>I have to implement RTS/CTS handshaking so I began studying the
>specifics and it turns out the RTS and CTS are both IO.  So I began
>thinking . How can I implement both input and output using a single
>PIC pin?  Can it be as simple as using diodes ? I doubt it although
>I'm sure diodes come into play.

CTS are RTS are _not_ bidirectional signals. Looking from PC side,
RTS is output and CTS is input.

>PIC IO pin ------------- MAX CMOS TX     MAX RS232 TX ----- TO PC RTS
>                    |____MAX CMOS RX     MAX RS232 RX ___|
>
>If I place a diode on the TX allowing current to flow only from PIC to PC
>and on the RX allowing current to flow from PC to PIC, will that work ?

Basically, you can use a single pin for input and output, if you only
need to check input from time to time, and can get away with not driving
the output all the time (in your case, you probably can't). what you
then do is something lke

IO pin ------------------- MAX CMOS TX     MAX RS232 TX ----- TO PC CTS
                |_<RRRR>___MAX CMOS RX     MAX RS232 RX _____ TO PC RTS

the value of <RRRR> should probably be couple of kOhms. However,
whenever
you turn your PIC pin aroud to read the input, CTS and RTS will be
effectively connected together, probably breaking your flow control
scheme unless the PC side software is written to expect it.

Cheers,