A.5.119 IN: Input from I/O Port
IN AL,imm8 ; E4 ib [8086]
IN AX,imm8 ; o16 E5 ib [8086]
IN EAX,imm8 ; o32 E5 ib [386]
IN AL,DX ; EC [8086]
IN AX,DX ; o16 ED [8086]
IN EAX,DX ; o32 ED [386]
IN reads a byte, word or doubleword from the specified I/O port, and
stores it in the given destination register. The port number may
be specified as an immediate value if it is between 0 and 255, and
otherwise must be stored in DX. See also OUT (section A.5.194).