I made a circuit, and hooked up all 8 data pins (P1.0 through P1.7) of an AT89C2051 to pins 7 through 14 of the LCD. Everything seems to be ok, except that in certain cases, wrong characters are being printed.

for example, when I wanted to see "Mini FM Receiver", I see " Mioi!GM!Seceiwe". (yes, there's a space in front).

so I checked the LCD datasheet, and I have come to the conclusion that the output of pin P1.0 is always high.

I first tried using 10K pull-up resistors across all pins, and then I removed the 10K resistors, and I got the same results.

I now tried to use a 10K pull-down resistor for P1.0 and I get the following text instead: "Lhnh FL Rdbdhvdr"

So this makes me think that P1.0 needs to have a special resistor to it to satisfy my LCD.

I could do the LCD in 4-bit mode, but this port (along with the rest of port 1) also drives a latch data input (chip: 74HC573) as well.

Maybe I am overlooking something with port P1.0.

can anyone help me?
thanks.