1.3 Creating Virtual Devices

You create a virtual device either by modifying a sample device or by writing a device from scratch. You can write virtual devices in assembly language, and you may be able to write some portions of your virtual device in a high-level language such as the C language.

To create a virtual device, you need to:

1.Read the chapter in this manual that describes the virtual device for your type of hardware device. For general information about virtual devices, read Chapter 3, “Virtual Device Basics.”

2.Write the required control procedures, virtual device services, and API functions.

3.Create a module-definition file that identifies the appropriate module name for your virtual device, and exports the required device description block.

4.Assemble and link your device.

5.Test your virtual device using the debugging version of 386 enhanced-mode Windows. For information about debugging virtual devices, see the appendix, “WDEB386 Virtual Device Commands.”

6.Create an installation file (OEMSETUP.INF) for your virtual device and related files. You install a virtual device by specifying a DEVICE setting in the [386ENH] section of the SYSTEM.INI file. The setting must specify the full path of the virtual device file. In general, virtual device files should be copied to the Windows SYSTEM directory.

7.Create your final distribution disk or disks.