITAL LETTER Q|Q}}
|{{chset-cell1|U+0052 LATIN CAPITAL LETTER R|R}}
|{{chset-ctrl1|U+0020 SPACE|SP}}
|{{chset-cell1|U+0024 DOLLAR SIGN|[[Finance:Dollar sign|$]]}}
|{{chset-cell1|U+002A ASTERISK|*}}
|{{chset-ctrl1|U+001F INFORMATION SEPARATOR ONE|{{Control code link|US|IUS}}/<br/>{{Control code link|IUS/ITB|ITB}}|style=line-height:1}}
|{{chset-ctrl1|U+0004 END OF TRANSMISSION|{{Control code link|EOT}}}}
|{{chset-ctrl1|U+0010 DATA LINK ESCAPE|{{Control code link|DLE}}}}
|-
|{{chset-cell1|U+002D HYPHEN-MINUS|-}}
|{{chset-cell1|U+002F SOLIDUS|/}}
|{{chset-cell1|U+0053 LATIN CAPITAL LETTER S|S}}
|{{chset-cell1|U+0054 LATIN CAPITAL LETTER T|T}}
|{{chset-cell1|U+0055 LATIN CAPITAL LETTER U|U}}
|{{chset-cell1|U+0056 LATIN CAPITAL LETTER V|V}}
|{{chset-cell1|U+0057 LATIN CAPITAL LETTER W|W}}
|{{chset-cell1|U+0058 LATIN CAPITAL LETTER X|X}}
|{{chset-cell1|U+0059 LATIN CAPITAL LETTER Y|Y}}
|{{chset-cell1|U+005A LATIN CAPITAL LETTER Z|Z}}
|{{chset-ctrl1|U+001B ESCAPE|{{Control code link|ESC}}}}
|{{chset-cell1|U+0027 APOSTROPHE|'}}
|{{chset-cell1|U+0025 PERCENT SIGN|[[Percent sign|%]]}}
|{{chset-ctrl1|U+0005 ENQUIRY|{{Control code link|ENQ}}}}
|{{chset-ctrl1|U+0003 END OF TEXT|{{Control code link|ETX}}}}
|{{chset-ctrl1|U+0009 CHARACTER TABULATION|{{Control code link|HT}}}}
|-
|{{chset-cell1|U+0030 DIGIT ZERO|[[0|0]]}}
|{{chset-cell1|U+0031 DIGIT ONE|[[1|1]]}}
|{{chset-cell1|U+0032 DIGIT TWO|[[2|2]]}}
|{{chset-cell1|U+0033 DIGIT THREE|[[3|3]]}}
|{{chset-cell1|U+0034 DIGIT FOUR|[[4|4]]}}
|{{chset-cell1|U+0035 DIGIT FIVE|[[5|5]]}}
|{{chset-cell1|U+0036 DIGIT SIX|[[6|6]]}}
|{{chset-cell1|U+0037 DIGIT SEVEN|[[7|7]]}}
|{{chset-cell1|U+0038 DIGIT EIGHT|[[8|8]]}}
|{{chset-cell1|U+0039 DIGIT NINE|[[9|9]]}}
|{{chset-ctrl1|U+0016 SYNCHRONOUS IDLE|{{Control code link|SYN}}}}
|{{chset-cell1|U+0023 NUMBER SIGN|#}}
|{{chset-cell1|U+0040 COMMERCIAL AT|@}}
|{{chset-ctrl1|U+0015 NEGATIVE ACKNOWLEDGE|{{Control code link|NAK}}}}
|{{chset-ctrl1|U+0019 END OF MEDIUM|{{Control code link|EM }}}}
|{{chset-ctrl1|U+007F DELETE|{{Control code link|DEL}}}}
|}

==Code table (from 2780 manual)==
{| class="wikitable" style="font-family: 'Courier New';"
! Character<br>&nbsp; !! [[Engineering:Punched card|Punched card]]<br>code !! 6-bit<br>transcode !! Hex&nbsp;
|-
| SOH || 12-9-1 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;P || 00
|-
| A || 12-1 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5&nbsp;&nbsp; || 01
|-
| B || 12-2 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4&nbsp;&nbsp;&nbsp;&nbsp; || 02
|-
| C || 12-3 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4&nbsp;5&nbsp;P || 03
|-
| D || 12-4 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; || 04
|-
| E || 12-5 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3&nbsp;&nbsp;&nbsp;5&nbsp;P || 05
|-
| F || 12-6 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3&nbsp;4&nbsp;&nbsp;&nbsp;P || 06
|-
| G || 12-7 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3&nbsp;4&nbsp;5&nbsp;&nbsp; || 07
|-
| H || 12-8 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; || 08
|-
| I || 12-9 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5&nbsp;P || 09
|-
| STX || 12-9-2 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;&nbsp;&nbsp;4&nbsp;&nbsp;&nbsp;P || 0A
|-
| . || 12-8-3 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;&nbsp;&nbsp;4&nbsp;5&nbsp;&nbsp; || 0B
|-
| ⌑ || 12-8-4 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;P || 0C
|-
| BEL || 0-9-8-7 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;3&nbsp;&nbsp;&nbsp;5&nbsp;&nbsp; || 0D
|-
| Sub || 9-8-7 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;3&nbsp;4&nbsp;&nbsp;&nbsp;&nbsp; || 0E
|-
| ETB || 0-9-6 || &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2&nbsp;3&nbsp;4&nbsp;5&nbsp;P || 0F
|-
| & || 12 || &nbsp;&nbsp;&nbsp;1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; || 10
|-
| J || 11-1 || &nbsp;&nbsp;&nbsp;1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5&nbsp;P || 11
|-
| K || 11-2 || &nbsp;&nbsp;&nbsp;1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4&nbsp;&nbsp;&nbsp;P || 12
|-
| L || 11-3 || &nbsp;&nbsp;&nbsp;1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4&nbsp;5&nbsp;&nbsp; || 13
|-
| M || 11-4 || &nbsp;&nbsp;&nbsp;1&nbsp;&nbsp;&nbsp;3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;P || 14
|-
| N || 11-5 || &nbsp;&nbsp;&nbsp;1&nbsp;&nbsp;&nbsp;3&nbsp;&nbsp;&nbsp;5&nbsp;&nbsp; || 15
|-
| O || 11-6 || &nbsp;&nbsp;&nbsp;1&nbsp;&nbsp;&nbsp;3&nbsp;4&nbsp;&nbsp;&nbsp;&nbsp; || 16
|-
| P || 11-7 || &nbsp;&nbsp;&nbsp;1&nbsp;&nbsp;&nbsp;3&nbsp;4&nbsp;5&nbsp;P || 17
|-
| Q || 11-8 || &nbsp;&nbsp;&nbsp;1&nbsp;2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;P || 18
|-
| R || 11-9 || &nbsp;&nbsp;&nbsp;1&nbsp;2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5&nbsp;&nbsp; || 19
|-
| Space || no punch || &nbsp;&nbsp;&nbsp;1&nbsp;2&nbsp;&nbsp;&nbsp;4&nbsp;&nbsp;&nbsp;&nbsp; || 1A
|-
| $ || 11-8-3 || &nbsp;&nbsp;&nbsp;1&nbsp;2&nbsp;&nbsp;&nbsp;4&nbsp;5&nbsp;P || 1B
|-
| * || 11-8-4 || &nbsp;&nbsp;&nbsp;1&nbsp;2&nbsp;3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; || 1C
|-
| US || 11-9-8-7 || &nbsp;&nbsp;&nbsp;1&nbsp;2&nbsp;3&nbsp;&nbsp;&nbsp;5&nbsp;P || 1D
|-
| EOT || 9-7 || &nbsp;&nbsp;&nbsp;1&nbsp;2&nbsp;3&nbsp;4&nbsp;&nbsp;&nbsp;P || 1E
|-
| DLE || 12-11-9-8-1 || &nbsp;&nbsp;&nbsp;1&nbsp;2&nbsp;3&nbsp;4&nbsp;5&nbsp;&nbsp; || 1F
|-
| - || 11 || &nbsp;0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; || 20
|-
| / || 0-1 || &nbsp;0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5&nbsp;P || 21
|-
| S || 0-2 || &nbsp;0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4&nbsp;&nbsp;&nbsp;P || 22
|-
| T || 0-3 || &nbsp;0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4&nbsp;5&nbsp;&nbsp; || 23
|-
| U || 0-4 || &nbsp;0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;P || 24
|-
| V || 0-5 || &nbsp;0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3&nbsp;&nbsp;&nbsp;5&nbsp;&nbsp; || 25
|-
| W || 0-6 || &nbsp;0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3&nbsp;4&nbsp;&nbsp;&nbsp;&nbsp; || 26
|-
| X || 0-7 || &nbsp;0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3&nbsp;4&nbsp;5&nbsp;P || 27
|-
| Y || 0-8 || &nbsp;0&nbsp;&nbsp;&nbsp;2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;P || 28
|-
| Z || 0-9 || &nbsp;0&nbsp;&nbsp;&nbsp;2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5&nbsp;&nbsp; || 29
|-
| ESC || 0-9-7 || &nbsp;0&nbsp;&nbsp;&nbsp;2&nbsp;&nbsp;&nbsp;4&nbsp;&nbsp;&nbsp;&nbsp; || 2A
|-
| ' || 0-8-3 || &nbsp;0&nbsp;&nbsp;&nbsp;2&nbsp;&nbsp;&nbsp;4&nbsp;5&nbsp;P || 2B
|-
| % || 0-8-4 || &nbsp;0&nbsp;&nbsp;&nbsp;2&nbsp;3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; || 2C
|-
| ENQ || 0-9-8-5 || &nbsp;0&nbsp;&nbsp;&nbsp;2&nbsp;3&nbsp;&nbsp;&nbsp;5&nbsp;P || 2D
|-
| ETX || 12-9-3 || &nbsp;0&nbsp;&nbsp;&nbsp;2&nbsp;3&nbsp;4&nbsp;&nbsp;&nbsp;P || 2E
|-
| HT || 12-9-5 || &nbsp;0&nbsp;&nbsp;&nbsp;2&nbsp;3&nbsp;4&nbsp;5&nbsp;&nbsp; || 2F
|-
| 0 || 0 || &nbsp;0&nbsp;1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;P || 30
|-
| 1 || 1 || &nbsp;0&nbsp;1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5&nbsp;&nbsp; || 31
|-
| 2 || 2 || &nbsp;0&nbsp;1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4&nbsp;&nbsp;&nbsp;&nbsp; || 32
|-
| 3 || 3 || &nbsp;0&nbsp;1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4&nbsp;5&nbsp;P || 33
|-
| 4 || 4 || &nbsp;0&nbsp;1&nbsp;&nbsp;&nbsp;3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; || 34
|-
| 5 || 5 || &nbsp;0&nbsp;1&nbsp;&nbsp;&nbsp;3&nbsp;&nbsp;&nbsp;5&nbsp;P || 35
|-
| 6 || 6 || &nbsp;0&nbsp;1&nbsp;&nbsp;&nbsp;3&nbsp;4&nbsp;&nbsp;&nbsp;P || 36
|-
| 7 || 7 || &nbsp;0&nbsp;1&nbsp;&nbsp;&nbsp;3&nbsp;4&nbsp;5&nbsp;&nbsp; || 37
|-
| 8 || 8 || &nbsp;0&nbsp;1&nbsp;2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; || 38
|-
| 9 || 9 || &nbsp;0&nbsp;1&nbsp;2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5&nbsp;P || 39
|-
| SYN || 9-2 || &nbsp;0&nbsp;1&nbsp;2&nbsp;&nbsp;&nbsp;4&nbsp;&nbsp;&nbsp;P || 3A
|-
| # || 8-3 || &nbsp;0&nbsp;1&nbsp;2&nbsp;&nbsp;&nbsp;4&nbsp;5&nbsp;&nbsp; || 3B
|-
| @ || 8-4 || &nbsp;0&nbsp;1&nbsp;2&nbsp;3&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;P || 3C
|-
| NAK || 9-8-5 || &nbsp;0&nbsp;1&nbsp;2&nbsp;3&nbsp;&nbsp;&nbsp;5&nbsp;&nbsp; || 3D
|-
| EM || 11-9-8-1 || &nbsp;0&nbsp;1&nbsp;2&nbsp;3&nbsp;4&nbsp;&nbsp;&nbsp;&nbsp; || 3E
|-
| DEL || 12-9-7 || &nbsp;0&nbsp;1&nbsp;2&nbsp;3&nbsp;4&nbsp;5&nbsp;P || 3F
|}

==Devices using Transcode==
* IBM 2701 Data Adapter Unit
* IBM 2703 Transmission Control
* IBM 2780 Data Transmission Terminal
* IBM System/370 model 135 Integrated Communications Adapter (ICA)

==References==
{{Reflist}}


[[Category:Character encoding]]

{{Sourceattribution|Transcode (character encoding)}}