Thank to all for their inputs.
I understand that a free running timer at full speed can be use as a random generator.
Perhaps I can use a 89C52 and use timer2 as Dennis suggest.

Hans I appreciatte your post and of course, they are Pseudo random, but the code I post is not a Pseudo random generator. It only generates 16 differents outputs number.
If you want I can mail you the excel sheet that show you this.

Thanks to all.
Daniel