This chapter describes the purpose and function of Windows-based device drivers. You should create a Windows-based device driver for your device if it is not 100 percent compatible with the devices supported by the Windows retail device drivers, or if you want to offer Windows users access to unique features of your device.
A Windows-based device driver is a dynamic-link library (DLL) that Windows uses to interact with a hardware device such as a display or a 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, communication ports, mouse, and network. Printer, pen, and modem drivers are required if the user adds these optional devices to the system.