IN
Usage: IN accum,port Modifies flags: None
A byte, word or dword is read from 'port' and placed in AL, AX or EAX respectively. If the port number is in the range of 0-255 it can be specified as an immediate, otherwise the port number must be specified in DX. 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. Valid port ranges on the PC are 0-1024, though values through 65535 may be specified and recognized by third party vendors and PS/2's. See also OUT.
Example:
in eax 220