ORG 000H
        JMP     MAIN
ORG 023H
        JMP     SERIAL
ORG 030H
MAIN:
        MOV     SCON,#50H
        MOV     TMOD,#20H
        MOV     TH1,#-24
        SETB    TR1
        SETB    EA
        SETB    ES
        MOV R1,#01
        MOV DPTR,#0000H
        MOV SBUF,DPH
        JMP$

SERIAL:
        CLR     TI
        DJNZ R1,SKIP
        MOV R1,#02 ; here you can see that the value of R1 is 2 here so first it will send the MSBYTE and than LSBYTE
        MOV SBUF,DPL
        INC DPTR
        RETI
        JMP$
SKIP:
        MOV     SBUF,DPH
RETI
END