You may connect a 2line x 16 char LCD display directly to the data bus making it accessible for writing (not reading) in the xdata address space. (No I/O port is needed in this setup) Use the following connection.

Display 89c51
1 20 Ground
2 40 + 5V
3 Trim-pot Contrast adjust
4 RS A0 (Address latch)
5 R/W tied to ground (only write)
6 E (Enable) Active HIGH decoded address with wr
7 .. 14 39..32 Data bus

E (pin 6 of the LCD) has to be high when WR is active in the selected address range.
Writig to even addresses in the decoded address space issues commands. Writing to odd addresses writes characters. Be shure to wait for at least 15ms after each command.