Interesting problem. It's been a long time. I gave away my
model 15 Teletype and typing reperferator around 1975.
It isn't clear from your post what you are trying to do. If
the "box" is a ham radio, then the usual method of driving
the radio is program that generates the RTTY signals via
the sound card, i.e. the standard is a two-tone audio
shift. The modulated audio then goes to the mic input to
the radio and the radio transmits using SSB. There is no
need for a UART running at 45 baud.
This might be useful--
http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=17558
Before sound cards and processors that were fast enough and
had the MMI instructions, the method was to connect the
computer to a box called the TNC via the serial port. The
UART usually ran at 1200 baud. The TNC then translated the
data speed and code and modulation/demodulation to the
radio. Again there was no need for the PC UART to run at
45 baud.
If the PC is going to directly drive a radio with 45 baud
baseband (i.e. only the carrier is frequency shifted; no
audio modulation), there is more involved than just the
baud rate. The program that translates the typing into
level 5 codes has to handle thing such as LTR/FIG
(letters/figure) shift insertion, as well as collapsing the
8-bit input codes to the limited code set.. IIRC some of
the 5 level machines had an option to unshift at the end of
the line so a bogus figure shift didn't continue beyond the
current line (this was used when plain text was the
predominat data). I don't remember what it was for the
amateur standard. Push-to-talk also has to be implemented.
I suspect that the programs that are out there will be
MSDOS, since the days of driving a teletype machine
directly with the 5 level 45 baud days were well before
Linux (and Windows). The model 33 Teletype (w the paper
tape reader/punch) was 8 level ASCII codes and were the
standard input/output for the PDP8 and PDP11 machines and
the old, slow 5 level machines were only used for ham
radio, (which used audio modulation and hence the eventual
migration to using the sound card, for which there are mnay
programs available).
Don, W4DH
On Monday 23 February 2009 10:47:03 am Ron Youvan wrote:
> Hi all:
>
> I have a need for a way to send my typing and files to
> and display data from a box from my computer's serial
> port in the TTY format of 5 bit Baudot code at 45 or 50
> baud, which a UART can handle with no problem, but the
> minicom terminal program fail to go slower than 300 baud
> and "terminal", "TTY, RTTY" or "TTY emulator" all Google
> as X windows terminal emulators and such.
> There has to be a simple way to do this, in the X system
> or a console with Slackware. There should be simple a way
> to pipe a LINUX terminal or a simple program that can
> save a capture file through to the serial port and have
> the serial port put out the "TTY" data. Any help will be
> appreciated.
>
> The speed and code are NOT alterable, the box is a HAM
> radio and that is THE mode and THE speed that is sent and
> received.
>
> If all else fails I have a "portable" DOS computer
> (6.2) that I could use, but after being out of M$ since
> 1997 I have no idea how it would be done with that
> either.
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