CDC display code

Display code is the six-bit character code used by many computer systems manufactured by Control Data Corporation, notably the CDC 6000 series in 1964, the 7600 in 1967 and the following Cyber series in 1971. The CDC 6000 series and their successors had 60 bit words. As such, typical usage packed 10 characters per word. It is a six-bit extension of the four-bit BCD encoding, and was referred to as BCDIC (BCD interchange code.)

There were several variations of display code, notably the 63-character character set, and the 64-character character set. There were also 'CDC graphic' and 'ASCII graphic' variants of both the 63- and 64-character sets. The choice between 63- or 64-character character set, and between CDC or ASCII graphic was site-selectable. Generally, early CDC customers started out with the 63-character character set, and CDC graphic print trains on their line printers. As time-sharing became prevalent, almost all sites used the ASCII variant - so that line printer output would match interactive usage. Later CDC customers were also more likely to use the 64-character character set.

A later variation, called 6/12 display code, was used in the Kronos and NOS timesharing systems in order to support full ASCII capabilities. In 6/12 mode, an escape character (the circumflex, octal 76) would indicate that the following letter was lower case. Thus, upper case and other characters were 6 bits in length, and lower case characters were 12 bits in length.

The PLATO system used a further variant of 6/12 display code. Noting that lower case letters were most common in typical PLATO usage, the roles were reversed. Lower case letters were the norm, and the escape character preceded upper case letters.

The typical text file format used a zero-byte terminator to signify the end of each record. The zero-byte terminator was indicated by, at least, the final twelve bits of a 60-bit word being set to zero.[1] The terminator could actually be anywhere from 12- to 66-bits long - depending on the length of the record. This caused an ambiguity in the 64-character character set, when a colon character needed to be the final character in a record. In such cases a blank character was typically appended to the record after the trailing colon.

Display code characters (64-character character set version)

			ASCII	CDC
Binary	Decimal	Octal	Graphic	Graphic	Name
000 000	0	00	:	:	colon[2]
000 001	1	01	A	A
000 010	2	02	B	B
000 011	3	03	C	C
000 100	4	04	D	D
000 101	5	05	E	E
000 110	6	06	F	F
000 111	7	07	G	G
001 000	8	10	H	H
001 001	9	11	I	I
001 010	10	12	J	J
001 011	11	13	K	K
001 100	12	14	L	L
001 101	13	15	M	M
001 110	14	16	N	N
001 111	15	17	O	O
010 000	16	20	P	P
010 001	17	21	Q	Q
010 010	18	22	R	R
010 011	19	23	S	S
010 100	20	24	T	T
010 101	21	25	U	U
010 110	22	26	V	V
010 111	23	27	W	W
011 000	24	30	X	X
011 001	25	31	Y	Y
011 010	26	32	Z	Z
011 011	27	33	0	0
011 100	28	34	1	1
011 101	29	35	2	2
011 110	30	36	3	3
011 111	31	37	4	4

			ASCII	CDC
Binary	Decimal	Octal	Graphic	Graphic	Name
100 000	32	40	5	5
100 001	33	41	6	6
100 010	34	42	7	7
100 011	35	43	8	8
100 100	36	44	9	9
100 101	37	45	+	+
100 110	38	46	-	-
100 111	39	47	*	*
101 000	40	50	/	/
101 001	41	51	(	(
101 010	42	52	)	)
101 011	43	53	$	$
101 100	44	54	=	=
101 101	45	55			blank
101 110	46	56	,	,
101 111	47	57	.	.
110 000	48	60	#	≡	equiv
110 001	49	61	[	[
110 010	50	62	]	]
110 011	51	63	%	%	[3]
110 100	52	64	"	≠	not eq
110 101	53	65	_	→	concat[4]
110 110	54	66	!	∨	log OR
110 111	55	67	&	∧	log AND
111 000	56	70	'	↑	super
111 001	57	71	?	↓	sub[5]
111 010	58	72	<	<
111 011	59	73	>	>
111 100	60	74	@	≤
111 101	61	75	\	≥
111 110	62	76	^	¬	NOT
111 111	63	77	;	;

CDC often used the term byte to refer to 12-bit quantities, even though characters were only 6-bits long.
Display code 00 has no associated graphic in the 63-character set
Display code 63 (octal) is a : (colon) in the 63-character set
In CDC PASCAL, this is the left brace, {, character
In CDC PASCAL, this is the right brace, }, character

6/12 display code

The NOS 6/12 display code is one of the character sets used on CDC Cyber NOS computers to represent all ASCII characters.

ASCII			display code
Dec	Hex	Abbr	Dec	Oct	6/12
0	00	NUL	62 32	76 40	^5
1	01	SOH	62 33	76 41	^6
2	02	STX	62 34	76 42	^7
3	03	ETX	62 35	76 43	^8
4	04	EOT	62 36	76 44	^9
5	05	ENQ	62 37	76 45	^+
6	06	ACK	62 38	76 46	^-
7	07	BEL	62 39	76 47	^*
8	08	BS	62 40	76 50	^/
9	09	HT	62 41	76 51	^(
10	0A	LF	62 42	76 52	^)
11	0B	VT	62 43	76 53	^$
12	0C	FF	62 44	76 54	^=
13	0D	CR	62 45	76 55	^
14	0E	SO	62 46	76 56	^,
15	0F	SI	62 47	76 57	^.
16	10	DLE	62 48	76 60	^#
17	11	DC1	62 49	76 61	^[
18	12	DC2	62 50	76 62	^]
19	13	DC3	62 51	76 63	^%
20	14	DC4	62 52	76 64	^"
21	15	NAK	62 53	76 65	^_
22	16	SYN	62 54	76 66	^!
23	17	ETB	62 55	76 67	^&
24	18	CAN	62 56	76 70	^'
25	19	EM	62 57	76 71	^?
26	1A	SUB	62 58	76 72	^<
27	1B	ESC	62 59	76 73	^>
28	1C	FS	62 60	76 74	^@
29	1D	GS	62 61	76 75	^\
30	1E	RS	62 62	76 76	^^
31	1F	US	62 63	76 77	^;

ASCII			display code
Dec	Hex	Glyph	Dec	Oct	6/12
32	20		45	55
33	21	!	54	66	!
34	22	"	52	64	"
35	23	#	48	60	#
36	24	$	43	53	$
37	25	%	51	63	%
38	26	&	55	67	&
39	27	'	56	70	'
40	28	(	41	51	(
41	29	)	42	52	)
42	2A	*	39	47	*
43	2B	+	37	45	+
44	2C	,	46	56	,
45	2D	-	38	46	-
46	2E	.	47	57	.
47	2F	/	40	50	/
48	30	0	27	33	0
49	31	1	28	34	1
50	32	2	29	35	2
51	33	3	30	36	3
52	34	4	31	37	4
53	35	5	32	40	5
54	36	6	33	41	6
55	37	7	34	42	7
56	38	8	35	43	8
57	39	9	36	44	9
58	3A	:	60 4	74 04	@D
59	3B	;	63	77	;
60	3C	<	58	72	<
61	3D	=	44	54	=
62	3E	>	59	73	>
63	3F	?	57	71	?

ASCII			display code
Dec	Hex	Glyph	Dec	Oct	6/12
64	40	@	60 1	74 01	@A
65	41	A	1	01	A
66	42	B	2	02	B
67	43	C	3	03	C
68	44	D	4	04	D
69	45	E	5	05	E
70	46	F	6	06	F
71	47	G	7	07	G
72	48	H	8	10	H
73	49	I	9	11	I
74	4A	J	10	12	J
75	4B	K	11	13	K
76	4C	L	12	14	L
77	4D	M	13	15	M
78	4E	N	14	16	N
79	4F	O	15	17	O
80	50	P	16	20	P
81	51	Q	17	21	Q
82	52	R	18	22	R
83	53	S	19	23	S
84	54	T	20	24	T
85	55	U	21	25	U
86	56	V	22	26	V
87	57	W	23	27	W
88	58	X	24	30	X
89	59	Y	25	31	Y
90	5A	Z	26	32	Z
91	5B	[	49	61	[
92	5C	\	61	75	\
93	5D	]	50	62	]
94	5E	^	60 2	74 02	@B
95	5F	_	53	65	_

ASCII			display code
Dec	Hex	Glyph	Dec	Oct	6/12
96	60	'	60 7	74 07	@G
97	61	a	62 1	76 01	^A
98	62	b	62 2	76 02	^B
99	63	c	62 3	76 03	^C
100	64	d	62 4	76 04	^D
101	65	e	62 5	76 05	^E
102	66	f	62 6	76 06	^F
103	67	g	62 7	76 07	^G
104	68	h	62 8	76 10	^H
105	69	i	62 9	76 11	^I
106	6A	j	62 10	76 12	^J
107	6B	k	62 11	76 13	^K
108	6C	l	62 12	76 14	^L
109	6D	m	62 13	76 15	^M
110	6E	n	62 14	76 16	^N
111	6F	o	62 15	76 17	^O
112	70	p	62 16	76 20	^P
113	71	q	62 17	76 21	^Q
114	72	r	62 18	76 22	^R
115	73	s	62 19	76 23	^S
116	74	t	62 20	76 24	^T
117	75	u	62 21	76 25	^U
118	76	v	62 22	76 26	^V
119	77	w	62 23	76 27	^W
120	78	x	62 24	76 30	^X
121	79	y	62 25	76 31	^Y
122	7A	z	62 26	76 32	^Z
123	7B	{	62 27	76 33	^0
124	7C	\|	62 28	76 34	^1
125	7D	}	62 29	76 35	^2
126	7E	~	62 30	76 36	^3
127	7F	DEL	62 31	76 37	^4

External links

Charsets for CDC machines

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[1] CDC often used the term byte to refer to 12-bit quantities, even though characters were only 6-bits long.

[2] Display code 00 has no associated graphic in the 63-character set

[3] Display code 63 (octal) is a : (colon) in the 63-character set

[4] In CDC PASCAL, this is the left brace, {, character

[5] In CDC PASCAL, this is the right brace, }, character

Character encodings
Early telecommunications	Telegraph code Needle Morse Non-Latin Wabun/Kana Chinese Cyrillic Korean 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 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 1034 1040 1042 1043 1044 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	37 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 Adobe Standard Adobe Latin 1 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 Fieldata GEM GSM 03.38 HP Roman HP FOCAL HP RPL SQUOZE LICS LMBCS MSX NEC APC NeXT PETSCII SAM Coupé Sega SC-3000 Sharp calculators Sharp MZ Sinclair QL Symbol 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 Big5 Digital encoding of APL symbols ISO-IR-68 ARIB STD-B24 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 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

CDC display code

Display code characters (64-character character set version)

6/12 display code

Further reading

External links