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Extended Binary Coded Decimal Interchange Code (EBCDIC; /ˈɛbsɪdɪk/) is an eight-bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems. It descended from the code used with punched cards and the corresponding six-bit binary-coded decimal code used with most of IBM's computer peripherals of the late 1950s and early 1960s. It is supported by various non-IBM platforms, such as Fujitsu-Siemens' BS2000/OSD, OS-IV, MSP, and MSP-EX, the SDS Sigma series, Unisys VS/9, 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 computers. It is an eight-bit character encoding, developed separately from the seven-bit ASCII encoding scheme. It was created to extend the existing Binary-Coded Decimal (BCD) Interchange Code, or BCDIC, which itself was devised as an efficient means of encoding the two zone and number punches on punched cards 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, ICL System 4, and Fujitsu FACOM, thus so did EBCDIC.

All IBM's mainframe operating systems, and its IBM i operating system for midrange computers, use EBCDIC as their inherent encoding (with toleration for ASCII, for example, ISPF in z/OS can browse and edit both EBCDIC and ASCII encoded files). Software can translate to and from encodings, and modern mainframes (such as IBM Z) include processor instructions, at the hardware level, to accelerate translation between character sets. Modern z/OS compilers for the C and C++ languages on IBM Z mainframes, and earlier OS/390 C and C++ compilers on IBM System/390 mainframes, support a POSIX-compatible execution environment that makes use of ASCII by default.

Not all operating systems running on IBM hardware use EBCDIC; IBM AIX, Linux on IBM Z, and Linux on Power all use ASCII, as do all operating systems that run on the IBM Personal Computer and its successors.

Compatibility with ASCII

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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 for (c = 'A'; c <= 'Z'; ++c) putchar(c); 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) that were 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, 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 invariant repertoire, except the exclamation mark.) It also shows (in gray) missing ASCII and EBCDIC punctuation, located where they are in Code Page 37 (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 languages using the ISO basic Latin alphabet, such as English (excluding loanwords and some uncommon orthographic variations) and Dutch (if the "ij" and "IJ" ligatures are written as two characters).

Definitions of non-ASCII EBCDIC controls

Following are the definitions of EBCDIC control characters which either do not map onto the ASCII control characters, 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. 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 registry, meaning that they do not have an assigned control set designation sequence (as specified by ISO/IEC 2022, and optionally permitted in ISO/IEC 10646 (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)

Different countries have different code pages because these code pages originated as code pages with country-specific character repertoires, and were later expanded to contain the entire ISO 8859-1 repertoire, meaning that a given ISO 8859-1 character may have different code point values in different code pages. They are known as Country Extended Code Pages (CECPs).

Criticism and humor

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Open-source software advocate and software developer Eric S. Raymond writes in his Jargon File 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: /eb´s@·dik/, /eb´see`dik/, /eb´k@·dik/, n. An alleged character set used on IBM dinosaurs. It exists in at least six mutually incompatible versions, all featuring such delights as non-contiguous letter sequences and the absence of several ASCII punctuation characters fairly important for modern computer languages (exactly which characters are absent varies according to which version of EBCDIC you're looking at). IBM adapted EBCDIC from punched card code in the early 1960s and promulgated it as a customer-control tactic (see connector conspiracy), spurning the already established ASCII standard. Today, IBM claims to be an open-systems company, but IBM's own description of the EBCDIC variants and how to convert between them is still internally classified top-secret, burn-before-reading. Hackers blanch at the very name of EBCDIC and consider it a manifestation of purest evil.

— The Jargon file 4.4.7

EBCDIC design was also the source of many jokes. One such joke, found in the Unix fortune file of 4.3BSD Reno (1990) went:

Professor: "So the American government went to IBM to come up with an encryption standard, and they came up with—"
Student: "EBCDIC!"

References to the EBCDIC character set are made in the 1979 computer game series Zork. In the "Machine Room" in Zork II, EBCDIC is used to imply an incomprehensible language:

This is a large room full of assorted heavy machinery, whirring noisily. The room smells of burned resistors. Along one wall are three buttons which are, respectively, round, triangular, and square. Naturally, above these buttons are instructions written in EBCDIC...

In 2021, it became public that a Belgian bank was still using EBCDIC internally in 2019. A customer insisted that the correct spelling of his surname included an umlaut, which the bank omitted, and 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's argument included the fact that their system used EBCDIC, as well as that it did not support letters with diacritics (or lower case, for that matter). The appeals court ruled in favor of the customer.

See also

• UTF-EBCDIC

References

1. ^ Mackenzie, Charles E. (1980). Coded Character Sets, History and Development (PDF). The Systems Programming Series (1 ed.). Addison-Wesley Publishing Company, Inc. ISBN 0-201-14460-3. LCCN 77-90165. Retrieved 2022-04-06.
2. Donovan, John J. (1972). Systems Programming. McGraw-Hill. p. 65. ISBN 0-07-085175-1.
3. ^ Bemer, Bob. "EBCDIC and the P-Bit (The Biggest Computer Goof Ever) - Computer History Vignettes". Archived from the original on 2018-05-13. Retrieved 2013-07-02. ...but their printers and punches were not ready to handle ASCII, and IBM just HAD to announce.
4. "Doug Jones's punched card codes". homepage.cs.uiowa.edu. Retrieved 2023-01-14.
5. "X3.4-1963". 1963. p. 4. (NB. IBM had four staff members on the final 21-member ASA X3.2 sub-committee.)
6. IBMnt (2008). "IBM confirms the use of EBCDIC in their mainframes as a default practice". Archived from the original on 2013-01-03. Retrieved 2008-06-16.
7. "Enhanced ASCII". z/OS UNIX System Services Planning. 2024-08-28.
8. "Rationale for International Standard – Programming Languages – C" (PDF). Revision 5.10. April 2003. § MSE.4: Support for invariant ISO/IEC 646. Archived (PDF) from the original on 2016-06-06. Retrieved 2022-11-24.
9. PDP-10 Reference Handbook, Book 2: Assembling the Source Program (PDF). Digital Equipment Corporation. p. 221.
10. "Invariant character set". IBM Knowledge Center. 2018-08-14.
11. ^ Umamaheswaran, V.S. (1999-11-08). "3.3 Step 2: Byte Conversion". UTF-EBCDIC. Unicode Consortium. Unicode Technical Report #16. The 64 control characters...the ASCII DELETE character (U+007F)...are mapped respecting EBCDIC conventions, as defined in IBM Character Data Representation Architecture, CDRA, with one exception -- the pairing of EBCDIC Line Feed and New Line control characters are swapped from their CDRA default pairings to ISO/IEC 6429 Line Feed (U+000A) and Next Line (U+0085) control characters
12. ^ Steele, Shawn (1996-04-24). "cp037_IBMUSCanada to Unicode table". Microsoft/Unicode Consortium.
13. Heninger, Andy (2019-02-15). "NL: Next Line (A) (Non-tailorable)". Unicode Line Breaking Algorithm. Revision 43. Unicode Consortium. Unicode Standard Annex #14.
14. ISO/TC 46 (1986-02-01). Additional Control Functions for Bibliographic Use according to International Standard ISO 6630 (PDF). ITSCJ/IPSJ. ISO-IR-124.{{citation}}: CS1 maint: numeric names: authors list (link)
15. ISO/IEC International Register of Coded Character Sets To Be Used With Escape Sequences (PDF), ITSCJ/IPSJ, ISO-IR
16. ISO/IEC JTC 1/SC 2 (2017). "12.4: Identification of control function set". Information technology — Universal Coded Character Set (UCS) (5th ed.). ISO. pp. 19–20. ISO/IEC 10646. For other C0 or C1 sets, the final octet F shall be obtained from the International Register of Coded Character Sets....If such an escape sequence appears within a code unit sequence conforming to this International Standard, it shall be padded in accordance with Clause 11.{{citation}}: CS1 maint: numeric names: authors list (link)
17. Unicode Consortium (2019). "23.1: Control Codes". The Unicode Standard (PDF) (12.0.0 ed.). pp. 868–870. ISBN 978-1-936213-22-1.
18. ^ "Appendix G-1. EBCDIC control character definitions". Character Data Representation Architecture. IBM Corporation. Archived from the original on 2018-09-11.
19. ^ GOST (1993). "Информационная технология. Наборы 8-битных кодированных символов. Двоичный код обработки информации" [Information technology. 8-bit coded character sets. Binary code for information processing] (in Russian). GOST 19768-93.
20. IBM. "Character Data Representation Architecture (CDRA)". IBM. p. 327. The mnemonic for the Start of Significance control character in EBCDIC has been modified to include a dot (.) at the end (SOS.). This has been done to distinguish it from the SOS mnemonic used in ISO-8 for the Start of String control character. The dot does not alter the property of the control in any way.
21. "iso8859.txt". Kermit project / Columbia University.
22. Raymond, Eric S. (1997). "The New Hacker's Dictionary". p. 310.
23. "EBCDIC". Jargon File. Archived from the original on 2018-05-13. Retrieved 2018-05-13.
24. 4.3BSD-Reno/share/games/fortune/fortunes
25. "Court of Appeal of Brussels - 2019/AR/1006 - GDPRhub".
26. Eden, Terence (2021-10-25). "EBCDIC is incompatible with GDPR – Terence Eden's Blog".

External links

• IBM-related:
  • Character Data Representation Architecture (CDRA) from IBM at the Wayback Machine (archived 2018-05-13). Contains IBM's official information on code pages and character sets.
    • Code page 37 at the Wayback Machine (archived 2015-06-19)
    • Code page 1047 at the Wayback Machine (archived 2015-06-07)
  • 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)
  • "Code Pages". IBM. from "IBM i globalization". IBM.
• XHCS V2.0 manual, shows code charts for several single-byte Siemens/Fujitsu (as opposed to IBM) EBCDIC pages used on the BS2000.
• EBCDIC character list, including decimal and hex values, symbolic name, and character/function at the Wayback Machine (archived 2016-03-03)
• EBCDIC-code pages with Latin-1-charset (JavaScript) at the Wayback Machine (archived 2018-04-18)
• All EBCDIC code pages and 3270 graphics escape codes at the Wayback Machine (archived August 27, 2016)
• ICU Character Set Mapping Tables Contains computer readable Unicode mapping tables for EBCDIC and many other character sets

v t e Character encodings
Early telecommunications	Telegraph code Needle Morse Non-Latin Wabun/Kana Chinese Cyrillic Baudot and Murray Fieldata ASCII ISO/IEC 646 BCDIC Teletex and Videotex/Teletext T.51/ISO/IEC 6937 ITU T.61 ITU T.101 World System Teletext background sets Transcode
ISO/IEC 8859	Approved parts -1 (Western Europe) -2 (Central Europe) -3 (Maltese/Esperanto) -4 (North Europe) -5 (Cyrillic) -6 (Arabic) -7 (Greek) -8 (Hebrew) -9 (Turkish) -10 (Nordic) -11 (Thai) -13 (Baltic) -14 (Celtic) -15 (New Western Europe) -16 (Romanian) Abandoned parts -12 (Devanagari) Proposed but not approved KOI-8 Cyrillic Sámi Adaptations Welsh Barents Cyrillic Estonian Ukrainian Cyrillic
Bibliographic use	MARC-8 ANSEL CCCII/EACC ISO 5426 5426-2 5427 5428 6438 6862
National standards	ArmSCII Big5 BraSCII CNS 11643 DIN 66003 ELOT 927 GOST 10859 GB 2312 GB 12345 GB 12052 GB 18030 HKSCS ISCII JIS X 0201 JIS X 0208 JIS X 0212 JIS X 0213 KOI-7 KPS 9566 KS X 1001 KS X 1002 LST 1564 LST 1590-4 PASCII Shift JIS SI 960 TIS-620 TSCII VISCII VSCII YUSCII
ISO/IEC 2022	ISO/IEC 8859 ISO/IEC 10367 Extended Unix Code / EUC
Mac OS Code pages ("scripts")	Armenian Arabic Barents Cyrillic Celtic Central European Croatian Cyrillic Devanagari Farsi (Persian) Font X (Kermit) Gaelic Georgian Greek Gujarati Gurmukhi Hebrew Iceland Inuit Keyboard Latin (Kermit) Maltese/Esperanto Ogham Roman Romanian Sámi Turkish Turkic Cyrillic Ukrainian VT100
DOS code pages	437 668 708 720 737 770 773 775 776 777 778 850 851 852 853 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 897 899 903 904 932 936 942 949 950 951 1040 1042 1043 1046 1098 1115 1116 1117 1118 1127 3846 ABICOMP CS Indic CSX Indic CSX+ Indic CWI-2 Iran System Kamenický Mazovia MIK
IBM AIX code pages	895 896 912 915 921 922 1006 1008 1009 1010 1012 1013 1014 1015 1016 1017 1018 1019 1046 1124 1133
Windows code pages	CER-GS 932 936 (GBK) 950 1169 Extended Latin-8 1250 1251 1252 1253 1254 1255 1256 1257 1258 1270 Cyrillic + Finnish Cyrillic + French Cyrillic + German Polytonic Greek
EBCDIC code pages	Japanese language in EBCDIC DKOI
DEC terminals (VTx)	Multinational (MCS) National Replacement (NRCS) French Canadian Swiss Spanish United Kingdom Dutch Finnish French Norwegian and Danish Swedish Norwegian and Danish (alternative) 8-bit Greek 8-bit Turkish SI 960 Hebrew Special Graphics Technical (TCS)
Platform specific	1052 1053 1054 1055 1056 1057 1058 Acorn RISC OS Amstrad CPC Apple II ATASCII Atari ST BICS Casio calculators CDC Compucolor 8001 Compucolor II CP/M+ DEC RADIX 50 DEC MCS/NRCS DG International Galaksija GEM GSM 03.38 HP Roman HP FOCAL HP RPL SQUOZE LICS LMBCS MSX NEC APC NeXT PETSCII PostScript Standard PostScript Latin 1 SAM Coupé Sega SC-3000 Sharp calculators Sharp MZ Sinclair QL Teletext TI calculators TRS-80 Ventura International WISCII XCCS ZX80 ZX81 ZX Spectrum
Unicode / ISO/IEC 10646	UTF-1 UTF-7 UTF-8 UTF-16 UTF-32 UTF-EBCDIC GB 18030 DIN 91379 BOCU-1 CESU-8 SCSU TACE16 Comparison of Unicode encodings
TeX typesetting system	Cork LY1 OML OMS OT1
Miscellaneous code pages	ABICOMP ASMO 449 Digital encoding of APL symbols ISO-IR-68 ARIB STD-B24 Fieldata HZ IEC-P27-1 INIS 7-bit 8-bit ISO-IR-169 ISO 2033 KOI KOI8-R KOI8-RU KOI8-U Mojikyō SEASCII Stanford/ITS Symbol TRON Unified Hangul Code
Control character	Morse prosigns C0 and C1 control codes ISO/IEC 6429 JIS X 0211 Unicode control, format and separator characters Whitespace characters
Related topics	CCSID Character encodings in HTML Charset detection Han unification Hardware code page MICR code Mojibake Variable-length encoding
Character sets

• IBM mainframe operating systems
• EBCDIC code pages