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Extended Binary Coded Decimal Interchange Code (EBCDIC; ) is an eight-
bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...
character encoding Character encoding is the process of assigning numbers to Graphics, graphical character (computing), characters, especially the written characters of Language, human language, allowing them to be Data storage, stored, Data communication, transmi ...
used mainly on
IBM mainframe IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the large computer market. Current mainframe computers in IBM's line of business computers are developments of the basic design of th ...
and IBM
midrange computer Midrange computers, or midrange systems, were a class of computer systems that fell in between mainframe computers and microcomputers. This class of machine emerged in the 1960s, with models from Digital Equipment Corporation ( PDP line), Data Ge ...
operating systems. It descended from the code used with
punched card A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...
s and the corresponding
six-bit binary-coded decimal BCD (''binary-coded decimal''), also called alphanumeric BCD, alphameric BCD, BCD Interchange Code, or BCDIC, is a family of representations of numerals, uppercase Latin letters, and some special and control characters as six-bit character cod ...
code used with most of IBM's
computer peripheral A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by th ...
s of the late 1950s and early 1960s. It is supported by various non-IBM platforms, such as
Fujitsu-Siemens Fujitsu Siemens Computers GmbH was a Japanese and German vendor of information technology. The company was founded in 1999 as a 50/50 joint venture between Fujitsu Limited of Japan and Siemens of Germany. On April 1, 2009, the company became Fuji ...
' BS2000/OSD, OS-IV, MSP, and MSP-EX, the
SDS Sigma series The SDS Sigma series is a series of third generation computers that were introduced by Scientific Data Systems of the United States in 1966. The first machines in the series are the 16-bit Sigma 2 and the 32-bit Sigma 7; the Sigma 7 was the firs ...
,
Unisys Unisys Corporation is an American multinational information technology (IT) services and consulting company headquartered in Blue Bell, Pennsylvania. It provides digital workplace solutions, cloud, applications, and infrastructure solutions, ...
VS/9 VS/9 is a computer operating system for the UNIVAC Series 90 mainframes (90/60, 90/70, and 90/80), used during the late 1960s through 1980s. The 90/60 and 90/70 were repackaged Univac 9700 computers. After the RCA acquisition by Sperry, it ...
, Unisys MCP and ICL VME.


History

EBCDIC was devised in 1963 and 1964 by IBM and was announced with the release of the IBM System/360 line of mainframe
computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
s. It is an eight-bit character encoding, developed separately from the seven-bit
ASCII ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...
encoding scheme. It was created to extend the existing Binary-Coded Decimal (BCD) Interchange Code, or
BCDIC BCD (''binary-coded decimal''), also called alphanumeric BCD, alphameric BCD, BCD Interchange Code, or BCDIC, is a family of representations of numerals, uppercase Latin letters, and some special and control characters as six-bit character code ...
, which itself was devised as an efficient means of encoding the two ''zone'' and ''number'' punches on
punched cards A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to d ...
into six bits. The distinct encoding of 's' and 'S' (using position 2 instead of 1) was maintained from punched cards where it was desirable not to have hole punches too close to each other to ensure the integrity of the physical card. While IBM was a chief proponent of the ASCII standardization committee, the company did not have time to prepare ASCII peripherals (such as card punch machines) to ship with its System/360 computers, so the company settled on EBCDIC. The System/360 became wildly successful, together with clones such as
RCA Spectra 70 The RCA Spectra 70 was a line of electronic data processing (EDP) equipment manufactured by the Radio Corporation of America’s computer division beginning in April 1965. The Spectra 70 line included several CPU models, various configurations ...
,
ICL System 4 4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is a square number, the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures. In mathematics Four ...
, and Fujitsu FACOM, thus so did EBCDIC. All IBM mainframe and
midrange In statistics, the mid-range or mid-extreme is a measure of central tendency of a sample defined as the arithmetic mean of the maximum and minimum values of the data set: :M=\frac. The mid-range is closely related to the range, a measure of st ...
operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
s use EBCDIC as their inherent encoding (with toleration for ASCII, for example,
ISPF In computing, Interactive System Productivity Facility (ISPF) is a software product for many historic IBM mainframe operating systems and currently the z/OS and z/VM operating systems that run on IBM mainframes. It includes a screen editor, the us ...
in
z/OS z/OS is a 64-bit operating system for IBM z/Architecture mainframes, introduced by IBM in October 2000. It derives from and is the successor to OS/390, which in turn was preceded by a string of MVS versions.Starting with the earliest: * O ...
can browse and edit both EBCDIC and ASCII encoded files). Software can translate to and from encodings, and modern mainframes (such as
IBM Z IBM Z is a family name used by IBM for all of its z/Architecture mainframe computers. In July 2017, with another generation of products, the official family was changed to IBM Z from IBM z Systems; the IBM Z family now includes the newest mod ...
) include processor instructions, at the hardware level, to accelerate translation between character sets. There is an EBCDIC-oriented
Unicode Transformation Format Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, wh ...
called
UTF-EBCDIC UTF-EBCDIC is a character encoding capable of encoding all 1,112,064 valid character code points in Unicode using one to five one-byte (8-bit) code units (in contrast to a maximum of four for UTF-8). It is meant to be EBCDIC-friendly, so that legac ...
proposed by the
Unicode Consortium The Unicode Consortium (legally Unicode, Inc.) is a 501(c)(3) non-profit organization incorporated and based in Mountain View, California. Its primary purpose is to maintain and publish the Unicode Standard which was developed with the intenti ...
, designed to allow easy updating of EBCDIC software to handle
Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology Technical standard, standard for the consistent character encoding, encoding, representation, and handling of Character (computing), text expre ...
, but not intended to be used in open interchange environments. Even on systems with extensive EBCDIC support, it has not been popular. For example, z/OS supports Unicode (preferring
UTF-16 UTF-16 (16-bit Unicode Transformation Format) is a character encoding capable of encoding all 1,112,064 valid code points of Unicode (in fact this number of code points is dictated by the design of UTF-16). The encoding is variable-length, as cod ...
specifically), but z/OS only has limited support for UTF-EBCDIC. Not all IBM products use EBCDIC;
IBM AIX AIX (Advanced Interactive eXecutive, pronounced , "ay-eye-ex") is a series of Proprietary software, proprietary Unix operating systems developed and sold by IBM for several of its computer platforms. Background Originally released for the ...
,
Linux on IBM Z Linux on IBM Z or Linux on zSystems is the collective term for the Linux operating system compiled to run on IBM mainframes, especially IBM Z / IBM zSystems and IBM LinuxONE servers. Similar terms which imply the same meaning are ''Linux/390'', ...
, and
Linux on Power PowerLinux is the combination of a Linux-based operating system (OS) running on PowerPC- or Power ISA-based computers from IBM. It is often used in reference along with ''Linux on Power'', and is also the name of several Linux-only IBM Power Sys ...
all use ASCII.


Compatibility with ASCII

There were numerous difficulties to writing software that would work in both ASCII and EBCDIC. * The gaps between letters made simple code that worked in ASCII fail on EBCDIC. For example would print the alphabet from A to Z if ASCII is used, but print 41 characters (including a number of unassigned ones) in EBCDIC. * Sorting EBCDIC put lowercase letters before uppercase letters and letters before numbers, exactly the opposite of ASCII. * Most programming languages and file formats and network protocols designed for ASCII used available punctuation marks (such as the curly braces and ) that did not exist in EBCDIC, making translation to EBCDIC systems difficult. Workarounds such as trigraphs were used. Conversely EBCDIC had a few characters such as (
US cent The cent, the United States one-cent coin (symbol: ¢), often called the "penny", is a unit of currency equaling one one-hundredth of a United States dollar. It has been the lowest face-value physical unit of U.S. currency since the abolition o ...
) that got used on IBM systems and could not be translated to ASCII. * The most common newline convention used with EBCDIC is to use a NEL (NEXT LINE) code between lines. Converters to other encodings often replace NEL with LF or
CR/LF Newline (frequently called line ending, end of line (EOL), next line (NEL) or line break) is a control character or sequence of control characters in character encoding specifications such as ASCII, EBCDIC, Unicode, etc. This character, or a ...
, even if there is a NEL in the target encoding. This causes the LF and NEL to translate to the same character and be unable to be distinguished. * If seven-bit ASCII was used, there was an "unused" high bit in 8-bit bytes, and many pieces of software stored other information there. Software would also pack the seven bits and discard the eighth, such as packing five seven-bit ASCII characters in a 36-bit word. On the PDP-11 bytes with the high bit set were treated as negative numbers, behavior that was copied to C, causing unexpected problems if the high bit was set. These all made it difficult to switch from ASCII to the 8-bit EBCDIC (and also made it difficult to switch to 8-bit extended ASCII encodings).


Code page layout

There are hundreds of EBCDIC code pages based on the original EBCDIC character encoding; there are a variety of EBCDIC code pages intended for use in different parts of the world, including code pages for non-Latin scripts such as Chinese, Japanese (e.g., EBCDIC 930, JEF, and KEIS), Korean, and Greek (EBCDIC 875). There is also a huge number of variations with the letters swapped around for no discernible reason. The table below shows the "invariant subset" of EBCDIC, which are characters that ''should'' have the same assignments on all EBCDIC code pages that use the Latin alphabet. (This includes most of the
ISO/IEC 646 ISO/IEC 646 is a set of International Organization for Standardization, ISO/International Electrotechnical Commission, IEC standards, described as ''Information technology — ISO 7-bit coded character set for information interchange' ...
invariant repertoire, except the
exclamation mark The exclamation mark, , or exclamation point (American English), is a punctuation mark usually used after an interjection or exclamation to indicate strong feelings or to show emphasis. The exclamation mark often marks the end of a sentence, f ...
.) It also shows (in gray) missing ASCII and EBCDIC punctuation, located where they are in
Code Page 37 Code page 37 (CCSID 37; label ), known as "USA/Canada - CECP", is an EBCDIC code page used on IBM mainframes. It encodes the ISO/IEC 8859-1 repertoire of graphic characters. Code page 37 is one of the most-used and best-supported EBCDIC code pag ...
(one of the code page variants of EBCDIC). The blank cells are filled with region-specific characters in the variants, but the characters in gray are often swapped around or replaced as well. Like ASCII, the invariant subset works only for English, excluding loan words.


Definitions of non-ASCII EBCDIC controls

Following are the definitions of EBCDIC control characters which either do not map onto the
ASCII control characters The C0 and C1 control code or control character sets define control codes for use in text by computer systems that use ASCII and derivatives of ASCII. The codes represent additional information about the text, such as the position of a cursor, ...
, or have additional uses. When mapped to Unicode, these are mostly mapped to C1 control character codepoints in a manner specified by IBM's Character Data Representation Architecture (CDRA). Although the default mapping of New Line (NL) corresponds to the ISO/IEC 6429 Next Line (NEL) character (the behaviour of which is also specified, but not required, in Unicode Annex 14), most of these C1-mapped controls match neither those in the ISO/IEC 6429 C1 set, nor those in other registered C1 control sets such as
ISO 6630 The C0 and C1 control code or control character sets define control codes for use in text by computer systems that use ASCII and derivatives of ASCII. The codes represent additional information about the text, such as the position of a cursor, ...
. Although this effectively makes the non-ASCII EBCDIC controls a unique C1 control set, they are not among the C1 control sets registered in the
ISO-IR ISO/IEC 2022 ''Information technology—Character code structure and extension techniques'', is an ISO/ IEC standard (equivalent to the ECMA standard ECMA-35, the ANSI standard ANSI X3.41 and the Japanese Industrial Standard JIS X 0202) in the ...
registry, meaning that they do not have an assigned control set designation sequence (as specified by
ISO/IEC 2022 ISO/IEC 2022 ''Information technology—Character code structure and extension techniques'', is an ISO/IEC standard (equivalent to the ECMA standard ECMA-35, the ANSI standard ANSI X3.41 and the Japanese Industrial Standard JIS X 0202) in the ...
, and optionally permitted in
ISO/IEC 10646 ISO/IEC JTC 1, entitled "Information technology", is a joint technical committee (JTC) of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). Its purpose is to develop, maintain and pr ...
(Unicode)). Besides U+0085 (Next Line), the Unicode Standard does not prescribe an interpretation of C1 control characters, leaving their interpretation to higher level protocols (it suggests, but does not require, their ISO/IEC 6429 interpretations in the absence of use for other purposes), so this mapping is permissible in, but not specified by, Unicode.


Code pages with Latin-1 character sets

The following code pages have the full Latin-1 character set (ISO/IEC 8859-1). The first column gives the original code page number. The second column gives the number of the code page updated with the euro sign (€) replacing the universal currency sign (¤) (or in the case of EBCDIC 924, with the set changed to match
ISO 8859-15 ISO/IEC 8859-15:1999, ''Information technology — 8-bit single-byte coded graphic character sets — Part 15: Latin alphabet No. 9'', is part of the ISO/IEC 8859 series of ASCII-based standard character encodings, first edition published in 1999. ...
)


Criticism and humor

Open-source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Op ...
advocate and software developer Eric S. Raymond writes in his ''
Jargon File The Jargon File is a glossary and usage dictionary of slang used by computer programmers. The original Jargon File was a collection of terms from technical cultures such as the MIT AI Lab, the Stanford AI Lab (SAIL) and others of the old ARPANET A ...
'' that EBCDIC was loathed by hackers, by which he meant members of a subculture of enthusiastic programmers. The Jargon File 4.4.7 gives the following definition: EBCDIC design was also the source of many jokes. One such joke, found in the Unix fortune (Unix), fortune file of 4.3BSD Reno (1990) went: References to the EBCDIC character set are made in the 1979 computer game series ''
Zork ''Zork'' is a text-based adventure game first released in 1977 by developers Tim Anderson, Marc Blank, Bruce Daniels, and Dave Lebling for the PDP-10 mainframe computer. The original developers and others, as the company Infocom, expanded a ...
''. In the "Machine Room" in ''
Zork II ''Zork'' is a text-based adventure game first released in 1977 by developers Tim Anderson, Marc Blank, Bruce Daniels, and Dave Lebling for the PDP-10 mainframe computer. The original developers and others, as the company Infocom, expanded an ...
'', EBCDIC is used to imply an incomprehensible language: In 2021, it became public that a Belgian bank was still using EBCDIC internally in 2019. This came to attention because a customer insisted that the correct spelling of his surname included an umlaut, which the bank omitted. The customer filed a complaint citing the guarantee in the General Data Protection Regulation of the right to timely "rectification of inaccurate personal data." The bank argued in part that it could not comply because its computer system was only compatible with EBCDIC, which does not support umlauted letters. The appeals court ruled in favor of the customer.


See also

*
UTF-EBCDIC UTF-EBCDIC is a character encoding capable of encoding all 1,112,064 valid character code points in Unicode using one to five one-byte (8-bit) code units (in contrast to a maximum of four for UTF-8). It is meant to be EBCDIC-friendly, so that legac ...


Notes


References


External links

* IBM-related: ** . Contains IBM's official information on code pages and character sets. *** tp://ftp.software.ibm.com/software/globalization/gcoc/attachments/CP00037.pdf Code page 37*** tp://ftp.software.ibm.com/software/globalization/gcoc/attachments/CP01047.pdf Code page 1047*
Host Code Page Reference
from IBM, shows code charts for several single-byte IBM EBCDIC pages. *
ICU Converter Explorer
Contains more information about EBCDIC derived from IBM's CDRA, including DBCS EBCDIC (Double Byte Character Set EBCDIC) *
ICU Charset Mapping Tables
Contains computer readable Unicode mapping tables for EBCDIC and many other character sets ** from
XHCS V2.0 manual
shows code charts for several single-byte
Siemens Siemens AG ( ) is a German multinational conglomerate corporation and the largest industrial manufacturing company in Europe headquartered in Munich with branch offices abroad. The principal divisions of the corporation are ''Industry'', '' ...
/
Fujitsu is a Japanese multinational information and communications technology equipment and services corporation, established in 1935 and headquartered in Tokyo. Fujitsu is the world's sixth-largest IT services provider by annual revenue, and the la ...
(as opposed to IBM) EBCDIC pages used on the
BS2000 BS2000 is an operating system for IBM 390-compatible mainframe computers developed in the 1970s by Siemens (Data Processing Department EDV) and from early 2000s onward by Fujitsu Technology Solutions. Unlike other mainframe systems, BS2000 p ...
. * * * {{Character encodings IBM mainframe operating systems