I know that when you use external RAM the 16 bit address is put out on ports 0 and 2 so even if you only address 256 bytes of external RAM, P2 will still have the upper part of the address put on it during the memory access. I've read that because of this, you normally should not use P2 for anything else unless a complex multiplexing scheme is used.

All I want to do with P2 is read a DIP switch once, when the system is started up. I figure that if I use moderate pullups (about 1k or so) to 5 volts for the switches that are ON and drive the P2 outputs all low momentarily just to read the DIP switches (where no external memory access is needed) then I should be ok right? I figure that the subsequent external RAM reads (which won't use any high addressing bits used by the DIP switch) won't be affected...