21 Feb
2013
21 Feb
'13
2:49 p.m.
On 02/21/2013 11:01 AM, Ethan Dicks wrote:
I know some guys who do WWII historical re-enactment
as a Signal Corps
(and by a strange coincidence, I was the point of commonality to
someone whose father was in the unit they portray. They were all
happy to meet each other). One of the guys has an old 5-bit TTY they
now use in the field for passing messages during events. It was "fun"
getting it to work as a peripheral with modern hardware (to store then
send "messages from HQ"). ISTR the relay in the TTY won't fire under
about 80VDC.
I believe those were 60ma current loop. Back in the day, it wasn't
uncommon for amateur computer hobbyists to use one of the 5-level TTYs
as a printer. The driver software had to be aware of which half of the
character set was being printed ("letters" versus "figures") or you
got
gibberish. I seem to remember that it was also common practice for RTTY
operators to send something like "LTRS LTRS LTRS" when beginning a
message to make certain that the receiving end was in the correct mode.
--Chuck