setport1: mov ax,03f8h ;MDTA EQU 03F8h ; 8250 DATA REGISTER
          mov mdta,ax
          mov ax,03f9h ;IER  EQU 03F9h ; 8250 INTERRUPT ENABLE REGISTER
          mov ier,ax
          mov ax,03fch ;MCR  EQU 03FCh ; 8250 MODEM CONTROL REGISTER
          mov mcr,ax
          mov ax,03fdh ;LSR  EQU 03FDH ; 8250 LINE STATUS REGISTER
          mov lsr,ax
          mov ax,03feh ;MSR  EQU 03FEH ; 8250 MODEM STATUS REGISTER
          mov msr,ax
          mov  al,30H   ; IRQ4 (RS232_IO) VECTOR
          mov  INT_0C,al
          mov  al,10H
          mov  IMR_RS232,al
          mov  ax,0000h
          mov  portno,ax
          mov  al,'1'
          mov  portstr,al
          ret