Anti-crosstalk for Network I/O

This example is using a PIC16F628 - a real favorite of mine recently.   Among its other features is a full function hardware UART.  This circuit was part of a servo motor controller circuit using a 74LS07 in the design.  One (left over) section of this chip is used to provide the open collector output drive.   Input in normally routed thru the 10k resistor to the RX input.  In order to provide anti-crosstalk (keeping the the output data from comming back into the input), a small pnp transistor keeps the input line from going low durring the low levels of the output line.  Beats the heck out of doing it in software!