[GreenKeys] A portable Baudot terminal

[epvgk at limpoc.com]

Depending on how you feel about hardware fiddling, you could use a small
embedded microcontroller and a tty-loop interface. 

http://heepy.net/mediawiki/index.php/Optocouplers_for_teletype_current_loop

I use this with this dev board: http://pjrc.com/store/teensy.html

You can have my code and board layout if you like.  It's sort of half-assed
but works fine as a simple terminal, and the computer doesn't have to know
bout 5 bit framing or weird speeds. 


eric


On Thu, Jan 24, 2013 at 04:29:55PM -0600, Jim Haynes wrote:
> Sometimes I've wished for a portable Baudot terminal to use in testing
> TTY gear.
> 
> I have an old Dell C610 laptop and those are dirt cheap on ebay, and
> have a COM port.  There are some old DOS programs that make a PC
> into a "glass TTY" and are still available.  One I have used is
> called rtty12g - you can google for it.
> 
> Now the trouble is that the laptop has Windows XP, and while rtty12g will
> run under Windows XP it doesn't do the right thing.  Specifically it
> doesn't set the UART to 5 bit characters; it sets the baud rate correctly
> but sends 8 bit characters.  I guess in DOS the program can poke the
> UART registers directly to get the desired properties.
> 
> So one solution would be if someone knows how to set the UART to 5 bits
> in Windows XP and later.
> 
> A rather grubby way I have working now is that I have a floppy drive on
> the laptop.  I formatted a floppy on a Win98 machine, then copied the
> rtty12g files to it, and boot from the floppy.  This works, but I wouldn't
> suggest to anybody to go through that process.
> 
> Another possibility is to create a partition on the hard drive in the
> laptop and install FreeDOS and rtty12g.  Right now I don't know enough
> about how to install just enough of FreeDOS and make it bootable along
> with the other stuff on the laptop (WinXP and Linux).  I'm assuming
> FreeDOS would let the program do what it wants to do to the hardware
> registers.
> 
> Jim W6JVE
> 
> jhhaynes at earthlink dot net
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