hi,
PORT0 might be open drain type and might need pullup resistors

If external memory access write cycle (via MOVX) is used then no pull-ups need because MCU hardware switches PORT0 output to strong pull-ups internally. When external memory access read cycle (via MOVX) is used then it is task of external hardware to produce strong 0/1 signals. (74245 does it without problems).

Only if original poster uses software-emulated read/write processes then yes, port0 must have external pull-ups.


Regards,
Oleg