> The pins that DO NOT have clamps are very very very clearly specified in
> the data sheet. Example: MCLR has only one clamp. 10 big red ponits for
> good documentation to Microchip (I did NOT say that it was well structured
> though).

The open-collector output pins (e.g. RA4 on 16C84) are not clamped to VDD,
and can safely take a voltage above VDD; one of the Microchip guys quoted
14 volts.  Unfortunately, Microchip has not in most/any of their data sheets
mentioned this feature.  Without a documented ability to go above VDD that
pin would be more useful with a clamp diode; with that ability, however, it
can be used for controlling higher voltages than would be possible without.