Int 14/AX=FF01h

AX = FF01h
CX = length of buffer (0000h to cancel buffer assignment)
DX = port (00h-03h)
ES:BX -> send buffer

Return:
Nothing

See Also: AH=18h - AH=83h"COURIERS" - AH=A5h"BAPI" - AH=FCh - Category: Serial I/O - Int 14h - I