> Another question: could this work? A pic is used as a serial switch for
> 9600 baud. It recieves a command to allow a serial transmission to pass
> through it, or to stop the transmission. Would the delay from the bit
> twiddling (transferring inputs to an outputs and visa versa) mess up the
> serial transmission?

I do this in my WISP programmer. The PC talks to the programmer via the
serial port. In normal mode the programmer (a 16f84) interprests the
communication, and it manipulates the RB6 ad RB7 pins of the connected PIC
(also a 16f84) to program it. A certain command puts the programmer is
pass-through mode, so the firware copies the serial lines to and from the
RB6 and RB7 of the programmed PIC. So I can program the target and
communicate with it, without leaving my PC. The speed of the pass-through
is mainly limited by the check for a break condition, which takes the
programmer out of the pass-through mode. The trick is that with propper
choice of the pins a simple shift of the port buffer can copy both
directions, so without the check for a break you can copy takes 3
instructions (1 for the shift, 2 for the goto), or 3 * 4 * 0.1uS ~ 1uS with
a 10 MHz xtal, which will be sufficient up to ~ 100kbaud.

Wouter