ASR33 Teletype interfacing

From: Ian Primus <>
Date: Sun Oct 19 15:49:56 2003

On Sunday, October 19, 2003, at 03:11 PM, Eric Smith wrote:

> Tony wrote:
>> To avod further confusion, ASR33s are ASCII machines (the Model 32 is
>> the
>> baudot equivalent). You don't need any code conversion for the ASR33.
> You need at least a little bit of code conversion if you're using a
> model
> 33 with the standard type element with equipment that uses modern
> character
> sets, as the model 33 uses the 1963 ASCII standard (ANSI X3.4-1963)
> rather
> than the later versions of X3.4 or the current ANSI INCITS 4-1986.
> For instance, the modern caret (ASCII 0x5e, Unicode 0x005e) and
> underscore
> (ASCII 0x5f, Unicode 0x005f) characters are not available on the model
> 33.
> And the model 33's up arrow and back arrow characters, 0x5e and 0x5f,
> should
> be translated to Unicode 0x2191 and 0x2190, respectively. I don't
> recall
> whether the model 33 escape key sends the X3.4-1963 escape code, 0x7e,
> or the modern escape code, 0x1b. In modern ASCII and most
> ASCII-derived
> character sets, 0x7e is the tilde character.

I'm not really sure what kind of type element my model 33 has. One
thing I did notice, however, is that the zero and the letter O are both
'switched'. Normally, on a modern system, the zero will have a line
through it, and the letter O will not. On this teletype, it is the
other way around. The keyboard and the type element both are like this,
and it is the only teletype I have seen that has them reversed. The
other model 33's I have seen pictures of on the 'net have normal zero
and O keys.

Ian Primus
Received on Sun Oct 19 2003 - 15:49:56 BST

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