Dear Sam,

I pasted your code into my development board, corrected it as below and the Hyperterminal was filled with HELLO WORLD :

.org 0x0000

;mov TMOD, #20H ;T1 is mode2
;mov TH1, #-96 ; 300 baud
;mov SCON, #50H ;8b, 1stop, 1start, REN enabled
;setb TR1 ;start timer T1

MOV PCON, #80H
MOV TMOD, #22H
MOV TH1, #256-13 ; for 4800Baud
MOV TL1, #256-13
SETB TCON.6
MOV SCON, #052H

( rest of your code remained as it is )


I just replaced your initialization code with a standard one that I normally use. The chip was a 89c51RD2 (6clk mode ) and the crystal was 6MHZ and the baud was 4800.

Please try and revert.

Raghu