Bill.Higgins@p17.f122.n249.z1.fidonet.org (Bill Higgins) (10/03/90)
Index Number: 10820
Hi Ross,
Allow me to quote the letter you mailed on 29-Sep-90
RC> Hi Jeff, Sorry it has taken me so long to reply. I didn't forget
RC> about you. You were looking for TDD-TO-MODEM software. It doesn't
RC> exist in a software-only solution. Mainly because everything about
RC> the Baudot protocol is different than your basic ASCII asynchronous
RC> modems. There are special modems, however, that are built to be
RC> dual-purpose, ie. both TDD and MODEM in one box that work with special
RC> software. Most notable of this is the one made by: Phone-TTY Inc. 202
RC> Lexington Avenue Hackensack, NJ 07601 USA It is called a CM-4
RC> Intelligent Modem and allows the user to use his computer to
RC> communicate to TDD's as well as regular BBS's and information
RC> services, like Compu$pend. Hope this helps. kyl, Ross
RC>
RC>
I think that the now obsolete Hayes 300 bauder had that ability as well to
act as a TDD system with a certain command. Write to or call Hayes and see
if I'm right, I suspect I might be close with this one.
Thought I'd put my two cents worth in.
TTFN!!!
--
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Internet: Bill.Higgins@p17.f122.n249.z1.fidonet.orgmbeck@rice-chex.ai.mit.edu (Mark Becker) (10/04/90)
Index Number: 10870 In article <14653@bunker.UUCP> Bill.Higgins@p17.f122.n249.z1.fidonet.org says: >Index Number: 10820 > > I think that the now obsolete Hayes 300 bauder had that ability as well to > act as a TDD system with a certain command. Write to or call Hayes and see > if I'm right, I suspect I might be close with this one. > I knew there was a varient of some Novation modem that, with some special ROM's, could handle Baudot. I found out (the hard way) that a conventional ASCII modem will lock to a TDD signal.. and then (if the default parameter settings are used) disconnect when the caller let go of the keyboard. This nearly drove me bananas when developing my TDD BBS system.. TDD callers started whomping on their keyboards before the system discovered it was dealing with a Baudot caller. After wrestling with the problem for awhile, I gave up. The documentation was changed to tell TDD callers to wait about 10-15 seconds for the TDD banner to pop up. Regards, Mark mbeck@ai.mit.edu
rbarth@tumtum.cs.umd.edu (Dick Barth) (10/09/90)
Index Number: 10946 In Digest # 1543 mbeck@rice-chex.ai.mit.edu (Mark Becker) writes: > I think that the now obsolete Hayes 300 bauder had that ability as well to > act as a TDD system with a certain command. Write to or call Hayes and see > if I'm right, I suspect I might be close with this one. > I knew there was a varient of some Novation modem that, with some special ROM's, could handle Baudot. True. It was the Novation Applecat, and came with an in-ROM program called DEAFWARE. Another package was written by Bill Blue to use the hardware, and some users thought it an improvement over what came with the modem card. It was called "ASCII Express", if I remember correctly. I found out (the hard way) that a conventional ASCII modem will lock to a TDD signal.. and then (if the default parameter settings are used) disconnect when the caller let go of the keyboard. TDDs are half duplex. They talk and listen on the same tone pair, and so have to shut off their transmit tones when you stop keying. If your -103 modem is broad enough (and doesn't filter out the mid-band frequencies at 1400 and 1800 where TDDs operate) it will think a TDD is an ASCII carrier. Until you stop typing, the carrier drops, and the modem disconnects. Some Bell-103 type modems work the same way. They can't tell the difference between a 300 baud carrier and a 1200 or 2400 baud carrier. They'll tell the computer a carrier has called and the computer will collect a snootful of garbles before the caller hangs up. This nearly drove me bananas when developing my TDD BBS system.. TDD callers started whomping on their keyboards before the system discovered it was dealing with a Baudot caller. Funsies. After wrestling with the problem for awhile, I gave up. The documentation was changed to tell TDD callers to wait about 10-15 seconds for the TDD banner to pop up. I haven't found a better solution either. ------