function GetPortAddress(PortNo: integer): word; assembler; stdcall;
asm
 push es
 push ebx
 mov ebx, PortNo
 shl ebx,1
 mov ax,40h // Dos segment adress
 mov es,ax
 mov ax,ES:[ebx+6] // get port adress in 16Bit way :)
 pop ebx
 pop es
end;