Date   : Wed, 30 May 2007 07:31:33 +0100
From   : dl.harper@... (David Harper)
Subject: PC/Beeb serial cable woe

David Hunt wrote:

> My cable is the same as Dom's, I used 4 individually screened core cable 
> and
> I get a reliable 19,200 baud over 5m. It works on all my PCs including a
> 1989 vintage 386, I just set the port for CTS/RTS hardware flow control.

I have found that a 4-core cable will often work in practice. But there must 
somewhere be a common 0V line. So if the cable is working, and there is no 
dedicated 0V line, then the system has to be relying on something else. This 
must be either the screening (which must be connected at both ends), or else 
the common earth (via the mains plug).

Although these may work in the right circumstances, it seems less chancy to 
connect the 0V pins together to make a proper signal ground.

David Harper