EBCDIC

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Extended Binary Coded Decimal Interchange Code (EBCDIC) is an 8-bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems.

EBCDIC 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.[1]

It is also employed on various non-IBM platforms such as Fujitsu-Siemens' BS2000/OSD, OS-IV, MSP, MSP-EX, HP MPE/iX, and Unisys VS/9 and MCP.

History[edit]

EBCDIC /ˈɛbsɨdɪk/ 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 8-bit character encoding, in contrast to, and developed separately from, the 7-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 6 bits.

While IBM was a chief proponent of the ASCII standardization committee,[2] they 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.[3] The System/360 became wildly successful, and together with clones such as RCA Spectra 70, ICL System 4, and Fujitsu FACOM, thus so did EBCDIC.

All IBM mainframe and midrange peripherals and operating systems use EBCDIC as their inherent encoding,[4] but AIX running on the RS/6000 and its descendants including the IBM Power Systems, Linux running on the zSeries, and operating systems running on the IBM PC and its descendants use ASCII. Software and many hardware peripherals can translate to and from encodings, and modern mainframes (such as IBM zSeries) include processor instructions, at the hardware level, to accelerate translation between character sets.

EBCDIC has no technical advantage compared to some ASCII-based character encodings, such as the ISO-8859 series, except for the inclusion of the "¢" (cent) character; however, the ASCII-based Unicode does include the cent character. While EBCDIC, like ASCII, has one bit flagging upper or lower case, unlike ASCII the EBCDIC alphabet is non-contiguous, interleaved with unassigned characters which may or may not be in use. Data portability is hindered by a lack of many symbols commonly used in programming and in network communications, and by different, incompatible translations for EBCDIC characters not included in 7-bit ASCII. The collating sequence of upper case alphabetic characters is higher than lower case and numerics are higher still — the exact opposite of ASCII. As with single-byte extended ASCII codepages, EBCDIC codepages are language-dependent with no nomenclature or internal mechanism to denote non-"standard" usage.

Where true support for multilingual text is desired, a system supporting far more characters is needed. Generally this is done with some form of Unicode support. There is an EBCDIC Unicode Transformation Format called UTF-EBCDIC proposed by the Unicode consortium, but it is not intended to be used in open interchange environments and, even on EBCDIC-based systems, it is almost never used. IBM mainframes support UTF-16, but they do not support UTF-EBCDIC natively.

Arabic EBCDIC versions are typically in left-to-right presentation order as displayed by older mainframes and line printers rather than in the right-to-left logical order used by later encodings such as Unicode.

Codepage layout[edit]

The table below is based on CCSID 500, one of the code page variants of EBCDIC; it shows only the basic (English) EBCDIC characters. Characters 00–3F and FF are controls, 40 is space, 41 is no-break space (RSP: "Required Space"), E1 is numeric space (NSP: "Numeric Space"), and CA is soft hyphen. Characters are shown with their equivalent Unicode codes. Invariant alphanumeric, punctuation, and control characters common to all EBCDIC code pages are shown in bold. Unassigned codes are typically filled with international or region-specific characters in the various EBCDIC code page variants.

In each table cell below, the first row is an abbreviation for a control code or (for printable characters) the character itself; the second row is the Unicode code; and the third row is decimal value of the EBCDIC code.

EBCDIC
_0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _A _B _C _D _E _F
 
0_
 
NUL
0000
0
SOH
0001
1
STX
0002
2
ETX
0003
3
SEL

4
HT
0009
5
RNL

6
DEL
007F
7
GE

8
SPS

9
RPT

10
VT
000B
11
FF
000C
12
CR
000D
13
SO
000E
14
SI
000F
15
 
1_
 
DLE
0010
16
DC1
0011
17
DC2
0012
18
DC3
0013
19
RES ENP

20
NL
0085
21
BS
0008
22
POC

23
CAN
0018
24
EM
0019
25
UBS

26
CU1

27
IFS
001C
28
IGS
001D
29
IRS
001E
30
IUS ITB
001F
31
 
2_
 
DS

32
SOS

33
FS

34
WUS

35
BYP INP

36
LF
000A
37
ETB
0017
38
ESC
001B
39
SA

40
SFE

41
SM SW

42
CSP

43
MFA

44
ENQ
0005
45
ACK
0006
46
BEL
0007
47
 
3_
 


48


49
SYN
0016
50
IR

51
PP

52
TRN

53
NBS

54
EOT
0004
55
SBS

56
IT

57
RFF

58
CU3

59
DC4
0014
60
NAK
0015
61


62
SUB
001A
63
 
4_
 
SP
0020
64
RSP
00A0
65


66


67


68


69


70


71


72


73


74
.
002E
75
<
003C
76
(
0028
77
+
002B
78
|
007C
79
 
5_
 
&
0026
80


81


82


83


84


85


86


87


88


89
!
0021
90
$
0024
91
*
002A
92
)
0029
93
;
003B
94
¬
00AC
95
 
6_
 
-
002D
96
/
002F
97


98


99


100


101


102


103


104


105
¦
00A6
106
,
002C
107
%
0025
108
_
005F
109
>
003E
110
?
003F
111
 
7_
 


112


113


114


115


116


117


118


119


120
`
0060
121
:
003A
122
#
0023
123
@
0040
124
'
0027
125
=
003D
126
"
0022
127
 
8_
 


128
a
0061
129
b
0062
130
c
0063
131
d
0064
132
e
0065
133
f
0066
134
g
0067
135
h
0068
136
i
0069
137


138


139


140


141


142
±
00B1
143
 
9_
 


144
j
006A
145
k
006B
146
l
006C
147
m
006D
148
n
006E
149
o
006F
150
p
0070
151
q
0071
152
r
0072
153


154


155


156


157


158


159
 
A_
 


160
~
007E
161
s
0073
162
t
0074
163
u
0075
164
v
0076
165
w
0077
166
x
0078
167
y
0079
168
z
007A
169


170


171


172


173


174


175
 
B_
 
^
005E
176


177


178


179


180


181


182


183


184


185
[
005B
186
]
005D
187


188


189


190


191
 
C_
 
{
007B
192
A
0041
193
B
0042
194
C
0043
195
D
0044
196
E
0045
197
F
0046
198
G
0047
199
H
0048
200
I
0049
201
SHY
00AD
202


203


204


205


206


207
 
D_
 
}
007D
208
J
004A
209
K
004B
210
L
004C
211
M
004D
212
N
004E
213
O
004F
214
P
0050
215
Q
0051
216
R
0052
217


218


219


220


221


222


223
 
E_
 
\
005C
224
NSP
2007
225
S
0053
226
T
0054
227
U
0055
228
V
0056
229
W
0057
230
X
0058
231
Y
0059
232
Z
005A
233


234


235


236


237


238


239
 
F_
 
0
0030
240
1
0031
241
2
0032
242
3
0033
243
4
0034
244
5
0035
245
6
0036
246
7
0037
247
8
0038
248
9
0039
249


250


251


252


253


254
EO

255
_0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _A _B _C _D _E _F

Criticism and humor[edit]

Open-source-software advocate and hacker Eric S. Raymond writes in his Jargon File that EBCDIC was almost universally loathed by early hackers and programmers because of its multitude of different versions, none of which resembled the other versions, and that IBM produced it in direct competition with the already-established ASCII.

The Jargon File 4.4.7 gives the following definition:[5]

Another popular complaint is that the EBCDIC alphabetic characters follow a punched card encoding convention rather than a linear ordering like ASCII. One consequence of this is that incrementing the character code for "I" does not produce the code for "J", and likewise there is a gap between the codes for "R" and "S".

These incompatibilities were also the source of many jokes. One such joke 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 classic Infocom adventure game series Zork. In the "Machine Room" in Zork II, there is a collection of ancient computers and other machines of uncertain purpose. The following is the description of the room, with EBCDIC used to imply an incomprehensible language:

Furthermore, a similar description can be found in the "Maintenance Room" in Zork:

See also[edit]

References[edit]

External links[edit]