OUT              Output to Port                      Flags: not altered

OUT port,accumulator

Logic:    (port)   accumulator

OUT transfers a byte or a word from AL or AX to the specified port.
The port may be specified with an immediate byte constant (allowing
access to ports 0 through 255) or with a word value in DX (allowing
access to ports 0 through 65,535).

                                                                          
Operands                  Clocks   Transfers  Bytes   Example
                        byte(word)
immed8, accumulator       10(14)       1        2     OUT 254,AX
DX, accumulator           8(12)        1        1     OUT DX,AL
                                                                          

Note:          It is advised that hardware not use I/O ports F8h
through FFh, since these are reserved for
controlling the math coprocessor and future
processor extensions.

See also: IN

OUT Output to Port