Nothing to worry about.. You will need: the controller, an EPROM and a latch (eg. 74HCT573). It is usually black, has 20 pins and costs around $1. When the controller fetches from external memory, it first outputs the low byte of the address on P0, and uses its ALE pin to make the latch hold this value. Then P0 switches to input, and PSEN will turn the EPROM outputs on. So P0 is used for address as well as data transport.
You will probably want to use external program memory, because the internal program memory of your chip (infineon?) is not programmable. You can tell, because the model number starts with 80. (87 is one-time programmable or EPROM with a window, 89 usually means flash).
Using external program memory gobbles up ports P0 and P2. That's why most people on this board are using controllers with flash program memory inside. It is easily reprogrammable, and it keeps P0 and P2 free for more useful things.