Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!yale!bunker!wtm
From: rbarth@tumtum.cs.umd.edu (Richard Rbarth)
Newsgroups: misc.handicap
Subject: Re: tty
Message-ID: <10118@bunker.UUCP>
Date: 13 Feb 90 05:04:10 GMT
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Reply-To: rbarth@tumtum.cs.umd.edu (Richard Rbarth)
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Index Number: 6709

In Digest #1086


   Hi,
   how can I make my computer talk to a tty machine....then I only have to
   deal with one box!
   >>>>==Frank==*>>>

The first thing you have to do is recognize that your TDD talks using the
Baudot code, rather that the ASCII code used by a computer. Also, the TDD
uses a modem that is different from those used by computers. 

If you use a Tandy Color Computer, an IBM-PC (not a clone) or a PCjr,
you can get free software from the HEX BBS by John Spalding that will
do the code conversion and also emulate a TDD modem, so that no modem
is necessary. If you have another computer you will need to build or
buy a modem. There are several available from Phone-TTY Inc, Krown and
Ultratech. You can also build one from scratch using such readily
available chips as the XR2206 and X211 from EXAR inc. Or you can
modify an old Bell-103 compatible (which is FSK, like the TDD modem)
to use TDD tones.

If you buy a commercial modem, the software either comes with it (in
the case of the CM-4) or is built into the modem (in the case of the
other two). If you build your own you will have to provide your own
code conversion and comms software. Which is not difficult to do; I've
written such software in three languages for three different chips and
I'll be glad to provide you with an outline of what's necessary. 

-----------------------------
Richard Barth, W3HWN,  rbarth@tumtum.cs.umd.edu
Handicapped Educational Exchange... (301) 593-7033 (TDD & 300 baud ASCII)
                                    (301) 593-7357 (300/1200 baud, 8N1)