SASHA@THINK.COM (Sarah Ferguson) (04/17/87)
Does anyone out there know how to convert a standard modem+terminal setup for use as a TTY/TTD machine (phone for the deaf)? I am told it can be done, but no one I know seems to know how. Thanks in advance - Sarah Ferguson Sasha@Think.com
dennisg@fritz.UUCP (04/22/87)
In article <KPETERSEN.12295905003.BABYL@SIMTEL20.ARPA> SASHA@THINK.COM (Sarah Ferguson) writes: >Does anyone out there know how to convert a standard modem+terminal >setup for use as a TTY/TTD machine (phone for the deaf)? > >I am told it can be done, but no one I know seems to know how. A TTD uses BAUDOT coding, and a strange bit rate. Since BAUDOT has a small number of bits per character, half of the characters must be accessed via an escape mechanism ("letters" and "figures" shift). This means that the problem is a bit more difficult than a pair of UARTs with an EPROM in between. You will need some latches and comparators. And you want it bidirectional, so we need two EPROMs. This is getting messy. Sounds like the optimum outboard solution is a single-board micro, with two serial ports and some minimal software. Do you really want to convert an existing terminal? The simplest other way to do this would involve a cheap computer, say a Radio Shack Color Computer, bunning a BAUDOT terminal emulator. If you can't find such a thing in amateur radio periodicals, it would be easy to write. If you want a TTD for the use of a deaf associate, go to the phone company! They have been collecting money for years. The line on my bill reads something like "communications equipment for the deaf". This should make such a device cheap or free to a qualified user.
ciaraldi@rochester.ARPA (Mike Ciaraldi) (04/28/87)
In article <4262@fritz.UUCP> dennisg@fritz.UUCP (Dennis Griesser) writes: >In article <KPETERSEN.12295905003.BABYL@SIMTEL20.ARPA> SASHA@THINK.COM >(Sarah Ferguson) writes: >>Does anyone out there know how to convert a standard modem+terminal >>setup for use as a TTY/TTD machine (phone for the deaf)? >> >>I am told it can be done, but no one I know seems to know how. > >A TTD uses BAUDOT coding, and a strange bit rate. >The simplest other way to do this would involve a cheap computer, say a Radio >Shack Color Computer, bunning a BAUDOT terminal emulator. If you can't find >such a thing in amateur radio periodicals, it would be easy to write. In addition, the modems used by the deaf are not Bell 103 or 212 compatible. As I understand it, when "Deafnet" began in the 1950's, not many people were telecommunicating, and equipment was very expensive, so compatibility with industry standards was not very important. Because WW2-surplus Teletypes (TM) were available fairly cheaply, and they used Baudot, the deaf standardized on Baudot. Someone designed a simple modem that worked at the low baud rate required (45, I think) and was cheap to build. So that's what they used. Nowadays, the mass market has driven down the price of ASCII terminals and 103 and 212 modems, but has not affected TDD quite as much. Still, I have seen people from NTID (National Technical Institute for the Deaf, part of Rochester Institute of Technology) with CRT terminals that are switchable ASCII/Baudot and have switchable modems. I think these go for about $600. For more info, try the newsgroup misc.handicap, or the local or national chapter of ACM SIGCAPH (Association for Computing Machinery, Special Interest Group on Computers and the Physically Handicapped). Good luck. Mike Ciaraldi ARPA: ciaraldi@cs.rochester.edu uucp: seismo!rochester!ciaraldi
wtm@bunker.UUCP (Bill McGarry) (04/29/87)
In article <KPETERSEN.12295905003.BABYL@SIMTEL20.ARPA> SASHA@THINK.COM (Sarah Ferguson) writes: >Does anyone out there know how to convert a standard modem+terminal >setup for use as a TTY/TTD machine (phone for the deaf)? > >I am told it can be done, but no one I know seems to know how. I am posting three separate articles on TDD's. These three articles are from the Handicapped Educational Exchange (HEX) bulletin board, which was the first TDD and Ascii compatible bulletin board. The phone number of HEX is: 301-593-7033 (300 baud only) Dick Barth is the sysop of HEX and is the answer man when it comes to TDD's. These articles will explain a bit about TDD's, the modems available and how to interface a computer and a TDD. If you have any questions, please contact me or Dick Barth (MIT-MC.ARPA!BARTH). There is also information about TDD's posted in the Handicap News net news group ("misc.handicap") and for you non-news people, the same articles go out in the Handicap Digest mailing list. I'm the moderator of both, so contact me for more information or to join the mailing list. Hope this helps! Bill McGarry Bunker Ramo, Shelton, CT (203) 337-1518 PATH: {philabs, decvax, fortune, yale}!bunker!wtm
ddodell@gryphon.CTS.COM (Dave Dodell) (05/02/87)
I have a program called TANDY.100 which uses a Model 100 to emulate a TDD.
If anybody wishes it, I be glad to send it via netmail to their node.
David
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