Device Drivers

A Windows device driver is a DLL that Windows uses to interact with a hardware device, such as a display or keyboard. Rather than access devices directly, Windows loads device drivers and calls functions in the drivers to carry out actions on the device. Each device driver exports a set of functions; Windows calls these functions to complete an action, such as drawing a circle or translating a keyboard scan code. The driver functions also contain the device-specific code needed to carry out actions on the device.

Windows requires device drivers for the display, keyboard, and communication ports. Other drivers may also be required if the user adds optional devices to the system.

The DDK provides independent hardware and software vendors (IHVs and ISVs) with the resources to build device drivers and VxDs that are compatible with the Windows 95/98. The resources include a configurable development environment, documentation, tools, and header files and libraries for several device types. The DDK contains the following components:

• Header files and libraries for building device drivers and VxDs.
• Sample source code for device drivers and VxDs.
• 16- and 32-bit versions of the driver development tools.