INT 14h,  00h (00)       Initialize Serial Port Parameters
INT 14h,  01h (1)        Send One Character
INT 14h,  02h (2)        Receive One Character
INT 14h,  03h (3)        Get Serial Port Status
INT 14h,  04h (4)        Advanced Initialization                       Some
INT 14h,  04h (4)        Advanced Port Control                         Some