Linux-Hams archive - June 1999: Re[2]: 75 baud, Baudot, 1.5 Stop Bits

Re[2]: 75 baud, Baudot, 1.5 Stop Bits

Bill Kasper (zlnig.fnkvsks@mail.dy.fi)
Wed, 02 Jun 1999 10:15 -0500


Hi Riley, et al

You're right! My (Trademark) TTY ASR33 was a current-loop
ASCII machine -- upper case only with the tape reader and punch.

As I recall the output ic on the computer serial board was an
open-collector unit that I had to lift one leg from the board
and insert a current limiting resistor. It worked fine for over
a year until the dot-matrix was invented by Fred and Barney!

Tnx for the bandwidth, all,
Bill WB2SXY

______________________________ Reply Separator _________________________________
Subject: Re: 75 baud, Baudot, 1.5 Stop Bits
Author: pqmzaibv@hrbi.hr (Riley Williams) at internet
Date: 6/2/99 7:41 AM

Hi Bill.

>> How can I get a 75 Baud, Baudot, 1.5 stop Bits directly
>> on my serial port ? I would like to interface an old
>> teleprinter with my PC.

> YES and NO

> 75/1.5 should be no problem

None at all, as far as I can see.

> Current loop conversion will require a mod to the output circuit
> not too difficult I did this years ago with a serial port
> running an ASR-33. You should be able to find Current Loop
> circuits in older RTTY book.

That assumes that his teleprinter was current loop. Not all of them
were - I've used both current loop and RS232B (yes, B) voltage level
teleprinters in the past.

> Then you need a software mod for ZER0 (not Slashed) to Oh
> (slashed) printing!!

To be accurate, that would be part of the ASCII <=> Baudot code
conversion driver, and said driver will probably be the most difficult
part of the project.

Best wishes from Riley.

+----------------------------------------------------------------------+
| There is something frustrating about the quality and speed of Linux |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch. |
+----------------------------------------------------------------------+
* ftp://ftp.MemAlpha.cx/pub/rhw/Linux
* http://www.MemAlpha.cx/kernel.versions.html

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