ASR 33 Emulation - help!

From: Derek Peschel <dpeschel_at_eskimo.com>
Date: Fri Oct 19 00:05:46 2001

On Thu, Oct 18, 2001 at 07:35:04PM +0100, Tony Duell wrote:
> > The ASR-33 uses ASCII over a serial line, so you don't have to deal with
> > strange character sets. (Older Teletypes use the 5-bit Murray code.)
>
> True. The exact chracters printed depends on the type cylinder fitted, of
> course (Sometimes the square brackets are replaced by back-arrow, and so
> on). I doubt this will be a big problem for you. Unless you have one of

No, the square brackets always look like square brackets. It's the
underscore that may be a left-pointing arrow. The circumflex may be an
upward-pointing arrow. In a _really_ old version of ASCII, escape (a.k.a
ALT MODE) was in a different place too (125 or 126 instead of 27). I think
that version was defined without lowercase, but Stanford University used
lowercase and never bothered to move escape, so they had to shuffle the
right brace and vertical bar. For good measure they even defined printed
characters "on top of" the control characters.

Aren't character sets fun? At least ASCII doesn't generally use shift
characters, like the Murray code or the FIODEC code I'm currently playing
with.

Thanks for the explanation of current loops. Could you call RS-232 a
current loop too, or is there something else that remains constant, or not?

Now that I think about it, I believe the US and UK phone systems are
incompatible for a similar reason.

-- Derek
Received on Fri Oct 19 2001 - 00:05:46 BST