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

Do you really expect your controller to stop doing what it is doing, just because you put a label end: in your code?
Check in the hex file where your label "end:" has gone to... Also check the instruction set for a "stop" or "end" instruction. Let me know what you found..

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

That's what you kept saying about your DPTR...
You kept on saying that 03EB was in DPTR...
If your code works, then why does it not produce the desired result?

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)!!

This means that upto "mov p1,A" your program is correct..

But it transmits nothing to my PC!!

Wait a moment, I need to polish my crystal ball...

Why should it transmit anything to your PC? We have not yet seen anything in your code that could send something to a PC... I've also checked your posts. You have never never mentioned sending anything whatsoever to a PC, and now you ask us to find the errors?

(No, I haven't found the problem yet, still polishing my crystal ball...)...

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).

If you think the problem is in your board, I suggest you either fix the problem or look further until you are sure that the board is or is not the problem.
Thinking that the board is the problem will not solve it. You will have to do more than thinking to solve your problem...

Regards
Patrick