VDialog: A VxD that Demonstrates How to Serialize I/O to a Device

VDialog is a virtual device (VxD) that demonstrates how to serialize I/O to a device in Microsoft(R) Windows(TM) enhanced mode. Install this VxD as described below and try running the accompanying sample programs, WINACC and DOSACC. These two programs simply try to perform an IN instruction to a predetermined but undefined port. VDialog protects multiple virtual machines (VMs) from accessing (either reading from or writing to) the port and displays a dialog box to resolve the contention.

1.Add a DEVICE=VDIALOG.386 line to the [386Enh] section of your SYSTEM.INI file.

2.Restart Windows.

3.Open an MS-DOS(R) box.

4.Execute DOSACC.EXE in the MS-DOS box.

5.Switch back to Windows without destroying the MS-DOS box (that is, do not "exit").

6.Execute WINACC.EXE, and choose Read! from its menu bar.

7.Admire the contention dialog box that has appeared.

If the contention dialog box does not appear, you've probably done something wrong. Make sure that you've added the DEVICE=VDIALOG.386 line to SYSTEM.INI and that the file VDIALOG.386 is in the Windows SYSTEM subdirectory.

VDialog uses the following services:

Install_IO_Handler

Shell_Resolve_Contention

Enable_Local_Trapping

Disable_Local_Trapping

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."

VDialog was built and tested under Microsoft Windows version 3.1.

{ewc navigate.dll, ewbutton, /Bcodeview /T"Click to open or copy files in the vdialog project." /C"samples}

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