jmp start

org 0023H
acall serial
reti

org 0050H
start:
mov TMOD,#20H
mov TCON,#40H
mov TH1,#0F7H 
mov PCON,#80H
mov SCON,#50H
mov IE,#90H
printstop: bit 0
clr printstop
sir1: db "Window$"   <b>string i want to write</b>
sir2: db "Window1$"

main:
jb printstop,exit
setb printstop
mov dptr,#sir1
mov R1,#00H
acall print
exit:
jmp loop1

print:
mov A,R1
movc A,@A+dptr
cjne A,#"$",print_ok
clr printstop
jmp printexit
print_ok:
inc R1
mov SBUF,A
loop:
jnb SCON.1,loop
printexit:
ret

serial:
jb SCON.1,output
jmp serialexit
output:
clr SCON.1
acall print
serialexit:
ret

loop1:
jmp loop1
end