VWatchD: Illustrates the Basic Structure of a VxD

VWatchD, the virtual watch device, demonstrates the basic structure of a VxD. TEST.EXE is an MS-DOS(R) application that calls the VWatchD V86 API entry.

To install VWatchD, copy the file VWATCHD.386 to your Microsoft(R) Windows(TM) SYSTEM directory. Add the line DEVICE=VWATCHD.386 to the [386Enh] section of your SYSTEM.INI file, and restart Windows. Start an MS-DOS Virtual Machine (VM), and run TEST.EXE in that VM. Start another MS-DOS VM and run TEST in it. TEST.EXE will ask the VWatchD device when the VM was created and report that number in milliseconds.

You should set up a debug terminal to see the debugging output produced by VWatchD. Run the debugging version of WIN386.EXE, which is located in the VxD TOOLS directory. Read the "VxD Tools" abstract or "The VxD-Lite Mini-DDK" technical article for information on switching between debug and retail versions of WIN386.

VWatchD uses the following virtual machine manager (VMM) services:

_Allocate_Device_CB_Area

Get_System_Time

Fatal_Memory_Error

This sample code requires special VxD tools and include files; see the "VxD Tools" and "VxD Include Files" abstracts to copy these files to your development system. For more information on using the Microsoft Windows version 3.1 Device Driver Kit (DDK) files included on this CD, read the technical article "The VxD-Lite Mini-DDK." For more information on virtual device programming, see the DDK "Virtual Device Adaptation Guide."

VWatchD was built and tested under Microsoft Windows version 3.1.

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