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From: kent@decwrl.DEC.COM (Christopher A. Kent)
Newsgroups: comp.dcom.modems
Subject: Re: modem interface to TDD (deaf communications), how?
Message-ID: <7415@decwrl.DEC.COM>
Date: Thu, 8-Jan-87 13:28:23 EST
Article-I.D.: decwrl.7415
Posted: Thu Jan  8 13:28:23 1987
Date-Received: Thu, 8-Jan-87 22:46:17 EST
References: <763@sdcc12.ucsd.EDU>
Reply-To: kent@decwrl.UUCP (Christopher A. Kent)
Distribution: na
Organization: DEC Western Research Laboratory
Lines: 17
Keywords: TDD deaf

Fortunately or unfortunately, TDDs have been around a long time. Longer than
ASCII, in fact. Thus, they don't speak ASCII. They use a 5 or 6 bit code
called Baudot (it's been too long since I thought about this to recall 
the details). So while the modems might be compatible, the "terminals"
aren't. 

At one time, I played with the design of a box that would translate. It's
really quite straightforward to do; a look-up table and a small finite
state machine (implemented in a micro, of course) connected to two UARTs.
There might even be a market to do this commercially, though most TDDs have
a fairly limited display (typically one line of 30-50 characters) so they
aren't much good for general purpose terminals.

chris
-- 
Chris Kent	Western Research Laboratory	Digital Equipment Corporation
kent@decwrl.dec.com	decwrl!kent			(415) 853-6639