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IN               Input Byte or Word                  Flags: not altered

IN accumulator,port

          Logic:    accumulator . (port)

    IN transfers a byte or a word from a port to AL or AX. The port may be
    specified by an immediate byte value (for ports 0 through 255) or by
    the DX register (allowing access to all ports).

  --------------------------------------------------------------------------
   Operands                  Clocks   Transfers  Bytes   Example
                           byte(word)
   accumulator, immed8       10(14)       1        2     IN AL,45h
   accumulator, DX           8(12)        1        1     IN AX,DX
  --------------------------------------------------------------------------

       Notes:         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.