8051 simple program

Hello,
i am beginer with asembler and i need help with my program. I am trying to write program to print arithmetic average of numbers in external memory, last number is 0FFH, numbers are positive and negative 8 bit. Could you help me or send some link for this problem? I have read many tutorials but i could not solve this problem.
Thank you very much
Marek

What have you got so far... There is a wealth of examples using movx.. Movx is the command to access external memory..

Write a small program trying to do what you want, then I'll help you!