"party line" for terminals?

[James Fogg]

> I purchased an odd terminal display (no keyboard) from ebay 
> recently and it arrived today.  Its manufactured by 
> Westinghouse Canada and has
> 3 ports that look like DB25 female style and 1 DB9 style 
> female port that says "party line".  I'll post more detail 
> later, but oddly enough this terminal monitor doesn't appear 
> to have a keyboard port, unless it connects to one of the 
> data ports on the back.
> 
> What is the "party line" port and what's it used for?  A 
> search of the cctalk archives didn't yield anything.


There are some terminal protocols that use a daisy-chained RS232. The
Burroughs/Unisys Poll Select protocol is one. It relies on the handshake
lines in standard RS232.