Hi all, I want to link the port P9 to a LCD with a 80C509. I have already linked a keyboard to the port P4 and I manage to declare a bit with this instruction: sbit P4_0 = P4^0; but when I try the same thing whit P9, the compiler says to me: P9 : invalid base adress I think it's because P9 is not bit adressable but I'm not sure. So I try to read the value of P9 with this instruction: unsigned char val = P9; but the compiler says: error C247: non-adress/-constant initializer It seems that P9 is a constant, I can read its value but I can't change it. Is someone who know how to do to change the value of P9? Thanks. ps: Sorry for my bad english, I'm a french student ;-).