I can't write into serial

[jaaaelpumuki]

i everyone,

I'm trying to send data to arduino(serial) from assembler (8086 -windows).

I can read data but write doesn't work. I always receive 80H in AX, this is the code:

send proc
    MOV AH,00 ; init port 
    MOV AL,11101011b ; 9600, N,1 bit stop, 8 bit data
    MOV DX,00 ; com1
    INT 14H 
     MOV AH, 1 ; write function 
     MOV AL, 'S' ; char to send
     MOV DX, 00 ;  com1
     INT 14H
     RET
send endp

This is the code to read, which works perfectly

recibir proc
    push bx
    MOV AH,00 ;inicializar el puerto 
    MOV AL,11110011b ; velocidad 9600, N,un bit de stop, 8 bit de datos....
    MOV DX,00 ; puerto com1
    INT 14H
    
Esperar:  
  mov dx,0000
    mov ah,03h
  int 14h
  test ah,01h; si el bit 1(dato listo) esta puesto a cero no hay dato listo  
  jz Esperar ;salta y vuelve a verificar
  mov dx,0000
  mov ah,02h
  int 14h
  mov car, al
    pop bx
    ret
recibir endp

Regards