Meaning of IN in English
Input Byte or Word From Port
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.
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.
Code analysis English vocabulary. Английский словарь анализа кода. 2012