With a 16F877, I would like to use the USART to receive asynchronous
    data but use the TX pin as a general purpose I/O. ....

    Disabling the entire USART when I want to use the TX as an output is
    not an option because receive data can arrive at any time.  A software
    USART is also not an option.

Well, if you want an output, and you're driving something like an LED
for "user" interaction, you can probably get away with actually
transmitting characters when you want the LED to light (or be off.)
Shucks, you can even get cheap PWM brightness control.  :-)

I was going to suggest leaving the trasnmitter "idle" to output a 1,
and sending a BREAK condition to output a 0, but it doesn't look to me
like the PIC USART has the ability to generate BREAK on its own...

BillW

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