Please a little help. I have a uVision Demo. I am trying to display a message using the printf function. I wrote my aplication then made a copy of the putchar.c file that comes with the application. I put such a a copy in my project folder and a modified it. I just wrote this: void Dispcharac (unsigned char u); then I added to my project finally, I defined this subroutine in my main source to go to write data on the display. this is my subroutine: void Dispcharac (unsigned char u) { writedata(u,1); } writedata(u,1) subroutine writes the data in the port. I wonder what's wrong? Is there anyone on Earth that can help me? Thanks for any help Omar