ASR33 Teletype interfacing

From: James M. Walker <>
Date: Thu Oct 9 09:07:51 2003

as for the "Line or Local" issue, you stated that the local side worked
fine. As in when
you type on the keys it prints what you type.

A rather simple test is to take a "fresh" 9 volt battery, find the two "RX
lines and connect
them to the battery, with the TTY in line mode the basket should quiet, if
it does, then
connect the keyboard leads between one side of the battery and the "RX" line
and try
typing again. If that works then your interface is lacking in the ability to
provide the
20/60 MA required by the TTY.


----- Original Message -----
From: "David Gesswein" <>
To: <>
Sent: Monday, October 06, 2003 9:51 PM
Subject: Re: ASR33 Teletype interfacing

> From: Ian Primus <>
> >One problem is that I don't know
> >what the Teletype is _supposed_ to do. I have never seen one
> >operational
> >
> Did you see my teletype page? It has movies of an operating teletype
> Not too different than operation
> in local mode.
> >I have been attempting to get my ASR33 teletype connected to something
> >and communicating, but so far I have not been successful. I have built
> >the interface here :
> >
> >
> It looks pretty marginal, a lot of serial ports aren't going to have the
> drive. I made a converter with optoisolators & rs-232 chips etc
> which is a lot more complex than needed and also was a little strange
since I
> made it before I got that degree. If nobody has pointed you to a better
> I can scan my schematic, >15 years ago radio shack had the parts.
> David Gesswein
> -- Run an old computer with blinkenlights
> Have any PDP-8 stuff you're willing to part with?
Received on Thu Oct 09 2003 - 09:07:51 BST

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