Mauro, Chuck wrote:

> BTW: The true EIA spec's for RS232 define a voltage swing even larger
> than 112V (I forget how large, but it's either 115V or 125V), but PC
> supplies don't generate anything over 12V (when did they ever?), and the
> larger delta V just isn't necessary.

The first RS232 was +/- 25V as I recall, I think that the later A & B
versions switched to +/- 15V, the current RS232C (current?) uses
+/-12V.

I once had the fun of playing with a newspaper photo processor that
used a DB25 female plug the had the same (or very similar) interface
as today's PC parallel port. But the voltage swing was +/- 25V and it
was designed in the late 40's. Weird!

--
Neil Cherry     http://home.att.net/~ncherry    ncherry@worldnet.att.net