I described it as not being tied to a positive voltage until the µ-controller writes a 1 (a positive voltage) to that pin
I guess that a reference to chapter 3 of "the bible"
http://www.semiconductors.philips.com/acrobat/v...WARE_1.pdf where ports are described in some detail may clear up the confusion.

Anyhow, we still need the exact derivative, since some of the newer ones have different port designs.

Erik