what if i only need to use port 2 for memory interface. can i directly connect (without drivers) the pins to memory address pins and in that case can the port pins supply 5v?
The guaranteed Voh is NOT 5V, but a bit less

Quoting from the datasheet for the P89C66x:
Port 0 is an open-drain .... P0 ... also [access] external memory. In this case it uses strong pullups when emitting 1s. Port 2 is .... with internal pullups.

Again, everyting is ambigous if you do not specify what derivative you are talking about. The above statement refer to the P89C66x and many other derivatives, I can not say if it apply to the one you are using.

In other words: READ THE DATASHEET.

Erik