ATMEL's 89S8252 first program

Hello,
I am trying to send some volts to my databus and i meter them.
The program is following.

#include <reg51.h>
#define XBYTE ((unsigned char volatile xdata*) 0)


void main(void) {

while(1) {
XBYTE[0x8001] = 0xFF; // Arxikopoihsh toy 8255 se mode 0
}
}

I put the while for the data to remain as it loops forever.

So with this command i am sending to the 8001(A15,A0,A1=1) address the FF comand(DB0->DB7 = 1111 1111)

So these are the volts i want to have in my outs.

But i meter values like 0,62 volt, 2.10 volt, 4.10 volt and of;course not in the order i want them.

Could someone tell me if is something obvious why it is not working??

I am new so excuse me if i make a serious mistake

This site may help. There are example programs and datasheets.

This site has additional data sheets on the Atmel 89S8252.

gg