lorien@dartvax.UUCP (Lorien Y. Pratt) (05/01/84)
My grandfather has a friend who owns a teletype for the deaf. TTD, I
guess, is the acronym. He is considering purchasing a computer
terminal or small home micro so that he can speak with her. Does
anyone know of the compatibility situation between RS-232 and whatever
protocol the TTD uses? Is the TTD a computer or a terminal, or what?
What is the minimum configuration, in terms of phone equipment and
hardware, that is necessary to speak with one?
Please mail to me and I'll post a summary.
--Lorien Y. Pratt
Dartmouth College Library
Hanover, NH 03755
decvax!dartvax!lorienfair@dual.UUCP (Erik E. Fair) (05/03/84)
To the best of my knowledge, TTD devices use Baudot code, which is a 5 bit
(as opposed to 7/8 bit ASCII) code, and it uses an old modem standard
called (I think) Whitehead, which has some interesting characteristics.
Among other things, there is no carrier unless the modem is transmitting
data. It does predate Bell 103.
Most of my information on the subject comes from a Uni-Ops talk given
by Dave Fylstra, formerly of SRI, who was at the time working on a
project called DeafNet, which will eventually look like USENET, in
the sense that there will be regional nodes which communicate with each
other w/ high speed (1200) modems, and have dialins for the local members
which are whitehead modems.
Unfortunately, I don't have a current address for Dave Fylstra, nor do
I know anything more about DeafNet...
Erik E. Fair ucbvax!fair fair@ucb-arpa.ARPA
dual!fair@Berkeley.ARPA
{ihnp4,ucbvax,cbosgd,decwrl,amd70,fortune,zehntel}!dual!fair
Dual Systems Corporation, Berkeley, California