Communicating Between Windows Virtual Machines with DDE

The information in this article applies to:

• Microsoft Windows Software Development Kit (SDK) for Windows versions 3.0 adn 3.1

Windows 286 supported DDE (dynamic data exchange) for MS-DOS (non-Windows) applications; however, Windows/386 and Windows versions 3.x do not include this functionality. There are no plans to add this functionality in future versions of Windows.

The following are methods descrive several different ways for an MS-DOS- based application to communicate with a Windows-based application:

1. The Clipboard. MS-DOS-based applications can read from or write to the Clipboard. The methods for doing this are documented in the Windows SDK (Software Development Kit). Microsoft Word incorporates this capability. This is the preferred method of communication.

2. A shared file. To improve performance, SMARTDRV or a RAM disk can be used. SHARE.EXE should be loaded before starting Windows to allow for proper file sharing and locking

3. MS-DOS TSR (terminate-and-stay-resident) program. Another method that can be used is to start an MS-DOS TSR program with a buffer at a fixed location that can be read/written to by different applications. For this method to work, the memory region used must be below the load point of Windows 3.x, otherwise the different virtual machines will have their own private copies of the address space.