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From: dik@cwi.nl (Dik T. Winter)
Newsgroups: comp.dcom.telecom
Subject: Re: The 'Public Telegraph Office'
Message-ID: 
Date: 24 Sep 89 23:44:45 GMT
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X-TELECOM-Digest: volume 9, issue 405, message 4 of 5

> [Moderator's Note: Well I believe it was the 'shift - 7' now that you mention
> it; and of course control-G is Ascii 7.

No, it was shift-J.

>                                         Weren't the 'number-shift' keys
> essentially like control keys? How did they get line feed, carriage return,
> ENQ (who are you?) and answerback without control codes?

I have here CCITT #2 which says that LF and CR are valid both shifted and
unshifted and ENQ=shift-D.

This gives me some remembrances.  The first computer I did use had Telex
typewriters as consoles.  However, they where very advanced.  They had
a four row keyboard and would remember whether the last shift was figures
or letters.  So when you entered a symbol not in the current shift the
apparatus whould not generate it unless you entered the correct shift
first.  (Yes, it was made by Siemens.)  Here follows the CCITT #2 code table:
	Letters				Figures
	0	8	16	24	0	8	16	24
0	space	LF	E	A	space	LF	3	-
1	T	L	Z	W	5	)	+	2
2	CR	R	D	J	CR	4	ENQ	BEL
3	O	G	B	figures	9	undef	?	figures
4	nil	I	S	U	nil	8	'	7
5	H	P	Y	Q	undef	0	6	1
6	N	C	F	K	,	:	undef	(
7	M	V	X	letters	.	=	/	letters
A question is: where in this whole lot of bits figures the sprocket hole;
i.e. is it 1.2.4.o.8.16 or 16.8.4.o.2.1?  Next to me lies a lot of 5-level
paper taper, but I cannot yet figure it.

This is CCITT #2 or Baudot.  There is another 5-level code: CCITT #1
which has also another name.  I must have the code somewhere, but am
not inclined to dig it up unless requested.

There appears also to be some different Telex codes in the US.  If I
remember right, a 3 out of 7 code or somesuch and a 8 level code (but
not ASCII).  I have the codings somewhere (in the same place as CCITT #1)
but do not know under what circomstances they were used.  Any help is
appreciated.


dik t. winter, cwi, amsterdam, nederland
dik@cwi.nl