X86 INSTRUCTIONS:::OTHER INSTRUCTION:::I/O INSTRUCTIONS

The IN instruction almost always has the operands AX and DX (or EAX and EDX) associated with it. DX (src) frequently holds the port address to read, and AX (dest) receives the data from the port. In Protected Mode operating systems, the IN instruction is frequently locked, and normal users can't use it in their programs. Syntax 1 : in src, dest #GAS Syntax in dest, src #Intel syntax The OUT instruction is very similar to the IN instruction. OUT outputs data from a given register (src) to a given output port (dest). In protected mode, the OUT instruction is frequently locked so normal users can't use it. Syntax 2 : out src, dest #GAS Syntax out dest, src #Intel syntax