From: "Peter O. Brackett"
Subject: Re: telex interface
Date: Thu, 28 Nov 2002 19:12:20 -0500
Organization: MindSpring Enterprises
X-Server-Date: 29 Nov 2002 00:12:16 GMT
X-Newsreader: Microsoft Outlook Express 5.00.2919.6600
The Bell System ran the TWX network, using voice frequency carrier telegraph
systems, in the US only Western Union
ran the DC 20mA loop Telex network.
Indialantic By-the-Sea, FL
"Spehro Pefhany" wrote in message
> On Thu, 28 Nov 2002 13:26:42 -0500, the renowned "Peter O. Brackett"
> >Wow is the Telex network still in operation?
> >In the USA it used to be Western Union that ran that network, who runs
> >in the USA today?
> >The line protocol... it's a simple DC 20 mA current loop driven by
> >DC battery [-48VDC] on-off keyed [OOK], runs asynchronous protocol, i.e.
> >character at a time, 45 baud, International Alphabet #2(ITU/CCITT 5 bit
> >code). But you gotta know your WRU code, heh, heh... All of this is
> >documented in "old" CCITT documents, probably Yellow Book or Blue Book
> Neat, so I was in the right ballpark. I can still remember 'chatting'
> with a supplier in Japan, one character at a time
> HOW R U?
> Normally you (for some reason most companies had operators doing this,
> it was considered too specialized for normal folks(!)) cut a paper
> tape with the entire message and then ran the tape. If you made
> mistakes you could null them out by punching a character that
> consisted of all holes in the tape. You could then, if it was
> worth it, run the tape through the reader and made a copy without
> the money-wasting null characters. A typical Telex message might have
> cost $5 or $10 to send to Asia. Now we can all receive graphic
> pornographic spams from Asia for free- we've come a long way, in
> I thought Western Union in the US ran the TWX network, which was
> distinct from Telex, but you could send messages between the two
> Best regards,
> Spehro Pefhany
> "it's the network..." "The Journey is the reward"
> firstname.lastname@example.org Info for manufacturers:
> Embedded software/hardware/analog Info for designers: