>Thank for the answer.
>
>What I meant by "growing" is that the file pass from 900K to 2.2 Mg. Maybe it is a wrong word for saying that the file is larger than before and for no reason we know. You said that windows bundle VxD together so it answers my question. Thanks.
>
>Another question:
>
>Is it possible for a programmer to call function in those VxD file. If yes How? (just for curiosity)

Yes - you do it it every time you access hardware; for example, reading or writing a file passes through the VxD to get from the OS to the underlying piece of hardware. There are also publsihed mechanisms for accessing functions in a VxD through things like the DeviceIOControl API call, or using things in the DDK. In general, it's not trivial to do directly in VFP.