I just saw a post that stated when a PIC pin is in output mode it's an open drain? Is this true of all the 8-bit series? I think the post was about the 16f or 18f specifically, but I was wondering about the 12f? I can't seem to find it now.
It's usually RA4 - which of course doesn't apply to 12F series.
The datasheet will tell you if there is one, on any PIC.
BTW - you can get exactly the same (as far as 5V levels go) on any PIC I/O pin, by setting the pin LOW and switching TRIS to input and output - my I2C routines work like that, as do most.
For PIC12F629 and 675 (and possibly others) GP3 (pin4) is input only. In all my projects, I use this pin for inputs such as a switch. It needs an external resistor to achieve "pin change."