Generic: Illustrates the Basic Structure of a VxD

Revised: February 1993

Generic illustrates the basic structure of a virtual
device (VxD). This VxD can be used as a base set of source
files for starting a VxD project. Generic can be loaded,
but it performs no function.


To build Generic:

You will need Microsoft(R) Macro Assembler version 6.0 or
higher, as well as some special tools and include files;
see the "VxD Tools" and "VxD Include Files" abstracts to
copy these files to your development system. Configure
your development environment as described in the "VxD-Lite
Mini-DDK" technical article on the Microsoft Developer
Network CD.

If you have the Windows(TM) version 3.1 Device Driver Kit
(DDK), you can build its version of Generic using the DDK-
supplied MASM5.EXE (a special version of Macro Assembler
version 5.10). Note that the DDK samples require a
specific structure for the source and include
subdirectories, whereas the corresponding samples in the
"VxD-Lite Mini-DDK" utilize the INCLUDE environment
variable to give you more flexibility in structuring your
development files.


To execute Generic:

1.  Run GENERIC.EXE from the MS-DOS(R) prompt before
starting Windows. When enhanced-mode Windows starts up,
the VxD will load automatically. Thus, you do not need to
modify the SYSTEM.INI file to load this VxD. Generic will
automatically load each time you start Windows until you
reboot your computer; once rebooted, the stub loader is
cleared from memory and the VxD will not load.

If you prefer to have Windows load the VxD without first
executing it from the MS-DOS prompt, rename GENERIC.EXE to
GENERIC.386 and move it to the Windows SYSTEM
subdirectory. Add the line DEVICE=GENERIC.386 to the
[386Enh] section of the SYSTEM.INI file.

2.  Run Windows in enhanced mode. The code responsible for
self-loading the VxD is in the VXDSTUB.ASM file and is
linked into the final VxD file by the STUB 'VXDSTUB.EXE'
module definition (.DEF) file statement. When executed
from the MS-DOS prompt, the VxDStub hooks Interrupt 2Fh,
terminates, and stays resident. When Microsoft Windows
initializes itself, the TSR responds to the Interrupt 2Fh,
AX=1605h broadcast and returns a structure that causes the
VxD to be loaded. This technique is discussed in the "TSR
Support in Microsoft Windows Version 3.1" technical
article on the Microsoft Developer Network CD.

Generic was built and tested under Microsoft Windows
version 3.1 using Microsoft MASM versions 6.0 and 6.1 and
the tools and include files provided in the "VxD-Lite Mini-
DDK."

KEYWORDS: PR-CD1; CD3 (revised)

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