Hi Srikanth,

Try this code

BYTE EQU 040H ;it is up to you
ORG 00000H
JMP START
ORG 00023H
JMP SERIAL
ORG 00040H
;setting is your responsibility
START: MOV IE,#090H
MOV TMOD,#020H
MOV SCON,#050H
MOV IE,#090H
MOV TH1,#0FDH
MOV TCON,#040H
SETB TI ;at first time
LOOP: JMP LOOP ;endless loop
RET
;
SERIAL: JBC TI,TRN
JBC RI,RCV
RETI
;
TRN: MOV SBUF,#041H ;send character A
RETI
;
RCV: MOV BYTE,SBUF ;receive byte
RETI
END

By,

George