>
>> Don't use pin RA4 without a protection diode, it is open-drain(it's
>> also inverted).
>
>Bob:
>
>Inverted?  How so?
>
>-Andy

I guess it must not be. I recall reading that RA4 is inverted when used as
an output(I even seem to recall double-checking a Microchip data sheet to
make sure), but now that you questioned it, I tried and tried to find the
reference, but couldn't. Even looking in the more-complete RA4 block diagram
in the 16c84 data sheet doesn't show anything really different(other than
the lack of the P-channel FET and driver) from the other pins. Sorry to make
an incorrect posting, but thanks for the correction. I'd always used RA4 as
an input, so never proved it.

Now if only IBM had kept all the input pins on the printer ports the same
polarity, I'd be walking on Cloud 9. Wake me up when the ride is over!

Cheers, Bob