> Hi All,
> I have seen somewhere a circuit for how to connect standard
> 5v output ports to RS232 serial port of a PC using a couple
> of diodes... but  can't find it again.
>
> Anyone point me in the right direction please?

http://www.xs4all.nl/~/wouter/pic/wisp
http://www.xs4all.nl/~/wouter/pic/wloader

Note: such circuits are non-inverting, so they can NOT be used with for
instance the f877 hardware uart!

(I'm sure there are plenty other such circuits)
Wouter