Denis B said:
i want to write to xdata register with keypad and see the address and data on lcd.....


You need to consider this one step at a time:

1. how to interface a keypad;
2. how to write stuff to an LCD.

Then you just need to bring them together to achieve your complete goal.

Both of them have been thoroughly discussed before, and there is plenty of material on the web.

For the LCD, you coudl start with:
http://www.8052.com/tutlcd.phtml
http://www.8052.com/tutlcd2.phtml
and see: http://www.8052.com/forum/read.phtml?id=139205

how i can to write "scanf" function for LCD ????


You can't!
scanf is an input function; an LCD is an output device!

You will have to read the Manuals for your particular compiler to find out how to configure the standard 'C' input functions (scanf, etc) to receive input from custom devices (such as a keypad), and the standard 'C' output functions (printf, etc) to send output to custom devices (such as an LCD)

For Keil, it's here: http://www.keil.com/support/m...source.htm
other compilers will vary!