[GreenKeys] speed conversion (was Smith Corona...)

[gil smith]

Hi Henry:

>I have thought about this problem ; I have a Model 28 geared at 100 WPM, but
>I want a paper tape punch and reader, and they might be geared at
>60 WPM, and it might be a pain to find 100 WPM gears. But I think the right
>way to do this is to convert everything to a standard rs232 speed, say 19.2,
>and the make converters that plug into that for 60 and 100 WPM.

Well, that is what I have now, 19.2 ascii rs-232 to x-wpm baudot current
loop.  But putting two of them back-to-back for different baudot speeds is
a lot of hardware for something that could be much simpler (the TTY232
board provides loop power etc).  Not that there's anything wrong with that.
 And each would power its respective loop.  Hmm.

I was kinda thinking of a simple bridging device that could connect between
two externally-powered tty current loops running at different speeds (maybe
even different currents).  More like my TTY232-TAP gizmo, each loop would
connect through a diode bridge (so loop polarity can be ignored), and
opto-isolators.  The pic in the middle would handle the speed conversions.
Could probably steal power from one loop to power the pic, and only need
one set of opto-isolators.  Dunno if it is worth the effort.

>You could have the thing speak software flow control as well.

The easy xon/xoff flow control aspect is lost without a pc and its big 232
buffers.  For an embedded pic, the simplest thing is to buffer the 232 rx
chars using internal ram (eg: I often use 80-bytes of internal pic ram,
which can work with or without xon/xoff control).  Or, an external ram chip
of some sort can be employed for buffering -- which may be worth looking
into.  Hmm.

gil


;-----------------------------------------------------------
;  vaux electronics, inc.             480-354-5556   
;  http://www.vauxelectronics.com     (fax: 480-354-5558)
;-----------------------------------------------------------