If your problem is of limited pins, you need to expand the number of ports your device can access using an IC like the 8255. Using the 8255, u can replace one 8-bit port + 4 pins on the 8051 with three 8-bit ports (using multiplexing)

the generally used layout is:
prt 0 + port 1 -> external ROM
port2 + port 3.4,5,6,7 -> 8255
interrupt pins(3.1,3.2 etc) are kept free for interrupt signals

I would advise you to give any interrupt signal directly to the 8051 interrupt lines tho', since u'll have to continuously poll the 8255 pins, which is a very crappy way to handle interrupts when u have hardware support for it

However in ur case u would probably need a lot more I/O lines and u'll have to "cascade" 8255s. If you want to save pins, use internal flash memory to store your program, so ports 0 and 1 are freed. Using Flash I have managed to interface a hd4470 LCD, an 8-bit DAC and a 4-button keypad directly to 8051 with 7 pins to spare!!

I am not in touch with the latest developments in the chip industry, but there may be better alternatives than the 8255... :D

kundi