TELEX machine, modems

From: Gooijen H <GOOI_at_oce.nl>
Date: Fri Feb 21 08:01:00 2003

Hi George.

Most likely this is a 45.45 Baud tty, often used by HAM radio amateurs.
Nowadays most amateurs have turned to PC solutions for RTTY reception.
We call that teletype a "carrot crusher" over here in Holland.
The 5-bit code is called Baudot, and allows for uppercase characters,
numbers and some punctuation.

When you say "wait a minute, how is that possible with 32 combinations?"
Simple, 2 characters are reserved to shift the whole mechanism from
"LETTER" to "DIGIT", so depending on the previous reception of such a
special character the characters that follow are readable or garbage.

Radio amateurs include something called UOS (Unshift on Space). When
the "LETTER" character is not properly received, the first space char
makes everything "normal" again.

So, to connect a 5-bit teletype to (any) computer you need a conversion
program to convert ASCII to Baudot, and at the correct transmission speed.

73

- Henk, PE1CKF Ham Radio amateur and PDP-11 addict.


> -----Original Message-----
> From: George R. Gonzalez [mailto:grg2_at_attbi.com]
> Sent: vrijdag 21 februari 2003 14:31
> To: cctalk_at_classiccmp.org
> Subject: TELEX machine, modems
>
>
> Hi, I have just bought a nice clean TELEX machine, it's a
> TTY-32, 5-level coding,
> with what looks like a phone line hookup, dial-type phone.
>
> I wonder if anybody knows what the modem standard is for
> this, and/or any
> phone number I could call to test this thingy out!
>
> Thanks,
>
> George
Received on Fri Feb 21 2003 - 08:01:00 GMT