Hello Patrick

I use label End because my prgram have some small subroutines to init serial connection. I want to connect my board to PC.

I dont' think my code don't work (I simulate it serval times and get good results : It does what I think)

But when I write it to my real board (use 89C51) it doesn't work ??
At the first line, I always use
Mov a, #055h
mov p1, a

To see that my board work or not.
It still work untill there (p1=55h)!!
But it transmits nothing to my PC!!

So there is some errors in somewhere I havent found. Maybe in my code (I check it very carefully), or in my board (I think so).